New approach to evaluate the wettability of low-rank coal powders based on multiple light scattering

Wettability is an important interfacial property that affects the separation of micro-fine particles. This paper carried out a new approach to evaluate the wettability of low-rank coal (LRC) powder based on multiple light scattering. Four collectors are used to modify the coal powder to obtain different wettabilities. The stability analyzer is used to investigate the wettability and wetting process of coal sample, which is observed by transmitted light. The stability of coal samples dispersed in a sample cell completely wetted by water is analyzed by Turbiscan Stability Index (TSI). The TSI value shows that stronger wettability of coal sample can make the system less stable. Moreover, the change law of the transmitted light shows that the coal sample with high wettability is quickly wetted by water, resulting in a shorter time for the transmitted light intensity (T) to decrease to 0% due to the volume concentration of the particles entering the water phase increase rapidly. Therefore, the wettability is characterized by the variation time of T. The shorter time represents the stronger wettability. While ΔT/t is used as an evaluation of the wetting rate, the larger absolute value shows a faster wettability rate. This provides a basis for rapid and accurate evaluation of the wettability of LRC samples.