Research On The Treatment Of Tin Refining Sulfur Residue By Atmospheric Vulcanization-vacuum Gasification

Tin is an important strategic metal,and China is the largest country in tin production and consumption.Crude tin is produced from tin concentrate by reduction smelting and refined by crude tin refining.Sulfur slag is a kind of hazardous waste produced in the process of adding sulfur to remove copper in tin refining.Its main components are tin,copper and sulfur,and its main components are elemental tin,stannous sulfide,cuprous sulfide,sulfur,etc.At present,the existing treatment process of sulfur slag is mainly the combination of pyrometallurgy and hydrometallurgy,but there are some problems such as long operation process and large process investment.Therefore,it is urgent to develop a new clean and environmental protection technology for sulfur slag treatment,realize the clean and efficient recovery of tin and copper in sulfur slag,in order to promote the green development of tin smelting industry.In this project,the treatment of tin refining sulfur slag by atmospheric sulfuration-vacuum distillation is proposed.The existing state of substances in sulfur slag system was studied.The gas-liquid distribution characteristics of tin and copper in sulfur slag were simulated.The saturated vapor pressure of each substance in the system was analyzed.The thermodynamic data of sulfidation and decomposition of tin and copper are calculated.The results show that stannous sulfide and stannous trisulfide can be formed by the reaction of tin and sulfur.The sulfide of tin decomposes and the stable sulfide of tin is stannous sulfide.Copper reacts with sulfur to form cuprous sulfide and copper sulfide.The stable sulfide of copper is cuprous sulfide.The sulfidation reaction and volatilization of tin and copper were analyzed and calculated,which provided a theoretical basis for the treatment of tin refining sulfur slag by atmospheric sulfuration-vacuum distillation.In this project,we carried out the atmospheric sulfuration-vacuum distillation experiment of tin and copper with sulfur,tin and cuprous sulfide.The results show that: Tin and sulfur are treated by atmospheric sulfuration to obtain tin sulfide,which decomposes and volatilizes at high temperature in vacuum to obtain stannous sulfide.Copper and sulfur are treated by atmospheric sulfuration to obtain copper sulfide,which decomposes at high temperature in vacuum to obtain cuprous sulfide,cuprous sulfide is nonvolatile.The mixture of tin and cuprous sulfide is sulfurized at atmosphere to obtain stannous sulfide,stannous sulfide volatilizes at high temperature in vacuum,and the residue is tin copper sulfide compound.The atmospheric sulfuration-vacuum distillation experiment of sulfur slag was carried out.The effects of different mass ratio of sulfur slag with sulfur,sulfuration temperature and time,distillation temperature and time on the experiment were explored.The optimal conditions of atmospheric sulfuration-vacuum distillation experiment of sulfur slag were obtained as follows:sulfur slag with sulfur content ratio is 5:2,sulfuration temperature is 573 K,sulfuration time is 4h,distillation temperature is 1273 K,distillation time is 4 h.Under the optimum experimental conditions,the volatile was stannous sulfide,in which the contents of tin and copper were 74.95%and 0.46%,respectively;the residue was cuprous sulfide,in which the contents of tin and copper were 0.26% and 76.41%,respectively.The results show that stannous sulfide with purity more than 95%.The direct yield of tin and copper can reach 99.96% and 99.08%,respectively.Tin sulfide was prepared from sulfur slag and tin and copper were separated efficiently.