Study on the classification and floc-flotation process of Huangling coal slime

Abstract

ABSTRACT This study primarily investigates the effect of particle classification on flotation of Huangling (HL) coal slimes with aiming to recover more combustible and clean fuels. The ash composition of fresh slime was analyzed using XRD and ICP-AES. The results showed that HL coal slime had high ash content and difficult washability. Conventional flotation and floc-flotation tests of coarser fraction (0.500 − 0.125 mm) and finer fraction (−0.125 mm) were performed to investigate comprehensively the flotation parameters. Results indicated that particles classification could effectively improved the flotation capacity of coarser fraction. Conventional flotation was suitable for coarser fraction, whereas floc-flotation was suitable for finer fraction. However, finer fraction has a large specific surface area, poor attachment with the air bubbles and entrained a large amount of impurity mineral particles. These features caused conventional flotation ineffective in finer fraction, whereas the addition of Polyacrylamide (PAM) anionic flocculant significantly enhanced flotation recovery. The excessive flocculant could not be continuously improved flotation effect, possibly because the excessive PAM molecules were adsorbed on the surface of coal particles, which accelerated the rupture of liquid film between coal particles and bubbles. Furthermore, the floc-flotation could effectively increased the particle size and reduced specific surface area of finer fraction.