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In this current economic climate, companies are constantly searching for new processes, technologies and equipment to add value to their organisations and reduce costs. In this article by Scott Will, we will cover how roller mill grinders add value to many applications and reduce long-term processing costs. We also discuss recent technology improvements that further improve roller mill capabilities and efficiencies.
Digital Re-print - March | April 2010 Feature title: Roller Mill Grinders - Advantages, limitations and how roller mill grinders are changing for the better Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2010 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872 www.gfmt.co.uk NEXT PAGE Roller mills Feature Feature Roller mills Side bar: Obtaining a narrow particle size distribution should add value to your process. less energy than an attrition mill of the same However, materi- r Mill Grinders capacity. If you are wondering what savings als like wood, rubber, Rolle that means in dollars, an additional 10hp and soft plastics are costs our factory US$6500/year (based on not good candidates 24/7/365 at US$0.10/kWhr). for roller grinding. changing for the better and how roller mill grinders are Limited feedstock Product Limitations Advantages, limitations size: The maximum Due the low-impact grinding nature of size of the feedstock ses, technologies and y searching for new proces ate, companies are constantl Scott Will, we will cover roller mills, it is typically best suited for (unground material fed In this current economic clim uce costs. In this article by their organisations and red sing costs. We also materials that break apart under pressure, to the roller grinder) equipment to add value to and reduce long-term proces value to many applications and efficiencies. otherwise know at ‘friable’ materials. This varies based on the how roller mill grinders add rove roller mill capabilities rovements that further imp can range from polyester plastics used in material properties; roll discuss recent technology imp solid surface countertops to coffee. Roller speeds and corruga- mills are also superior grinding systems for tions, and other factors. “Roller-Style Grinders are typically by Scott Will various abrasive materials such as limestone Generally, the feedstock must more expensive than hammer and elemental silicon. be 25.4mm (1 inch) or smaller. In any case, we have listed the two most mills but give better particle size more of these days. Change for the better! Now that is something we all need a little common product requirements for success- Changing for the better distributions. If the only sizing ful roller mill operation. Roller mill technology continues concern is to reduce the material Only suitable for friable materials: The to evolve. below a certain size with no product to be ground must fracture under One of the greatest advances in limits to the permissible amount stress rather than flatten or deform. This technology involves roll materials. of dust or size consistency, then does not mean that the product must be Today, various material advances brittle; a roller-style grinder can be used allow roller mills to be utilized in a roller mill grinder may not be for products as hard as elemental silicon or increasingly abrasive applications. appropriate for your needs” F or those of you unfamil- rial in size to a narrow particle size limestone. No longer are we limited to steel iar with roller mills, the Figure 1 distribution and with few unwanted basic principal of operation fines (see Figure 2). is simple: Two parallel rolls rotate towards one another Roller mill advantages at high speeds, say 400 – Now that we understand the basic 3000rpm. Material is gravity principles of operation, there are four fed between the parallel rolls main advantages that direct people to We pride ourselves in implementing > Turnkey installations and as it enters the ‘nip’ of use a roller mill rather than a hammer- the latest technological the rollers, it experiences both mill, ball mill, cone mills or some other improvements > Cleaning equipment crushing and shearing forces attrition grinding method. > Milling equipment We strive for the highest quality that grind the particle into Narrow particle size distributions. & con dence in our products & > Transfer equipment smaller pieces. Roll surfaces can Fracturing of the material is accom- services be either corrugated or smooth plished only by the induced stress/shear > Extraction Control on the surface, depending action of the roll surface on the prod- Our goal is complete customer > Packaging on the need, and typically a uct. There is no attrition, high speed satisfaction in the production of our our milling machines > Complementary machines speed differential between the impact, or internal screening. rolls, ranging from 1:1 to 3:1, For many materials, this results in is necessary (see figure 1). significant narrowing of the particle size distribution. Most roller mills are compromised Minimal dust (fines) creation: of multiple grinding sections vertically Without high speed impact, dust gen- stacked on top of one another and eration is reduced. material falls by gravity from one pair Low temperature rise: With no of rollers to the next. high speed impact and since there Konya Organize Sanayi Bölgesi 7 Sokak The number of sections is deter- is no recirculation of product inside No: 3 Konya/TÜRKİYE mined by the material properties and the grinder, heat generation is mini- the amount of reduction required to mal. Also, grinding rolls can be cooled T: +90 332 239 1016 (pbx) achieve the desired grind size. internally for especially heat sensitive F: +90 332 239 1348 The roll corrugations, speed products. E: email@example.com ratio between the rolls, and the gap Low energy consumption: There is between the grinding rolls are all no high speed particle impact and zero precisely engineered for each product. The objective is to reduce the mate- friction between particles; thus, a roller mill grinder typically uses 30-50 percent www.unormak.com.tr Realizing your future by your voice Unormak.indd 1 24/11/2009 15:56 18 | march - april 2010 Grain &feed millinG technoloGy Grain &feed millinG technoloGy PREVIOUS PAGE NEXT PAGE march - april 2010 | 19 Roller mills Feature s crudest “Some may still think of roller mills in it y pulverizing form, w ith “crushers” haphazardl But today’s friable materials down to a reduced size. to produce precisio n roller mills are designed pletely “controlled explos ions” that achieve a com d particle size” contro lled and highly-engineere Modern manufacturing methods and grinding, especially with polyester, acrylics or even hardened steel rollers. Modern roller CNC machines provide precision equipment and other hard plastics. This is no longer mills use exotic roll materials, various coatings tolerances that were simply not possible necessary with the advent of water-cooling and in extreme cases ceramics that offer hard- years ago. on roller mill grinders. ness values above the Rockwell C hardness Today, roll gaps can be held to 10 Additionally, various foods such as coffee microns and pepper boil off volatile oils and aromas (+/-0.0005 above 35 degrees C (95 degrees F). Water- Figure 2 inch) while cooling eliminates product temperature rise rotating at as materials pass through the grinder, thus 3000rpm. eliminating the need for expensive liquid This allows nitrogen and simultaneously improving prod- roller mills uct quality. to grind materi- Today’s precision rollers als down Roller mill technology has evolved and to 50 become much more refined over the past microns, 50 years. continu- Some may still think of roller mills in ously and its crudest form, with ‘crushers’ haphaz- accurately, ardly pulverizing friable materials down to day after a reduced size. But today’s precision roller day and mills are designed to produce ‘controlled year after explosions’ that achieve a completely con- year. trolled and highly-engineered particle size. Water- Friable materials can now be reduced in size cooling also with less dust, greater uniformity and higher scale. These coatings and ceramics can virtually plays a part in expanding applications. efficiencies. eliminate wear numerous applications. In the past, cryogenic grinding methods Not only is this change for the better, were required on a number if applications but this is change for the better than can be to eliminate heat elevation during proven and quantified. More InforMatIon: Modern Process Equipment, Inc. 3125 S Kolin Avenue Chicago, IL 60623, USA Tel: +1 773 254 3929 Fax: +1 773 254 3935 Web: www.mpechicago.com 20 | march - april 2010 Grain &feed millinG technoloGy PREVIOUS PAGE NEXT PAGE LINKS This digital Re-print is part of the March | April 2010 edition of Grain & Feed Milling Technology magazine. Content from the magazine is available to view free-of-charge, both as a full online magazine on our website, and as an archive of individual features on the docstoc website. Please click here to view our other publications on www.docstoc.com. April 2010 • See the full issue • Regulating granularity • Visit the GFMT website In this issue: • Designing bagging • Roller Mill lines to meet • Contact the GFMT Team Grinders requirements Advantages, limitations - Specifying and and how roller mill designing bagging lines grinders are changing for the food processing for the better industry • Residue-free • German technology conveyance of convinces in • Subscribe to GFMT grain the Australasian hemisphere • Global Grain & Feed market report A subscription magazine for the global flour & feed milling industries - first published in 1891 To purchase a paper copy of the magazine, or to subscribe to the paper edition please contact our Circulation and Subscriptions Manager on the link adove. 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