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以云南元江代表性镁质氧化镍矿为研究对象,在工艺矿物学研究的基础上系统研究了煤作还原剂较低温度下矿的金属化还原过程并对其进行优化.矿物学研究表明硅酸盐为主要组成矿物,占89％;铁氧化物占约10％;前者为主要镍负载矿物,后者为主要铁负载矿物.单因素实验详细考察了温度、时间和煤量对镍、铁富集效果的影响,然而在得到的最优工艺条件下镍、铁回收率仅为14.2％,32.5％.在对氧化镍矿金属化还原热力学分析和过程分析的基础上提出加入促进剂改善镍、铁富集效果.实验研究表明加入促进剂CaF2可明显改善镍、铁富集效果,具体为优化条件下镍、铁品位分别从2.6％,62.6％升高到6.9％,71.4％;镍、铁回收率分别从14.2％,32.5％升高到96.5％,73.4％;金属化产物中镍铁合金由1 μm颗粒状变为20 ～ 150 μm带状.表明CaF2可有效破坏矿物结构并降低矿物相界面表面张力,促进镍铁合金相生成/聚合.

Based on mineralogy study,a representative magnesium-rich nickel oxide ore from Yuanjiang of Yunnan province was treated by metalized reduction using coal as reductant at relatively low temperature,whose reaction process and improvement were investigated in this study.Mineralogy study results showed that silicates were the major minerals,accounting for 89％;iron oxides accounted for about 10％;nickel mainly distributed in the former minerals and iron mainly in the latter ones.Single factor experiments were conducted to determine the effect of various parameters including temperature,duration,and coal dosage on concentration of nickel and iron.However,the recovery of nickel and iron was only 14.2％ and 32.5％,respectively,under the obtained optimum conditions.Based on thermomechanical analysis and process analysis of metalized reducing nickel oxide ores,improving concentration of nickel and iron using an accelerant was proposed.Experimental results showed that CaF2 addition could distinctly improve concentration of nickel and iron.The fact was that nickel and iron grades in the concentrate increased from 2.6％,62.6％ to 6.9％,71.4％,respectively;nickel and iron recoveries increased from 14.2％,32.5％ to 96.5％,73.4％,respectively;and ferronickel alloy in the metalized product changed from granular distribution with particle size of 1 μm to zonal distribution with length of 20 ～ 150 μm.It indicated that CaF2 could effectively destroy minerals structure and decrease surface tension of mineral phase interface,which resulted in ferronickel alloy phases generate and aggregate.