TinfromScrap

The recycling of metals from consumer goods becomes of huge importance in the controlled management of these resources. Although less often mentioned than precious metals or rare earths, tin is a important issue because of its varied applications. In particular, this metal represents 10% of the weight of printed circuit boards (PCBs) of personnal computers (PCs). In 2014, solders (electronics and industry) accounted for nearly 50% of the global tin consumption of 359 kt.

The TinfromScrap project aims to develop an electrochemical process for recovering tin from PCBs of PCs. The process, based on a single reactor, involves the selective extraction of tin from a mixture of metals by anodic leaching, then depositing it in the form of a pure metal on the cathode. Electroplating of tin is difficult in aqueous media because it is associated with water reduction, leading to dendritic deposition and low faradic yield. In the TinfromScrap project, the operation will therefore be carried out in ionic liquids (ILs), electrolytes of very low volatility and great chemical and electrochemical stability, very promising for hydrometallurgy purposes. The use of mixtures of two ILs, one to promote the leaching of the metal by complexation, and the other to allow its recovery by electrochemical reduction makes it possible to consider good selectivity when the target wastes contain several metals. Moreover, the ILs, very stable chemically and electrochemically, have a long life duration as well as a good recyclability.