China Nonferrous Metallurgy

The recovery of tin from low-grade tin middling by reduction smelting method was studied, and the recovery behavior of tin was investigated when copper oxide was used as an additive. The results show that under a certain conditions, increasing the melting temperature, increasing the amount of coke addition, extending the holding time and increasing the amount of copper oxide addition can improve the recovery of tin, however, when the temperature is too high, iron oxide in the slag is reduced to metallic iron and alloyed with reduced metal tin to form Fe-Sn alloy, which has a high melting point and is easily entrapped in the slag during the separation of slag and metal resulting in the loss of tin. With copper oxide as an additive, it can generate metallic copper by reduction reaction and then alloy with metallic tin to form Cu-Sn alloy, which thermodynamically reduces the activity of Sn in the product and promotes the reduction and recovery of tin. Under the conditions of 7% coke addition, 5.8% copper oxide addition, 1250℃ melting temperature and 150min holding time, the recovery of tin can reach 95.24%, and tin is distributed in copper-tin alloy (distribution ratio 90.20%) and tin containing dust (distribution ratio 5.04%), which realizes efficient recovery of tin from low-grade tin-bearing middling.