Research On The Recovery Of Valuable Metals From Waste Tinned Copper-clad Steel Wire By Sulfidation Volatilization Metho

Tin-coated copper-clad steel wire scrap is a kind of high value-added tinning waste generated during the production and replacement of electronic products.Its main components are tin and iron,followed by small amounts of nickel,copper and other impurity elements.The existing treatment methods of tinning scrap mainly include chemical method,electrochemical method and pyro-electrolysis method,but there are disadvantages such as large waste liquid treatment volume,high equipment anti-corrosion cost,and low tin recovery rate.It is urgent to develop a clean and environmentally friendly new technology for the treatment of tin-coated copper-clad steel wire scrap to achieve clean and efficient recovery of tin in waste tin-plated copper-clad steel wire to improve the comprehensive utilization rate of secondary resources of tin.In this paper,the sulfuration-volatilization method is proposed to treat tin-coated copper-clad steel wire scrap.The elemental occurrence state and phase composition of tincoated copper-clad steel wire scrap were studied,and the thermodynamic data of interphase equilibrium,Gibbs free energy,equilibrium component and vapor pressure were calculated,and the results showed that stannous sulfide was a high-temperature stable existing phase,and increasing the temperature and reducing the pressure in the system were conducive to the volatilization of tin to stannous sulfide,which provided a theoretical basis for the recovery of valuable metals from scrap tinned copper-clad steel wire by sulfuration method.In this paper,the experimental study on recovery of valuable metals from tin-coated copper-clad steel wire scrap was carried out.Sulfur and pyrite were used as sulfurizing agents to make the surface of tin-coated copper-clad steel wire scrap to form stannous sulfide,which was volatilized at high temperature and vacuum,and finally collected by condensation on the condensing plate.(1)The optimum experimental conditions for treating tin-coated copper-clad steel wire scrap with sulfur as sulfurizing agent are as follows: molar ratio of sulfur to tin 1.8,sulfurizing temperature 573 K at atmospheric pressure,sulfurizing time 4 h;Vacuum volatilization temperature 1323 K,holding time 3h.Under the best experimental conditions,the direct yield of tin reaches 24.11%,and partial recovery of tin is realized.(2)The optimum experimental conditions for treating tin-coated copper-clad steel wire scrap with pyrite as sulfurizing agent are as follows: system pressure10 Pa,molar ratio of ferrous disulphide to tin 1.8,vacuum sulfurizing temperature 1323 K,and holding time 4 h.Under the optimal conditions,the straight yield of tin reached 91.26%and the purity of stannous sulfide reached 98.12%.(3)Scale-up experiments were carried out.The tin straight yield was 88.23%,the purity of stannous sulfide was 98.44%,and the content of iron in the residue was 93.64%.It was collected as raw material of steel smelting for further treatment,and the feasibility of expanding the treatment of tin-coated copperclad steel wire scrap by sulfuration-volatilization technology was verified.