脱除铅阳极泥中贱金属的预处理工艺选择

Selection of pretreatment process for removing base metals from lead anode slime

提出碱性NaOH体系分步氧化浸出和盐酸浸出相结合的工艺预处理铅阳极泥,在碱性分步氧化浸出过程中,实现As的氧化溶解和Bi等金属的氧化沉淀,然后用盐酸溶解碱性浸出渣中的Bi,使贵金属富集在盐酸浸出渣中。结果表明:无论碱性直接浸出或酸性直接浸出都不能有效分离铅阳极泥中的有价金属;改变烘烤温度、延长空气氧化时间和改变碱性加压氧化浸出温度都不能实现有价金属的分步分离。当双氧水用量大于0.2以后,碱性浸出过程As的浸出率达到92%以上,碱性浸出渣盐酸浸出时,Bi和Cu的浸出率分别达到99.0%和97.0%,且残余的As不溶解,实现铅阳极泥中有价金属分步分离的目的。

The united process that combining alkaline multistage oxidation leaching and hydrochloric acid leaching was used to pretreat lead anode slime. When lead anode slime was leached by alkaline multistage oxidation, arsenic is dissolved into the solution, while bismuth, copper and other metals were oxidized and remained in the alkaline leaching residue. The alkaline leaching residue was leached with hydrochloric acid solution. The result shows that valuable metals can not be separated effectively whether the direct leaching is performed in alkaline solution or hydrochloric acid solution. The valuable metals can not be separated step by step when different oxidation modes, such as roasting, prolonging the time of air oxidation leaching and decreasing the temperature of pressure oxidation leaching, are applied to strengthen the NaOH leaching procedure. When HzO2 is added to strengthen NaOH leaching, the base metals in lead anode slime can be removed efficiently. The leaching ratio of arsenic can reach 92% when the coefficient of I-I202 is 0.2, while the alkaline leaching residue is leached in hydrochloric acid solution, the leaching ratios of bismuth and copper reach 99% and 97%, respectively, and the remained arsenic can not be dissolved in the acidic leaching solution.