Effects of particle size on the flotation behavior of coal fly ash.

The effect of particle size on the flotation behavior of coal fly ash was investigated in this study. Three narrow particle size fractions, -125 + 74 μm, -74 + 45 μm, and -45 μm, and the unclassified particle size fraction of -500 μm of coal fly ash were chosen to study the basic properties by the measurement of induction time, contact angle, and wetting heat. Furthermore, flotation kinetic tests of coal fly ash with different particle size fractions were conducted. The results show that particle size significantly affects the flotation kinetics of coal fly ash, and the intermediate particle size fractions of -125 + 74 μm and -74 + 45 μm had better flotation performance and higher flotation rate than the fine particle size of -45 μm. Six flotation kinetic models were used to fit the test data of the cumulative unburned carbon recovery in the coal fly ash flotation. The parameters of flotation rate (k), maximum unburned carbon recovery (ε), and correlation coefficient (R) were analyzed in detail. The fitted results from the data showed that, for each size fraction, the froth flotation of coal fly ash can be best described by the classical first-order model.