(北京科技大学 土木与环境工程学院，北京 100083)
摘 要: 在较大Na2SO4用量范围内，研究Na2SO4对高铁低镍型红土镍矿选择性还原焙烧的作用机理。结果表明：Na2SO4的作用随其用量变化有本质的区别；随其用量增加，磁选镍铁产品中镍的品位和回收率以及镍铁回收率差均先提高后降低，而铁产率和回收率则是先降低后升高；当Na2SO4用量为5%时，选择性还原效果最佳；Na2SO4会损耗煤中的固定碳，减弱还原气氛，使试样中的铁矿物还原为不具磁性的FeO；而当Na2SO4过量时，会导致部分铁矿物还原为含镁磁铁矿，造成铁回收率呈现先降低后提高的变化规律，同时过量的Na2SO4还会生成多余的Na2S，与焙烧体系中的NiO和FeO发生反应生成NiS和FeS，二者混熔生成(Ni,Fe)S，导致镍的品位和回收率都降低。
关键字: 红土镍矿；选择性还原焙烧；镍铁；Na2SO4
（School of Civil and Environment Engineering,University of Science and Technology Bejing, Beijing 100083, China）
Abstract:The mechanism of sodium sulphate in a large range of dosage on selective reduction roasting of high iron and low nickel laterite was studied. The results show that, the effect of sodium sulphate was fundamentally different as its dosage changes. With increasing dosage of sodium sulphate, in the ferronickel product, the magnetic separation, the content of nickel, the recovery of nickel and the difference between recovery of nickel and iron first improve and then decrease, while the yield and the recovery of iron first decrease, and then improve. When the dosage of sodium sulphate is 5%, selective reduction is the most significant. Sodium sulphate reacts with carbon in coal and weakens the reducing atmosphere, resulting in that iron minerals in the ore sample used are reduced to non-magnetic wustite. And when it is excessive, part of iron minerals are reduced to magnesioferrite. Those caused that the recovery of iron first decreases and then improves. Meanwhile, excessive sodium sulphate ill make excessive sodium sulphide, which reacts with nickel oxide and wustite, producing monosulfidic nickel and troilite. Both of them would mixed melt to (Ni,Fe)S, leading to decreasing about content and recovery of nickel.
Key words: laterite; selective reduction roasting; ferronickel; sodium sulphate
