Study On Recovering Indium And Tin From ITO Waste Targets

The preparation of indium and tin oxide films is the main application field of indium. A large amount of waste ITO target is produced in the manufacturing process of ITO film and need to be recovered. The leaching of waste ITO (indium and tin oxide) target was investigated experimentally and the optimum leaching condition was determined to be as follows: temperature 363 K, after leaching solution acidity 100gH₂SO₄/L, leaching time 120 min., L/S 8-12, particle size of waste ITO target -200 mesh. The results show that under the optimum leaching condition, leaching ratio of indium is higher than 99.5%, and that of tin is 8.0%.A novel technology of separating indium and tin in sulphuric acid leach solution of ITO waste target by sulphuration precipitation is developed, and its feasibility is verified by chemical equilibrium calculation. The effects of temperature, acidity and time on separating process are investigated experimentally. The optimum conditions are determined by orthogonal experimental design: temperature 323K, time 20 min., initial acidity 100 g H₂SO₄/L. The results show that under the optimum condition, the removal rate of tin can reach 100% from leach solution, and the loss of indium in sulphuration residue is only 0.47%.Besides, tin in leaching residue of smoke furnace is recycled in the form SnS. The whole technology possesses such advantages as low energy consumption, little pollution and high In and Sn recovery rate.