Work index, size reduction

The work index, Wjr is basically an indication of ore hardness, but also includes equipment efficiency. The Bond method has been the mainstay of size reduction circuit. It still holds a value, specially for initial design calculations, and for simple checks on efficiency. 

Bond terms Ei the work index, and expresses it as the amount of energy required to reduce unit mass of material from an infinite particle size to a size L2 of 100. im, that is q = 00. The size of material is taken as the size of the square hole through which 80 per cent of the material will pass. Expressions for the work index are given in the original papers 8,9) for various types of materials and various forms of size reduction equipment. 

Bond work index -particle size reduction [SIZE REDUCTION] (Vol 22)... 

Wilson equation, activity coefficients, 374 Wilson-Lobb-Hottel eqiration, 214 application, 219 Winkler process 582 Wire mesh deentrainers, 615 calculation example, 620 disengaging space, 616 kev dimensions, 618 k-values, 615 pressure drop, 616 tvnical installations, 616 Work index, size reduction, 342 Wyssmont dryer, 237,251... 

When Xi and X2 are measured in micrometers and E in kWh/ton, K = 5Ei, where E is the Bond Work Index, defined as the energy required to reduce a unit mass of material from an infinite particle size to a size such that 80% passes a 100 pm sieve. The Bond s work index is obtained from laboratory crushing tests on the feed material. Bond s law holds reasonably well for a variety of materials undergoing coarse, medium, and fine size reduction. 

Equation 7-1 is based on reduction of the rock size in a 2.44 m (96 in) ball miU. This equation applies in the case of wet grinding, which is often the first step in a slurry circuit. Typical examples of the grindabihty work index F are presented in Table 7-1. 

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