(内蒙古科技大学 材料与冶金学院，包头 014010)
摘 要: 包头混合稀土精矿络合浸出分离稀土后的废液中含有大量的铝离子，经过特殊的工艺技术能够将废水中大量的铝合成冰晶石，但该冰晶石中的硅含量超标，发现采用硫酸-氢氟酸-盐酸的混酸可以有效地脱除冰晶石中硅的化合物。确定以下优化的脱硅条件：硫酸浓度0.4 mol/L、氢氟酸浓度0.8 mol/L、盐酸浓度0.4 mol/L、反应时间90 min、反应温度80 ℃、液固比5:1；在该条件下硅的脱除率达到74.24%，除硅后冰晶石中硅的含量为0.23%，达到冰晶石国家标准要求。XRD分析结果表明大部分硅和杂质已经被脱除；SEM测试结果表明混酸法脱除冰晶石中硅的过程中使冰晶石分散性变好，而冰晶石本身的化学结构并没有被破坏。
关键字: 络合浸出；废液；冰晶石；脱硅
（School of Material and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China）
Abstract:After rare earth separation by complexation extraction from Baotou mixed rare earth concentrate, the obtained waste liquid contains a large number of aluminum ions. The aluminum ions in waste liquid can be transformed into cryolite through a special processing technology, but the content of silicon in cryolite exceeds the content required in Chinese national standard. The compounds of silicon could be removed by the mixture of H2SO4-HF-HCl. The optimized conditions for removing silicon are obtained as follows: 0.4 mol/L HCl, 0.8 mol/L H2SO4, and 0.4 mol/L HCl for 90 min reaction at 85 ℃ under the liquid-solid ratio of 5:1. The removal rate of silicon reaches 74.24% under the optimized conditions. The content of silicon in the cryolite after desilication is 0.23%, which meets the requirement of the content of silicon in cryolite in Chinese national standard. XRD results indicate that most of the silicon and impurities is removed. SEM images show that, during the process of desilication, the dispersity of cryolite is enhanced while the chemical structure of cryolite is maintained.
Key words: complexation extraction; waste liquid; cryolite; removing silicon
