Green and efficient removal of arsenic and recovery of tin from hazardous waste tin refined copper slag

• Published in: Separation and purification technology Vol. 354; p. 128785
• Main Authors: Ma, Jinping, Li, Yifu, Yang, Bin, Tian, Yang, Xu, Baoqiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: Arsenic removal; Copper slag; Phase regulation; Stannous sulfide products; Vacuum separation; Stannous sulfide products; Arsenic removal; Copper slag; Vacuum separation; Phase regulation
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2024.128785

[Display omitted] •The arsenic in the copper slag is changed into arsenic sulfide.•The tin in copper slag is recovered in the form of stannous sulfide.•Removal of arsenic from stannous sulfide by vacuum volatilization.•The arsenic sulfide volatilization ratio and removal rate reached 100%.•The safe collection and application of arsenic needs further consideration. Arsenic contamination and low tin yields pose significant challenges in the utilization of copper slag for tin refining. Typically, tin in copper slag can be converted into a tin-rich concentrate or metallic tin via electrolysis, oxidation roasting, and acid leaching, facilitating tin resource recovery. However, copper slag roasting results in significant arsenic volatilization and environmental pollution. Herein, a novel copper slag treatment strategy for efficient tin recycling and arsenic removal. The thermodynamics of sulfuration reaction between copper slag and sulfur indicate that in the presence of sulfur, arsenic in copper slag can be converted into arsenic sulfide, effectively enhancing the arsenic thermostability. In addition, tin, cuprous sulfide, and iron are transformed into stable metal sulfides. The saturated vapor pressure of arsenic sulfide is higher than that of stannous sulfide, cuprous sulfide and iron sulfide. The conditions of sulfuration pretreatment were observed to be 1.6 times more sulfur, sulfuration temperature 573 K, and contact time of 4 h. The single vacuum distillation experiments for sulfides were carried out at 10 Pa and 1273 K held for 4 h to separate SnS, As2S3, and FeS, Cu2S. One-factor-at-a-time method was used to optimize operational parameters of secondary vacuum distillation, which include temperature and time. The optimum separation conditions of arsenic sulfide and stannous sulfide were 973 K and 2 h. The removal rate of arsenic is about 100%, and the purity of stannous sulfide is 99.9%. Arsenic is recovered as arsenic sulfide. This study will shed light on the development of new technologies for the treatment of arsenic-containing solid waste.