砷碱渣综合利用工艺及机理研究

Process and mechanism investigation on comprehensive utilization of arsenic-alkali residue

砷碱渣是锑冶炼行业产生的固体废渣,对环境和人体健康构成严重威胁。目前,常见的砷碱渣湿法处理工艺不仅有价元素回收率低、砷碱分离不完全,还会产生砷碱混合盐,无法实现砷碱渣完全无害化处理。为解决这些问题,本文采用氧化水浸处理砷碱渣,实现了砷和锑的分离,砷、锑的浸出率分别为91.79%和0.62%,浸出渣可返回锑冶炼系统回收锑。通过碳热还原直接从砷碱混合盐(砷碱液蒸发结晶产物)中分离砷和碱,98.3%的砷可被脱除并制备成具有商业价值的无毒高纯金属砷,纯度达到99.9%;碱可从还原后渣中实现回收,良好地实现了砷碱混合盐的无害化和资源化处理。通过热力学、物相和砷价态分析研究了砷还原路径及挥发机理。

Arsenic-alkali residue is a solid waste produced by the antimony smelting industry,which can pose a threat to the environment and human health.The common wet treatment process of arsenic-alkali residue has a low recovery of valuable elements,incomplete separation of arsenic and alkali,and also produces arsenic-alkali mixed salt,which cannot realize the completely harmless treatment of arsenic-alkali residue.In order to solve these problems,the oxidative water leaching process was used to treat arsenic-alkali residue,which realized the separation of arsenic and antimony.The leaching efficiencies of arsenic and antimony were 91.79%and 0.62%,respectively.The leaching residue could be returned to the antimony smelting system to recover antimony.Then the arsenic and alkali were directly separated from the arsenic-alkali mixed salt by carbothermal reduction,and 98.3%of arsenic was removed,and the non-toxic metallic arsenic with 99.9%purity was prepared.The alkali could be recovered from the slag after reduction,which solved the problem of harmless and recycling treatment of arsenic-alkali mixed salts.The mechanism of arsenic reduction pathway was studied through thermodynamic,phase,and arsenic valence state analyses.