CHEN Lishi, LI Pengcheng, WU Meizhen, SU Ruichun, FAN Tongwen, ZHANG Zhang, LIU Qingdong
With the dust from a tin smelter as raw material, the occurrence state of tin (Sn) and indium (In) therein was firstly studied. Then, a combined processing technique consisting of water leaching and oxidative acid leaching was adopted to separate and recover the key elements of Sn, In, Zn and Cd from the tin smelting dust, and effects of factors including suluric acid concentration, liquid-solid ratio, reaction temperature and reaction time on the leaching process were explored. The results show that Sn and In in the tin smelting dust mainly exist in the forms of SnO2, In2S3 and Zn2SnO4. After water leaching treatment, the dust was leached with sulfuric acid at a concentration of 200 g/L by adding potassium permanganate at a dosage of 1.5%, with liquid-solid ratio of 5.0, at a temperature of 65 ℃ for 120 min, resulting in the leaching rates of In, Zn and Cd at 82.00%, 95.60% and 94.30% respectively, while the leaching rate of Sn at 0.84%. After such treatment, the Sn content in the dust increased from 42.44% to 60.87% with an enrichment ratio of 1.43. The particles of the acid leaching residue were porous on the surface, showing that the dust with dense structure changed to the residue with loose one. This tin-rich acid leaching residue with low impurity content can be back to tin smelting process, and indium can go to the subsequent process for extraction and recovery. By this way, efficient recovery and utilization of valuable metals from tin smelting dust can be actualized.
