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随着金属Li需求量的迅猛增加和真空技术的不断发展,真空金属热还原法是一种具有工业应用前景的炼锂方法。本文对常压下以氢氧化锂、氧化铝和氧化钙为原料合成Li5AlO4熟料以及以硅铁为还原剂真空热还原提取金属Li进行了探索性实验研究。研究了不同煅烧条件对Li5AlO4合成的影响以及不同还原条件对硅热还原制取金属Li过程的影响。结果表明:常压下可以煅烧获得富锂熟料,其物相为Li5AlO4和CaO以及少量的LiAlO2。采用该熟料在系统压强-5 Pa,还原温度1473 K,还原时间120 min,硅铁不过量的条件下,金属锂的还原率为98%,还原渣主要成分为2CaO·SiO2。该硅热法炼锂工艺可行,其料锂比为9.9∶1。
With the rapid increase in demand for metal Li and the continuous development of vacuum technology, the vacuum metal thermal reduction method is a lithium refining method with industrial application prospects. In this paper, Li5AlO4 clinker synthesized by using lithium hydroxide, alumina and calcium oxide as raw materials under atmospheric pressure and metal Li by vacuum thermal reduction with ferrosilicon as reductant were explored experimentally. The effects of different calcination conditions on the synthesis of Li5AlO4 and the effect of different reduction conditions on the process of metal Li prepared by thermal reduction of silicon were investigated. The results show that lithium-rich clinker can be calcined at atmospheric pressure with Li5AlO4 and CaO phases and a small amount of LiAlO2. Under the conditions of system pressure -5 Pa, reduction temperature 1473 K, reduction time 120 min and no excess ferrosilicon, the reduction rate of metal lithium was 98%, and the main component of reduced slag was 2CaO · SiO2. The silicon thermal lithium refining process feasible, the material lithium ratio of 9.9: 1.