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Cobalt is not found as a native element

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					   Cobalt is the last metal in our series of metals. Cobalt is very similar to iron in its magnetic
properties and is also present along with iron in meteorites. Like many other metals in the earth,
cobalt is not found as a native element. Cobalt has many known mineral and just some of these
are cobaltite (CoAsS), erythrite Co3(AsO4)2.8H2O), glaucodot ((Co,Fe)AsS), and skutterudite
(CoAs3). Cobaltite is metallic steel grey and is a brittle, hard, transition metal. These facts are
based on the crystalline structure of the metal. The metal happens to have a hexagonal close
packing structure (hcp) at standard temperature. This metallic structure also provides the metal
with a relatively high density of 8900 kgm-3. The metal is also given the ability to display
various oxidation states. The main oxidation state is +2 and has the colour blue associated with
it. But the metal can also exhibit other oxidation states. And much like the +2 state, they have
colours associated with them. The colour of erythrite varies from adamantine to pearly crimson
red. Glaudocot is a variation of arsenopyrite (FeAsS) and its color is metallic white. Finally,
skutterudite is also metallic white. The hardness of these minerals can vary over a range, but the
overall hardness of the metal will be discussed further on in the reports. Hardness of these
minerals is about 5 to 6 except for the erythrite around 24.
   Cobalt has been in use since at least 2250 BC, when the Persians used it to color glass. It was
not until 1735, however, that Swedish scientist G. Brandt first isolated metallic cobalt and it was
not until 1780 that it was recognized as an element. The metal has 27 protons in an atom and a
matching number of electrons orbiting the nucleus. The atom also has 32 neutrons that reside in
the nucleus along with the protons. Today, cobalt is used mainly in high-temperature steel alloys,
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magnetic alloys and hard-facing alloys resistant to abrasion. Alloys containing 25 percent cobalt
have been developed for use as fasteners in gas turbine engines. Presently, 747 jet engines are
estimated to contain 400 pounds of cobalt apiece. U.S. resources of the silver-gray metal are
estimated to be about 1.3 million tonnes, most of which are in Minnesota; however, there are
other deposits in Alaska, California, Idaho, Missouri, Montana and Oregon1. Below 417° C
(783° F), cobalt (Co) has a stable hexagonal close-packed crystal structure. At higher
temperatures up to the melting point of 1,495° C (2,723° F), the stable form is face-centered
cubic. The metal also has use as a tracing element. The metal has 12 radioactive isotopes but
none of them occur naturally as an alternative to the main elemental form. The most useful and
commonly produced isotope of these manmade radioactive atoms is the best known is cobalt-60,
which has a half-life of 5.3 years and is used in medicine and industry.
   The magnetic properties of cobalt are also quite significant and large. In fact, of the three
common ferromagnetic metals (iron, nickel, and cobalt), cobalt has the highest Curie point,
which is the temperature above which its magnetic properties are weakened. It is unique in that,
when it is added in moderate amounts to iron, it raises that metal's saturation magnetization (the
limit to which its magnetic properties can be raised). Magnetic alloys form the most important
use of cobalt2.
   The cobalt supplies from the production areas listed above are all secondary production or by-
products of the processing of other metals like iron or copper or nickel. All except the Idaho
production area that is. Cobalt supply is expected to continue to increase over the next few years,
primarily from new nickel mines, where cobalt is produced as a by-product. The U.S. Geological
Survey estimated that 1998 world mine production was 30,300 tones of contained cobalt, up
from 27,000 tones a year earlier. The U.S. cobalt reserve base, USGS estimates, is about 860,000
tones. Identified world resources are about 11 million tones. The vast majority of these resources
are nickel-bearing laterite deposits, with most of the rest occurring in nickel-copper sulfide
deposits hosted in mafic and ultramafic rocks in Australia, Canada and Russia, as well as in
sedimentary copper deposits in the Democratic Republic of the Congo and Zambia. In addition,
there are millions of tones of hypothetical and speculative cobalt resources in manganese nodules
and crusts on the ocean floor, according to the USGS. U.S. cobalt consumption in 1998,
according to the USGS, was 8,090 tones of contained cobalt, down from 8,400 tones in 1997.

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Seven countries supplied 91 percent of U.S. imports of unwrought cobalt and cobalt chemicals
with Norway leading the way. Other sources included Finland, Zambia, Russia, Canada, Congo
(Kinshasa) and Belgium. The United States imported about 130 gross tons of unwrought cobalt
alloys valued at around $5.5 million in 1998. The leading suppliers included Belgium, Japan,
Sweden and the Congo1.
   The most important of these sources, the sulfide sources of Congo (Kinshasa) and Zambia
produce the copper-cobalt ores and these are processed in the conventional manner to produce a
copper-cobalt concentrate. The production of the metal is very much a limited endeavour since a
large portion of the metal is already made in the by-product process of the other metals that we
have covered over the past week.
   But despite this fact, the metal does have a method for production of the pure metal from the
ores that are taken from the ground. After the cobalt-copper ores are processed the resultant
concentrate is then treated by the flotation process (this was covered in two previous reports and
it is the method whereby a metallic mixture is concentrated by the removal of impurities and
add-ins by the use of sulphide compounds) to separate a cobalt-rich concentrate for treatment in
the cobalt circuit. The separation by flotation utilizes pneumatic and mechanical agitation to
produce air bubbles that carry the mineral particles to the surface. Different reagents are used to
attract the cobalt minerals to the bubbles in preference to copper. Cobalt concentrates, which can
contain as much as 15 percent cobalt, are then processed further, using either pyrometallurgical
or hydrometallurgical extractive processes, which are the processes used for the extraction of the
cobalt metal from the refining processes of copper and nickel.
   With the copper process, the cobalt that is contained in, and smelted with, copper concentrate
is oxidized along with iron during the final conversion to blister copper. It then enters the slag
layer, which can be treated separately, usually in an electric furnace. The cobalt can then be
recovered by reduction with carbon to a copper-iron-cobalt alloy. In nickel smelting, however,
most of the cobalt is recovered during electrolytic refining of the nickel by precipitation from
one of its solutions; the cobalt is recovered usually as a cobaltic hydroxide. But even in nickel
smelting, cobalt starts to oxidize before the nickel and can be recovered from the final converter
slag. In the ammonia pressure leaching of nickel, cobalt is recovered from solution by reduction
with hydrogen under pressure. In refineries using a chloride leach for nickel matte, solvent

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extraction is used to remove cobalt directly from the pregnant solution. The resulting
concentrated solution, after some purification, is suitable for the recovery of cobalt by
electrowinning3.
   As was mentioned above, the metal is not usually made from it‟s own ores. It is easier to
produce it as a by-product of other main stream and abundant metal processing mechanisms. As
to be expected then, the metal is usually hard to acquire in the pure form, unless the metal that is
refined was done so using cobalt ores in the individual process that nickel uses. In fact the metal
can often be found to contain traces of the main metal from whose process the cobalt was
produced. This can be used as a form of tracking the production of the cobalt from area to area.
Below is a list of the common impurities that can be fond in the cobalt metal on a regular basis.




Table showing the level of impurities in the plate form of Cobalt


                               Grade                     4N5
                                                               Analytical
                              Element       Specification
                                                               example
                                       Co   99.995% Max        99.998%
                                                1ppm
                                       Na                        <0.5
                                                 min
                                       Al         1              <0.4
                                       K          1               <1
                         Metal
                                       Cr         1              <0.3
                         impurity
                                       Mn         1              <0.2
                                       Fe         2              <0.6
                                       Ni         10              2.2
                                       Cu         2               0.8
                                       Pb         1              <0.1


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                                       C          50               20
                                       S          10              <10
                         Others
                                       O          100              30
                                       N          10               10
                         Size                     100 X 150 X 2 mm




   In the initial introduction, the physical properties, and some of the manufacturing properties,
of the metal was mentioned. Now, as is usually the case, we will consider the manufacturing
properties in more detail. The premiere property of the metal seems to be the hardness of the
metal. It can obtain a hardness in its ores that can makes the metal very useful in the production
of tools like drill bits and also in the use of making other steels and alloys. The metal also has
other attributes, like very high tensile strength coefficients. On the following page is a more
comprehensive list of the manufacturing properties of the metal cobalt.


List of Manufacturing Properties of Cobalt Metal6


Youngs modulus: 209 GPa
Rigidity modulus: 75 GPa
Bulk modulus: 180 GPa
Poissons ratio: 0.31
Vickers: 1043 MN m-2
Electrical Resistivity: 6 μΩ cm
Mineral hardness: 5.0
Brinell hardness: 700 MN m-2
Reflectivity: 67 %
Thermal conductivity: 100 W m-1 K-1
Coefficient of linear thermal expansion: 13.0 K-1 *106



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   But with the manufacturing properties we must also consider the shapes of the metal. One
form that was already considered for the metal is the plate form. The metal can also be made into
ingot form and can even be made into the powder form like molybdenum and tungsten metals.




Because these forms are very hard to quantize, the metal is usually dealt with in the ingot form or
the plate form when considering the price or transactions of the metal.


                                  Plates of Pure Cobalt


   The price of the metal is very fickle. Over the last 60 years the metal has skyrocketed in
value. This has mainly been due to the metal becoming more prominent in the eyes of the eyes pf
the world at large. On the following page is a concise analysis of the metal as it has fluctuated
over the past half century in the United States of America. These prices have been set in dollars
per pound of cobalt. On examination of the graph, it can be seen that the price jumped rather
drastically. This can be attributed to the opening of the Zaire mines to the free market system. As
stated earlier, the metal has a large concentration of its ores in the African region of the Congo
and Zaire. By allowing greater access for the metal, there came a greater demand for the
increased supply6. This really shifted the price towards the left. Other significant events were the
merger of two main mine producers in Zaire and also the release of a stockpile of US
government cobalt7.




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                                              Graph of the Price of Cobalt in Dollars per pound



                                                                       Price of Cobalt


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                           25
Price of cobalt in $/lbs




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                                                                       Year from 1937-1998




                           The price may have dropped of slightly in the nineties but this drop has not reduced the
demand for the metal in no way. And as such, it is the subject of this section, which informs us
as to the areas where we can acquire the cobalt. Most cobalt, as with other metals, can be bought
directly from the mining manufacturers of the metal. The metal has no real use outside of the
industrial industry. Unlike other metals like copper and iron, which are sold for both retail and
commercial use, the metal is only really sold to commercial companies, and at most to small
businesses that have a need for this precious metal. The metal may also be bought from those

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companies that specialize in scrap metal recycling or that buy the pure metal and use it in the
making of alloys and then sell this alloy to other companies tat have use for it. In this way, the
metal is sold and controlled by the companies that sell the metal. The metal prices can also be
controlled by the governments, which also have a hand in selling the metal, countries like Zaire
and the United States.
   One aspect of metal, which I have focused on in recent times is the ability of it to be recycled.
The metal lends itself to be recycled very well. As with other metals like aluminium and
tungsten, the recycling is necessary because of the difficulty and expense to produce and also the
limited abundance of the metal in the earth‟s crust to begin with. But another concern for those
who advocate the recycling aspect of the metal is it‟s relatively high level of toxicity and the
tendency of it to be poisonous to both animals and humans. Many companies that deal with the
metal have to issue warnings about the danger associated with the metal and they also issue
safety guidelines for dealing with a disaster that has cobalt poisoning at the core.
   Below is a guideline for the procedure of poisoning due to Cobalt exposure at a company that
deals heavily with the metal.


   Exposure Limits NIOSH REL: TWA 0.05 mg/m3 OSHA PEL†: TWA 0.1 mg/m3 Personal
Protection & Sanitation:
Skin: Prevent skin contact
Eyes: No recommendation
Wash skin: When contaminated
Remove: When wet or contaminated
Change: Daily First Aid.
Eye: Irrigate immediately
Skin: Soap, wash
Breathing: Respiratory support
Swallow: Medical attention immediately3.


   Despite the danger that might be associated with the metal and its ores and sues, the metal is a
vital component in the industry today. One of the major uses for cobalt is to be superalloyed with

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iron, nickel and other metals to make Alnico, an alloy of unusual strength, wear and corrosion-
resistant characteristics at elevated temperatures. This Alnico has many important uses. It is used
in the manufacturing of jet engines and gas turbine engines for pipeline compressors. It is also
used in the production of carrying containers for the molten metal (forges) when products are
being made and the forge is required to hold its shape time after time. Cobalt-based alloys are
also used in magnet steels and stainless steels where high abrasion-resistant qualities are
required. One important aesthetic use is in electroplating because of its appearance, hardness,
and resistance to oxidation. Even the compounds of the metal have uses. Cobalt oxide is an
important additive in paint, glass and ceramics, which gives them a brilliant and permanent blue
colour4. An example of this is the much sought after porcelain cups and ceramic items that have
invoked much desire for this beautiful craft. Porcelain has been in use for ages since the ancient
Chinese Dynasties and has also been a thing of beauty since then. A comprehensive list of the
use of cobalt appears below9.


Products                Specification           Applications


1)                      COBALT CATHODES         Min . 99.8% Cobalt           Super Alloys
                                                                             Permanent Magnets
                                                                             Batteries
                                                                             Paint Driers
                                                                             Pigment Industry
                                                                             Cobalt Powder

2)   COBALT SULPHATE             Min . 21% Cobalt         Animal Feed
                                                          Dyes
                                                          Anodising
                                                          Copper
                                                          Electrowinning


3)   COBALT OXIDE                Min . 71% Cobalt         Glass
                                 Higher Cobalt % can      Ceramic
                                 also be achieved by      Recording Media
                                 special demand


4)   COBALT CARBONATE            Min . 45% Cobalt         Ceramics
                                                          Animal Feed




                                                                                        K. Pile 9
5)     COBALT CHLORIDE            Min . 24% Cobalt        Silica Gel
                                                          Dyes
                                                          Glazed Tiles


6)     COBALT ACETATE             Min . 23.5% Cobalt      Pure Terepthalic Acid
                                                          Anodizing & Electronics
                                                          Electronics


7)     COBALT NITRATE             Min . 20% Cobalt        Catalyst Manufacturing
                                                          Ceramic Pigments
                                                          Batteries




     World cobalt demand is expected to rise along with production of superalloy use for jet
engines, spare engine parts and land-based gas turbines for power generation. Cobalt
consumption will also increase in rechargeable batteries, wear- and corrosion-resistant alloys,
and hydroprocessing catalysts for oil refining.




                                                                                       K. Pile 10
                                      Samples of Cobalt Tools

   Other products that are also quite high on our list of concerns are the tools that are made by
the cobalt. This metal is responsible for many of the tools that we use almost everyday. Tools
like drill bits, nails, saws and hammers. Due to the high hardness of the cobalt metal, it can be
made into items such as forges, high-heat robot parts and also industrial strength drilling tools
that have to be sent into the earth. Other tools also include those no traditional one such as paint
pigments and also, electrical components in computers and also as tools in the ceramics and
textile industries as a colouring for the pots and porcelain work.
   All in all, cobalt is a metal that has great versatility, not only is it strong and durable under
high stress and heat but it is also soft and lends itself well to aesthetic need in the use of pigments
in paints and pottery. Not many metals can claim that they have the best of both worlds. But
cobalt can. Man in many ways can use this metal, and he does. Over the course of the last ten
weeks, we as a class have looked at metals with varying characteristics and strengths. It is only
fitting that we should end this period of study with one metal that can sum up all the good points,
and some of the bad, of the metals that we have looked at. This metal is cobalt.




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                                         Works Cited
1. URL: “http://www.amm.com/ref/cobalt.htm” ,Checked 03-30-2001

2. URL: “ http://www.britannica.com/eb/article?eu=119880” ,Checked 03-30-2001

3. URL: “http://www.cdc.gov/niosh/npg/npgd0146.html” ,Checked 03-30-2001

4. URL: “http://www.galleries.com/minerals/sulfides/cobaltit/cobaltit.htm” ,Checked

        03-30-2001

5. URL: “http://minerals.usgs.gov/minerals/pubs/commodity/cobalt/” ,Checked

        04-01-2001

6. URL: “http://www.webelements.com/webelements/elements/text/Co/chem.html” ,

        Checked 04-01-2001

7. URL: “http://www.angelfire.com/biz/NYCLCompany/hss.html” ,Checked 04-01-2001

8. URL: “http://www.endmill.com/” ,Checked 04-01-2001

9. URL: “http://www.rubamin.com/metalsp&a.html” „Checked 04-02-2001




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