Size reduction power requirement, example

For example, coal which is destined for power generation may undergo size reduction to produce a product with a top size of 0.04 in. (1 mm). On the other hand, the size of the coal needed for a coking operation is coarse and the number of stages of size reduction involved in preparing a coal feed for a coking is somewhat less than required to prepare coal as the feedstock for power generation utilization. 

The circled value on the left shows an increased power requirement of approximately 1.4 times the optimum when a D/T of 0.25 is selected. This is because the reduction in D/T causes a decrease in primary flow. These two examples of an important application demonstrate the significant difference between the power requirements for varying D/Ts. A power savings of up to 60% is achieved simply by changing the D/T to its optimum value of 0.35. This means that the sizing process needs to be a function of D/T. The effect of D/T on solid suspension is illusfiated on the CD-ROM. 

For most particulates above 1 /xm in natural waters and wastewaters, the power-law coeflBcient appears to be greater than 3. Therefore, adequate removal of the particulate fraction by sedimentation or flotation requires a reduction in p by, for example, coagulation/flocculation, which shifts the major portion of particulate surface area and mass into size classes above about 30 /xm. If granular-media filtration is used as the particulate separation process, only particulate destabilization may be necessary to achieve desired removals. 

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