Bonds Law and Work Index

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  

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. 

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