Study on the influence mechanism of the grinding fineness on the floatability of coking middings

Abstract

In this paper, the influence mechanism of grinding fineness on the floatability of coking middings was analyzed by studying the flotation probability, cumulative flotation probability and water recovery in the flotation process. The results indicated that in a moderate-turbulence intensity flotation environment, the size, density and wettability of particles affect their flotation probability. The difference in flotation probability between particles of the same particle size but different densities were significantly affected by the particle size. Given a particle size of −0.25 + 0.075 mm, the flotation selectivity of the different density fractions was the highest. Under a moderate grinding fineness, the cumulative flotation probability of the −1.4 g/cm3 density fraction among the various grinding products was high, and the index could be reduced via insufficient or excessive grinding. In addition, insufficient grinding could cause inadequate coal slime dissociation, thus increasing the cumulative flotation probability of the 1.4–1.6 g/cm3 density fraction. Overgrinding could cause a higher water recovery and aggravate entrainment in the flotation process. All the above phenomena could reduce the floatability of ground coking middings. Coal subjected to a grinding time of 15 min obtained the best flotation performance in the flotation rate tests.