高压辊磨对超微细粒嵌布磁铁矿破碎和预选的影响

Effect of high-pressure grinding on crushing and preseparation of ultrafine particle embedded magnetite

针对某超微细粒嵌布贫磁铁矿开发难度大、原矿入磨品位偏低、磨矿能源消耗高的问题,本文进行高压辊磨—预选工艺试验,通过对比两种破碎产品的粒度特征、相对可磨度、Bond球磨功指数、预选指标,并结合破碎产品的表面形貌和内部微裂纹,研究高压辊磨所产生的微裂纹对于磨矿和分选的影响。结果表明:相对于常规破碎,辊压产品中<0.074 mm粒级质量分数增加了14.69个百分点,>2 mm的粗粒级质量分数降低了8.59个百分点;在160 kA/m预选磁场强度下,辊压产品的铁品位为31.96%,提高了1.46个百分点;磁性铁的回收率高达99.45%,提高了1.17个百分点,抛尾率提高了5.03个百分点。相对可磨度试验结果表明,当磨矿细度达到<0.03 mm粒级质量分数为85%时,辊压产品的耗时相对于常规破碎缩短了42.13%。辊压产品的Bond球磨功指数(目标粒度<0.15 mm)降低了27.90%。偏光显微镜和SEM扫描电镜结果表明,辊压产品结构疏松多孔、微裂纹发育充分,能产生大量的晶界裂纹,解离更充分。

In order to solve such problems as difficult development,low grinding grade and high grinding energy consumption of ultra-fine particle embedded poor magnetite,a high-pressure grinding preselection process test is carried out,and the influence of microcracks produced by high-pressure grinding on grinding and separation is studied by comparing the particle size characteristics,relative grindability,Bond ball milling work index and preselection index of two kinds of broken products.The results show that,compared with conventional crushing,the mass fraction of<0.074 mm in rolled products increases by 14.69%,and the mass fraction of coarse particles>2 mm decreases by 8.59%.Under the preselected magnetic field intensity of 160 kA/m,the iron grade of the rolled product concentrate is 31.96%,which is increased by 1.46%.The recovery rate of magnetic iron is as high as 99.45%,increased by 1.17%,and the tail-throwing rate is increased by 5.03%.The test results of relative grindability show that when the grinding fineness reaches less than 0.03 mm and the mass fraction of particle size is 85%,the time consumption of rolling products is shortened by 42.13%compared with conventional crushing.Bond ball milling work index(target particle size<0.15 mm)of rolled products is decreased by 27.90%.The results of polarized light microscope and SEM show that the rolled product has loose and porous structure,fully developed microcracks,a large number of grain boundary cracks and more complete dissociation.