cement industry by adnanwaheed15

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									Contents
ACKNOWLEDGEMENT................................................................................................................... 11 Authors ......................................................................................................................................... 11 DEDICATED TO .......................................................................................................................... 12 Our ................................................................................................................................................. 12 Parents, .......................................................................................................................................... 12 Respected Teachers ....................................................................................................................... 12 & .................................................................................................................................................... 12 INTRODUCTION ............................................................................................................................. 14 INRODUCTION ............................................................................................................................... 15 Cement .......................................................................................................................................... 15 History ....................................................................................................................................... 15 Development of strong concretes ................................................................................................. 17 Types of modern cement .............................................................................................................. 19 Hydraulic Cements ................................................................................................................. 19 Portland Cement ....................................................................................................................... 20 Portland Cement Blends ........................................................................................................ 20 Portland Blast Furnace Cement ................................................................................................. 20 Portland Fly Ash Cement ........................................................................................................... 21 Portland Pozzolan Cement ........................................................................................................ 21 Masonry Cements ..................................................................................................................... 21 Expansive Cements .................................................................................................................... 22 Non-Portland Hydraulic Cements............................................................................................. 22 Pozzolan-Lime Cements ............................................................................................................ 22 Calcium Aluminate Cements ..................................................................................................... 23 Calcium Sulfoaluminate Cements.............................................................................................. 23 Natural Cements........................................................................................................................ 23 Geopolymer Cements ................................................................................................................ 24

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Environmental Impacts .......................................................................................................... 24 Chemical Composition of Portland Cement .................................................................................. 25 Properties of Major Constituents of Portland Cement ............................................................... 26 Minor Constituents........................................................................................................................ 27 Gypsum (CaSO4.2H2O) ............................................................................................................... 27 Free Lime (CaO) ......................................................................................................................... 27 Magnesia (MgO) ........................................................................................................................ 28 Titanium Oxide (TiO2) ................................................................................................................ 28 Phosphorus Pentoxide (P2O5) .................................................................................................... 28 Raw Materials ............................................................................................................................ 29 1-Lime Stone.............................................................................................................................. 29 2-Clay ......................................................................................................................................... 29 Capacity Selection in Pakistan ....................................................................................................... 30 Sector Overview ........................................................................................................................ 30 CEMENT INDUSTRY IN PAKISTAN .................................................................................................. 31 Pakistan Cement Market ............................................................................................................... 32 1-North ...................................................................................................................................... 32 2-South ...................................................................................................................................... 32 Cement Industry Growth ............................................................................................................... 34 Conversion ................................................................................................................................. 35 Looking Into the Future ................................................................................................................. 37 List of Cement Industries in Pakistan ............................................................................................ 39 SURVEY OF SOME CEMENT INDUSTRIES IN PAKISTAN.................................................................. 40 SURVEY OF SOME CEMENT INDUSTRIES IN PAKISTAN................................................................ 41 1-Mapple Leaf Cement .............................................................................................................. 41 2-D.G Khan Cement Company Limited ...................................................................................... 41 3-Lucky Cement Limited ............................................................................................................ 41 4-Kohat Cement Company Limited ........................................................................................... 41 5-Pakistan Cement Company Limited ....................................................................................... 42 6-Fauji Cement Company Limited ............................................................................................. 42 Manufacturing Methods and Process Selection ........................................................................... 46

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A-Wet Process ........................................................................................................................... 46 B-Dry Process............................................................................................................................. 46 Dry Process Versus Wet Process ................................................................................................... 47 Choice Of Process ...................................................................................................................... 48 MATERIAL BALANCE ...................................................................................................................... 49 MATERIAL BALANCE ...................................................................................................................... 50 QUALITY CONTROL FORMULAE .................................................................................................... 51 1. 2. 3. 4. 5. Silica Ratio: ........................................................................................................................ 51 Lime Saturation Factor ...................................................................................................... 51 Hydraulic Ratio ................................................................................................................. 51 Alumina Ratio: ................................................................................................................... 52 Burn Ability Index .............................................................................................................. 52

RAW MIX PREPARATION ........................................................................................................... 53 DRY RAW MIX COMPOSITION ................................................................................................... 55 RAW MATERIAL REQUIRED ....................................................................................................... 57 CLINKER COMPOSITION ................................................................................................................ 60 ENERGY BALANCE .......................................................................................................................... 61 ENERGY BALANCE .......................................................................................................................... 62 Input Heat Calculations ............................................................................................................. 62 Heat Input by Consumption of Fuel ...................................................................................... 62 Heat Input As Sensible Heat In Fuel .......................................................................................... 62 2-Sensible Heat In Kiln Feed ...................................................................................................... 63 a-Dry Feed Required To Produced One Ton Clinker .............................................................. 63 b-Feed Water Present In Kiln Feed............................................................................................ 63 3-Secondary Air Sensible Heat .................................................................................................. 64 Basis: 1 Ton of Coal ...................................................................................................................... 64 5. Primary Air Sensible Heat ......................................................................................................... 66 Output Heat Calculation ................................................................................................................ 67 1) Heat of Reaction ................................................................................................................... 67 2) Heat Losses with Kiln Exit Gases ............................................................................................... 68 a. Exit gas from coal burning:- .................................................................................................. 68

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B-Exit Gas From Kiln Feed.......................................................................................................... 69 c. Exit Gas Analysis (Excess Air) ................................................................................................. 71 3. Heat Loss Due To Mixture in Raw Mix ...................................................................................... 72 4-Heat In Clinker At Kiln Discharge................................................................................................ 73 Heat Loss Radiation And Convection............................................................................................. 73 Heat Balance Sheet........................................................................................................................ 74 EQUIPMENT DESIGN...................................................................................................................... 75 EQUIPMENT DESIGN...................................................................................................................... 76 Kiln Design ................................................................................................................................. 76 Calculation For The Diameter Of The Rotary Kiln.................................................................. 76 Calculation Of The Length Of The Rotary Kiln ........................................................................... 78 Basis: 6700 ton/day clinker .................................................................................................. 78 Kiln Slope ................................................................................................................................... 79 Degree Of The Kiln Filling .......................................................................................................... 79 Kiln filling degree fluctuates within the limits of about 5 – 17%. Independent from the kiln‟s diameter. ............................................................................................................................ 79 Revolution Of The Rotary Kiln ................................................................................................... 80 Thermal Load Of The Cross – Section Of The Burning Zone.......................................................... 80 Residence Time.......................................................................................................................... 80 Thermal Expansion Of The Rotary Kiln ...................................................................................... 81 a) Linear Expansion.................................................................................................................... 81 b) Expansion along Diameter .................................................................................................... 82 c) Expansion Along circumference ............................................................................................ 82 Vertical Load Of Kiln ..................................................................................................................... 83 Horse Power Requirement Of The Rotary Kiln .............................................................................. 85 a-Load horse power................................................................................................................... 85 Friction horse power ................................................................................................................. 85 CRUSHER........................................................................................................................................ 87 PRINCIPLE OF CRUSHING ........................................................................................................... 87 Selection of Crushing Machinery ............................................................................................... 88 Selected Crusher Type ............................................................................................................... 88 Primary Crushing ....................................................................................................................... 90

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Jaw Crusher: .............................................................................................................................. 90 Overload Safety Device ............................................................................................................. 91 Speed Of Rotation ..................................................................................................................... 92 Calculation Of Speed Of Rotation.............................................................................................. 92 Capacity Of Jaw Crusher ............................................................................................................ 93 By LEWENSON ........................................................................................................................... 94 Drive Power For Jaw Crusher ........................................................................................................ 95 Designing Of Raw Material Crusher ............................................................................................. 96 Motor For Feed Driving ............................................................................................................. 96 Crusher For Lime Stone Crushing .............................................................................................. 96 Motor For Driving Crusher ........................................................................................................ 97 Motor For Driving Feeding Rolls ................................................................................................ 97 Belt Conveyor ............................................................................................................................ 97 Motor For Driving Belt ............................................................................................................... 97 Crusher Capacity........................................................................................................................ 97 Crusher Capacity Required ........................................................................................................ 98 Crusher Hopper Capacity........................................................................................................... 98 Feeder Capacity for Crusher ...................................................................................................... 98 Transportation from Crusher .................................................................................................... 99 Maximum Capacity of Dumpers ................................................................................................ 99 VERTICAL ROLLER MILL................................................................................................................ 101 Grinding Action Developed In The Roller Mill. ............................................................................ 102 Draw In Action Of The Grinding Element. ................................................................................... 103 Grinding Bed Formation .............................................................................................................. 104 BALL MILL .................................................................................................................................... 119 The Critical Speed .................................................................................................................... 119 Dia Of The Ball Mill .................................................................................................................. 119 According to Tavrov’s formula ................................................................................................ 119 Dynamic Angle Of Repose Of Grinding Balls ........................................................................... 121 Distribution Of Grinding Media In The Mill Cross Section ...................................................... 121 Degree Of The Ball Charge ...................................................................................................... 121

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Total Grinding Ball Charge ....................................................................................................... 121 Grinding Ball Charge And Clinker Load .................................................................................... 122 According to Mardulier ........................................................................................................... 122 Ball Mill Power Demand .......................................................................................................... 122 Empirical formula for Ball Mill Power ..................................................................................... 122 Blanc’s formula ........................................................................................................................ 122 Bond’s Equation....................................................................................................................... 123 Apply Bond’s Equation ............................................................................................................ 123 Site Selection ............................................................................................................................... 124 Site Selection ............................................................................................................................... 125 Raw Materials Availability ....................................................................................................... 125 Market ..................................................................................................................................... 125 Energy Availability ................................................................................................................... 125 Climate..................................................................................................................................... 126 Transportation Facilities .......................................................................................................... 126 Water Supply ........................................................................................................................... 126 Waste Disposal ........................................................................................................................ 126 Labor Availability ..................................................................................................................... 127 Taxation And Legal Restrictions .............................................................................................. 127 Site Characteristics .................................................................................................................. 127 Flood And Fire protection........................................................................................................ 128 Community Factors ................................................................................................................. 128 PLANT SAFETY.............................................................................................................................. 129 PLANT SAFETY.............................................................................................................................. 130 OPERATIONAL SAFETY AND PRECAUTIONS ............................................................................. 130 COST ESTIMAION ......................................................................................................................... 132 COST ESTIMAION ......................................................................................................................... 133 COST OF PRODUCTION ............................................................................................................ 133 Material ............................................................................................................................... 133 Labor ........................................................................................................................................ 133 Fuel .......................................................................................................................................... 134

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Power....................................................................................................................................... 134 Other Supplies: ........................................................................................................................ 135 Overhead Charges ................................................................................................................... 135 COST ESTIMATION OF PROJECT .................................................................................................. 136 PURCHASE EQUIPMENT COST ..................................................................................................... 136 Purchased Equipment Cost ..................................................................................................... 136 PURCHASED EQUIPMENT COST............................................................................................... 137 Purchased Equipment Cost ................................................................................................. 137 Total Direct Cost .......................................................................................................................... 138 Total Direct Cost = 9.075x109 Rs. .................... 138

Indirect cost ................................................................................................................................. 139 Total Indirect Cost = 3.713x109 Rs. .............................................. 139

Total Capital Investment =Fixed Capital Investment + Working Capital Investment ............................................................................................................ 140 Cost of Production ....................................................................................................................... 140 Fixed Cost .................................................................................................................................... 141 Market Price ................................................................................................................................ 141 Pay out Period of the Plant.......................................................................................................... 142 Instrumentation & Process Control ............................................................................................. 143 Instrumentation And Process Control ......................................................................................... 144 OBJECTIVES: ............................................................................................................................. 144 Safe Plant Operations: ............................................................................................................. 144 Production Rate: ...................................................................................................................... 144 Product Quality:....................................................................................................................... 144 Cost: ......................................................................................................................................... 144 Hardware Elements Of Control System: ...................................................................................... 145 Process:.................................................................................................................................... 145 Measuring Elements: ............................................................................................................... 145 Transducers: ............................................................................................................................ 145 Transmission Lines: ................................................................................................................. 145 Controller: ............................................................................................................................... 145 Final Control Element: ............................................................................................................. 146

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Recorder: ................................................................................................................................. 146 General Control Systems: ............................................................................................................ 146 Open Loop System:.................................................................................................................. 146 Closed Loop System:................................................................................................................ 146 Feed back Control System: ...................................................................................................... 147 Forward Control System: ......................................................................................................... 147 Combined Control System: ...................................................................................................... 147 Cascade Control System: ......................................................................................................... 147 Modes Of Control: ....................................................................................................................... 148 Proportional Control: .............................................................................................................. 148 Proportional Derivative Control: ............................................................................................. 148 Proportional Integral Control: ................................................................................................. 149 Proportional Integral Derivative Control: .......................................................................... 149 Typical Control System ................................................................................................................ 149 Recommended Thermocouple .................................................................................................... 150 For Kiln Process ....................................................................................................................... 150 Type – R ................................................................................................................................... 150 Temperature Indicator Controller: .......................................................................................... 150 Level Controller: ...................................................................................................................... 150 Pressure Controller:................................................................................................................. 150 Flow Controller: ....................................................................................................................... 151 Alarm & Safety Tips: ................................................................................................................ 151 Interlocks: ................................................................................................................................ 151 THE LETTER CODES FOR INSTRUMENT SYSTEM ...................................................................... 152 NOTE: ....................................................................................................................................... 153 ENVIROMENTAL PROTECTION & ENERGY UTILIZATION ......................................... 154

ENVIROMENTAL PROTECTION AND ENERGY UTILIZATION ....................................................... 155 ENVIROMENTAL PROTECTION IN THE CEMENT INDUSTRY..................................................... 155 COST OF ENVIRONMENTAL PROTECTION ............................................................................... 156 ENVIROMENTAL PROTECTION AS A PROBLEM OF PLANT LOCATION: .................................... 156 IMPACT OF ENVIRONMENTAL STANDARDS ON ENERGY CONSIDERATION:..................... 157

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TECHNICAL AND MANAGERIAL IMPEDEMENTS FOR IMPROVING ENERGY EFFICIENCY ......... 158 FUTURE TREND IN ENERGY EFFICINCY AND SUGGESTIONS OF STRATEGIES .......................... 159 MODREN FOUR STAGE SUSPENTION PREHEATER KILN .......................................................... 160 EFFICIENT USE OF CEMENT IN CONCRETE .............................................................................. 161 SUGGESTIONS .............................................................................................................................. 162 INDUSTRIAL LEVEL ................................................................................................................... 162 NATIONAL LEVEL ..................................................................................................................... 163 Bibliography................................................................................................................................. 165

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A PROJECT DESIGN REPORT ON

PRODUCTION OF ORDINARY PORTLAND CEMENT
Submitted to: BAHAUDDIN ZAKARIYA UNIVERISTY, MULTAN

In Partial Fulfillments of the Requirements for the Degree of B.Sc. Chemical Engineering Session: 2004-2008

Submitted by:
Adnan Waheed 2K4-CHE-157

Supervised by:
Engr.Tariq Malik Engr. Najaf Ali Awan

INSTITUTE OF ENGINEERING & TECHNOLOGICAL TRAINING NFC IET MULTAN

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ACKNOWLEDGEMENT
In the name of ALLAH, the all Corroborate Possessor of Majesty and Splendor, the Omnipresent, The whole benevolent and ever merciful. Who’s generosity and magnificence able us to complete to make this humble contribution to already existing ocean of knowledge. All praises to his last messenger Hazrat Muhammad (Peace Be Upon Him) who is a source of guidance and knowledge for humanity as a whole is an ever inspiring for all the learned personals by the order of ALLAH almighty. In presenting this design report of production of Ordinary Portland Cement 6700 MTPD,we express our heart felt thanks to our project advisor, Engr. Tariq Malik and Engr. Najaf Ali Awan for his guidance, valuable suggestions and constructive criticism in preparation of this design report. We are grateful to our director Dr. M. Afzal Haque for providing us all the facilities and encouragement regarding this project. Our acknowledgment is also due to our Head of Chemical Engineering Department Syed Nasir Abbas Abdi, for all his full moral support as well as his helpful suggestions whenever needed. The authors also express their appreciation to Cement Research Institute & Development Center and D.G.Khan Cement Company Limited for helping us in taking difficult data and values of this project faced by us time to time.

Authors

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DEDICATED TO Our Parents, Respected Teachers

& Sincere Friends

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INTRODUCTION

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INRODUCTION
Cement
“Portland cement is the product obtained by finely pulverizing clinker produced by calcining to incipient fusion and intimate and properly proportioned mixture of agrillaceous and calcareous materials.” In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. The name "cement" goes back to the Romans who used the term "opus caementitium" to describe masonry which resembled concrete and was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives which were added to the burnt lime to obtain a hydraulic binder were later referred to as, cimentum, cäment and cement. Cements used in construction are characterized as hydraulic or non-hydraulic. The most important use of cement is the production of mortar and concrete - the bonding of natural or artificial aggregates to form a strong building material which is durable in the face of normal environmental effects.

History
The earliest construction cements are as old as construction, and were non-hydraulic. Wherever primitive mud bricks were used, they were bedded together with a thin layer of clay slurry. Mud-based materials were also used for rendering on the walls of timber or "wattle and daub" structures. Lime was probably used for the first time as an additive in these renders, and for stabilizing mud floors. A "daub" consisting of mud, cow
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dung and lime produces a tough and water-proof coating, due to coagulation, by the lime, of proteins in the cow dung. This simple system was common in Europe until quite recent times. With the advent of fired bricks, and their use in larger structures, various cultures started to experiment with higher-strength mortars based on bitumen (in

Mesopotamia), gypsum (in Egypt) and lime (in many parts of the world). It is uncertain where it was first discovered that a combination of hydrated non-hydraulic lime and a pozzolan produces a hydraulic mixture, but concrete made from such mixtures was first used on a large scale by the Romans. They used both natural pozzolans (trass or pumice) and artificial pozzolans (ground brick or pottery) in these concretes. Many excellent examples of structures made from these concretes are still standing, notably the huge monolithic dome of the Pantheon in Rome. The use of structural concrete disappeared in medieval Europe, although weak pozzolanic concretes continued to be used as a core fill in stone walls and columns. Modern hydraulic cements began to be developed from the start of the Industrial Revolution (around 1700), driven by three main needs: Hydraulic renders for finishing brick buildings in wet climates Hydraulic mortars for masonry construction of harbor works etc, in contact with sea water.

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Development of strong concretes
In Britain particularly, good quality building stone became ever more expensive during a period of rapid growth, and it became a common practice to construct prestige buildings from the new industrial bricks, and to finish them with a stucco to imitate stone. Hydraulic limes were favored for this, but the need for a fast set time encouraged the development of new cements. Most famous among these was Parker's "Roman cement". This was developed by James Parker in the 1780s, and finally patented in 1796. It was, in fact, nothing like any material used by the Romans, but was”Natural cement" made by burning septaria - nodules that are found in certain clay deposits, and that contain both clay minerals and calcium carbonate. The burnt nodules were ground to a fine powder. This product, made into a mortar with sand, set in 5-15 minutes. The success of "Roman Cement" led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk. John Smeaton made an important contribution to the development of cements when he was planning the construction of the third Eddystone Lighthouse (1755-59) in the English Channel. He needed a hydraulic mortar that would set and develop some strength in the twelve hour period between successive high tides. He performed an exhaustive market research on the available hydraulic limes, visiting their production sites, and noted that the "hydraulicity" of the lime was directly related to the clay content of the limestone from which it was made. Smeaton was a civil engineer by profession, and took the idea no further. Apparently unaware of Smeaton's work, the same principle was identified by Louis Vicat in the first decade of the nineteenth century. Vicat went on to devise a method of combining chalk and clay into an intimate mixture, and, burning this, produced”artificial cement" in 1817. James Frost, working in Britain,

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produced what he called "British cement" in a similar manner around the same time, but did not obtain a patent until 1822. In 1824, Joseph Aspdin patented a similar material, which he called Portland cement, because the render made from it was in color similar to the prestigious Portland stone. All the above products could not compete with lime/pozzolan concretes because of fast-setting (giving insufficient time for placement) and low early strengths (requiring a delay of many weeks before formwork could be removed). Hydraulic limes, "natural" cements and "artificial" cements all rely upon their belite content for strength development. Belite develops strength slowly. Because they were burned at temperatures below 1250°C, they contained no alite, which is responsible for early strength in modern cements. The first cement to consistently contain alite was that made by Joseph Aspdin's son William in the early 1840s. This was what we call today "modern" Portland cement. Because of the air of mystery with which William Aspdin surrounded his product, others (e.g. Vicat and I C Johnson) have claimed precedence in this invention, but recent analysis of both his concrete and raw cement have shown that William Aspdin's product made at North fleet, Kent was a true alite-based cement. However, Aspdin's methods were "rule-of-thumb": Vicat is responsible for establishing the chemical basis of these cements, and Johnson established the importance of sintering the mix in the kiln. William Aspdin's innovation was counter-intuitive for manufacturers of "artificial cements", because they required more lime in the mix (a problem for his father), they required a much higher kiln temperature (and therefore more fuel) and because the resulting clinker was very hard and rapidly wore down the millstones which were the only available grinding technology of the time. Manufacturing costs were therefore considerably higher, but the product set reasonably slowly and developed strength

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quickly, thus opening up a market for use in concrete. The use of concrete in construction grew rapidly from 1850 onwards, and was soon the dominant use for cements. Thus Portland cement began its predominant role.

Types of modern cement
Hydraulic Cements
Hydraulic cements are materials which set and harden after combining with water, as a result of chemical reactions with the mixing water and, after hardening, retain strength and stability even under water. The key requirement for this is that the hydrates formed on immediate reaction with water are essentially insoluble in water. Most construction cements today are hydraulic, and most of these are based upon Portland cement, which is made primarily from limestone, certain clay minerals, and gypsum, in a high temperature process that drives off carbon dioxide and chemically combines the primary ingredients into new compounds. Nonhydraulic cements include such materials as (non-hydraulic) lime and gypsum plasters, which must be kept dry in order to gain strength, and oxychloride cements which have liquid components. Lime mortars, for example, "set" only by drying out, and gain strength only very slowly by absorption of carbon dioxide from the atmosphere to re-form calcium carbonate. Setting and hardening of hydraulic cements is caused by the formation of water-containing compounds, forming as a result of reactions between cement components and water. The reaction and the reaction products are referred to as hydration and hydrates or hydrate phases, respectively. As a result of the immediately starting reactions, a stiffening can be observed which is very small in the beginning, but which increases with time. After
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reaching a certain level, this point in time is referred to as the start of setting. The consecutive further consolidation is called setting, after which the phase of hardening begins. The compressive strength of the material then grows steadily, over a period which ranges from a few days in the case of "ultra-rapid-hardening" cements, to several years in the case of ordinary cements.

Portland Cement
Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and most nonspeciality grout. The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element.

Portland Cement Blends
These are often available as inter-ground mixtures from cement manufacturers, but similar formulations are often also mixed from the ground components at the concrete mixer.

Portland Blast Furnace Cement
It contains up to 70% ground granulated blast furnace slag, with the rest Portland clinker and a little gypsum. All compositions produce high ultimate strength, but as slag content is increased, early strength is reduced, while sulfate resistance increases and heat evolution diminishes. Used as an economic alternative to Portland sulfate-resisting and low-heat cements.
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Portland Fly Ash Cement
It contains up to 30% fly ash. The fly ash is pozzolanic, so that ultimate strength is maintained. Because fly ash addition allows a lower concrete water content, early strength can also be maintained. Where good quality cheap fly ash is available, this can be an economic alternative to ordinary Portland cement.

Portland Pozzolan Cement
It includes fly ash cement, since fly ash is a pozzolan, but also includes cements made from other natural or artificial pozzolans. In countries where volcanic ashes are available (e.g. Italy, Chile, Mexico, and the Philippines) these cements are often the most common form in use. Portland Silica Fume cement Addition of silica fume can yield exceptionally high strengths, and cements containing 5-20% silica fume are occasionally produced. However, silica fume is more usually added to Portland cement at the concrete mixer.

Masonry Cements
These are used for preparing bricklaying mortars and stuccos, and must not be used in concrete. They are usually complex proprietary formulations containing Portland clinker and a number of other ingredients that may include limestone, hydrated lime, air entertainers, retarders, water proofers and colouring agents. They are formulated to yield workable mortars that allow rapid and consistent masonry work. Subtle variations of Masonry cement in the US are Plastic Cements and Stucco Cements. These are designed to produce controlled bond with masonry blocks.

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Expansive Cements
These contain, in addition to Portland clinker, expansive clinkers (usually sulfoaluminate clinkers), and are designed to offset the effects of drying shrinkage that is normally encountered with hydraulic cements. This allows large floor slabs (up to 60 m square) to be prepared without contraction joints.

Non-Portland Hydraulic Cements
Pozzolan-Lime Cements
Mixtures of ground pozzolan and lime are the cements used by the Romans, and are to be found in Roman structures still standing (e.g. the Pantheon in Rome). They develop strength slowly, but their ultimate strength can be very high. The hydration products that produce strength are essentially the same as those produced by Portland cement. Slag-lime cements Ground granulated blast furnace slag is not hydraulic on its own, but is “activated” by addition of alkalis, most economically using lime. They are similar to pozzolan lime cements in their properties. Only granulated slag (i.e. water-quenched, glassy slag) is effective as a cement component. Super sulfated cements These contain about 80% ground granulated blast furnace slag, 15% gypsum or anhydrite and a little Portland clinker or lime as an activator. They produce strength by formation of ettringite, with strength growth similar to a slow Portland cement. They exhibit good resistance to aggressive agents, including sulfate.

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Calcium Aluminate Cements
These are hydraulic cements made primarily from limestone and bauxite. The active ingredients are monocalcium aluminate CaAl2O4 (CA in Cement chemist notation) and Mayenite Ca12Al14O33 (C12A7 in CCN). Strength forms by hydration to calcium aluminate hydrates. They are welladapted for use in refractory (high-temperature resistant) concretes, e.g. for furnace linings.

Calcium Sulfoaluminate Cements
These are made from clinkers that include ye‟elimite (Ca4 (AlO2)6SO4 or C4A3 in Cement chemist‟s notation) as a primary phase.

They are used in expansive cements, in ultra-high early strength cements, and in "low-energy" cements. Hydration produces ettringite, and specialized physical properties (such as expansion or rapid reaction) are obtained by adjustment of the availability of calcium and sulfate ions. Their use as a low-energy alternative to Portland cement has been pioneered in China, where several million tonnes per year are produced. Energy requirements are lower because of the lower kiln temperatures required for reaction and the lower amount of limestone (which must be

endothermically decarbonated) in the mix. In addition, the lower limestone content and lower fuel consumption leads to a CO2 emission around half that associated with Portland clinker. However, SO2 emissions are usually significantly higher.

Natural Cements
These correspond to certain cements of the pre-Portland era, produced by burning argillaceous limestone at moderate temperatures. The level of clay components in the limestone (around 30-35%) is such

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that large amounts of belite (the low-early strength, high-late strength mineral in Portland cement) are formed without the formation of excessive amounts free lime. As with any natural material, such cements have very variable properties.

Geopolymer Cements
These are made from mixtures of water-soluble alkali silicates and aluminosilicate mineral powders such as metakaolin.

Environmental Impacts
Cement manufacture causes environmental impacts at all stages of the process. These include emissions of airborne pollution in the form of dust, gases, noise and vibration when operating machinery and during blasting in quarries, consumption of large quantities of fuel during manufacture, release of CO2 from the raw materials during manufacture, and damage to countryside from quarrying. Equipment to reduce dust emissions during quarrying and manufacture of cement is widely used, and equipment to trap and separate exhaust gases are coming into increased use. Environmental protection also includes the re-integration of quarries into the countryside after they have been closed down by returning them to nature or re-cultivating them. Cement manufacture can also provide environmental benefits by using wastes from certain other industries, including slag from steel manufacture, fly ash from coal burning, silica fume from silicon and ferrosilicon manufacturing, and sometimes recycled concrete from demolition of older structures.

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Chemical Composition of Portland Cement
Portland cement consists of mainly lime (CaO), silica (SiO2), alumina (Al2O3), and iron oxide (Fe2O3). The combined content of the four oxides is approximately 90% of the cement weight and they are generally referred as the „major oxide‟. The remaining 10% consists of magnesia (MgO), alkali oxides (Na2O and K2O), Titania (TiO2), phosphorus pentaxide (P2O5), and gypsum (A few percent of gypsum is added during grinding to regulate the setting time of the cement). These are referred to as „minor constituents‟. An idea of the composition of present-day, Portland cement can be obtained from the approximate limits in the following table. OXIDE CaO SiO2 Al2O3 Fe2O3 MgO Na2O + K2O TiO2 P2O5 SO3 COMPOSITION (WT %) 60-67 17-25 3-8 0.5-6.0 0.1-5.5 0.5-1.3 0.1-0.4 0.1-0.2 1-3

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Properties of Major Constituents of Portland Cement
Compound Celite Chemical tetracalcium Formulae aluminoferrite 55% 4CaO.Fe2O3.Al2O3 2-8% Rate of rapid Hydration (minutes) Strength rapid Development day) Ultimate Strength Heat of Medium: Hydration j/g Remarks to the Constituent of Portland its Cements characteristic Color Grey attack sensitive to sulphate cement Characteristic unstable in water, imparts 500 j/g 250 j/g 850j/g 420 Medium: Low: very high: high probably high Low Low (one day) (one Rapid (days) Slow (weeks) Very rapid very Rapid (hours) Slow (days) Instantaneous very 10-19% 5-12% 3CaO.SiO2 (C3S) 2 CaO.SiO2. (C2S) 3CaO.Al2O3(C3A) Tricalcium silicate Dicalcium silicate Tricalcium aluminate Alite Belite --------

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Minor Constituents
Gypsum (CaSO4.2H2O)
Gypsum is added during grinding of the clinker in order to regulate the setting time of the cement. There is an optimum gypsum content which imparts to the cement maximum strength and minimum shrinkage, and this optimum depends on the alkali oxides and C3A contents of the cement and on its fineness. On the other hand, the gypsum content must be limited because an excess may cause cracking and deterioration in the set cement. This adverse effect is due to the formation of ettringite (C3A.3CaSO4.31H2O) resulting from reaction between gypsum and C3A.

Free Lime (CaO)
The presence of free (uncombined) lime in the cement may occur when the raw materials used in the manufacturing process contain more lime than can combined with the acidic oxides SiO2, Al2O3, and Fe2O3. Alternatively, free lime may occur when the amount of lime in the raw materials is not excessive, but when its reaction with the oxides is not complete after the clinkering process due to coarse raw meal and low heat input.

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Magnesia (MgO)
The raw material for the cement usually contains a certain amount of MgCO3 which on burning dissociates to magnesium oxide and carbon dioxide. The magnesia does not combine with the major oxides. Some of it is taken up in solid solution in the clinker material, and the remainder crystallizes as periclase (MgO).

Alkali Oxides (K2O, Na2O)
The alkali oxides are introduced into the cement through the raw materials and their content varies from 0.5% to 1.3%. On burning, the alkali oxides combine, usually, with sulfur trioxide (SO3) giving a solid solution of sodium potassium sulfate which tends to have the approximate composition 3K2SO4. Na2SO4.

Titanium Oxide (TiO2)
Titania (TiO2) occurs in the cement to a small extent and its content varies from 0.1% to 0.4%. The titamia is introduced onto the cement through the clay of the shale used in its manufacture.

Phosphorus Pentoxide (P2O5)
The (P2O5) is usually introduced into the cement through the limestone used in its manufacture. Its presence slower the cement hardening because it breaks down the C3S to C2S, which contains the (P2O5) in solid solution and CaO.

28

Raw Materials
Two types of raw materials are necessary for the production of Portland cement, one rich in calcium such as limestone, and one rich in silica such as clay.

1-Lime Stone
Calcium carbonate (CaCO3) is wide spread in nature. Calcium carbonate of all geological formations qualifies for the production of Portland cement. The purest grades of lime stone are calspar (calcite) and aragonite. Calcite crystallizes hexagonally and aragonite is rhombic. The specific gravity of calcite is 2.7 and of aragonite are 2.95. The hardness of lime stone depends on its geological age. The hardness of limestone is between 1.8 and 3.0 of the Moh‟s scale of hardness. Only the purest varieties of lime are white. Lime stone usually contains admixtures of clay substance, iron and aluminum compounds, which influence its colour. In cement raw material the lime component is generally represented up to an amount of 74-80%.

2-Clay
Clay is another raw material for cement manufacturing. Clay is formed by the weathering of alkali and alkaline earth containing aluminum silicates and of their chemical conversion products, mainly feldspar and mica. The main component of clay is formed by hydrous aluminum silicates. Iron hydroxide is the principal colouring agent in clays; also organic matter may give the clay with different colors. Clays with no impurities are white. In addition to natural raw material some plants use slag and precipitated carbonated obtained as by product from ammonium sulfate

29

industry Sand, waste bauxite and iron ore is some time used in small amount to adjust the composition of the mixture. Gypsum is added to regulate the setting time of the cement.

Capacity Selection in Pakistan
Sector Overview
There are 29 cement production units in the country. Upto May 2007, the total installed cement production capacity is 36.841 million tones. By the end of June 2011, the installed cement capacity will touch to the level of 49.597 million tones. Due to political instability and lack of allocation of funds for public sector development program, cement industry of Pakistan was in the recession phase had registered an average growth rate of 2.96% for the period from 1990 to 2002. For the period from 2003 to 2007 cement industry of Pakistan had registered an average growth rate of 20%. The boost in cement sector is because of the rising construction activity in the country, reconstruction activity in Afghanistan and increasing development expenditure by the government. Construction of dames and export of cement in the future will also increase the demand of Cement in Pakistan. So to meet the future demand of the cement in Pakistan 6700 ton per day capacity (the minimum feasible) plant should be designed.

30

CEMENT INDUSTRY IN PAKISTAN
The Cement industry of Pakistan plays a vital role in the socio economic development of the country. The development of cement sector has made rapid strides, both in public and private sectors during the last two decades. At the time of independence there were only four units in the county having the capacity of 470,000 tons per annum. These units were located at Karachi, Rohr, Wan, and Dandot. The country at present has almost attained self-sufficiency in the supply of cement with very little imports whatsoever during the last few years. But now, it has exceeded 36.841 million tones per anima as a result of establishment of new manufacturing facilities and expansion by the exiting units. Privatization and effective price decontrol in 1991-92 hearted a new era in which the industry has research a level where surplus production after meeting local demand is expected in 2006. The competitive environment, in the cement sector contributes to the common benefits of the industry and the end users. Infect, the framework of mixed economy is today truly evidence in cement sector leading to the maximization of social and economic advantages.

The cement industry in Pakistan faces two serious threats: closure of units based on the wet process. And the poor cash flow rendering the units in capable of debts servicing due to the increasing cast of electricity and furnace oil.

31

Pakistan has remained a net importer of the cement but due to the privatization of the units operating under state control and subsequent expansion programs by the new owners supported by financial institution has pushed the industry to a point where the country is bound to reach an oversupply situation. However, the recent increase in the energy cast provides opportunity sustain the situation for a relatively longer period. It would be possible because the expansion by the existing units and establishment of new units are being delayed.

Pakistan Cement Market
Pakistan‟s cement market is divided into two distinct regions. 1-North 2-South

1-North
The northern region comprises the entire province of Punjab, NWFP, Azad Kashmir and upper parts of Balochistan, whereas the southern region comprises the entire province of Sindh and some parts of Balochistan.

2-South
Traditionally, the southern region has always been surplus in cement production but with the establishment of more plants in the northern parts of the country the regions has become almost sufficient in the supply of cement.

32

Demand Vs Supply
The demand supply gap which for the decade was in favour of manufactures is now set to switch the other way with supply outpacing demand by the end of 2006. Historically the demand has grown at an average rate of 22.74% in the northern region while 22.65% in the Southern region. There is much pessimism about the industry, future due to the tremendous increase in supply expected by the end of next year.

The way new plants are being established and existing plants are undertaking expansion, the demand supply equation is creating surpluses. However, it has been observed that actual progress is slower than planned to avoid a possible glut situation. This will effectively narrow down the gap between demand and supply and thereby, ease the pressure on prices. Factors that can possible change the surplus position into the near equilibrium between the demand and supply are: 1. Formation of manufacturer‟s cartel to avoid price decline. 2. Delay in implementation of planned additions and expansions. 3. Efforts to export cement. 4. Increase in demand if construction of some of the mega-sized infrastructure project starts.

More Competition
As the cement market is moving from virtual “sellers” market to an oversupply situation, it is expected that when prices stagnate and profitability becomes a function of volume and economics of scale, location advantages and proximity to markets will become extremely important factors.
33

At present the freight charges are a massive 20% of the retail prices. The plants located very close to each other and tapping the same market will have to expand their markets, which will increase their freight expenses.

Dandot, pioneer, Mapple Leaf and Gharibwal are all located with in a radious of 100 kilometers and are selling bulk of their production in the same areas and will this face serious competition from each other.

Cement Industry Growth
With the resurgence in demand, improvement at retention level, coal conversion and debt restructuring, cement industry has entered the era of improving profitability. With growth of the economy being linked to infrastructure development, special emphasis was being paid to the construction sector. The prospects of economic growth and construction sector are being linked to each other.

Presently, a number of factors are attributed to this tremendous growth represented by various indicators. Cement exports, mainly to Afghanistan doubled during the three quarter period of the current years, Attaining a level of 0.78 millions tones, but that accounts of only 8% of the total production.

For a third world country like Pakistan in the process of development, cement is very a very important commodity. The number of cement plants and their production volume gives an indication of the stage of the development in the country.

34

The cement industry in Pakistan, with a fixed investment of over 79 billion rupees has started recovering at an increased pace after waging a long struggle to survive. Domestic demand for cement, which was 66% of capacity last year, was expected to reach over 92-95% by the end of current financial year. But it surpassed the expectations and is already utilizing 92-95% capacity due to unprecedented increase in demand of cement. These phenomena generated optimism about the future prospects of the cement industry in the country.

The government plays a vital role in the development of infra structure, it is important for steering the economy towards accelerated growth. The economy is now poised to take off, in the backdrop of all the positive indicators. The government is also trying its utmost to bring local and foreign investment in the different sectors of the economy. In order to attract new investment for industrialization, substantial fiscal incentives have been offered by the government to improve infra structure, which would be huge quantities of cement.

Conversion
Conversion from furnace oil plants to coal firing system has already taken place in majority of the cement processing units, which have started getting high benefits, but they are also reluctant to pass on the benefits to the consumer on the pretext that the industry has suffered great losses in the past due to the high prices of furnace oil hence unless the losses of the past are recovered they are not in the position to pass on the benefits of end users. On the contrary, the experience shows that when ever the prices of oil were increased the traditional cast was always passed on to the consumers.
35

The conversion of furnace oil plants to coal fired the production cost of the company resulting in the improved bottom-line. It is reported that the domestic coal is not a very high quality how ever the processing and blending the local coal with the imported one can produce required heating content that is much cast –effective than the furnace oil.

End users would also be given their due share in the larger interest of the economy, because reduction in price means increase in economic activity. The cement industry has benefited a lot by shifting towards dry process. Installation of electrostatic precipitators and preheaters, automation of processes and installation of online analyzer which has resulted in environmentally better and energy efficient industries. The production of cement is high-energy intensive process. The cement manufacturers that have utilized 100% of their installed production capacity are busy in the rebottling process to further enhance their capacities. They require upgrading of certain portions their production process to increase their capacity. This might add one million in cement production capacity of the country it would however come under pressure by 2007 planned additional capacity would be operational.

However cement demand from PSDP is directly linked to actual government spending on mega projects where the work on mega projects where the work on mega projects remains slow and the government however has not made any announcement regarding the construction of any mega dam project.

36

Looking Into the Future
The radical change in the fuel system that from furnace oil to coal and the increase in demand for cement has lifted the spirits of the industry in fact in a sense plays the role of a mother industry if all the development of infrastructure base of the country is taken into account. The increase in consumption also pushes the economic activity. Besides encouraging increase in cement consumption through positive policies and use the cement in large public sector projects, this strong industrial sector deserves incentives through considerable relaxation in the government levies to make it competitive in the export market.

Besides current export trend to Afghanistan which has injected a new life in our sick cement industry, there were ample scope of export in the countries like Bangladesh where annual demand for cement is estimated 5 million tons a year, Sri Lanka 3 million tons, Singapore 5 million tons, Egypt 4 million tons, Myanmar 1million tons, Vietnam 1 million tons, Malaysia 2 million tons and Nepal 0.5 million tons All these countries are not the producers of cement and meet their cement needs through imports.

Another factor to keep this sector vibrant is to use cement in the construction of huge national project of Gawader port in Balochistan, Karachi-Makran coastal highways. The use of cement in huge network of irrigation canals and new projects contributing in bridging the gap bet demand and supply in cement network.

37

The cement outlook for cement industry looks positive. The capacity utilization in the current year has improved due to increase in demand. The earning of cement sector will show further growth in the fourth quarter ending June, 30 owing to better retention prices, improved volume and stable to declining production cost.

38

List of Cement Industries in Pakistan
1-D.G Khan Cement Company Limited 2-Dandot Cement Company Limited 3-Gharibwal Cement Limited 4-Javedan Cement Company Limited 5-Mustehkam Cement Limited 6-National Cement Industries Limited 7-Pioneer Cement Limited 8-Thatta Cement Company Limited 9-Zeelpak Cement Industries 10-State Cement Corporation of Pakistan Limited 11-Bestway Cement Limited 12-Cherat Cement Company Limited 13-Dadabhoy Cement Industries 14-Essa Cement Industries 15-Fecto Cement Limited 16-Galadari Cement (Gulf) Limited 17-Haryana Asbestos Cement Industries Limited 18-Anwarzaib White Cement Limited 19-Associated Cement Rohri Limited 20-Nizampur Cement Plant 21-Pakistan Slag Cement Industries Limited 22-Sakhi Cement Limited 23-White Cement Industries Limited 24-Mapple Leaf Cement 25-Askari Cement Limited 26-Lucky Cement 27-Kohat Cement Company Limited 28-Pakistan Cement Company Plant 29-Fauji Cement Company Plant

39

SURVEY OF SOME CEMENT INDUSTRIES IN PAKISTAN

40

SURVEY OF SOME CEMENT INDUSTRIES IN PAKISTAN

The cement industries in Pakistan are:1-Mapple Leaf Cement 2-D.G Khan Cement 3-Lucky Cement 4-Kohat Cement Company Limited 5-Pakistan Cement Company Plant 6-Fauji Cement Company Plant

1-Mapple Leaf Cement
Plant Capacity: 6,700 + 5,000 (TPD) plant Plant Location: Located in Daudkhel District Mianwali at Northern Pakistan Products: Ordinary Portland Cement White Cement Sulfate Resisting Cement Low Alkali Oil Well Cement

2-D.G Khan Cement Company Limited
Plant Capacity: 6,700(TPD) plant Plant Location: Located In Dera Ghazi Kahar, District Punjab, Pakistan Products: Ordinary Portland Cement Sulfate Resisting Cement

3-Lucky Cement Limited
Plant Capacity: 4,200(TPD) plant Plant Location: Located In Mian Indus Highway, Pezu District Lucky Marwat, N.W.F.P Products: Ordinary Portland Cement Sulfate Resisting Cement Slag Cement

4-Kohat Cement Company Limited
Plant Capacity: 6,700(TPD) plant Plant Location: Located at Kohat, Pakistan Products: White Cement (Kohat Super White) Grey Cement 41

5-Pakistan Cement Company Limited
Plant Capacity: 6,000(TPD) plant Plant Location: Located at Kalar Kahar, District Chakwal, Punjab, Pakistan Products: Ordinary Portland Cement Sulfate Resisting Cement

6-Fauji Cement Company Limited
Plant Capacity: 7,200(TPD) plant Plant Location: Located at Jhang Bahtar, Tehsil Fateh Jhang, District Attock, Punjab, Pakistan Products: Ordinary Portland Cement

42

Cement:The product obtaining by calcining the intimate and proper proportionate mixture of argillaceous and calcareous material to produce clinker and then adding gypsum to it.

Raw Materials
1-Calcareous
A-Limestone B-Chalk

2-Agrillaceous
A-Clay B-Shale C-Slate D-Gypsum

Manufacturing Process:There are two (2) processes for manufacturing of cement. 1-Dry Process 2-Wet Process

Manufacturing Steps:1-Crushing & grinding of raw material 2-Storage of raw material 3-Correction Vats 4-Kiln Feeder 5-Rotary Kiln 6-Collection of Clinker 7-Grinding Of Clinker with gypsum 8-Packing & Storage

43

CLAY CRUS HER CRUS HER

LIMEST ONE

ST AGE OR Y ARD

ST AGE OR Y ARD

HOOPE R

HOOPE R

CONS ANT T FEED RAT E

CONS ANT T FEED RAT E

RW R D GM L A G IN IN IL

COR RECT ION VAT

OIL/GAS

ROT ARY KILN

COOL ER

HOOP ER

GR INDING MILL

GYPSUM 3-4%

S ORAGE T & P ACKING

44

CLAY

WAT R E

LIMEST ONE CRUS HER

WAS MILL H

ST AGE OR BAS IN

ST AGE OR BAS IN

WTGIN IN M L E R D G IL

COR RECT ION VAT S

S ORAGE BAS T IN

KILN FEEDE R

OIL/GAS

ROT ARY KILN

1400-1500 C

CLINKER

HEAT ER

GR INDING MILL

GYPSUM 3-4%

S ORAGE T & P ACKING

45

Manufacturing Methods and Process Selection
Two fundamental methods are known for the preparation of the feed for rotary kilns: a. The Wet Process; slurry with a water content of approximately 18 – 45% is prepared in wash mills or by wet grinding. b. The Dry Process, where the dry state of the raw material components is exploited to prepare the raw mix.

A-Wet Process
1. The long wet process rotary kiln with internal heat exchangers such as chains, segments of other arrangements. 2. The short wet process rotary kiln without internal installation, working in conjunction with a heat exchanger for partial drying of the slurry. These heat exchangers are known under the terms “slurry dryers”, “concentrator”, “calcinatory”. 3. The medium long wet process rotary kiln with preliminary mechanical dewatering of the slurry by suction or pressure filters. For disintegration and final drying of the filter cake fed into the rotary kiln with a moisture content of 15 – 20%, the kiln is furnished with a short chain section. 4. The short wet process rotary kiln without internal installation with mechanical preliminary dewatering of the slurry. The resulting filter cake is then processed to nodules. These are fed into a preheater , or to a heat exchanger grate.

B-Dry Process
1. The long dry process rotary kiln without internal installation. 2. The long dry process rotary kiln with internal heat exchangers, such as chains, refractory bridges, etc.

46

3. The short dry process rotary kiln working in conjunction with preheaters, such as suspension preheaters. 4. The dry process rotary kiln with waste boiler.

Dry Process Versus Wet Process
 The basic advantage of the dry production method over the wet process is the lower specific heat consumption for clinker burning.  When deciding which production method to select for a new project, it should be realized that there is no general valid rule, because of the absence of a uniform method for a comparable appraisal of the effectiveness of both production methods, and consequently the impossibility of proving unequivocally the superiority of one over the other method.  For this purpose, Expert developed a formula which tells in what case the wet or dry process can be economically applied. However, the factors used in this formula are based on charge prices of the socialistic planned economy, and are therefore not applicable in the domain of the competitive economy.  Previously, clinker produced by the wet method was considered to be of higher quality and uniformity, because of the better homogenization of the raw components in the state of slurry. Now, highly sophisticated pneumatic homogenizing machinery and methods for dry raw mix, allow the preparation of the raw mix with the same degree of uniformity as raw mix prepared by the wet method. There is no difference in the quality of the clinker.  Proportioning of dry raw material components to the required composition is much easier than proportioning of moist, wet or plastic raw material component. It is known that grinding of slurry requires a lower grinding cost. When grinding the same material to the same fineness, dry grinding requires approximately 30% more energy than wet grinding. However, this advantage is neutralized by the fact that 47

the dry grinding wear rate of mill liners and grinding media is only 30 – 40 % of the wet grinding wear rate. Thus the higher wet grinding wear rate offsets the cost of higher energy consumption of dry grinding of the raw mix.  A wet process cement plant requires about 20% more silo volume for slurry storage, compared to the raw mix silo volume of a dry process cement plant with equal capacity.  A conventional heat consumption figure for the wet production process is 860,000 Btu/bbl of clinker, whereas the heat consumption figure for the dry process suspension pre heater kiln is roughly 529,000 Btu/bbl; the difference is 331,000 Btu/bbl in favor of the dry process. For example, using an average price of $ 0.35 per million Btu (1000 cf of natural gas), and an assumed plant capacity of 3,850,000 bbl/year, we get $ 447,000 saving per year on fuel.

The volume of kiln exit gases per bbl of clinker in the dry production process is 529 cf natural gas X 12 = 6348 scf combustion gases plus 1815 scf carbon dioxide form raw mix, thus a total of 8163 scf/bbl. The gas volume for the wet process is 860 cf gas X 12 = 10,320 scf combustion gases, plus 1815 scf carbon dioxide, plus 323 lb water X 20 =6460 scf water vapor from slurry . The total volume of kiln exit gases for the wet process is 18,595 scf, thus 18,595 – 8163 = 10,432 scf/bbl of clinker more than at the dry process.

Choice Of Process
As a result of above discussion, the Dry Process is selected for the manufacturing of Portland cement.

48

MATERIAL BALANCE

49

MATERIAL BALANCE
ANALYSIS OF LIMESTONE, CLAY AND CLINKER

C1 Component Limestone (Wt.% ) SiO2 Al2O3 Fe2O3 CaO SO3 MgO Na2O Cl2 K2O Insoluble residue LOI 1.29 0.32 0.10 53.53 0.02 0.70 0.81 0.003 0.04 43.18

C2 Clay (Wt. %) 48.72 12.03 2.60 7.95 0.02 2.93 0.74 0.005 2.14 22.86

C3 Clinker (Wt. %) 20.89 5.378 3.53 62.64 0.04 2.5 0.48 0.85 1.7 -

50

QUALITY CONTROL FORMULAE
1.
As

Silica Ratio:
SR = [SiO2]/ (Al2O3 + Fe2O3)

By putting values, we get

SR = 20.89/[5.378 +3.53] SR = 2.34

Range = 1.9 - 3.2 (In Range)

2.
As

Lime Saturation Factor
LSF = CaO / [2.8SiO2 + 1.65 AI2O3 + 0.35.Fe203]

By putting values, we get = 62.64/ [(2.8 x20.89) + (1.65 x5.378) + (0.35 x3.53)] = 62.64/68.60 =0.91 Range = 0.5 - 1.3 (In Range)

3.

Hydraulic Ratio

HR = CaO/ [SiO2 + Al2O3 + Fe2O3] By putting value, we get HR = 62.64 / [20.89+ 5.378 +3.53] = 2.1 Range = 1.7-2.3 (In Range)

51

4.

Alumina Ratio:

AR = Al2O3 / Fe2O3 By putting values, we get

AR = 5.378/3.53 = 1.52 Range = 1.5-2.5 (In Range)

From these formulae it has been proved that the cement obtained from this clinker has well and quality control is maintained.

5.

Burn Ability Index

BI = C3S/ [C4AF + C3A] Where C3S = 4.07 Hca - (7.6HSi + 6.72 HAl + 1.43HFe + 2.85 HMg) And HSi, HAl, HFe and HMg are compositions of SiO2, Al2O3, Fe2O3 and MgO in clinker.

Putting the values, we get = (4.07 x62.64) – {(7.6 x 20.89) + (6.72 x5.378) + (1.43 x 3.53) + (2.85 x 2.5)} =47.87

52

C4AF = 3.04 HFe C4AF = 3.04 x 3.53 = 10.73 C3A = 2.65 HAl - 1.69 HFe C3A = 2.65 x 5.378 - 1.69 x 3.53

C3A = 8.29 Putting all these values in Eq.1, we get

BI = 47.87/[10.73 + 8.29] BI = 2.52

RAW MIX PREPARATION
Hydraulic Modulus

HM = C/[S + A + F] HM = Cm/[Sm + Am + Fm] (For raw mix)

According to this method of calculations: Cm = [XC1 + C2] / [X + 1] Sm = [XS1 + S2] / [X+1] Am = [XA1 +A2] / [X+1] Fm = [XF1 + F2] / [X+1] Where 'X' is parts of limestone in raw mix
53

C1 = Composition of CaO in limestone C2 = Composition of CaO in clay S1, A1, F1 = Composition of SiO2, Al2O3 & Fe2O3 in limestone S2, A2, F2 = Composition of SiO2, Al2O3 & Fe2O3 in Clay Putting these values of Cm, Sm, Am & Fm in above formula we get

HM =

(XC1+ C2)/ (X+1)___________________ [{(XS1+S2)/(X+1)}+{(XA1+A2)/(X+1)}+{(XF1+F2)/(X+1)}]

By solving and rearranging, we get X = HM (S2+A2+F2)-C2 C1-HM (S1+A1+F1) Assume HM = 2.1

Putting the values we get X= 2.1 (48.718+12.03+2.6)-7.95 53.53-2.1(1.29+0.32+0.1) X = 2.5

If HM Value of clinker is 2.1, we have to mix 2.5 parts of lime stone and one part of clay. Thus raw mix consists of R1 R2 Where R1 =composition of limestone in raw mix R2 =Composition of clay in raw mix
54

= [2.5 /3.5] = [1/3.5] x100

x 100 =

=

71.43%

28.57%

DRY RAW MIX COMPOSITION
SiO2 =SiO2 X R1 +SiO2 x R2 =1.29 x 0.7143 +48.718 x 0.2857 =14.84 %

AI2O3 =Al2O3X R1 + Al2O3x R2 = [0.32 x 0.7143] + [12.03x 0.2857] =3.66%

F e2O3 = Fe2O3 x R1 + Fe2O3 x R2 = [0.1 x 0.7143] + [2.6x 0.2857] = 0.814%

CaO = CaO x R1 +. CaO x R2 =[53.53 x 0.7143] + [7.95x 0..2857] = 40.51%

MgO = MgO X R1 + MgO x R2 = [0.7 x 0.7143] + [0.93x.2857] =1.34% Na2O = Na2O X R1 + Na2O x R2 = [0.81x 0.7143] + [0.74x 0.2857] = 0.79 % K2O = K2OX R1 + K2O x R2 = [0.04 x 0.7143] + [2.14 x 0.2857] =0.64% SO3 = SO3 X R1 + SO3 X R2 = [0.02 x 0.7143] + [0.02 x .2857]
55

= 0.02% Cl= Cl X R1 + Cl X R2 = [0.003 x 0.7143] + [0.005 x 0.2857] = 0.00357% LOl =LOI x R1 + LOI x R2 = [43.18 x 0.7143] + [22.86 x 0.2857] =37.37% So Dry Raw Mix Composition

SiO2 Al2O3

14.8 4%. 3.66%

Fe2O3 CaO MgO Na2O K2O SO3 Cl LOI Total

0.814% 40.51% 1.34% 0.79% 0.64% 0.02 % 0.00357 37.37% 99.99

56

RAW MATERIAL REQUIRED
BASIS: 6700 TPD clinker (Dry basis) Raw mixture required for 1 ton= 100/ (100-LOI) = 100/ (100-37.37) = 1.597 ton/day

Raw mix required for 6700 TPD

=1.597 x 6700 =10699.99 tons/day

Dust factor =1.005

Raw mix required for 6700 T/day =10699.9x 1.005 =10753.4 TPD Moisture in raw material = 0.5%

Lime Stone =[10753.4/0.995]x 0.7143 =7719.7 TPD

Clay

=[10753.4/0.995] x 0.2857 =3087.7 TPD

57

For 6700 tons/day manufacture of cement, we require Limestone Clay =7719.7 TPD =3087.7 TPD

SiO2

=

SiO2 raw mix x 6700 1-[LOI/100]

=0.1484/[1-0.3737] x 6700 =1587.54 TPD

Al2O3 =

Al2O3 raw mix x 6700 1-[LOI/100]

=0.0366/[1-0.3737] x 6700 =391.62 TPD

Fe2O3 =

Fe2O3 raw mix x 6700 1-[LOI/100] = 0.00814 / [1-0.3737] x 6700 = 87.09 TPD

CaO

=

CaO raw mix x 6700 1-[LOI/100]

=0.4051/[1-0.3737] x 6700 =4334.66 TPD MgO = MgO raw mix x 6700 1-[LOI/100] = 0.0134/[1-0.3737] x 6700 = 143.38TPD

SO3 =

S03 raw mix. x 6700 1-[LOI/100] 58

= 0.0002/[1-0.3737] x 6700 =2.14 TPD

Na2O =

Na2O raw mix x 6700 1-[LOI/100]

=0.0079/[1-0.3737] x 6700 =84.53 TPD

K2O

=

K2O raw mix x 6700 1 - [LOl/ 100]

= 0.0064/[1-0.3737] x 6700 = 68.48 TPD Cl = Cl raw mix x 6700 1 - [LOl/ 100] =0.000036/[1-0.3737] x 6700 = 0.385 TPD

59

CLINKER COMPOSITION
SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O K2O Cl Total 1587.54tons/day 391.67tons/day 87.09 tons/day 4334.67 tons/day 143.38 tons/day 2.14 tons /day 54.53 tons/day 68.48 tons/day 0.385 tons/day 6699.9tons/day

60

ENERGY BALANCE

61

ENERGY BALANCE
The energy balance is carried out on the pre calciner kiln system. During the balance many assumed values may appear as due to unavailability of data.

Input Heat Calculations
Heat Input by Consumption of Fuel
By the calculations it was found that the coal required to produced 1ton of Clinker Calorific value of Coal Heat input through the combustion of fuel =0.12 x 6700,000 =804,000 kcal/ton of clinker For 6700 ton clinker = 804,000 x 6700 =5.41 x 109 kcal/6700 ton clinker About 60% fuel is burning in calciner and about 40% burning is carried out at kiln. = 0.120 ton. =6700, 000 kcal/ ton

Heat Input As Sensible Heat In Fuel
Mass of coal Mean specific heat capacity of coal Temperature of coal at inlet Reference temperature Heat input =0.12 ton/ton of clinker = 225 kcal / ton.oC =100oC =25 oC = m Cp ∆t = 0.12 x 225 x (100 – 25) =2025 kcal/ ton clinker For 6700 ton of clinker clinker =1.355 x 107 kcal/6700 ton

62

2-Sensible Heat In Kiln Feed
a-Dry Feed Required To Produced One Ton Clinker
= 1/[1 – (LOI/100)] =1/[1 – 0.3737] = 1.597 ton /ton of clinker Temperature of feed at pre heater entrances = 60 oC Specific heat of dry feed Reference temperature Heat input as sensible heat = 236 kcal/ton. oC = 25 oC = m Cp ∆t = 1.597 x 236 x (60 – 25) =13191kcal/ton of clinker.

b-Feed Water Present In Kiln Feed
= 0.5% (water in kiln feed for dry Process should be less than 1%) Temperature of feed Reference temperature Specific heat of water Sensible heat due to water in kiln feed = 60 oC = 25 oC = 1000 kcal/ton oC = (0.5/100) x1.597x100x (60-25) = 279 kcal/ton of clinker Total sensible heat in kiln feed = 13191+279 = 13470 kcal/ton of clinker

For 6700 ton of clinker

=9.03x107 kcal/6700 ton of clinker

63

3-Secondary Air Sensible Heat
Coal required = 0.12 ton

Coal used for burning has following analysis

Ultimate Analysis C H O N2 S Ash = = = = = = 86.70% 2.2% 2.9% 0.8% 0.5% 6.9%

Combustion of fuel gives following reaction C + O2 CO2

H2 + ½ O2

H2O

S

+

O2

SO2 2NO2

N2 + 2O2

Basis: 1 Ton of Coal
Theoretical Air Required According to the above four reaction, oxygen required for combustion = 2.312 + 0.176 + 0.0183 + 0.01 = 2.5163 ton of O2 O2 present already in coal So net O2 required = 0.029 ton = 2.5163 – 0.029 =2.4873 ton of O2

64

Air required 23 ton O2 present in 1 ton O2 present in 2.4873 ton O2 present in = 100 ton of Air = 100/23 ton Air = 100 x 2.4873/ 23 = 10.81 ton of Air /ton of coal One ton clinker required coal = 0.12 ton

So Air required to produced one ton clinker = 10.81 x 0.12 = 1.297 ton Air /ton of clinker For 6700 ton clinker = = 1.297 x 6700

8689.9 ton Air /6700 ton clinker

Excess Air depends upon type of fuel and burner, Assume excess air used Total Air required = 12% = 1.12 x 1.297 = 1.452 ton Air/ ton clinker About 60% of this Air required for combustion is fed as secondary Air So mass of secondary Air =1.452 x 0.6 =0.872 ton Air /ton clinker Temperature of secondary Air Reference temperature Specific heat of secondary Air Heat input in secondary Air = 900oC = 25oC = 279.9 kcal/ton.oC = m Cp ∆t = 0.872 x 279.9 x (900 – 25) = 213461.8 kcal/ton clinker For 6700 ton of clinker = 213461.8 x 6700 = 1.43 x 109 kcal/6700 ton clinker

65

5. Primary Air Sensible Heat
About 40% of total air is fed as primary Air, primary air required for combustion = 1.452 x 0.4 = 0.581 ton Air /ton clinker = 25oC = 239 kcal/ton.oC = m Cp ∆t =0.581 x 239 x (25 – 25) = 0 kcal/ton clinker

Temperature of primary Air

Specific heat of primary Air Heat input as sensible heat

66

Output Heat Calculation
1) Heat of Reaction
The raw mix yield the following analysis of clinker

Component SiO2 Al2O3 Fe2O3 CaO MgO Na2O SO3 K2O I.R

percentage (%) 20.89 5.378 3.53 62.64 2.5 0.48 0.04 0.85 1.5

During the clinker formation exothermic and endothermic reaction takes place, the heat evolved can be calculated as Heat . of Reaction = 4.11%Al2O3 + 6.48%MgO + 7.646%CaO – 5.11%SiO2 – 0.59%Fe2O3 = 4.11 x 5.378 + 6.48 x 2.5 + 7.64 x 62.64 – 5.11 x . 20.89 – 0.59 x 3.53

= 0.59 x 3.53 = 408.04 kcal/kg clinker = 408040kal/ton clinker For 6700 ton clinker = 2.734 x 109 kcal/6700 ton clinker

67

2) Heat Losses with Kiln Exit Gases
a. Exit gas from coal burning:As the composition of coal is Ultimate Analysis C H O N2 S Ash = = = = = = 86.70% 2.2% 2.9% 0.8% 0.5% 6.9%

Combustion of fuel gives following reaction C + O2 H2 + ½ O2 S + O2 CO2 H2O SO2 2NO2 = 10.814 x 0.12 = 1.297 ton/ton clinker

N2 + 2O2 Air required to produced 1 ton clinker

N2 in Air CO2 in exit gases CO2 formed for 1 ton of clinker H2O in exit gases

= 1.297 x 0.77 = 0.9987 ton N2/ton clinker = 44 x 0.897/12 = 3.179 ton CO2 / ton of coal = 3.179 x 0.12 = 0.381 ton CO2 /ton clinker = 18 x 0.022/2 68

= 0.198 ton H2O /ton coal For 1 ton clinker = 0.198 x 0.12 = 0.237 ton H2O/ton clinker SO2 in exit gases SO2 for 1 ton clinker NO2 in exit gases NO2 for 1 ton clinker Total exit due to fuel burning = 64 x 0.005/32 = 0.01 SO2 /ton of coal = 0.01 x 0.12 =1.2 x 10-3 ton SO2 /ton clinker = 60 x0.008/28 = 0.0171 ton NO2 /ton coal = 0.0171 x 0.12 = 2.05 x 10-3 ton NO2/ton clinker = 0.381 + 0.237 + 1.2 x 10-3 + 2.05 x 10-3 = 0.4079 ton gas/ton clinker

B-Exit Gas From Kiln Feed
Kiln feed required Composition of feed Component SiO2 Al2O3 Fe2O3 CaO MgO LOI Percentage (%) 14.84 3.66 0.814 40.51 1.34 37.37 = 1.597 ton feed / ton clinker

69

CaCO3 MgCO3 56 ton CaO required 0.4051 ton CaO required

CaO + CO2 MgO + CO2 = 100 ton CaCO3 = 100 x 0.4051/56 = 0.724 ton CaCO3/ton feed

For 1 ton clinker

= 0.724 x 1.597 = 1.156 ton CaCO3 /ton clinker

40 ton MgO required 0.0134 ton MgO required

= 84 ton MgCO3 = 84 x 0.0134/40 = 0.02814 ton MgCO3/ton feed

For 1 ton clinker

= 0.02814 x 1.597 = 0.045 ton MgCO3 /ton clinker

CO2 evolved due to CaCO3 = 44 x 1.156/100 = 0.51 ton CO2 / ton clinker CO2 evolved due to MgCO3 Total CO2 due to kiln feed = 44 x 0.045/84 = 0.024 ton CO2 /ton clinker = 0.51 + 0.024 = 0.534 ton CO2/ton clinker H2O (free) evaporated in kiln feed = 0.5 x 1.597/100 = 0.008 ton H2O/ton clinker H2O Combined evaporated = (0.02/1.597) x (0.00075%SiO 2) + (0.0035%Al2O3) = (0.02/1.597) x (0.00075 x 14.84) + (0.0035 x 3.66) =0.014 ton water/ ton clinker Total water due to feed in exit gases = 0.008 + 0.014 = 0.022 ton water/ton clinker

70

c. Exit Gas Analysis (Excess Air)
Excess Air Weight of Excess Air = 12% = %age excess air x air used for Combustion = 0.12 x 1.297 =0.1556 ton Air / ton clinker N2 in excess air O2 in excess air = 0.1556 x 0.77 = 0.1198 ton N2/ton clinker = 0.1556 x 0.23 = 0.0358 ton O2/ton clinker

Weight of gases in exit gases as follows N2 = 0.9987 + 0.12 CO2 = 0.381 + 0.534 O2 H2O = 0.0237 + 0.02 SO2 NO2 = 1.118 ton /ton clinker = 0.915 ton /ton clinker = 0.358 ton /ton clinker = 0.0437 ton /ton clinker = 1.2 x 10-3 ton /ton clinker = 0.002052 ton /ton clinker

Exit gas temperature is 300oC. Its specific heat is given as 259.9 kcal /ton.oC 489.9 kcal /ton.oC 259.9 kcal /ton.oC 179.9 kcal /ton.oC 239.9 kcal /ton.oC 249.5 kcal /ton.oC

CO2 H2O N2 SO2 O2 NO2 T1 T2 CO2 = = =

= = = = = = 25oC 300 oC

Heat loss due to m Cp ∆t 71

= 0.915 x 259.9 x (300 – 25) = 65379.3 kcal/ton clinker H2O = m Cp ∆t

= 0.449 x 489.98(300-25) = 5887.37 kcal/ton clinker N2 = m Cp ∆t

= 1.118 x 259.9 x (300-25) = 79906.25 kcal/ton clinker O2 = m Cp ∆t = 0.0358 x 239.9 x (300-25) = 2361.81kcal/ton clinker SO2 = m Cp ∆t =1.20 x 179.9 x (300-25) = 59.37kcal/ton clinker NO2 = m Cp ∆t = 0.002055 x 249.9 x (300-25) = 141.22 kcal/ton clinker Therefore total heat output due to exit gas =1543735.02 kcal/ton clinker For 6700 ton clinker =153735.02 x 6700 =1.03x109kcal/6700 ton clinker

3. Heat Loss Due To Mixture in Raw Mix
Moisture in raw mix Raw mix required Specific heat of water Latent heat of vaporization Temp. Of kiln feed Heat loss due to moisture = 0.5% = 1.597 ton/ton clinker =1000 kcal/tonoC =510 kcal/ton =60oC = m Cp ∆t+mλ = (0.5/100) x 1000 x (100-25) + (0.5/100) x 1.597 x 510 = 7.984+4.072 = 12.056 kcal/ton clinker 72

For 6700 ton

=12.056 x 6700 =80775.2 kcal/6700ton clinker =8.07x104 kcal/6700ton clinker

4-Heat In Clinker At Kiln Discharge
Reference temperature Temp. of clinker at outlet of kiln Specific heat of clinker at 1300oC T1=25oC T2=1300 oC = 270 kcal/tonoC

Heat loss Due to Clinker Discharge = m Cp ∆t = 1 x 270 x (1300-25) = 344250 kcal/ton clinker For 6700 ton =344250 x 6700 = 2.306x109 kcal/6700 ton clinker

Heat Loss Radiation And Convection
Heat loss by convection and radiation from whole the system is given as; = 90.149 kcal/kg clinker = 90149 kcal/ton clinker For 6700 ton = 90149 x 6700 = 6.04x 108 kcal/6700 ton clinker

73

Heat Balance Sheet

Heat Input Heat Input by Consumption of Fuel Heat Input As sensible Heat in Fuel Sensible Heat in Kiln Feed Primary Air Sensible Heat Secondary Air Sensible Heat Total

Kcal/6700 ton clinker 5.41x10 9 1.355x107 9.03x10 7 1.43x10 9 0.0 6.94 x 109

Heat Output Heat of reaction Heat losses with kiln exit gases Heat losses due to moisture in raw mixture Heat in clinker at kiln discharge Heat losses by radiation and convection Total

Kcal/6700 ton clinker 2.734 x 109 1.3 x 109 8.07 x 104 2.306 x 109 6.04 x 10 8 6.94 x 109

74

EQUIPMENT DESIGN

75

EQUIPMENT DESIGN
Kiln Design
Calculation For The Diameter Of The Rotary Kiln Basis
6700 ton/day clinker Martin‟s formula considering thermodynamic condition in the rotary kiln: This formula reads Q = 2.826D2 . V/Vg Notation: Q = Kiln capacity, t/h D = Kiln diameter on bricks, m V = Gas velocity in the gas discharge end, m/s Vg = Specific gas volume, m3/kg clinker Since the kiln capacity formulas take into consideration only a fraction of the factors influencing the kiln‟s capacity, they have merely limited application. Applying martin‟s formula to dry kiln of a capacity of 125 t/h (3000 t/day) with the kiln diameter 4.15m on the bricks, we get following results. 125 = 2.826(4.15)2 V/Vg V/Vg = 2.568

Keeping the same value of V/Vg, for a dry process cement kiln of capacity 279.167 t/h (6700 t/day), the diameter of the kiln will be as follows;

76

279.167 = 2.826D2 (2.568) D2 D2 = 38.47 = 6.2m

Similarly the outlet diameter of the kiln will be given as: 125 = 2.826 (3.75)2 V/Vg V/Vg = 125/[2.826(3.75)2 ] V/Vg = 3.145 Where 3.75m is the on brick dia of a 125t/h capacity dry process kiln. The same ratio of V/Vg for a 279.167t/h (6700 ton/day) capacity kiln. Replacing values in martin‟s formula: 279.167 = 2.826 D2 (3.145) D2 D = 31.41 = 5.6 m

77

Calculation Of The Length Of The Rotary Kiln
Basis: 6700 ton/day clinker
The length of the rotary kiln can be calculated by the formula: Q= D.L [45 + K {(D/L) – 0.02}] 1000 [1 + (W – 40)(1.6/100)] The above formula is simplified for dry process when water contents will be zero. Q= D.L [45 + K {(D/L) – 0.02}]

Notation; Q = Rotary Kiln capacity/h D = Mean Kiln dia on brick, m L = length of the kiln, m K = characteristic index of kiln, t/h.m2 Data Q = 279.167 t/h D = 5.902 m K = 3064 t/h.m2

The length can be calculated as follows; 279.167 = 5.902 x L [45 + 3064{(5.902/L) – 0.02}] L = 64.75 m

78

Kiln Slope
No generally valid rule exists for the proper slopes of rotary kiln. Rotary kilns show slopes from 2 to 6%. Lower kiln slopes require higher number of revolutions. This has the benefit of better mixing of the kiln feed, together with a more intensive heat exchange. Lower slopes also permit higher degrees kiln filling or kiln load. The following kiln slopes were found by Bohman to the correct. 5% slope for kiln with dia upto 9‟2” 4% slope for kiln with dia from 9‟10” to 11‟2” 3% slope for kiln with dia above 11‟2” As until now, this recommendation is proved good, since most of the rotary kilns with dia above 11‟2”, show slopes of about 2 – 3.5% on the basis of the result of Bohman the slope assigned to the kiln is 3%.

Degree Of The Kiln Filling
The feed form a segment of the rotary kiln‟s crosssection. The area ratio of this segment to the area of the kiln‟s cross-section expressed in percent is called kiln‟s degree or percent of filling. Kiln filling degree fluctuates within the limits of about 5 – 17%. Independent from the kiln‟s diameter. Selecting degree of kiln filling 15%. From the graph of %age filling and centric angle the following results were obtained for kiln. Kiln load = 15% Centric angle ά = 108o

79

Revolution Of The Rotary Kiln
Form the graph between kiln dia and revolutions in the case of circumferential speed of 14.7 in/sec, kiln revolutions were calculated to be 1.8rpm. Thermal Load Of The Cross – Section Of The Burning Zone The quantity of heat which glows during one hour through 1 m 2 of the cross –section of the kiln‟s burning zone. Formulae read: Qp = 1.4 x 106 x D (kcal/m2.h) Qp = 1.4 x 106 x (5.902) Qp = 8.26 x 106 kcal/m2.h

Residence Time
Formula for calculating residence time of the rotary kiln is: Residence time = t = 1.77 x L x 6.325 x F PxDxN Notation: t = Residence time, min L = Length of rotary kiln, m D = Diameter of rotary kiln, m P = Slope of the kiln degree N = Number of revolutions per min F = Factor = 1 Replacing values, we get t= 1.77 x 64.75 x 6.325 x 1 1.717 x 5.902 x 1.8 t = 39.74 min By using proper kiln slope and varying the number of revolutions, can control the residence time (t).

80

Thermal Expansion Of The Rotary Kiln
a) Linear Expansion
When in operation, length and circumference of the rotary kiln are larger than in the inactive state. These circumferences must be taken into consideration, so that the riding rings can always rest entirely on the roller and that the seals on both ends of the kiln will not be impaired. The linear expansion in the rotary kiln‟s length is given as: A1 = α [{(t1 + t2)/2} – t] L1 A2 = α [{(t1 + t2)/2} – t] L2 Notation: α = Linear expansion index for steel, = 0.000012 t1 = Highest temperature on the kiln‟s circumference = 350oC t2 = temperature on the kiln‟s ends, 155oC and 60oC respectively L1&L2 = Length from the highest temperature point to both kiln ends L1 = 10.79 m = 10790mm L2 = 53.96 m = 53960mm T = Ambient Temperature = 25oC Then the linear expansion is given as: A1 = = A2 = = 0.000012[{(350+155)/2} – 25] 10790 29.456 mm 0.000012[{(350+60)/2} – 25] 53960 116.55mm

Total expansion = 29.45 + 116.55 = 146.01mm Linear expansion, expressed in percent = 146.01 x 100/64750 = 0.225%

81

b) Expansion along Diameter
The formula is given as: = α (300 – t) D = 0.000012(300 – 25)6200 = 20.46mm

c) Expansion Along circumference
From previous case it is clear that the kiln‟s dia on heating will be 6220.46mm. Some result can be obtained after considering the expansion in the circumference. Expansion = α (300 – t) U U = πD = 3.1415 x 6200 = 19477.87 mm Expansion = 0.000012 (300 – 25) x 19477.87 = 64.28 mm Expansion Along total circumference = 19477.87 + 64.28 = 19542.45mm Kiln‟s dia in hot state = 19542.45/ π = 6220.45mm

82

Vertical Load Of Kiln
The vertical load of kiln is due to the a) b) Mass of kiln shell Mass of kiln lining

a) Mass of kiln shell D = Dia of kiln shell (without lining) = 6.2m L = Length of kiln shell = 64.75m

Thickness of kiln sheet Area = (D22 – D12) π Area = (6.242 – 6.22) x 3.1415 Area = 1.56 m2 Density of steel (at 200oC) = 7830kg/m3 Volume of kiln shell = Area x length = 1.56 x 64.75 = 101.01 m3 Mass of kiln shell = volume x density = 101.01 x 7830 = 790908.3 kg b) Mass of kiln lining Dia of kiln with lining Dia of kiln without lining Length of kiln Cross sectional area of lining

= 0.02m

= 5.78m = 6.2m = 64.75m = (6.22 – 5.782) x 3.1415 = 15.8m2

Length of calcining zone

= 64.75 x 0.4 = 25.9m = 25900mm

83

Length of burning zone

= 64.75 x 0.35 = 22.66m =22660mm

.

Length of cooling zone

= 64.75 x 0.25 = 16.19 m . 16190mm

Mass of lining in calcining zone (fire bricks)

= 25.9 x 15.8 x 2100 = 859362kg

Mass of lining in burning zone

= 22.66 x 15.8 x 2550 = 912971.4 kg

Mass of lining in cooling zone

= 16.19 x 15.8 x 2900 = 741825.8kg

Total Mass of lining

= 859362 + 912971.4 + 741825.8

=2514159.2kg

Density of fire bricks Having basic material chansotte Density of high Alumina bricks Having basic material bauxite Having basic material dolomite = 2550 kg/m 3 = 2900 kg/m 3 = 2100kg/m 3

Total vertical load of kiln of lining

= Mass of kiln shell + Total mass

=

790908.3 + 2514159.2

= 3305067.5kg

84

Horse Power Requirement Of The Rotary Kiln
Horse power requirement can be calculated by the following formula:

a-Load horse power
It is calculated by formula: Hp = (D x Sin θ)3 x N x L x K Notation D = Inside kiln dia (ft) Sin θ = Factor calculated by % of kiln load N L K Data D Kiln load Sin θ N L Hp = = = = = 20.33 ft 15 % 0.82 ( from the graph) 1.8 RPM 212.38 ft = RPM of kiln = = Length of kiln (ft) 0.00076 for dry process.

= (20.33 x 0.82)3 x 1.8 x 212.38 x 0.00076 = 1346 hp

Friction horse power
Formula for friction horse power is given as:

Hp = W x bd x td x N x F x 0.0000092 rd

85

Notation W = Total vertical load on all roller shaft bearing (lb) bd = Roller shaft bearing dia, inch rd = Roller dia, inch td = Riding tyre dia. inch N = RPM of kiln F = Co-efficient of friction of roller bearing, 0.018 for oil Lubricated bearing.

Hp =

7286351.8 x 16 x 174 x 1.8 x 0.018 x 0.0000092 42 = 143.96 hp

Total horse power required

= Load horse power + friction horse power = 1346 + 143.96 = 1489.96 hp = 1111.9 KW

86

CRUSHER
PRINCIPLE OF CRUSHING
The raw materials are quarried in lumps up to 1-2 m and must be reduced to less than 0.2 mm. This reduction is carried out in two stages, crushing down to 25 mm because the mill is designed for a feed of that maximum size and subsequent grinding. Raw materials occur in widely varying forms and a large range of crusher types is available. Combination, i.e. the process of fragmenting materials, can be effected according to three different principles.   

Impact: (Hammer, crusher, drier-crusher) Compression: (Jaw crusher, cone crusher) Shearing: (roll-jaw crusher, roller crusher)

The relationship between feed size and exit size of the material is termed as the reduction factor. Crushers with high reduction factors like hammer crushers can crush to the required size in one stage. The material is delivered from the quarry usually by dampers, and tipped into the reinforced inlet chute whose bottom a lamellate conveyor is feeding the crusher. The remaining crusher types are used for very hard and abrasive respectively soft and sticky materials. They all have low reduction factors and in the cement factory they are normally operated in multi-stage crushing. After the first stage, the fine fraction of pre-crushed material is removed on a vibrating screen and added to the coarse fraction which is finish crushed in a smaller secondary cone crusher.

87

Selection of Crushing Machinery
The table should be guidance to the selection of crushers for cement raw materials. Material Limestone, hard., abrasive Crusher used Cone crusher Jaw crusher sandstone, hard and massive Cone Crusher

Selected Crusher Type
1. Jaw Crusher 2. Blake Jaw crusher 3. Hammer crusher The hammer crushers without inlet grate are basically secondary crushers, but their robust and sturdy design makes them well-suited for primary crushing for materials which have been quarried by ripping or similar fragmenting methods as well as for gypsum and raw coal. They can also handle materials containing some degree of moisture. Hammer crushers without inlet grate are available with rotational speeds suitable for primary as well as secondary crushing, and can be tailored to suit individual raw materials. The slot widths in the outlet grates may be adapted to the operational conditions in question. Hammer crushers without inlet grate are available with one or two sets of rotors. The rotor shafts are fitted with hammer discs on which the hammers are pivotally mounted.

88

The rotor shafts run in sturdy oil bath-lubricated roller bearings and are supported on the crusher casing of heavy cast steel and welded up sections bolted together. The casing is fined with replaceable wear plates. The double hammer crusher has a heavy anvil with replaceable crushing plates which are adjustable in relation to the hammers to compensate for wear. The double hammer crusher has a heavy anvil with replaceable crushing jaws and outlet grate, both of which can be adjusted to compensate for wear.

The single hammer crusher has an outlet grate with replaceable grate bars and an adjustable crushing plate. Hammer crushers without inlet grate are designated EUI (single without inlet grate) and DUI (double without inlet grate), followed by two digits specifying the diameter across the hammers and the width of the rotor unit.

89

Primary Crushing
   For outlet slots 34 ≥50 mm, base calculations on 1.2 x rated output for the motor size stated. For outlet slots 34 ≥75 mm, base calculations on 1.4 x rated output for the motor size stated. For outlet slots 34 ≥1000mm, base calculations on 1.6 x rated output for the motor size stated. For secondary crushing, outlet slots larger than 34 mm are used only in exceptional cases.

Jaw Crusher:
In the cement industry the jaw crusher is in general use; this is due to its relatively simple design and also to the circumstance that this is manufactured in large units. The jaw crusher serves mainly as a primary crusher. The size reduction of the crusher feed is performed between two crusher jaws; one of them is stationary, and the other is moved by toggle pressure. The jaws are lined with ribbed liners, consisting of chill cost or quenched steel. The crusher frame consists of cast steel; frames of large units consist of 4 to 6 assembled sectional steel frame plates. To crush hard, semi-hard and brittle rocks, ribbed liners are used. The included angle of the ribs amounts to 90-100°. For crushing of coarser and considerably harder rocks, the ribs should be corrugated; here the rib angle should be 100-110°. For large and very hard rocks, liners with more widely spaced ribs are used. The most effective ratio between the rib width and its height is expressed as: t ~ 2 /3h Depending on the size of the crusher feed, the width of the ribs in Jaw crushers employed as primary crushers 2 to 6 inches. Jaw crushers employed as secondary crushers have ribs with a width of 0.4-1.6 inches. The width of the 90

crushers discharge opening is being measured from the fop of the rib of one liner to the opposite notching of the other liner; it is the distance between the planes. When working very hard materials, the ribs generate lateral forces which have a negative influence on the swing Jaw shaft, in such cases even jaw liners are preferred. For the pre crushing of limestone, so called super elevated ribs are successfully employed. Every third or fourth rib has a greater height than the normal liner ribbing. Formation of lamella or needle-shaped pieces in the crushed material is hereby prevented. The greater wear shows at the lower part of the fixed jaw plate; next the lower part of the swing jaw plate. The constructional design of the jaw liners makes it possible to turn over a worn jaw liner 180°, so that the worn sides come upwards, this makes it possible to extend the life time of the jaw liners. The liners consist of austenitic manganese steel with a Mn content of 12-14%. The life time of the liners amounts to 800-1000 working hours, depending upon the hardness of the crushed material.

Overload Safety Device
If unbreakable objects such as tramp iron, digger teeth etc, enter the crusher, they can cause considerable damage to the crushing elements. To prevent this, toggle plates which shatter, when tramp iron causes an overload were developed as safety devices for protecting the crusher from serious damage. Two different modifications of safety toggle plates with predetermined cracking lines. After cracking, the toggle plates have to be replaced; this usually results in an extended interruption of production time. To avoid this, a hydraulic overload safety device has been developed; because of it un-crushable objects can automatically be removed from the crushing space without any interruption of operation. With this construction the stationary jaw is designed as a swing jaw, capable of giving way and having its fulcrum at the upper end. The lower end is supported on three hydraulic cylinders the pistons of which are in the front end position when the swing jaw is closed.

91

In case an un-crushable object enters the space between the crushing jaws, the resulting over-pressure in the hydraulic system opens the jaw and the foreign materials falls out of the crushing space. Subsequently, the hydraulic cylinders move the swing jaw back to the normal operating position. During this procedure the feeding of the material to be crushed is automatically interrupted, whereas the crusher drive runs continuously. The increase in investment cost for the hydraulic protection device is approximately 25% of the crusher price.

Speed Of Rotation
In addition to its size, the through put capacity of a jaw crusher is also determined by the number of revolutions. However, the speed of rotation should not be excessive, since practical experience has proved that an increase in speed beyond a certain limit does not yield an increase in capacity. The backward and forward motion of the swing jaw must be regulated so as to give the crushed material enough time to leave the discharge opening of the crusher. The formula derived for the speed of rotation of the jaw is n n = Number of revolutions/min S = Way length of the swing jaw α = Angle of the crusher jaw, degree = √(tgα)/S

Calculation Of Speed Of Rotation
Feed opening = 47 x 36 inches Jaw crusher angle = α = 22° Way length of swing jaw = S = 4.5 cm

92

n

= =

√(tgα)/S tan√(22/45)

However, regarding the friction between the crusher feed and crusher jaw the upper limit of the jaw crusher recommended is 170 RPM.

Capacity Of Jaw Crusher
According to LEWENSON

Q Where, Q = crushed capacity, ton/hr B = Width of the Jaw, centimeter

=

150 n.b.s.d.µ.r

d = mean size of the crushed material n = RPM of drive shaft

Loading factor of crushed material depending upon its physical property.

µ = about 0.25 to 0.5

r = specific gravity of crushed feed (Ton/m3) RPM of Drive shaft = 220 RPM

Width of the swing Jaw = 1.20 m

Amplitude of swing jaw = S = 4.5 centimeters

93

Mean size of crushed material = 0.17 meter Specific gravity of limestone =2.7 ton/m3 (Perry) µ = 0.3 (By literature for limestone)

By LEWENSON
Q = 150 x 170 x 1.20 x0.045 x 0.17 x 0.3 x 2.7

Q =190 Ton/hr.

By TAGGART

Q=0.093 b.d.

Where,

Q = crushed capacity, ton/hr b= Width of the Jaw, centimeter d = size of the crushed material b=120 cm d=17 cm

SO, Q = 0.093 x 120 x 17 Q = 190 Ton/hr.

94

Drive Power For Jaw Crusher
According to Viand's formula
N=0.0155 b.D Where, N=Jaw Crusher motor size b=Width of swing jaw, cm D=Maximum dimension of crusher feed, cm

According to Lewenson's formula
N = [n.b (D2-d2)]/0.34 Where, N = Motor size of jaw crusher n = RPM of the main drive shaft b= Width of the swing jaw, meter D = Mean dimension of crusher feed So, Width of Jaw = b = 1.2 meter RPM of main shaft = n = 170 RPM Dimension of crushed feed = D = 0.5 meter. Dimension of crushed feed = 0.17 meter

According to Viand's formula
N = 0.0255 x 120 x 50 N=153 HP

95

According to Lewenson's formula
N = 170 x 1.2 [(0.5)2 - (0.17)2] 0.34 N = 132 HP Safety factor = 10~15% Actual Motor HP = 132(1.15) =152 HP

Designing Of Raw Material Crusher
Heavy Duty Feeder For Limestone Feeding
SIZE : 2200*10000mm WIDTH : 2200mm DISTANCE OF CENTER : 100000mm

Motor For Feed Driving
POWER: 55Kw ROTATING SPEED: 980rpm

Crusher For Lime Stone Crushing
INPUT SIZE: 2400*2500mm ROTATING SPEED: 375rpm CAPACITY: 650 T/Hr

96

Motor For Driving Crusher
POWER: 1000Kw VOLTAGE: 6000V

Motor For Driving Feeding Rolls
POWER: 45KW VOLTAGE: 380V ROTATING SPEED: 740rpm

Belt Conveyor
CAPACITY: 650T/Hr BELT SPEED: 106 m/s

Motor For Driving Belt
POWER: 18.5KW

Crusher Capacity
Qdk = Kiln Capacity = 6700 TPD BDls = Bulk density of limestone = 1.4 tons/m3 K1 Cl = Factor for converting clinker = k1 = 1.8 = Total lime stone component = 85 %

Tcrw = No. of days Crusher runs = 6 days/week Thd = No of hours Crusher runs in a day = 12 hours/day Ht = Hopper to hold material equivalent to Crusher = 20 min RMw = Raw material req. per week = Qdk*K1*7 = 6700* 1.8*7 97

= 84420 tons/week

LSw = Lime stone req. per week = Cl*RMw/100 = 85*84420/100 = 71757 tons/week

Crusher Capacity Required
Qcr = Lsw / Tcrw * Thd = 71757/(6*12) = 996.62tons/hr

Crusher Hopper Capacity
Hv = (Qcr * Ht) / (BDls * 60) = (996.62*20) / (1.4*60) = 237.29 m3

Feeder Capacity for Crusher
As Qcr = 996.62 tons/hr k2 = 1.2 (Over capacity factor)

Qcrf = Qcr * k2 = 1195.94 tons / hr

98

Transportation from Crusher
Q tcro = 1.5 * Qcr = 1494.93 tons / hr

Maximum Capacity of Dumpers
Vd = Hv / Nd = 237.29/2 = 118.64 m3

99

Where Nd = No of Dumpers Hv = Hopper capacity =2 = 237.29 m3

Size & Dimension Size of the feed opening Max. feed size Width of discharge opening Drive shaft RPM Drive motor HP Throughput capacity t/hr Fly Wheel diameter Width of fly Wheel Weight of crusher, Ton Width, inches Height Length

Setting dimensions, inches 47 x 35 23 6-8 170 152 190 82 21 68 148 89 177

100

VERTICAL ROLLER MILL
The vertical mill is the most common type of mill for grinding of raw materials. Due to excellent grinding efficiency combined with a high production capacity as well as a high drying capacity, this type of mill has replaced the ball mill now a day. Rollers mills have a lower energy consumption than ball mills, and require less space per unit and capacity at substantial lower investment cost. Roller mills are developed to work as air swept grinding mills. The working Principe of vertical roller mills is based on two to four grinding rollers with shaft carried on hinged arms and riding on a horizontal grinding table or grinding bowl.

Design Features.
A common characteristic of all the roller mill is that size reduction is effected by rollers or grinding table traveling over a circular bed of material and that the material, after passing under the rollers, is subjected to a preliminary classifying action by a stream of air sweeping through the mill. Depending on the air flow velocity, a certain proportion of the pulverized material is thus carried into a classifier (Air separator ) which normally forms an integral feature of the upper part of the casing of the mill. Oversize particles rejected by the classifier fall back into the grinding chamber, while the fines are swept with the air out of the mill and are collected in a filter or a set of cyclones. As the pneumatic conveying of the material in the mil to the separator requires considerable air flow rate, and as the material leaving the grinding bed and carried up into the classifier comes into intimate contact with air, roller mills are especially suitable for drying of moist feed materials in combination with grinding. This is particularly advantageous because these mills can accept large quantities of hot air or gas at relatively low temperature. The roller mills employed in cement industry have grinding elements of various shapes. Thus, in some mills there are cylindrical rollers, in other the rollers are of truncated conical shape or have flat lateral rollers and a convex circumferential surface. The force that keeps the rollers pressed in contact with the bed of material on the grinding path may be centrifugal force, spring pressure, tension action etc. 101

The material is comminuted by the grinding element rolling on a circular bed of feed material. The larger pieces of material are crushed by the rollers while the smaller one are reduced by the rubbing action. The pulverized material spilling over the edge of grinding table is entrained by the high velocity stream of air, so that the smaller particles are swept upward into the classifier, and the coarser one fall back on the roller path.

Grinding Action Developed In The Roller Mill.
This is the preliminary classifying effect, as distinct from the final separation accomplished in the internal classifier in the upper part of the casing. Because of the shorter residence time of the feed material in the grinding chamber, the bed of material is kept substantially free from fine particles which do not require further grinding, unnecessarily load the mill and tend to form undesirable agglomerations. The important basic conditions for effective grinding in a roller mill are that the grinding element develops a good draw in action and adequate pressure and that a stable bed of material is formed.

102

Draw In Action Of The Grinding Element.
In roller mills, the maximum feed particle size of between 1/20 and 1/ 15 of the roller diameter are permissible. If the material coarser than this is fed to the mill, then there is a danger that the coarser particle will not be drawn in under the rollers but will simply displaced be i.e. pushed in front of the rollers. Furthermore, with in the permissible maximum particle size limit, the draw in action is governed by the granulometric composition and coefficient of friction of the feed material. Thus the bed of material should possess adequate stability so as not to be displaced by the rollers. Also, in order that the rollers do indeed roll on the material and not merely slide along, a sufficiently large frictional force must be developed between their circumference and the material. It may occur when the mill is operating in steady state conditions, the granulometric composition of the feed material changes drastically, due to segregation on emptying the feed hopper, so that the mill temporally receives only feed material. This way adversely affect the stability of the bed, part of the material is displaced, the depth of the bed is, therefore, reduced and the pressure on the rollers to be unchanged. The specific pressure exerted on the material is increased. It may thus happen that the rollers punch through; the bed is displaced, causing mill vibration. As the condition of the feed material is liable to vary with regard to it grind ability, composition granulometric, and moisture content, mill should be designed keeping in view to achieve adequate draw in capacity of the rollers that will deal effectively with any variation likely to occur in the mill feed material. Measures required to achieve adequate draw in capacity of the rollers includes, providing the rollers and roller path with raised ridges and utilizing the joints of renewable segments on these components to provide positive grip.

103

Grinding Bed Formation.
The grinding process that the material undergoes between the rollers and the roller path on the grinding table comprises the following actions.

Drawn - In Of The material.
The particles of feed materials are gripped between the roller and grinding table. The larger which project above the other and are first subjected to the grinding action, are broken down.

Compaction Of The Bed Of Material.
In conjunction with the reduction in size there occurs intensive spatial rearrangement of the individual particles under crushing load. The compressive and shearing forces associated with crushing load have a further size reducing effect, mainly by attrition which indeed the key factor in achieving fine pulverization in a roller mill. The final size reduction is achieved substantially by rubbing together of the material particles subjected to compression and shear while undergoing rearrangement of their position in the bed. To accomplish this requires the fulfillment of several conditions. - Sufficiently high specific grinding pressure - Sufficiently large number of points and area of contact of the particle in relation to one another. - Sufficient large number of movement of the particles in relation to one another. These conditions are directly interrelated, if the bed of material increases in depth, the specific pressure exerted on the material, for a given pressure applied by the rollers, becomes less, if the depth of the bed decreases, the specific pressure increases, but the scope for relative movement of the particles is restricted and number of their points and areas of contact is reduced. Hence every bed of material in a roller mill must be a compromise between the specific grinding pressure that pulverize the material and the bed depth needed for achieving the product fineness required. In most cases, if the mill is fed with material which is uniform in its granulometric composition and size reduction properties and which develop sufficient friction, a stable bed of more or less Constant depth is formed on the grinding table. With difficult materials there is a scope for modifying and controlling the depth of the bed by dam rings. If the materials are too dry and has a high contents of fine particles, stabilization of the bed may be achieved by moistening it. For grinding of soft materials such as marl, the addition of high grade hard limestone is required primarily for correction of the deficient chemical 104

composition of the raw material, improves the performance of roller mills in term of throughput and of operational behavior. To achieve such improvement, the limestone should be as coarse as possible within the bed consisting largely of softer and finer particles. Particles including a very high proportion of recycled classifier rejects that have already been crushed, the coarse limestone particles act as individual “Hard spot" that offer high resistance to the rollers and cause them to lift slightly. The rollers with their mechanical or hydro pneumatic spring action then fall back onto the bed and perform Correspondingly more size reduction on the finer particles they then encounter. Moreover, these hard spot promote more intensive spatial re - arrangement of the particle of material in the bed and thus help to loosen it up, which likewise makes for more effective fine pulverization.

Grinding Speed
The grinding speed is determined by the dimensions of the grinding table and the magnitude of the centrifugal force needed for transporting the material. Apart from minor differences bound up with individual design feature of the various mills, the grinding speed is much the same in all the usual roller mills for any given grinding ring diameter. There is a characteristic value k which expresses the time of action of the grinding pressure (contact force per effective unit area) and provide a criterion for comparing roller mills differing in design:

k=

 kg  sec  2  V W  m  
Z P

z = number of rollers p = total contact force (kg ) v = angular velocity. Rolling circle radius (m / sec W = effective width of rollers ( m ). The effective width of conically tapered rollers can be taken as 100% of the actual width of the contact surface, while for rollers with convex surface about 60% may be adopted. For convex surface roller, a more precise value can be found by examining the extent of wear on the rolling surface.

105

Contact Area.
In Roller Mills size reduction take place by two mechanism : by crushing and by direct attrition on heavy bed of material. The particles of feed materials are gripped between the rollers and the grinding rings. The larger ones, which project above the other and are the first to be subjected to the crushing action, are broken. In conjunction with the reduction in size there occurs intensive spatial rearrangement of the individual particles under crushing load. The compressive and shearing forces associated with this have a further size reducing effect, mainly by attrition, which is indeed a key factor in achieving fine pulverization in a roller mill which in turn is a function of angle of friction between material and and the metal of grinding element. The limiting value of specific friction coeffici element, the larger the feed size it can be accepted. Contact area is proportional to Wd, where W is the roller width and d is the roller diameter. The theoretical power consumption of a vertical roller mill is expressed by the formula
N = KT  A  Z  V Where
KW( net)

A = roller projected area m^2 KT = specific grinding pressure kN z = number of rollers v = grinding track speed m/ sec N = Mill power intake Kw

Capacity Of Roller Mill. Rollers Projected Area
A=
DR  WR

DR = Roller diameter (m). WR = Roller width (m)

106

For Attox Mill The Flowing Applies
KT  N DR  W

KT : typically 500 ~ 700

DR  0.6  Do

W = 0.2  Do
DM  0.8  Do
56

(m)

n

=

Do

Where Do = Table diameter (m).

The following formulae apply for roller mills : The grinding force consists of
F=
FR  FH KN

where F = Grinding force (kN). FR = Roller grinding force (kN). FH = hydraulic grinding force ( kN) Mr = Roller assembly weight one roller ( kg )
But FR =
MR  9.81 1000

kN

107

And

FH =

Phyd   Dcyl  DPist on 
2

2

  4  100



( kN)

The specific grinding pressure will then be
KT 

 kN  A  2 m 
F

T=

KT  DR  W

Where T = Roller pressure per roller (kN) KT = specific roller pressure (kN) DR = Roller diameter (m) W = Roller width ( m)
V=
  DM  n 60

V

= velocity at mean diameter of track (DM) m/ sec ( m). ( rpm)

DM = Mean diameter of track n = Table speed

The power absorption of each roller is the tangential load on the table velocity at the mean diameter of the grinding track. Expressed by the specific roller pressure KT

N=

z   T  V=

z    KT  DR  W  DM   

n 60

Which inserted in the above equation gives
N=
0.844    KT  D
2.5

108

This reveals that the capacity of vertical mill, by direct upscaling, grows with the dimension in power 2.5. The capacity factor here 0.844 varies by different mills designs between 0.4- 1.0 .Most vertical mills for coal and cement raw meal are operated with a specific roller pressure KT between 400 and 800 kN/m^2. The coefficient of rolling friction increases with the grinding bed thickness upto a certain critical value, depending on the also grows with the grinding bed thickness upto a certain limit, which with smooth roller is usually in the range as follows :

Cement raw material Coal Cement

0.09 +/ - 0.02 0.10 +/ - 0.02 0.06 +/ - 0.01

The specific power consumption N/P and thereby the mill capacity P, depends not only on the grindability of the material and the required fineness, but also on the efficiency of the classifier, the air flow and other operational parameter. Typical value for cement raw materials are in the range 5 ~ 8 kwh / ton.

Material Movement On The Table.
In vertical mills the grinding table not only functions as a grinding member but also as a spreader dishes that distributes and transport the fresh material to the rollers. The speed of the table is so high that the centrifugal force exceeds the materials' friction against the table. The material particles are therefore in constant sliding motion toward the periphery of the table. For identical centrifugal field, the table rpm must be inversely proportional to the square root of the table diameter. For optimum operation table speed should be at such a value, which will give low mill vibration and maximum capacity at minimum power consumption. Table speed is determined by its diameter and by the magnitude of centrifugal force required for transporting the material. Its value is same for all type of roller mills.
56  Do

The high value gives a proportionally high production, also much higher vibration in case of hard materials. The shape of material layer and the movement of the particle are determined by the table profile, the table speed, the return of the material and friction against the table. 109

Gas Flow Through The Mill.

Roller mill production rate depends upon gas flow through the mill. Constant quantity of air flow is essential for stable mill operation. Mill output and gas flow can be approximated by a straight line exponential function.
Mill output =
a V
b

Where V is the gas flow and a and b are the empical constant. Minimum specific air flow is needed to maintain the rate of production in roller mill to carry the feed through the mill, classifier, and dust collector. The mill fan capacity is kept at higher rate than the specified volume of gases to cope with changes in gas temperature in the mill circuit and possible false air supply. An average of 10 % is taken for false air. Normally 2.3 kg gases per kg of clinker are required for vertical mill to grind raw mix. Normally 1.8 to 2.00 kg preheater gases per kg of clinker are available, hence it is possible to use entire preheater gas in the roller mill.At the nozzle ring, a gas velocity of around 80 to 90 m/sec is maintained. Nozzles are normally inclined at 45 degree to the grinding table which gives cyclonic effect to the material leaving the grinding table and coarse particles are thrown against the wall. Following gas velocities are maintained inside the mill above the rollers.

MPS And Polysius Make Roller Mills
1.5 Do

Loeshche And Atox Make Roller Mills
2.5 Do

Where Do is the table diameter. For proper operation of air classifier, a gas velocity of 3.2 m / sec should be maitained at the rotor of the classifier and 10 m / sec at the mill exit

Mill Differential Pressure Adjustment.
Mill differential pressure has a strong influence on mill capacity. Mill differential pressure is effected by grinding table speed. As table speed increases, more and more material is thrown on the table in the form to rain down evenly over the table area and the differential pressure increases which is an indicator for the mill loading and is always used for controlling the mill feed rate. Increase in product fineness also results in decrease in differential pressure. Mill differential pressure is controlled by feed rate to the mill and hydraulic pressure on rollers. Generally differential pressure in the mill in mm H2O is given by :

110

p=

350 Do

Where Do is the outer diameter of the grinding table in meter. Differential pressure is limited by ability of the system fan to provide the static pressure.

Mill Exit Temperature.
Mill exit temperature is very important for proper mill operation. Changes in mill temperature is caused by variation in moisture content of the feed. Mill temperature is controlled by regulating hot gases flow into the mill. Changing mill exit temperature cause change in gas volume, hence change in gas velocity inside the mill. Continuously varying mill conditions upset the internal balance of circulating load and destroyed the stability of the material bed .It has been found that fluctuating mill exit temperature results in reducing the mill capacities as much as by 50%.Generally mill exit temperature are maintained in raw mill at 85 to 95 oC and 80 to 85 oC in coal mill subject to the % of volatile matter. High mill temperature cause damage to seals, journals and bearings.

Slippage And Wear In Vertical Roller Mill.
All vertical mills operate with some slippage or speed difference between the surface of the roller and the grinding table. The slippage generates shear forces that contributes to the grinding and prevent agglomerates. The maximum slippage at the sides of the rollers 9 and 44% of the roller speed. The slippage causes no extra wear. Practically it appears that slippage has very little influence on the roller wear rate. Experience shows that the wear primarily where the pressure is highest which is close to the rolling point a little outside the middle of rollers. This is due to compression which generates a far larger Shear than the slippage.

111

CLINKER COOLING
The clinker cooling process greatly influences the mineralogical composition as well as the structure of the clinker. Besides this the grind ability and quality of the cement is also affected by the rate of cooling. Clinker cooling is very essential because of the following reasons, 1. Mechanical transportation of hot clinker to storage point is difficult to convey. 2. Hot clinker has negative effect on the grinding process. 3 Reclaiming of useful heat energy from hot clinker is about 200 kcal/kg clinker is an important factor for lowering production cost. 4. Proper and effective cooling improves the quality of cement.

Selection Criteria Of Clinker Cooler
The following requirement should be considered in choosing the appropriate type of cooler  Obtaining good quality clinker by optimum cooling rate.  Final cooling of the clinker to the lowest possible temperature.  Maximum thermal efficiency.  Best adaptation to the burning system preceding the cooler.  Least possible pollution impact on the environment.  Low susceptibility to faults i.e. minimum down time.  Low capital cost.  Low power consumption.  Low wear and maintenance cost.  Favourable heat balance with a high degree of recuperation to obtain secondary air temperature as stable and high as possible to achieve overall kiln operating stability and good fuel efficiency.  Cooler exit air temperature should be as low as possible and volume as small as possible to assure a minimal amount of heat wasted to atmosphere.
112

Cooler Selection Criteria On The Basis Of Cooler Size The sizes of cooler are normally designed on the basis of the the following operating parameters. Grates specific loading output. clinker temperature cooler inlet 1350 ~ 1450, 0C ~ 100, oC 30 ~ 40 tpd per cubic meter of grates at nominal kiln

cooler outlet 65

The cooling air required to reclaimed heat and obtained the desired temperature of the clinker is 3 ~ 3.5 kg air/ kg clinker. About 1.00 ~ 1.2 of the cooling air is used as secondary and tertiary air in the kiln and precalciner and the rest of this air vented or utilized for drying in coal mill. The cooler capacity and size is normally designed keeping in view the normal kiln output and expected maximum kiln production per day.

Cooler Performance Calculation 1. Weight of clinker in the cooler, G=A*h*ρ G= weight of clinker in cooler (Kg) A= area of the grates grate surface (m2) = 52.8 h= clinker bed depth (m ) = 0.500m

ρ = clinker density

(kg/m3 ) = 1350 kg/ m3

113

G=
A h 

52.8  0.500  1350 35.64 tons

 3.564  104

kg

Clinker Residence Time In Cooler

The clinker retention time in the cooler can be calculated on theoretical basis for the purpose of selection. The bed depth is directly proportional to the grate speed. If the area of the cooler, the bed depth under normal operating condition for a given kiln out put rate and density of clinker are known, then the clinker retention time can be calculated by the equation: T =( A*h* ρ) * 60/Gt

Area of grate surface = A = 48.6 m2 Clinker bed depth Density of clinker T = h = 0.660m = ρ = 1350kg/m3

= ( 52.8 * 0.5 * 1350 * 60)/100000 = 21.4 min.

Volume Of The Clinker Residing In The Cooler At Any Time V = T*Gt/ (60* ρ ) Gt = Grate Speed

114

V = 21.4 x 100000/(60 x 1350) V = 26.42m3 One of the most commonly used way of designating the efficiency of cooler is by using the heat recuperation efficiency. The heat recuperation efficiency expresses the ratio of the heat contained in the hot clinker to the cooler that is returned to the preprocess in the form of secondary and tertiary air

Secondary and tertiary air required for heat saving kilns per kg of clinker at the rate of 0.85 ~ 0.95 NM^3/kg of clinker. herefore, secondary air required per kg of clinker is assumed in the range of 0.347 to 0.373 NM^3 as well as he tertiary air 0.569 ~ 0.587Nm^3 Kiln production per day= 6700 tons 6700 x 1000/24 = 279166.67 kg/hr.

Secondary Air Required Per hr =279166.167x 0.347 =96870.8 m3/hr Density of ir at NTP = Do = 1.21 kg/m3 Volume of secondary air at NTP = 96870.8Nm3

115

Mass of secondary air at NTP = m = Do* Vo
=1.21*96870.8 =117213.67 Kg

Kg Of Secondary Air Required Per Kg Of Clinker =0.419

=11213.67/279166.67

Heat Contents In Secondary Air

Q = mCp(T2-T1) =0.419*0.239*(825-25) =80.12 kcal/kgxcl

116

Tertiary Air Requirement Kiln output rate = 279166.167kgs/hr

Tertiary air required per kg of clinker = 0.587 Nm3

Therefore tertiary air required per hr = 279166.167*0.587

=163870.83m3/kg cl Do=1.2m3/kg Vo=163870.83m3
Do  m Vo

M =163870.83*1.2 =196644.99 kg

Kg Of Tertiary Air Required Per Kg Of Clinker = =196644.99/279166.67 =0.704kcal/kg cl Heat Contents From Tertiary Air =

=0.419*0.235*(975-25) =93.54kcal/kg cl
117

kgs of tertiary air required per hour

= 117213.67kg

kgs of tertiary air required per hour Vent Air At Cooler Outlet

=196644.99 kg

vent air at cooler outlet is exhausted at the rate of 1.363 ~ 1.4 Nm3 per kg of clinker. killn out put rate=279.167ton/hr r =279.167*1000 =2.79x105 kg/hr Vo= 279167x1.363 =380504.621m3 Do= 1.21m3/kg

Mass = 380504.621*1.21 = 460410.59kgs

Kg of excess air per kg of of clinker in cooler

=460410.59/279167 =1.65 kg of excess air/kg of clinker

118

BALL MILL
The Critical Speed
The critical speed of a ball mill is that speed of rotation at which the centrifugal power neutralizes the force of gravity which influences the grinding balls; the grinding ball do not fall and therefore, perform grinding work. Critical speed = n = 76.6/√3.6

Dia Of The Ball Mill
Basis capacity = 6700 ton/day

According to Tavrov’s formula
Q = q× (a×b×c)/1000×6.7×v×√D.√GN
Where V = Volume = Π/4*d2 * L Q = Mill capacity q = Specific mill capacity = 40kg\kwh a = Grinding index = 0.7143 ×1.2+0.2857 ×1.4 = 1.26

b = Correction index for fine grinding = 0.82 c= Correction type for mill type =0.9 N = No. of revolutions 1/4*d2

119

Putting all above parameter in eq. 279.167 =40× (1.26×0.82×0.9)/1000×6.7×п/4×D2L√D√(D2L/(1/4)D2L) D2.5L = 713.98 Since for Ball mill L/D = 2 Let L/D = 2.8 (length to dia ratio)

D2.5L = 713.98 D =4.87 meter Dia of ball mill =4.87 meter Length of ball mill = 4.87×2.8 =13.64m Therefore, critical speed =76.6/√4.87 =34.71RPM Working speed is 65.90% of critical speed

So, N =32/√D =32/√4.87 = 14.47 RPM Critical speed = 34.71 RPM

Working speed = 14.47 RPM Optimum speed is one half or one third of critical speed.

120

Dynamic Angle Of Repose Of Grinding Balls
Theoretical calculation shows that the maximum kinetic energy of the fall balls is at a dynamic angle of repose equal to 35˚ 20’. Some time its value is 54˚40’.

Distribution Of Grinding Media In The Mill Cross Section
Since angle of repose =35˚20’ It means 35% of total ball is lifted and 63% of the total grinding ball falls.

Degree Of The Ball Charge
For steel ball = 28-45% For sylphs = 25-33%

Total Grinding Ball Charge
According to stiernin G = 4000 D2L Where G = total weight of ball charge in kg. D = inner dia of mill in meter = 4.87m L = useful mill length =13.64m G = [4000(4.87)2 ×13.364] /2 = 649843.06kg =649.84 ton

121

Grinding Ball Charge And Clinker Load
According to Mardulier Steel ball charge/clinker charge =8.1 to10.1 Steel ball charge = 45% of total ball So, weight of ball charge = 649.84×0.45 = 292.43ton Therefore, clinker charge =292.43/10 = 29.24 ton

Ball Mill Power Demand
Empirical formula for Ball Mill Power
P = 12.5×G G = 649.84 Ton P = 12.5×649.84 = 8123 Hp

Blanc’s formula
P = C.G√D C = index relating to grinding ball and mil charge (From grinding index,Peery) C = 7.00 G = 649.84 Ton D = 4.87 m P = 7.0 × 649.84 ×√4.87 P = 10038.5 Hp 122

Bond’s Equation
W = [10w√P]-[10w√F] Basis capacity = 6700 Ton/day

Gypsum = 352 ton/day Clinker = 6700 Ton/day Standard size of clinker 80% passing 9/16 inch F = 14300microns Standard size of cement 80% passing through 37 microns Work index for clinker 13.49×1.3 = 17.53 (1.3 is dry grinding factor)

Apply Bond’s Equation
W = 10×17.53 - 10×17.53 √37 √14300 = 28.83 – 1.46 = 27.7 kwh/ton = 27.37×1.113 = 30.46 kwh/ton

1.113 = cement fine product fraction

Cement production =293.833ton/hr = 293.833×30.46 =8950.15 × 1.341 Power = 11993.2 hp

123

Site Selection

124

Site Selection
Raw Materials Availability
The source of raw material is one of the most important factors influencing the selection of a plant site. This is partially true if large volumes of raw material are consumed, because location near the source of raw material permits considerable reduction in transportation and storage charges, attention should be given to the purchased price of the raw materials, distance from the source of supply, freight or transportation expenses, availability and reliability of supply, purity of the raw material and storage requirement.

Market
The location of markets or intermediate distribution center affects the cost of product distribution and the time of shipping. Proximity to the major markets is an important consideration in the selection of a plant site, because the buyer usually finds it advantageous to purchase from nearby source. Note that markets are needed for by-product as well as for major final products.

Energy Availability
Power and steam requirements are high in most industrial plants, and fuel is ordinarily required to supply these utilities. Consequently, power and fuel can be combined as one major factor in the choice of a plant site. Electrolytic processes require a cheap source of electricity. If the plant requires large quantities of coal or oil, location near a source of fuel supply may be essential for economics operation.

125

Climate
If the plant is located in a cold climate, cost may be increased by the necessity for construction of protective shelters around the process equipment, and special cooling towers or air conditioning equipment may be required if the prevailing temperature are high.

Transportation Facilities
Water, railroads, and highways are the common means of transportation used by major industrial concerns. The kind and amount of products and raw material determine the most suitable types of transportation facilities. In any case, care attention should be given to local freight rates and existing railroad lines. The proximate to railroad center and the possibility of canal, river, lake, or ocean must be considered.

Water Supply
The process industries use large quantities of water for cooling, washing, steam generation, and as raw material in plants, therefore, must be located where dependable supply of water is available. A large river or lake is preferable, although deep well or artesian wells may be satisfactory if the amount of water required is not too great.

Waste Disposal
In recent years, many legal restrictions have been placed on the methods for disposing of waste materials from the process industries. The site selected for a plant should have adequate capacity and facilities for correct waste disposal. Even though given areas have minimal restrictions on pollution, it should not be assumed that this condition will continue to exits.

126

Labor Availability
The type and supply of labor available in the vicinity of a proposed plant site must be examined. Consideration should be given to prevailing pay scales, restrictions on number of hours worked per week, competing industries that can cause dissatisfaction or high turnover rates among the workers, and variation in the skill and productivity of the worker.

Taxation And Legal Restrictions
State and local tax rates on property income, unemployment insurance and similar items vary from location to another. Similarly, local regulations on zoning, building codes and transportation facilities can have major influence on the final choice of a plant site.

Site Characteristics
Characteristics of the land at a proposed plant site should be examined carefully. The topography of the tract of land and the soil structure must be considered, since either or both may have a pronounced effect on construction costs. The cost of the land is important as well as local building costs and living conditions. Future changes may make it desirable or necessary to expand the plant facilities.

127

Flood And Fire protection
Many industrial plants are located along rivers or near large bodies of water, and there are risks of flood or hurricane damage. Before a plant site is chosen, the regional history of natural events of this type should be examined and consequences of such occurrences considered. Protection from losses by fire is another important factor in selecting the plant location. In case of a major fire, assistances from outside fire departments should be available. Fire hazards in the adjacent areas of plant site must be overlooked.

Community Factors
The characters and facilities of a community can have quite an effect on the location of the plant. If a certain number of facilities for satisfactory living of plant personals do not exist, it often becomes a burden for the plant to subsidize such facilities. Cultural facilities of the community are important to sound growth. Mosques, libraries, schools, civil theatres etc do much to make a community progressive. Recreation activities deserve special considerations.

128

PLANT SAFETY

129

PLANT SAFETY
OPERATIONAL SAFETY AND PRECAUTIONS
The ultimate goal of safety and fire protection is the complete protection of personnel injury, loss of life and destruction of property as a result of accidents, fires, explosion or other hazardous situation. The process industries introduce a wide range of hazards as a result of presence of sizeable quantities of flammable and sometimes unstable materials, Frequently at high temperature, which promote ignition or decomposition with high pressure the potential energy release is increased in the presence of structural failure, explosion, detonation, or violent exothermic reaction. In order to safeguard against accidents due mechanical failure under severing operating condition, the equipment should be designed to meet the specifications and need of recommended authorities. For example, the design and construction of pressure vessels and storage tanks should follow A.P.I or A.S.M.E. codes, and they should be tested two or more at the design pressure. Beside consideration of safety in the design of equipment, it is essential to select adequate instrument and control for safe operation. Safety beside other factor acts as a guide-line in the design of control system. Clear and effective operating procedures play an important role in safe operation of chemical plant. The equipment manufacturers normally provide operating instructions. But, in the plant where hundreds of small units are held it is necessary to lay down standard operating procedure (S.O.P) to ensure safe start up, operation and shut down. Accident on plant often results during handling and storage of hazardous material. Injury to plant personnel may also result due to the toxicity of chemical

130

being handled. It is therefore necessary to have a full understanding of chemical and physical properties of the materials being handled.

1. Delayed symptoms accruing within 48 hours after breathing light nitrous oxide fumes. This form of poisoning occurs most frequently in industry. 2. Mild immediate effects from which recovery is apparently complete after which pneumonia eventually follows:In type case of `NO` poisoning, the sequences of events may be:

i) ii) iii)

A few breaths of apparently harmless gas. Only slight discomfort with the worker continuing his job. 5-8 hours after exposure, the victim‟s lips and ears become cyanotic.

3. Increasing difficulty in breathing follows, accompanied by chocking, dizziness and irregular respiration. Severe untreated cases frequently terminated fatally from excessive pulmonary congestion or suffocation. Remedial measures to be taken as soon as possible after an indication that poisoning has occurred are:

i) ii)

Patient should be moved to uncontaminated atmosphere and no physically excretion permitted. But result should be enforced. Patient should breathe 100% Oxygen for 30 minutes every 6 hour. If after this time breathing is normal O 2 inhalation may be discontinued.

iii)

During period of O2 inhalation patient should exhale against a positive pressure of about 4 cm water unless there is indication or history of cardiovascular failure. This is intended to prevent the development of pulmonary.

131

COST ESTIMAION

132

COST ESTIMAION
COST OF PRODUCTION
Material
The cost of raw materials differs with in wide limits between one plant and another. Factors affecting it are royalties payable, the nature and accessibility of the deposit, its hardness the amount of overburden the depth available and are proximity to the works. A hard stone which requires drilling and its blasting before it can be handled will necessarily cost more per ton than soft material which can be dug direct with a digger. Again, as the removal of overburden is and unremunerative operation it adds to the cost in proportion to its depth. if there is little material available above water level we may be necessary to go lower, in which the case of cost continued pumping is incurred except in the case of clay or soft chalk, which can be dug below water. If the quarry is reasonably close to the works it may be found convenient to erect the crushing or washing plant in the quarry, and when the wet process is adopted the slurry can be conveniently pumped to the works. On the other hand, it may be necessary to load the material into trucks or vessels and convey them for long distance.

Labor
Unless labor is exceptionally is cheap, hand labour must be replaced by machinery in every department, and an output of two tons or more per day for every man employed on manufacturing operation may be looked for in modern plant. This takes no account of men employed on repair work or on packing ang shipping, and is of course only an approximate guide. It varies with the arrangement and equipment of the factory, and especially in cases where raw material or power may be purchased.

133

Fuel
The type of coal is to be used is usually settled by considerations of price, the particularly applies to the coal used for burning where something like one quarter of the work cost of manufacturing. Cement is incurred. Some coals are so high in ash content, or otherwise unsuitable, that they are not satisfactory no matter how they cheap may be. In England bituminous coals of fair quality are so readily obtainable that price becomes the final arbiter, and this in turn is affected by the relative positions of cement works and collieries and the means and cost of transport. In the best modern practice not more than 5 cwt. Of coal of 12,600 B.T.U's per lb. are used for burning a ton of cement on the wet process, and approximately 1 cwt. less per tons on the dry process. Oil is not used in British works as its cost is high in comparison with coal.

Power
Coal for power is usually of a more specialized character, depending upon the type of power plant, and as the tonnage required is so much smaller than that used in burning the higher cost of the selected quality is not of such serious import. If waste heat boilers are installed and power is obtained from the kiln gases, than the quantity of power coal required is further reduced. When electric power coal required is obtain from the kiln gases, and then the quantity of power coal required is further reduced. Where electric power is purchased its cost is usually on a sliding scale subject to coal prices and other factors. Agreements for such supplies customarily contain provisions for peak and minimum loads and in designing a new plant a careful balancing of units should be made in order to secure a constant load factor.

134

Other Supplies:
Gypsum, stores, lubrication oils etc. are usually purchased and costs can be calculated fairly accurately as a rule about 5% of raw gypsum stone is likely to be used. Some cements works have contracts under which their requirements of lubricants are supplied at a fixed price per ton of cement produced. Haulage and transportation again are much influenced by the location of the works in relation to material deposits and market. Machinery repairs and replacement are usually a heavy item, and the saving which can be affected under this head in designing a new plant is often considerable. The item, of course, tends to rise in every plant as time passes, and cement works machinery, notwithstanding its robust construction, has a relatively short life.

Overhead Charges
The cost of administration and management is usually the inverse ratio to the output, the larger the plant the less the cost per ton under this head. Rates and taxes, and insurance may amount to as much as 6 to 8 %of the manufacturing cost. Allowances of depreciation and obsolescence of plant and machinery should be at least 5% of their first cost and may well be 10% in some cases if a sound and conservative financial policy is purchased. Charges for raw materials depletion and reserves will depend upon very variable factor, and must be determined separately in each case.

135

COST ESTIMATION OF PROJECT
Before an industrial plant can be put into operation, a large amount of money must be supplied to purchase and install the necessary machinery and equipment, land and service facilities must be obtained and plant must be created complete with all piping, controls and services. In addition it is necessary to have money available for the payment of expenses involved in the plant operation.

PURCHASE EQUIPMENT COST
On way of estimating the equipment cost is by the use cost indexes. Because prices change considerably with time, due to change in equipment cost, other specifically to labor construction material or other specialized fields. A cost index is merely a number for given year showing the cost at that time when the past value is known. The equitant cost at the present time will be:

Purchased Equipment Cost
= Original cost x (Index value at present time index) x (Capacity of present plant ) (Value at time original cost is obtained)(Capacity of original plant)
0.6 0.6

The value of Marshal and Steven installed equipment index process for process industry, with base year 2005=1152, and in 2008 it is 1200. On the other hand, to estimate the cost of equipment when no cost data are available for particular size or operational capacity involved the Logarithmic relationship known as "Six-tenth-factor rule" is quite effective. According to this rule, if cost of the given unit at capacity is known, the cost of similar unit with x time the capacity of the first is approximately (X)0.6 time the cost of the initial unit.

136

PURCHASED EQUIPMENT COST
Purchased equipment cost can calculate by capacity ratio method or what is known as “Six-tenth-factor rule”. From a working industry purchased equipment cost for Purchased equipment cost for 2500 ton per day on dry basis =1.57x10 9 Rs. For 6700 ton per day capacity of same plant

Purchased Equipment Cost
E = Original cost x (Index value at present time index) x (Capacity of present plant )
0.6 0.6

(Value at time original cost is obtained)(Capacity of original plant)

E = 1.57x10)9x (1200/1152) x (6700/2500)0.6 E =2.95x109 Rs.

137

Total Direct Cost
Purchased equipment cost Purchased equipment installed = 2.95x109 Rs. = 39% E = 2.95 x 109 x 0.39 = 1.15x109 Rs. Instrumentation installed = 26% E = 2.95 x 109 x 0.26 = Conveyor Belt installed 7.6x108 Rs.

=31% E = 2.95 x 109 x 0.31 = 9.14x108 Rs.

Electrical (installed)

=

10 %

= 2.95 x 109 x 0.1 = Building (included services) 2.95x108 Rs.

= 29% E = 2.95 x 109 x 0.29 = 8.55x108 Rs.

Land

= 6% E = 2.95 x 109 x 0.6E = 1.77x108 Rs.

Yard improvement

= 12% E = 2.95 x 109 x 0.12 = 3.54x108 Rs.

Service facilities

= 55% E = 2.95 x 109 x 0.55 = 1.62x109 Rs.

Total Direct Cost

= 9.075x109 Rs.

138

Indirect cost
Engineering and supervision = 32% E =2.95 x109 x 0.32 = Construction Expenses 9.44x108 Rs.

= 34% E =2.95x109 x 0.34 = 1.00x109 Rs.

Legal expenses

= 4% E = 2.95x109 x 0.04 = 1.18x108 Rs.

Contractor fee

= 19% E = 2.95x109 x 0.19 = 5.61x109 Rs.

Contingency

= 37% E = 2.95x109 x 0.37 = 1.09x109 Rs.

Total Indirect Cost

=

3.713x109 Rs.

139

Fixed Capital Investment

= 9.075x109 + 3.713x109 Rs. = 12.788x109 Rs.

Working Capital Investment

= 15% ( Fixed Capital Investment) = 0.15x12.788x109 = 1.92x109 Rs.

Total Capital Investment =Fixed Capital Investment + Working Capital Investment

=12.788x109 + 1.92x109
Total Capital Investment = 14.69x109 Rs.

Cost of Production
Variable Cost 1. 2. 3. Raw and Packing Material Fuel and power Stores and Spares (Including Repair & Maintenance) Subtotal Rs. /Ton 326.93 1432.03 154.74 Rs. /Bag 16.35 71.60 7.74

1913.70

95.69

140

Fixed Cost
1. 2. 3. 4. 5. Salaries & Wages Depreciation Admin & Selling Expenses Financial Expenses Misc.Expenses 156.67 206.65 97.19 378.69 93.05 932.25 2,845.95 7.83 10.33 4.86 18.93 4.65 46.61 142.30

Sub Total Total Cost of Production (Variable Cost + Fixed Cost)

Market Price
Cost of production Excise Duty Sales Tax @ 15% Average Freight & Un-loading Dealers Commission Manufactures profit @ 10% on Equity Market Price (Total) 2,845.95 750.00 539.39 600.00 140.0 497.54 5,372.89 142.30 37.50 29.97 30.00 7.0 24.88 268.64

141

Pay out Period of the Plant
Pay out period = total capital investment Annual profit + annual depreciation Total Cement produced per day = 6700(clinker) + 352 (gypsum 5% ) = 7052 ton/day

Annual Profit

= 497.54 x 7052 x 300 = Rs. 1052595624

Annual Depreciation

= 206.65 x 7052 x 300 = Rs. 437188740 Rs. 14.69 x 109

Total Capital Investment

=

Pay out Period

=

14.69 x 10 9 1052595624 + 437188740

=

9.86 years

142

Instrumentation & Process Control

143

Instrumentation And Process Control
No plant can be operated unless it is adequately instrumented. The monitoring of flow .pressure, temperature and level is necessary in almost every process in ordered that the plant operator can see that all parts of plant are functioning as required. Additionally it may be necessary to record and display may other quantities which are more specific to the particular process in question. For example, the composition of process stream, the heat radiation produce or humidity of the gas stream.

OBJECTIVES:
The primary objective of the designer then specifying instrumentation and control scheme are;

Safe Plant Operations:
 To keep the process variables within known safe operating limit  To detect dangerous situations as they develop and to provide alarms and automatic shutdown system

.

Production Rate:
To achieve the design product output.

Product Quality:
To maintain the product composition within the specified quality standards.

Cost:
To operate at the lowest production cost.

144

Hardware Elements Of Control System:
Process:
“Material together with equipment, the physical and chemical operation that occurs” is called process.

Measuring Elements:
The instruments used to measure the process variables such as;  Pressure  Temperature.  Flow rate.  Level.

Transducers:
It converts the unstandard signals (sensor signal) into standard signals (control signals).

Transmission Lines:
These are used to carry the signals from measuring device to controller.  Standard electronic signal 4-20 mA.  Standard pneumatic signal 3-15psig.

Controller:
It generate the error by comparing process signal with set point and sending theses signals to final control elements.

145

Final Control Element:
It receives the signal from the controller and by some predetermines relationships changes the energy input to the process.

Recorder:
It is used to give the visual demonstration about the behavior of the process.

General Control Systems:
Following are the important general control systems.  Open and close loop system.  Feedback control system.  Forward control system.  Combined control system.  Cascade control system.

Open Loop System:
Control system in which information about the controlled variable is not used to adjust any of the system inputs to compensate for variation in the process variables. These terms is used to indicate uncontrolled process dynamic.

Closed Loop System:
The control system in which the controlled variable is measured and the result of this measurement is used to manipulate one of the process variable.

146

Feed back Control System:
In a close loop control system information about controlled variable is feed back as the basis for the controlled of the process variable .for automatic control ,a measuring device is used as the signal. The signal is feed to a controller, which compare it with a preset desired value or set point, if a difference exists the controller send a signal to final control element.

Forward Control System:
Process disturbances are measured and compensate without waiting for a change in a controlled variable, to indicate a disturbance has occurred. It is also useful when a final controlled variable cannot be measured.

Combined Control System:
Forward feed control system can rarely fulfill the entire control requirement so that feed control is normally used in combination with forward feed control system .such arrangement reduces accuracy and amount of process knowledge ,detailed requirement for specification of transfer function.

Cascade Control System:
It is often used for minimizing disturbance entering in a slow process. it also speed up the response of the control system by reducing time constant relating the manipulated variable process output. Instead of adjusting the final control element such as control valve, the output of primarily controller is made the set point of secondary controller.

147

Modes Of Control:
The various type of control are called “mode” and they determine the type of response obtained. in other words these describes the action of the controller that is the relationship of output signal to the input or error signal .it must be noted that it is the error that actuates the controller. The four basic modes of controls are;  Proportional control  Proportional derivative control  Proportional integral control  Proportional integral derivative control.

Proportional Control:
The output of proportional controller is fixed multiple of the measured error, that is, proportional controller is simply a multiplier. In this control system the controller variable is measure and signal is compared with a set point. The difference is the error () Manipulated variable derives the final control element. Which is amplified Kc times by proportional gain. The output of proportional controller, This controller is used when precise control is necessary. Offset and oscillatory response is tolerated. A special type of proportional control is on off control. it is simplest and most common mode of control such as thermostat used in space heating and refrigeration.

Proportional Derivative Control:
In this kind of control, offset remains but response to any change becomes smooth i.e. problem of oscillatory response can be overcome by use of this type of controller.

148

Proportional Integral Control:
The output of Proportional integral control consists of two parts, the first proportional to the error and second proportional to the integral of the error. Even small errors can eventually provide enough controller output to force the error to zero. This controller removes the offset but response of the system to a change may not be smooth.

Proportional Integral Derivative Control:
Three modes of controller combine an action of Proportional, integral and derivative elements into a single events. proportional elements give faster transient response but more oscillatory, integral element eliminates steady state offset and derivative elements allows higher proportional gain. This kind of controller is used to give very precise control and it is most expensive of all.

Typical Control System
A collective general description of the instruments used will be given which may be conveniently divided into following groups.  Temperature recorder  Temperature indictor controller  Level controller  Pressure controller  Flow controller  Temperature recorder The thermo couples are the most common Temperature measuring devices, particularly in industry. Since mercury may react with chemicals to form explosive components, the use of mercury filled pressure spring thermometer is avoided.

These are used to measure Temperature of the stream entering the units.
149

Recommended Thermocouple
For Kiln Process
Type – R
positive wire is PT 87-RH13 negative wire is platinum milli volts (minimum to maximum) per oC = 0.00645 – 0.0118 Temperature Range -18 to 1704oC Good at high temperatures, poor below 538oC

-

Temperature Indicator Controller:
The normal method of controlling a heat exchanger is to measure the exit temperature of the fluid being processed and to adjust the input of the cooling or heating medium to control the desired temperature. Therefore temperature recorder controllers are installed to control the heat exchanger.

Level Controller:
In any equipment where interface exits between two phases (e.g. liquid, vapor) some, means of equipments as is usually done for the automatic control of the flow from the equipment.

Pressure Controller:
Pressure control will be necessary for most system handling vapor or gas. The method of control will depend on the nature of process.

150

Flow Controller:
Flow control is usually associated with inventory control in a storage tank or other equipment. There must be a reservoir to take up the changes in the flow rate. To provide flow control on a compressor or pump running at fixed speed and supply a near constant volume output, by pass control would be used.

Alarm & Safety Tips:
Alarms are used to alert the operators of serious and potentially hazardous, deviations in process conditions .key instrument are fitted with switches and relays to operate audible and visual alarms on the control panels. Where delay or lack of response by the operator is likely to lead rapid development of a hazardous situation. The instruments would be fitted with a trip system to take action automatically to alert the operators, such as shutting down pumps, closing valves, operating emergency system. The basic components of an automatic trip system are;  A sensor to monitor the control variable and provide an output signal when present value is exceeded.  A link to transfer the signal to the actuator usually consisting of the system of pneumatic or electric relays.  An actuator to carry out the required action, close or open the valve, switch off motor.

Interlocks:
Where it is necessary to follow a fixed sequence of operations, interlocks are included to prevent operators departing from the required sequence. They may be incorporate in the control system design as pneumatic or electric relay or may be mechanical interlocks. Various propriety special interlocks and key system are available.

151

THE LETTER CODES FOR INSTRUMENT SYSTEM

Property measured Flow rate Level Pressure Temperature Radiation Weight Quality analysis

First letter
F L P T R W Q

Indicating only
FI LI PI TI RI TI WI

Recording only
FR LR PR TR RR WR QR

Controlling only
FC LC PC TC RC WC QC

Indicating and controlling
FIC LIC PIC TIC RIC WIC QIC

Recording and controlling
FRC LRC PRC TRC RRC WRC QRC

152

NOTE:
The letter A can be added to indicate the alarm, with H and L placed next to the instrument circle to indicate high or low. D is used to show difference or differential, PD for pressure differential. F as the second letter indicates ratios e.g. FFC = flow ration controller. The first letter indicate the property measured e.g. F = flow subsequent letter indicate the function e.g. I = indicating. RC = recorder controller. The suffixes E and A can be added to indicate the emergency action and / or alarm functions. The instrument connecting lines should be drawn in manner to distinguish them from the main process lines. Dotted or crosshatched lines normally used.

153

ENVIROMENTAL PROTECTION & ENERGY UTILIZATION

154

ENVIROMENTAL PROTECTION ENERGY UTILIZATION
ENVIROMENTAL PROTECTION IN THE CEMENT INDUSTRY

AND

The cement industry‟s duties in the relation to the environment come price mainly the following form of population: 1. Prevention of air population;

2. Noise abatement;

3. Prevention of vibration;

4. Protection of landscape and watercourses.

Environmental protection has for many decades been par and parcel of the entrepreneurial problems of our industry. it is gratifying to note that cement manufacturing to note that cement manufacturing activities are not among those industries that more particularly come in for criticism in the public debate on population prevention. I can furthermore be noted that the cement industry has recognized and accepted the principle of causer responsibility before it became a subject of conservationist discussion. Expert understanding of this comprehensive statutory requirement and their implementation calls more and more for not only the technical knowledge of the cement engineer, but also for substantial legal knowledge. The professional image of cement and process engineer will therefore have to undergo an evolution towards the training of environmental engineering legal experts.

155

The consequences of this mass of legislation as a cause of cost and as a deterrent to investment are something that may also appropriately be mentioned at this point.

COST OF ENVIRONMENTAL PROTECTION
In terms of amount spent by industry as a whole upon environmental protection, the rock product industry and thus the cement industry occupies a leading position. As revealed by the latest survey conducted by the institute of expenditure on environmental protective measures in the rock products industry in the years 1971-1975 amounted to 105 of the overall capital expenditure. The order of magnitude of the operating cost in respect to environmental protection can at present only be estimated within approximate ranges All public discussions on the burden that that can be imposed on the economy in fulfillment of environmental protection requirements should be on based on considerations of effect upon return on investment.

ENVIROMENTAL PROTECTION AS A PROBLEM OF PLANT LOCATION:
In the past, the prerequisite condition for establishing new cement plant sites or for the expansion or reestablishment of existing plants consisted in satisfactory coming to terms with the conventional planning factors such as raw material availability technical infrastructure, marketing possibilities and earning power. In recent years, however new planning criteria such as regional development, zonal economic planning, anti pollution planning, scheme for builtup-areas, land scope preservation and nature reserves, to mention just a few have emerged as important factors in deciding where to locate a cement work. The latitude and scope available for varying the sitting of the work are further narrowed down sometime to point of impracticability, by the imperative need to 156

remain close to the source of raw material. A further difficulty is that the forward planning of public authorities more particularly the municipalities seldom extended for more than ten years ahead. Whereas planner concerned with industrial raw material supplies have to think in term of 30-50 years in assessing the development potential of site if a dependable decision as to plant location is to be made. In addition to this uncertainty of planning there accrued changes, relatively short notice, in the requirement imposed by the environmental protection regulations. The statutory requirement on completion of the official approval and licensing procedure are often found to change in relation to these, which existed at the start of planning of an industrial project, has become an entrepreneurial risk. The minimum distance of industrial and commercial installations from residential areas, which in instances have to be compiled with also, increase the area of land required for quarries and cement works. Thus the total area required for quarry and works site is increased almost fourfold.

IMPACT OF ENVIRONMENTAL CONSIDERATION:

STANDARDS

ON

ENERGY

The cement industry in Pakistan has been observing environmental standards for the fall out of dust from Raw Dry grinding, cement grinding, packing, by controlling emission of dust by bag filters and electrostatic precipitator. The clinker dust in air is collected in multi cyclones before discharge. We need a constant check and efficient use of this equipment and may also go in for improved equipments where necessary. But we are not controlling fall out of dust from the flue gases of existing to two stage suspension preheat kiln in due course of time and will have to install electrostatic precipitators in such units. In these kiln where conversion would not be possible, we would have to go for dust collection equipment for flue gases. The other aspects of environmental standards are the following;

157

1-Noise abatement 2-Prevention of vibration 3-Prevention of land scope and water courses These aspect have not been received much attention in Pakistan as mostly the factories were as, with the tremendous growth in cities residential areas have stretched to cement factories in some cases. We will have to take cognizance of these facts ultimately for the existing factories and for planning the new sites for cement factories. Sound insolating buildings may be necessary in some cases and ventilation through silencers coupled with cooling the building may be required, in future. The energy requirement will increase in future for observing environmental standards.

TECHNICAL AND MANAGERIAL IMPEDEMENTS FOR IMPROVING ENERGY EFFICIENCY
The great demand of cement in country is keeping the industry in working on top speed and improvement in energy efficiency us not receiving the attention as it should as it would entail more stoppage for modification and conversion which cannot be afforded at present. But this to some extent, is compensated by high capacity utilization about 90% and keeping the imports of cement to minimum possible. The new projects however being planned on energy efficient modern processes. The government and industry relationship is quite good there is a barrier in improving energy efficiency. As a matter of fact, the government is keeping abreast of energy consumption and requirement of the industry. There is incentive to employees on production basis, which also help in energy efficiency indirectly.

158

The most important impediment in energy efficiency improvement is in training and technical assistance. The cement technology like other technologies is developing fast and it will be difficult to have improvement in energy efficiency without imparting good training and giving assistance to developing countries for operating modern energy saving cement plants efficiently. The training and assistance to developing countries for operating modern energy saving cement efficiently. The training and assistance should be in operation, maintenance and instrumentation so that the developing countries are able to keep the automatic control system in every good condition. The training in the latest energy efficient plants should not be less than the six months in any field It will be of interest to note that when cement factories were being established in fifties and sixties, the training period of personnel varied from six months to a year. Such training should be given to middle management technical personnel ant technical assistants in the form of experts should also be provided .

FUTURE TREND IN ENERGY EFFICINCY AND SUGGESTIONS OF STRATEGIES

1.

The pattern of consumption of energy in cement industry is;

75% to 95% energy as fuel for drying and calcining process and 10-25% for generating electrical power consumed. There has been much improvement in efficient use of fuel energy during the last 25 years; the modern dry process suspension preheated kiln with calcinatory has improved the efficiency of energy utilization from (28 to 50%) of the theoretical requirement. The improvement in utilization of electrical energy about 75% is in the raw meal and cement grinding processes, where the utilization of energy efficiency has not exceeded 20% The useful utilization is not in size reduction and greater part of energy emission is lost in the form of friction, heat and noise emission. The only useful utilization of fuel energy in cement industry is for calcining and for drying the raw materials and slurry. We should therefore go in for dry 159

process as for as possible and wet grinding is necessary; we should filter the slurry to a reasonable moisture, for drying by the hot gases from two stage preheated kiln.

The losses of fuel energy on other side are;    Losses through flue gases. Losses through cooler, sealing rings. Losses through radiation.

MODREN FOUR STAGE SUSPENTION PREHEATER KILN
The present day suspension pre heater-calcinator kiln utilizes the energy in the flue gases and hot gases from cooler for drying the raw material and source of air to calciner. The improvement of pre calcination process in suspension-preheated kiln has increased the calcinations. From 40-90% in the suspension preheated by secondary firing from a pre calcining furnace installed between the preheated and kiln inlet. This increase the kiln output capacity for the same kiln volume and vice versa. This kiln capacity may be increased by 70% the thermal load in the kiln is reduced which increases the refectory life kiln availability.

160

EFFICIENT USE OF CEMENT IN CONCRETE
The structural use of cement is governed by various codes where the use of cement is properly controlled, in relationship to quality, quantity of cement, aggregates and environmental conditions. Presently mixes are specially designed according to strength, which they give on maturity and this varies from aggregates to aggregate. The codes are fairly broad based and for larger works these can be further refined where the quality control could be employed. However in smaller jobs where the quality control cannot be established properly, some extra use of cement is unavoidable. In this respect the design parameters and limitations laid in various codes, need proper implementation. The efficient use of cement can further be ensured by maximum utilization of pre casting and pre stressing techniques which;

1. Reduces the consumption of cement as well as steel, which is also a sources and imported item in many developing countries. 2. Produces high strength concrete under factory-controlled conditions, which is more economical to use as against lower strength concrete for and equal load carrying capacity. The administrative authorities need to carry out following action;  Report maximum to design-cum-construction bid which will arouse, encourage and will reward maximum techniques that will save cement and overall cost.  Standardize a few say one or more dozens precast and prestressed concrete members at the National level so that standard shuttering could be used and production cost reduced on account of greater repetitive use shuttering.  Private industrialists be encouraged to set up plants for manufacture of hallow pre stressed concrete planks by extrusion methods and manufacture of Light Weight Aggregates which go a long way in 161

economizing 

construction

and

improving

insulations

an

energy

economizing step. Considerable cement can be saved from non-use as cement plasters can be replaced by gypsum /lime plaster inside the buildings. Similarly for masonry work can be done in lime or in mud.

SUGGESTIONS
INDUSTRIAL LEVEL 1. All new plants should be based on latest energy efficient cement
technologies proved beyond doubt. All plants where possible should be based on dry process 4 stage suspension preheated kiln preferably with pre calciner. As these are very modern, highly sophisticated plants, we should get technical assistance for one year in the form of expert for operation, maintenance instrumentation and control equipment, after commercial production. A large number of middle management technical officers are trained in foreign countries on such plants in these fields.

2. The wet plant may be converted to semi wet-wet or dry process plant in
due course of time but should be planned in advance.

3. The insolating firebricks should be tried where possible. 4. The moisture should be kept at minimum. 5. Belt conveyor possible may substitute the transportation by dumper. 6. The site should be chosen where homogeneous materials are available
and an economic raw mix with reference to burn ability can be designed.

7. We should try to reduce losses through cooler and sealing rings and
modify it where necessary.

8. The power factor the ratio of working power in KW or KVA in delivered
power may appear directly or indirectly on utility bills. It may be retained as

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an option on the part the utility. Most operation can and should work within the range of 90-95%. Working below 85% range contributes to poor energy affiance.

NATIONAL LEVEL
1. The government should encourage establishment of only latest energy
efficient plant of cement technologies proved beyond doubt.

2. The government may provide direct incentive to cement industry, that
those factories which improve fuel consumption per ton of clinker on yearly basis, from their most efficient fuel consumption recorded so far, for each type of product, by allowing the savings so accrued to be tax free. The new plant who improves upon their guaranties of fuel consumption will also be considered similarly.

3. We should promote generation of power on coal near their deposits near
the investment in coal machinery for power generation may be much lesser as compared to cement industry so that natural gas is available to cement and other industries.

4. In case it is not possible those cement factories are nearer to coal
deposits should use coal but the Government as a policy matter should help them to have better profitability than the cement factories fired with natural gas, as an incentive.

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REGIONAL LEVEL
1. The technical assistance in the form of technical experts and training to
middle management technical personnel is provided by the developed countries in the region for operation maintenance, instruments and control of modern cement plants.

2. The development work in cement technology in the region should be
made available to regional countries.

3. Regional financing agencies should help in modernization and balancing
as well as new projects preferably with untied loans.

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Bibliography
 Perry & Green Perry’s Chemical Engineering Hand Book  Peter Timmerhaus & Ronald E. West Plant Design and Economics for Chemical Engineers  Welter H. Duda Cement Data Book  D.Q. Kern Process Heat Transfer  George T. Austin Shreve’s Chemical Process Industries  Abdul Majid Hand Book For Cement Engineers  McCabe Smith Herriot Unit Operation of Chemical Engineering  Coulson and Richardson’s Chemical Engineering

In addition we are also thankful to various industries for their cooperation & co ordination with us in a friendly manner to accomplish this project.

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