Analyses on uniformity of particles under HPGR finished grinding system

Abstract

In order to deal with the disadvantages of excessive grinding and non-uniformity in finished particle under high-pressure grinding rolls (HPGR) finished grinding system, four aspects were investigated, including evaluating indicators, effects of operating factors, effect of particle uniformity on the flotation and formation mechanism of particle uniformity. Experiment of HPGR finished grinding system, cationic reverse flotation experiment and simulation test of particle bed comminution under the condition of quasi-static were carried out. Theoretical analyses indicated that both of uniformity coefficient and average particle size should be included in the uniformity analysis of the mineral particles. The results show that the effect of circulation fan impeller speed on particle uniformity is the most evident, HPGR working pressure and roll gap are second and HPGR roller speed is the last. Average particle size has a more obvious effect on the grade of flotation concentrate while uniformity coefficient has a more obvious effect on the flotation recovery. Considering the two aspects of grade and recovery, the optimal uniformity coefficient for flotation is 1.1–1.2 and the optimal average particle size for flotation is 50–55 μm. The operating factors which promote the shielding effect and compact effect in the HPGR finished grinding system should be strengthened based on the uniformity of particles.