The Effect of Bubble Size on Fine Coal Flotation

Abstract

To better understand the fundamental steps involved in the froth flotation process, the probability of collection has been determined for the flotation of a very hydrophobic, ash-free coal sample. The results show that probability of collection increases rapidly with decreasing bubble size, and the values are in good agreement with the theoretical collision probabilities predicted from Weber and Paddock's analysis. In the present work. Weber and Paddock's model has been expanded to predict the flotation rate constant as a function of bubble size and other operating variables. The flotation rate constants, determined experimentally using a run-of-mine coal, have been found to exhibit the same power dependence of bubble size as predicted by the model, but the values are lower than predicted by approximately 50%. This discrepancy may be attributed to the high ash content of the coal (15.5%) and, hence, a low probability of adhesion.