新型萃取剂NA萃取中重混合稀土的研究

Performance of New Extraction NA in Separation of Heavy Mixed Rare Earths

研究了一种新型酸性磷类萃取剂NA萃取中重混合稀土的性能,探讨了萃取过程中有机相的皂化度、有机相组成、混合稀土料液中杂质含量、料液初始p H对新型萃取剂萃取饱和容量的影响以及反萃过程中反萃酸度对反萃性能的影响,同时还探讨了新型萃取剂的损耗率。试验结果表明,控制混合稀土料液浓度与铝浓度比≥222,与铁浓度比≥2543、有机相的皂化度0.64~0.68 mol·L^(-1)、有机相中磺化煤油∶新型萃取剂=1∶1(新型萃取剂浓度为1.45 mol·L^(-1))及混合稀土料液初始p H=1.2的工艺条件下,萃取过程分相效果好,新型萃取剂的饱和容量大于0.20 mol·L^(-1),比传统萃取剂P507的最佳萃取饱和容量高15%~20%左右,新型萃取剂的损耗率为0.42%~0.45%;反萃过程,采用盐酸作为反萃剂,只要控制盐酸浓度为3.0 mol·L^(-1)时,负载有机相的单级反萃率即可达到98%以上;研究结果表明,该新型萃取剂,具有萃取饱和容量大、溶解损失少、循环使用性能好、反萃酸度低的特点,可以大大降低槽体有机积存量、稀土积存量和酸耗量,减少投资成本,改善工作环境,具有广泛的应用前景。

The present work proposed the extraction behaviors of a new acidic phosphorus extractant NA in solvent extraction of heavy mixed rare earth. The factors influencing the extraction saturation capacity of extractant NA were studied,such as saponification degree of organic phase,organic phase compositions,impurity contents in rare earth solution and initial p H value of rare earth solution. The attrition rate of extractant NA was also discussed. The results showed that the saturation capacity of new extractant exceeded 0. 20mol·L～（-1）and the attrition rate was 0. 42% ～ 0. 45% when the concentration of mischmetal to that of aluminum ratio was more than 222,while the concentration of mischmetal to that of iron ratio was more than 2543,the saponification degree of organic phase was 0. 64 ～0. 68 mol·L-1,the initial p H value was 1. 2,the proportion between sulfonated kerosene and new extractant in organic phase was 1∶ 1（extractant NA was 1. 45 mol·L-1）. In the same condition,the saturation capacity of new extractant was 15%～ 20% higher than the best result of P507. During stripping process,the re-extraction rate of organics loaded was above 98% when the hydrochloric acid concentration was 3. 0 mol·L-1,used as a stripping agent. This study indicated that the new extractant NA had a high saturation capacity with low dissolution loss and re-extraction acidity. It could greatly reduce the amount of accumulation of organic and rare earth,acid consumption,investment cost and improve working environment. The new extractant had a wide application prospect.