An investigation was carried out to predict the size-composition make-up of the product of a coal blend ground in a ball-and-race mill using the breakage characteristics of the individual components determined by separate grinding. Sometimes a pseudolinearity can be observed when the changes in the grinding rate for the components in the mixture occur in a compensated manner. In this case, the HGI of the blend appears to be additive. However, the composition of the product size intervals is different from the weighted sum of the two products from separate grinding. An empirical equation was used to predict; the change in the breakage parameters as a function of the blending ratio and the difference between the relative strength of the two materials. The grinding of the individual coals in the Hardgrove mill exhibited non-first-order grinding kinetics. Consequently, the false time concept fdr fines accumulation was used to predict the grinding behavior of the coal blends with reasonable accuracy. The locked-cycle simulation for grinding a binary mixture shows that the content of the mill charge becomes richer in the stronger component. The system attains steady state when the absolute production rates of both materials are the same, although the ratio of materials in the mill charge is not necessarily the same as the ratio in the feed. As a result, the production rate can be lower than expected based on the ratio of the feed.