Recovery of Platinum Group Metals from Spent Automotive Catalysts Using Lithium Salts and Hydrochloric Acid

The recovery of platinum group metals (PGMs) from waste materials involves dissolving the waste in an aqueous solution. However, since PGMs are precious metals, their dissolution requires strong oxidizing agents such as chlorine gas and aqua regia. In this study, we aimed to recover PGMs via the calcination of spent automotive catalysts (autocatalysts) with Li salts based on the concept of spent autocatalyst + waste lithium-ion batteries and leaching with only HCl. The results suggest that, when Li2CO3 was used, the Pt content was fully leached, while 94.9% and 97.5% of Rh and Pd, respectively, were leached using HCl addition. Even when LiF, which is a decomposition product of the electrolytic solution (LiPF6), was used as the Li salt model, the PGM leaching rate did not significantly change. In addition, we studied the immobilization of fluorine on cordierite (2MgO & BULL;2Al(2)O(3)& BULL;5SiO(2)), which is a matrix component of autocatalysts. Through the calcination of LiF in the presence of cordierite, we found that cordierite thermally decomposed, and fluorine was immobilized as MgF2.

Automated summary

The study aims to recover PGMs from waste materials using Li salts, where Pt leaching is achieved with Li2CO3, and Rh and Pd leaching with HCl. The leaching rates of PGMs do not significantly change even when using LiF as the Li salt model. Furthermore, fluorine can be immobilized as MgF2 in the presence of cordierite during calcination.