ISSN: 1003-6326
CN: 43-1239/TG

Vol. 29    No. 11    November 2019

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Removal of arsenic from acid wastewater via sulfide precipitation and its hydrothermal mineralization stabilization
Bin HU1,2, Tian-zu YANG1,2, Wei-feng LIU1,2, Du-chao ZHANG1,2, Lin CHEN1,2
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metals,
Changsha 410083, China
Abstract: To achieve a safe treatment of arsenic-containing acid wastewater, a new process was proposed, including arsenic removal via sulfide precipitation and hydrothermal mineralization stabilization. Under optimal conditions of sulfide precipitation, 99.65% of arsenic from wastewater was precipitated in the form of amorphous As2S3. The As leaching concentration of amorphous As2S3 in TCLP (toxicity characteristic leaching procedure) test was up to 212.97 mg/L, therefore, hydrothermal mineralization was adopted to improve the stability of amorphous As2S3. The results showed that the As leaching concentration of mineralized As2S3 was only 4.82 mg/L. Furthermore, the amorphous As2S3 could be transformed into crystallized As2S3 (orpiment) in the presence of mineralizer Na2SO4. Simultaneously, the As leaching concentration of crystallized As2S3 was further reduced to 3.86 mg/L. Hydrothermal mineralization was an effective method for the stabilization of As2S3. Therefore, this process has a greater application in the treatment of arsenic-containing wastewater.
Key words: arsenic-containing wastewater; arsenic removal; stabilization; sulfide precipitation; hydrothermal mineralization; hydrothermal crystallization
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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