Effects of a cyclonic microbubble flotation column operating parameters on coal process responses

Abstract

ABSTRACT Processing fine and ultrafine coal particles from primary resources is essential for sustainable development. As one of the most recently developed enrichment equipment, cyclonic microbubble flotation columns (FCMC) showed high efficiency in upgrading various fine minerals. However, understanding the effect of FCMC operating variables on coal upgrading process responses remains a black box and needs fundamental assessments. To fill the gap, this study examined the influence of circulating pump pressure and froth height on the recovery of different coal particle size ranges to assess and explore fundamental FCMC performance. The experimental results established that increased froth height would simultaneously reduce the collection and froth recovery. Coarse particles in the high froth height were detached due to bubble coalescence or rupture, while the liquid drainage reduced fine particle pollution of froth products. Increasing circulating pump pressure would increase the collection zone’s turbulence, lead to coarse particle detachment, and reduce collection recovery. Meanwhile, increasing circulating pump pressure could promote froth stability and decrease froth detachment in the froth zone. The calculated first-order rate constant (k c) confirmed that the flotation rate constants of coarse (−0.5 + 0.25 mm) and fine (−0.074 mm) particles were low, while the intermediate particles (−0.125 + 0.074 mm) had faster flotation kinetics.