A New Perspective on the Understanding of High-Intensity Conditioning: Incompatibility of Conditions Required for Coarse and Fine Coal Particles

Abstract

ABSTRACT This study examined the incompatibility of high-intensity conditioning (HIC) conditions required for fine and coarse coal particles. The effects of speed and time of stirring on the recovery of coarse and fine particles were investigated by using three different flotation processes. The results showed that the coarse particle recovery of surface cleaning (SC) flotation reached the maximum value of 69.71% at the stirring condition combination of ‘1400 rpm +2 min.’ However, the coarse particle recovery reached the maximum value of ~69.37% at a stirring condition combination of ‘1600 rpm +3 min’ or ‘2000 rpm +2 min’ in HIC flotation. Achieving the same coarse particle recovery, SC flotation consumes less energy than HIC flotation. The maximum recovery of fine particle 65.37% was achieved at a stirring condition combination of ‘1600 rpm +2 min’ in HIC flotation. SC failed to promote the recovery of fine particles and even produced some negative effects in some cases. Fine particles consume less energy than coarse particles with respect to their maximum recovery. In addition, the optimum stirring speed and time for SC were 1400 rpm and 2 min, respectively, while 2000 rpm and 3 min for HIC, respectively. The optimum energy requirements involving stirring speed and time for SC do not match that for reagent dispersion and particle-reagent collision. The best flotation result achieved by HIC is a compromise of the above three aspects. It is suggested that SC, reagent dispersion, and particle-reagent collision should be carried out separately.