The process of reduction roasting followed by low-intensity magnetic separation are usually used to recover nickel and iron from laterite ores. In order to strengthen the selective reduction of nickel in laterite ore,the effect of damp mill-ings for the mixture of a laterite ore,coal as a reductant,and sodium sulfate as an additive on selective reduction of nickel in the sample ore and its mechanism were investigated. The results showed that:① Within the fineness range of damp millings, damp millings was favorable to strengthen the selective reduction. When the fineness of the mixture is increased from -0. 074 mm of 52. 00% to -0. 074 mm of 75. 49%,nickel grade of the Ni-Fe product is improved from 6. 58% to 9. 27%,and the grade of the Ni-Fe product increased from three levels to a specific pole,accompanied with nickel recovery rate increasing from 91. 56% to 95. 57% and differences in nickel and iron recovery rising from 54. 30% to 68. 52%.②Damp millings made the particle size of the sample be reduced and the fresh surface of the nickel ore was sufficiently exposed,making the sample ore, lignite,and sodium sulfate being fully mixed. It improved the contact reaction probability of target minerals,lignite and sodium sulfate,contributing to strengthening the selective reduction of nickel.③Damp milling had no obvious influence on mineral composition of the roasted ores but remarkably affect the microstructure of roasted ore,which promoted aggregation of the fine Ni-Fe particles and was beneficial to realize monomer dissociation for the Ni-Fe particles during subsequent magnetic separa-tion.④Sum of nickel and iron grades was only 80. 33% with damp milling for the mixture fineness at-0. 074 mm of 75. 49%, because there were intergrowth and mechanical impurity inclusion in the Ni-Fe product,and the phenomenon of carburization of ferronickel particles existed. The former can be reduced through a two-section grinding and low-intensity magnetic concentration process,but the latter is difficult to avoid.%红土镍矿石中镍铁的回收通常采用还原焙烧—弱磁选工艺,为了强化对红土镍矿石中镍的选择性还原,研究了红土镍矿石、还原煤和添加剂硫酸钠的混合物料润磨对镍选择性还原的影响,并分析了其强化机理.研究结果表明:①在研究润磨细度范围内,润磨对试样的选择性还原有强化作用,当混合物料细度从-0.074 mm占52.00%提高至-0.074 mm占75.49%,镍铁产品镍品位由6.58%提高至9.27%,镍精矿品级由三级升至特极,而且镍回收率也由91.56%提高至95.57%,镍、铁回收率之差从54.30%提高至68.52%.②润磨能够使试样的粒度减小、充分暴露镍矿物的新鲜表面,使试样、褐煤和硫酸钠充分混匀,从而提高试样中目标矿物与褐煤和硫酸钠接触反应的概率,强化镍的选择性还原.③润磨基本不影响焙烧产品的矿物组成,主要影响焙烧产物的微观结构,使细小的镍铁合金颗粒聚集长大,这有利于镍铁合金颗粒在后续磨矿中实现单体解离.④润磨细度为-0.074 mm占75.49%时,镍铁产品镍铁品位之和仅为80.33%,主要是由于镍铁产品中存在连生体和脉石的机械夹杂,其次也与镍铁颗粒存在渗碳有关.连生体的存在和脉石的机械夹杂可通过二段磨矿—弱磁精选工艺进行降杂,镍铁颗粒的渗碳则难以避免.
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