Crushing, Screening & Conveying

If you are trying to evaluate the Efficiencies of Crushing and Grinding you may look at Ackermann, L. J. chem. Soc. S. Afr., 1946, 47 (1), 56. Discussing the paper of the same title by T. K. Prentice, S. Afr. Min. (Engng) J., 1946, 57, 427. Evidence is submitted to support the following statements: ore from one screen size to the next in any geometric screen series is constant under given conditions; secondly, that under usual operating conditions a wastage of power occurs which is approximately proportional to the average surface area of the particles passing through the machine, and which is additional to power losses due to friction and transmission in the driving mechanism; thirdly, that the available power input required to produce a unit area of fracture is nearly constant for most crushing and grinding machines; finally, the efficiency of industrial grinding machines varies from 0-5% for gyratory crushers to 0-0.18% for tube mills. It is concluded that the useful energy input is employed almost entirely in straining the ore particles up to the point of fracture, rather than in the production of new surface area. The energy consumed in actual fracture, apart from the initial straining period, is negligible from a practical point of view.