(西安建筑科技大学 冶金工程学院，西安 710055)
摘 要: 针对铁以铁橄榄石形式存在而难以直接还原磁选回收的问题，采用在镍渣中配加CaO提升镍渣碳热还原速率及铁金属化率的技术思路。将添加剂与镍渣按比例混合并配加适量还原剂后，在高温炉中进行还原，结合热力学计算及产物特征分析结果，研究添加剂强化还原的机理及还原效果。结果表明：CaO的加入有效促进了硅酸铁的解离，强化了还原过程，还原速率加快，金属相在渣相中的形态结构发生改变，金属铁的聚集长大明显，有利于后续分离回收。随着CaO添加量由0增加到10 %(质量分数)，还原产物的金属化率和Fe颗粒平均粒径呈先增大后减小的趋势，FeO含量和残碳量变化规律相反。在CaO添加量为8 %时，还原产物中铁的金属化率和粒径达到峰值，分别为87.25%和41.3 μm。
关键字: 镍渣；氧化钙；碳热还原；添加剂
（School of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China）
Abstract:Aiming at the problem that iron exists in the form of fayalite and the difficulty in direct reduction of the magnetic separation and recovery, the technical idea for adding CaO in nickel slag to improve the carbothermal reduction rate and iron metallization rate of nickel slag was used. The additive and the nickel slag were mixed in proportion and added with an appropriate amount of reducing agent, and they were reduced in a high temperature furnace. Combined with the thermodynamic calculation and product characteristic analysis results, the mechanism and the reduction effect of the additive strengthening reduction were studied. The results show that the addition of CaO can effectively promote the dissociation of iron silicate, strengthen the reduction process, accelerate the reduction rate, change the morphology of the metal phase in the slag phase, and increase the aggregation of metallic iron, which is beneficial for subsequent separation and recovery. As the amount of CaO increases from 0% to 10%, the metallization rate of the reduction product and the average particle size of Fe particles increases first and then decreases, with the changes of FeO content and residual carbon amount being opposite. The added amount of CaO being 8%, the metallization ratio and particle diameter of iron in the reduced product peak at 87.25% and 41.3 μm, respectively. With the added amount of CaO being 8%, the metallization rate and particle diameter of iron in the reduction products peak at 87.25% and 41.3 μm, respectively.
Key words: nickel slag; calcium oxide; carbothermal reduction; additive
