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Particle Reduction TechnologyFor a Rapidly Changing World

It’s a shrinking world: Faster transporta-tion, instant Internet information and im-mediate communication all combine tomake our enormous planet, for all practicalpurposes, a lot smaller and a lot more de-manding than it used to be.

In today’s manufacturing world, compa-nies are also demanding a lot more fromtheir processing equipment. More specifi-cally, companies are seeking competitiveadvantages through improved product char-acteristics, higher process efficiencies andless energy usage. In terms of particle re-duction, the Gran-U-Lizer™ achieves all ofthese objectives.

Why maximize particle uniformity?In many particle reduction applications,

the most important objective is to maxi-mize particle uniformity. Take, for in-stance, coffee. In the United States, coffeeis typically ground to achieve maximumyield on a 16 x 40 U.S. Mesh (1170 to 590microns) size range with minimal “fines”(in this case, those particles below 40Mesh). After grinding, the coffee is notclassified; rather, it proceeds directly to

packaging. This type of streamlinedprocess demands both preci-

sion grind uniformity and ultimateproduct consistency. If the grindsize varies or additional “fines”

(or dust) are created, the coffeeoverextracts during the brew

process. This overextractionincreases coffee bitterness –a characteristic that all cof-

fee producers try to minimize.In other particle reduction applications,

strict particle size requirements must bemet and, therefore, product classificationis required. When this is the case, “fines”are often thrown away, reprocessed orused in a secondary market. In eithercase, money is lost and energy is wasted.

Optimal applicationsIn general, there are two factors that

rule out using the Gran-U-Lizer-styleroller Technology for selection as the opti-mal particle reduction method for any ap-plication: (a) The product to be ground isnot friable or fragile/breakable… or (b)There is no value to be gained from main-taining a uniform particle size with minimal “fines”.

However, if both conditions (a) and (b)above are met, the Gran-U-Lizer will pro-vide superior particle reduction resultsover any other milling method, particularlyin those applications where the desired av-erage particle size range is between100–1500 microns.The variables at play

The Gran-U-Lizer utilizes roller milltechnology and adheres to three core

principals in order to maintain excellentsize distribution. First, the rollers that areused are not typically smooth. They are, infact, custom corrugated (or grooved) tosuit each specific application. There are lit-erally thousands of different corrugationsthat might be applied to a given roll. Byperforming real-world environment labtests, the best configuration for a given ap-plication can be determined. Rolls can begrooved with corrugations that run eitheralong the length of the roll (longitudinal)or around the roll’s circumference (circum-ferential). Flutes within each corrugationcan vary both in terms of shape as well asin size. For example, some products re-quire eight flutes per inch, while othersuse 30 flutes, depending on variables suchas material hardness and specified size.

The second important differentiatingvariable is relative roll speed ratio, or dif-ferential roll speed. Running the rolls atthe ideal relative speed as the materialpasses through them will achieve the de-sired shearing effect. For example, if oneroll rotates at 500 RPM and the other 1000RPM, the relative roll speed is defined at2:1 (1000/500). The relative roll speed

Model 1052 TP Gran-U-Lizer:Features non-corrosive materials ofconstruction and automatic particlesize control that is capable of stor-

ing 100 individual grind recipes.Model IMD 888 Gran-U-Lizer: Features car-bon steel construc-tion and threegrinding sections formaximum particlesize control.

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ratio is proportional to the amount of shearplaced upon a particle passing through the“nip” point of a roller. The higher theshear, the more tearing the crushed particlereceives. Depending on the material proper-ties and roll cuts being utilized, this rela-tionship has a definite impact on the particle size distribution.

Third, the operator has the ability tocontrol the product size by widening ornarrowing the gap between the rolls. Theroll gaps can be adjusted on the fly to alterparticle size distributions “on the fly” inseconds, eliminating the need to shut downa continuous process and allowing fastchangeover times between various grindsettings. The most critical element of thisfine-tuning capability is the need to keepthe rolls parallel. Perfectly parallel rolls area cornerstone of this roller mill technology.

Controlled explosionsRoller technology has evolved and be-

come much more refined over the past 50years. Some may still think of roller tech-nology in its crudest form, with “crushers”haphazardly pulverizing friable materialsdown to a reduced size. But today’s Gran-U-Lizer has been designed to produce“controlled explosions” that achieve a com-pletely controlled and highly-engineeredparticle reduction. Friable materials – basically any materials that can break asopposed to flatten under pressure - can nowbe reduced in size with less dust, less“fines” and greater uniformity. In fact,when compared with alternative methods ofgrinding, the finite advantages of this rollermill technology become dramatically clear.For example, compare roller mills withhammermills, or Fitzmills®, which grind byimpact at high speeds and rely on a perfo-rated sizing screen to control particle size.

Roller mills typically create 50-75% lessdust, or “fines”, and improve desired parti-cle uniformity by 50-100%. Plus, sincehammermills and other attrition millingmethods rely on multiple impacts, theytypically require a relatively higher energyusage. Energy savings can be a primaryreason to go with roller mills over moretraditional methods. In fact, because oftheir efficient reduction action, roller millgrinders will produce 15-40% more ton-nage/hour, at a given horsepower, thanhammermills.

Roller mill technology is not necessar-ily the best technology for every applica-tion. If you’re looking to produce veryfine grinding with final particles in the 40

micron range, pinmills may be your bestoption, even though pinmills have some in-herent disadvantages including relativelylow capacities with fairly high operatingand capital costs. But if you’re looking forsuperior, controlled reduction for distribu-tion targets ranging from 100 to 1,500 mi-crons, and you’re working with friable ma-terials, roller mill technology is your best option.

Growing markets for precision particles

Market demand for precision particles isgrowing. As companies strive to improveproduct characteristics, achieve higherprocess efficiencies and use less energy,

the utilized roller mill technologies be-come ever more important.

In general, we see food, chemical, min-eral and pharmaceutical companies in con-tinuous demand for particle reduction im-provements. More specifically, twomarkets we have very high expectationsfor in the next few years are the carbonand super-absorbent industries.

As these materials become more com-moditized, manufacturing efficiencies andproduct quality become increasingly im-portant. Regarding carbon, we see a highdemand for activated carbon for air andwater purification as well as carbon elec-trolytes, which are used in the steel manu-facturing process. The same story is truefor super-absorbent materials, which areused in various applications from napkinsto agriculture. As the super-absorbent mar-ket matures, competition increases andmanufacturing efficiencies become pro-gressively more important.

Carbon and super-absorbent productionare just a couple examples of the thou-sands of applications that can benefit fromthis roller mill technology. Basically, if acompany is looking to reduce friable parti-cle size, reduce waste and reduce costs,the controlled particle reduction technol-ogy of roller mills is increasingly becom-ing the way to go. While traditional crush-ers and other imprecise methods areliterally gathering dust, roller mills willcontinue to expand their role in this ever-reducing world.Modern Process Equipment, Chicago, IL 773-254-3929

Model LPP Gran-U-Lizer™: Suitable forlaboratory and GMPgrinding applications.

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