研究了印度尼西亚红土镍矿焙烧过程中的矿相转变过程以及焙烧温度对混合气体 (V (CO) : V (O2)=50 : 50)还原的影响. 采用差热/热重分析(differential scanning calorimeter/thermal gravimetric, DSC/TG)、比表面积分析法(Brunauer Emmett Teller, BET)、X射线衍射(X-ray diffraction, XRD)、扫描电镜(scanning electron microscope, SEM)等方法综合考察了各因素对红土镍矿焙烧过程及其对后续还原的影响. 结果表明: 在焙烧阶段, 红土镍矿中的针铁矿在 300°C 左右脱除结晶水形成赤铁矿, 600~700 °C时蛇纹石分解形成无定形态硅镁酸盐, 且当温度继续升高时无定形态硅镁酸盐会结晶形成橄榄石; 利用混合气体 (V (CO) : V (O2)=50 : 50)还原红土镍矿时, 随着焙烧温度的升高, 镍和铁的金属化率也逐渐升高, 经700°C焙烧后, 还原产物镍的金属化率最高可达86.81%, 但是当焙烧温度超过橄榄石结晶温度时则不利于红土镍矿的还原, 镍的金属化率降至66.73%.
This paper studies mineralogical phase transformations of Indonesia nickel laterite ores during roasting. The influence of pre-roasting temperature on the degree of gas(V (CO) : V (O2)=50 : 50)reduction is also investigated. Different factors affecting reduction of the laterite ores are tested and analyzed with various means such as differential scanning calorimeter thermal gravimetric (DSC/TG), Brunauer Emmett Teller (BET) specific surface area analysis, X-ray diffraction (XRD) and scanning electron microscope (SEM).The results show that, during the roasting process, goethite is dehydrolyzed at about 300°C. It is then transformed to hematite and serpentine decomposes around 600~700°C leading to formulation of olivine if agglomerating is at higher temperature. Nickel and iron metallization rate increases with the increasing pre-roasting temperature by using gas mixture (V (CO) : V (O2)=50 : 50). The highest reduction rate can reach 86.81% with the sample being roasted at 700°C. If the calcination temperature exceeds the olivine formation temperature, the nickel metallization rate declines to 66.73%.
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