红土镍矿选择性还原-熔分制备镍铁合金

Extraction of a nickel-iron alloy from nickel laterite ore through selective reduction and smelting process

以硅镁型红土镍矿为原料,采用金属化焙烧-熔分工艺,通过正交试验制备金属化球团,将所得金属化球团在1500℃条件下熔融分离30 min提取镍铁合金,考察影响因素对实验结果的影响.结果表明：在选择性还原制备金属化球团过程中,对金属化率的影响程度从大到小的因素依次是C/O摩尔比、焙烧温度、焙烧时间和碱度；实验可获得镍品位19%的镍铁合金；在碱度为0.8-1.2范围内,S和P分配比随着碱度的升高而增大.利用X射线衍射和扫描电镜对金属化球团及熔融分离出的渣进行微观分析,发现加入的石灰石与复杂矿相反应可释放出简单镍氧化物和铁氧化物,促进还原反应的进行,当石灰石不足时,少量铁以Fe3＋的形式存在于铁金属化率70%的金属化球团中.

ABSTRACT Metallization pellets were prepared from silicon-magnesium-type nickel laterite ore through metallization roasting and smelting process. Orthogonal experiment was carried out to investigate the effect of control parameters on the experimental results. A nickel-iron alloy was extracted from the metallization pellets after 30 min of smelting at 1 500℃. It is shown that C/O molar ratio has prior influence on the selective reduction process, followed by roasting temperature, roasting time and basicity. The nickel grade of the nickel iron alloy can be controlled at 19% in the extraction process by governing the manipulated factors. The sulphur and phosphorus distribution ratio increases when the basicity increases from 0.8 to 1.2. The metallization pellets and slag were microscopically analyzed by X-ray diffraction and scanning electron microscopy. The results show that the added limestone reacts rapidly with the complex ore to produce nickel oxide and iron oxide, and thus, promotes the reduction rate. When the amount of limestone is insufficient, little amount of iron in the form of hematite exists in the metallization pellets which have the metallization rate of 70%.