Grinding pins

FIGURE 4.65 Working in small radii with a grinding pin made from aluminum oxide and a grinding hand piece... 

Pin MiUs In contrast to peripheral hammers of the rigid or swing types, there is a class of high-speed mills having pin breakers in the grinding circuit. These may oe on a rotor with stator pins between circular rows of pins on the rotor disk, or they may be on rotors operating in opposite directions, thereby securing an increased differential of speed. See also the Mikro-ACM pulverizer described later. 

High-speed hammer or pin mills result in some selective grinding. Such mills combined with air classification can produce fractions with controlled protein content. An example of such a combination is a Bauer hurricane hammer mill combined with the Alpine Mikroplex superfine classifier. Flour with different protein content is needed for... 

FIGURE 4J2 Crushing and grinding equipment, (a) Jaw crusher, (b) gyratory crusher, (c) vibratory mill, (d) fluid shear mill, (e) pin mill, (f) fluid jet mill, (g) hammer mill, and (h) ball mill. Redrawn from various figures in Perry and Chilton [1], Lowrison [2], and VanCleef[3]. 

The generally accepted definition of micronization is the size reduction of particles down to 1-30 m in diameter. Although it is possible to use some of the previously discussed equipment to reduce the particle size distribution of a product down to this range they are not ideally suited to the application as the distribution curve can be fairly wide spread and possibly even bimodal where as a tight PSD and single node curve is the goal of most manufacturers (Fig. 21). The equipment commonly used are pin mills, hammermills, fine grind, and jet mills. 

Place a 100-mg vitamin C tablet between two sheets of wax paper and use a rolling pin to grind the tablet into powder. 

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