从污酸中萃取铼的工艺试验研究

Process tests of extracting rhenium from waste acid

某冶炼厂原采用萃取-反萃工艺回收污酸中的铼,存在铼与杂质不易分离、污酸中铼回收率低等问题。本文通过分析萃取工艺技术工业化过程中相关技术的难点,对比了增加污酸预处理回收铼与从污酸中直接萃取-反萃回收铼的工艺试验结果,结果表明:萃取剂配比选取N235∶仲辛醇∶煤油=20∶20∶60,铼的萃取率可达88.42%;增加负载有机相用水或酸洗涤工序,在用氨水反萃时仍会产生大量含铼的第三相反萃渣;负载有机相用氨水反萃,选取浓度10%~12%的氨水比较合适;对反萃渣进行热水洗与酸洗效果均不好,铼浸出率低,且不利于铼铋的分离;增加污酸预处理可最大限度分离主要杂质,富集铼元素;对经过预处理的铼液进行萃取-反萃制得铼酸铵,萃取率可达98%,反萃率可达99%。

An extraction-stripping process was used in a hydrometallurgical refinery to recover rhenium(Re) from waste acid.However,the separation of impurities was not thorough,and the Re recovery was low.The test study explored the technical challenges in the extraction process,and compared the process test results of extracting-stripping Re with and without pre-treating waste acid.The test results indicate that:when the extractants(N235:sec-caprylic alcohol:kerosene) are mixed at a ratio of 20∶20∶60,the Re recovery reaches 88.42%;that washing the loaded organic phase with water or acid does not prevent the yielding of large amounts of Re-bearing crud during stripping with ammonium;that washing the stripping residue with hot water or acid does not produce favorable results,with low Re leaching efficiency and difficulty in separating Re and Bi;that adding the waste acid pre-treatment procedure brings about the best result in removing main impurities and concentrating rhenium;and that extracting and stripping the pre-treated Re solution can produce high quality ammonium rhenate,with extraction efficiency at 98%,and stripping efficiency at 99%.