Study on indium leaching control of waste LCD panels

As a kind of rare and scattered metal, the amount of indium in the crust is little. The indium of waste liquid crystal display (LCD) panels has great resource value. It is of significant reference value for the optimization of the indium regeneration process of waste LCD panels to research on high-efficiency leaching of indium from waste LCD panels and synchronous transfer control of impurity ions. Waste LCD panels were used as test material and sulfuric acid as extractant to study the influences of sulfuric acid concentration, leaching time, liquid-solid ratio and reaction temperature on the leaching rate of indium, iron, aluminium and silicon. The results showed that the concentration of sulfuric acid had a great influence on the leaching of indium, iron, aluminium and silicon, the leaching of impurity elements could be inhibited effectively by controlling appropriate sulfuric acid concentration. Properly prolonging the leaching time was beneficial to the leaching of indium, but had little effect on the leaching of iron, aluminium and silicon. The optimum conditions of indium extraction were as follows: sulfuric acid concentration was 15%, the acid leaching time was 5 h, the liquid-solid ratio was 10, the reaction temperature was 20 ℃, and the indium extraction rate reached 98%.