Environmentally friendly recovery of valuable metals from spent coin cells through two-step bioleaching using Acidithiobacillus thiooxidans.

The technology for recycling the spent coin cells is pressing needed due to a large amount of generated spent coin cells. However, there is little information about the recycling technology of spent coin cells. In this work, a two-step bioleaching method for recovery of metals from spent coin cells by Acidithiobacillus thiooxidans is performed for the first time. In this regard, the growth characteristics of A. thiooxidans was investigated in pure culture and during the two-step bioleaching approach. The highest recovery of Li, Co and Mn was achieved at a pulp density of 30 g L-1, in values of 99%, 60%, and 20%, respectively. The structural analyzes confirmed the progress of bioleaching process. In addition, the kinetics models showed that the chemical reaction was the rate-controlling step of the two-step bioleaching of spent coin cells. The comparative results between bioleaching and chemical leaching showed that Acidithiobacillus thiooxidans can enhance the leaching of metals. Toxicity characteristic leaching procedure of the spent coin cells powder demonstrated that the bioleached residue met the environmental limitations for safe disposal. In fact, bioleaching is an effective and promising route to reduce the environmental hazard of spent coin cells.