Operations particle size reduction

Table 1 Unit Operation—Particle Size Reduction ... 

Comminution, or particle size reduction of solids, is considerably different from that of the breakup of one liquid by dispersal as small droplets in another. Particle size reduction is generally achieved by one of four mechanisms (1) compression, (2) impact, (3) attrition and (4) cutting or shear. Equipment for particle size reduction or milling includes crushers (which operate by compression, e.g., crushing rolls), grinders (which operate principally by impact and attrition, although some compression may be involved, e.g.,... 

The usual first beneficiation operation is size reduction, which may be achieved by crushing, grinding, or disaggregating by scrubbing and washing. Particle size reduction liberates mineral species so that they can be separated. Size separation usually follows size reduction. When gangue minerals are more indurated than the phosphate, it is often... 

In both cases, the variation of the sample estimate of the property of interest is reduced. In the latter case, reducing the particle size may not be practical. For example, reducing the particle size of the material in an entire landfill before sampling is impossible. Sometimes, surface soils can be tilled to a certain depth, and this may incidentally reduce the particle size of the top layer. On the other hand, in mining operations, various stages of grinding are commonplace, and sampling can be conducted after particle size reduction. 

Fig. 6 Diagram of operation of a piston gap homogenizer. Turbulence and cavitation result in particle size reduction during the homogenization process. From Professor Douglas Goff, Dairy Science and Technology Education, University of Guelph, Canada www.foodsci.uoguelph.ca/dairyedu/ home.html (accessed September 2004).

The advantage over conventional crystallization processes is that recrystallization and particle size reduction can be accomplished in a single step with minimal operator exposure and minimal use of organic solvents. ... 

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