Differences in dry and wet grinding with a high solid concentration of coking coal using a laboratory conical ball mill: Breakage rate, morphological characterization, and induction time

Abstract

This study explored the influence of wet and dry grinding conditions on breakage rate, shape factor and surface roughness of ground particles, induction time (the threshold for particle–bubble attachment to occur), and flotation recovery. The experimental results indicated that the dry grinding breakage rate was much higher than the wet grinding one. The first-order region was limited to a relatively short grinding time, where it was considered that little or no secondary breakage occurred. With the increasing time, the dry grinding breakage rate increased, while it decreased for wet grinding (solid concentration of 70 vol.%). The differences in shape factor and surface roughness of the wet- and dry-ground samples were attributed to different breakage mechanisms and grinding energy amounts generated by those two types of procedures. The wet-ground particles were characterized by more irregular shape factors and smoother surfaces, and thus presented shorter induction times and higher floatation recoveries compared to the dry-ground ones.