Bioleaching of indium and tin from used LCD panels

The demand for indium is increasing every year. This metal is mainly used as indium tin oxide (ITO) in the production of transparent conductive coatings for liquid crystal displays (LCD). This paper focuses on biohydrometallurgical methods used for the recovery of indium and tin from LCD sourced from spent mobile phones. Bioleaching experiments were carried out in two different leaching media: 9K medium and H2SO4 solution, using mixed, adapted bacteria Acidothiobacillus ferrooxidans and Acidothiobacillus thiooxidans. The main aim of this study was to evaluate the potential and efficiency of indium and tin extraction in the presence of acidophilic microorganisms. Within 35 days, using 9K medium, 55.6% of indium was bioleached, whereas the chemical leaching resulted in a value of 3.4%. Leaching efficiency of tin was 90.2% on the 14th day of the experiment for the biological system (9K) and 93.4% on 21st day of control leaching.