Size reduction Bond Work

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)... 

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. 

Using ultramicroelectrodes, it is possible to study reactions under the conditions of synthesis, including electrosynthesis. An example is the electrohydrodimerisation of acrylonitrile to adiponitrile (Scheme 6.11, top) mentioned in the introduction in industry this is typically carried out with an emulsion of acrylonitrile in an aqueous phosphate buffer as electrolyte. At substrate concentrations in the mM level, the reduction of acrylonitrile takes another route leading to saturation of the C—C double bond (Scheme 6.11, bottom). This precludes studies of the dimerisation using substrate concentrations at the mM level and thereby working electrodes of conventional sizes. The transition between the two mechanisms could be studied conveniently using an ultramicro electrode as the working electrode... 

A third version of the comminution law is the one attributed to Bond (1952, 1963), who considered that the work necessary for reduction was inversely proportional to the square root of the size produced. In Bond s consideration, n takes the value of 3/2, giving the following version (Bond s law) also by integration of Equation 4.1 ... 

---