Comparison of the Flotation Performance between Wide and Narrow Particle Size Ranges of Coal

The flotation completion degree tau and an energy parameter E were proposed to compare the flotation effect for wide and narrow particle size ranges. Flotation rate tests were conducted at different agitation speeds in a laboratory flotation cell on different particle-sized coal. The results showed that the particle constitution of the sample was unimodal and that the yields of the middle particle size (-250 mu m to +75 mu m) and middle density (1.40 g/cm(3) to 1.60 g/cm(3)) were high. Optimal flotation recovery for the various sizes occurred at the lower speeds (1500 rpm or 1800 rpm). During flotation, the tau value initially increased and then decreased. Compared with the narrow particle size, the wide particle size exhibited a better flotation effect, less ash in clean coal, and higher recovery.