The improvement of platinum recovery ratio in the recycling process using “dry aqua regia”

Abstract

The authors have investigated a novel process of platinum recycling using “dry aqua regia”. In our previous work, the recovery of platinum was successfully conducted by solvent leaching, but it yielded a mixture of K2(PtCl6) and FeOx. In this study, a solid-liquid separation process using KCl and NaCl solutions and a precipitation process using NH4Cl were adopted to obtain pure platinum. Impurities like FeCl3, FeOx, and KCl were removed by a solid-liquid separation process, and pure (NH4)2(PtCl6) was obtained by NH4Cl addition. Then, the obtained (NH4)2(PtCl6) was calcinated to yield pure platinum by thermal decomposition. High-purity platinum was obtained with a recovery ratio of up to 79%. Therefore, the usability of the recycling process using “dry aqua regia” was significantly improved.