An environmentally-friendly process for recovering, solidifying As and preparing bronze material from tin-bearing middling
Tin-bearing middling, a hazardous solid waste produced during beneficiation of tin deposits and tin-bearing tailings, presents a serious environmental pollution risk due to high levels of As. This paper aims to explore an environmentally friendly technology to reduce toxic substances and prepare a high value-added bronze material from tin-bearing middling. The co-process for tin-bearing middling, anthracite , and copper is first proposed at 1073–1123 K. Variables like temperature, amount of added anthracite, and holding time were optimized. Those results showed that 95.56% Sn and 92.79% As were recovered; levels of Fe in the residue reached 73.52 wt%. During roasting, SnO 2 in the tin-bearing middling was initially transformed into SnO(g), then into an Fe–Sn spinel (Fe 3-x Sn x O 4 ) and Ca 2 SnO 4 , and finally a Cu–Sn alloy. Generation of the Fe–Sn spinel came primarily from substitution of Fe 2+ by Sn 2+ , but small amounts of Sn 4+ replaced Fe 3+ in Fe 3 O 4 . Meanwhile, FeAsS and FeAsO 4 were initially transformed into As 4 (g) and then solidified as a Cu–As alloy. Interestingly, the residual As existed as Fe–As alloy, but As leaching levels did not exceed 0.02 mg/L. After initial treatment, the Cu alloy can be prepared for bronze. Meanwhile, subsequent volatilization and solidification of As resulted in a significant reduction of arsenic-bearing waste that minimizes environmental risk.
危险品化学品经营许可证（带存储）