Analyses on uniformity of particles under HPGR finished grinding system
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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.
Key wordshigh-pressure grinding rolls particle uniformity uniformity coefficient average particle size flotation shielding effect compact effect
针对高压辊磨终粉磨工艺中存在的过磨和粒度不均匀现象,本文采用高压辊磨终粉磨、阳离子 反浮选以及准静态料层粉碎模拟等试验方法从评价指标、工艺条件参数的影响、颗粒均匀性对浮选的 影响及颗粒均匀性强化机制等方面展开研究。理论分析表明,对颗粒均匀性分析的评价指标必须涵盖 均匀性系数和平均粒径两个方面;试验结果表明,高压辊磨终粉磨工艺中选粉机循环风机转速对颗粒 均匀性影响最为明显,其次是高压辊磨机工作压力和辊缝,辊面转速的影响最弱;颗粒平均粒径对方 解石浮选精矿品位有较大影响而均匀性系数对精矿回收率有较大影响,综合考虑浮选精矿回收率和品 位,终粉磨制备颗粒的平均粒径最佳值为50~55 μm、均匀性系数为1.1~1.2;为了提高产品颗粒均匀 性,高压辊磨终粉磨工艺中有利于料层屏蔽效应和密实效应的操作参数应该得到强化。
关键词高压辊磨 终粉磨 颗粒均匀性 均匀性系数 平均粒径 屏蔽效应 密实效应
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