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 FeO_x. 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, FeO_x, 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.

This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 83 (2019) 250–255.