Simple approach to estimation of the work index

The work index of the mill. feed of any mineral processing plant, determine d according to the procedure prescribed by F. C. Bond in 1961, is still con sidered useful for estimation of the required size and power of a mill, esp ecially in the preliminary phases of a feasibility study. The index, howeve r, is no longer considered very important from economic or operational poin ts of view. Moreover, scientific and technological advances in the design, operation and control of comminution circuits have rendered very precise de termination of the work index unnecessary. It is, therefore, considered log ical to develop a simple method of obtaining a fair estimate of the index t hat does not require special equipment and experimental procedures. An approach is presented that is based on a statistical analysis of data ac cumulated over four decades of experimental determination of the work indic es of a large number of ores, minerals and rocks. A simple model has been d eveloped that correlates the work index of a material and the parameters of the Rosin-Rammler size distribution of an experimental feed passing 6 mesh (-3327 mum). All that is needed is to crush a sample of the mill feed to - 3327 mum, determine the size-distribution parameters from sieve analysis wi th the aid of a computer and compute the work index from the correlation mo del.