CIRCULATION ATTRITORS

Union Process “Q” and “QL” Attritors Achieve Ultra-Fine, Uniform Dispersions Quickly and Consistently © 2017, Union Process, Inc. History From a revolutionary idea proposed and developed by Dr. Andrew Szegvari in 1945, Attritor technology grew to become the basis for Union Process, Inc., an independent family-owned American company founded in Akron, Ohio. Today, Attritors are considered to be the most efficient grinding/dispersing systems and are used in hundreds of industries and research laboratories worldwide. How Attritors Work The Attritor is often referred to generically as an “internally agitated high energy media mill.” The operation of an Attritor is simple and effective. The material to be ground is placed in a stationary tank with the grinding media. The materials and media are then agitated by a shaft with arms, rotating at high speed. This causes the media to exert both shearing and impact forces on the material. The final result of this remarkably efficient process is extremely fine material, measured in microns or fractions of microns, distributed on a very narrow curve. The Circulation Attritor The circulation grinding Attritor (“Q” machine) is a combination of an Attritor and a large holding tank which is generally about ten times the size of the Attritor. The Attritor is filled with media and contains grids which restrain the media while the slurry is allowed to pass through. The unique principle of the “Q” Attritor is the high circulating (pumping) rate. The entire contents of the holding tank are passed through the Attritor at least once every 7-1/2 minutes, or about 8 times per hour. This high pumping rate results in a faster grind and a narrower particle size distribution. This phenomenon is explained by the principle of preferential grinding (See Figure 1). The fast pumping stream through the agitated media bed makes the “Q” machine grinding chamber act as a dynamic sieve or filter, allowing the fine particles to pass and move quickly through, while the coarser particles follow a more tortuous path through the media bed. With the circulation process, unlike a continuous machine with the slurry making a single pass, the material makes many passes through the grinding chamber until the desired particle size is obtained. Grinding media used in circulation Attritors range in size from 3/32" to 1/4" in diameter. Chrome, steel, steatite, and zirconium oxide are commonly used media. Figure 1: Passage Of A Small & Large Particle Through A Layer Of Agitated Media Retaining Grids Circulation Grinding Attritor Premix Holding Tank The Union Process Advantage From years of experience in designing and building thousands of Attritors for use all over the world, Union Process has developed the “know-how” to custom-design units for specific requirements, whether for production or laboratory use, employing either a dry or wet grinding process. Union Process maintains a well-equipped laboratory and pilot plant where actual production conditions can be simulated to assure that the Attritor we build for you will satisfy your requirements. Skilled technical service representatives are available for consultation. They can arrange visits to customer and prospective customer facilities to answer questions and provide solutions. Advantages of Using a Circulation Attritor n Faster grinding with narrower particle size distribution n Uninterrupted, large-scale production n Excellent temperature control n Simple and safe to operate n Low maintenance and power consumption Common Applications for Attritors n Paints, toners, inks n Ceramics n Agricultural flowables n Food products n Chocolate, confectionery n Paper coatings, calcium carbonate, clay n Chemicals n Ferrites n Metal oxides n Minerals, ores, coal n Sulphur dispersions Retaining Grids

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