Process for the treatment of precious metal-containing compositions and other substances valuable for recycling

摘要

Novel treatment process for the recovery of precious metals such as platinum, palladium and rhodium and optionally other elements of value, such as rare earths and in particular cerium, which are present in various compositions, especially used or spent catalysts, for example motor vehicle exhaust catalysts, the said process being characterised in that it includes the following stages: (i) optionally the composition to be treated is first of all brought to a finely divided state so as to increase it reactivity, (ii) this composition is then mixed with sulphuric acid, (iii) the mixture thus obtained is then calcined between 150 DEG C and 450 DEG C, (iv) and, finally, the product thus calcined is treated in aqueous medium with, on the one hand, H+ ions and, on the other hand, with chloride ions, this being done simultaneously or separately, whereby there are finally obtained, on the one hand, a solid residue substantially free from precious metals and, optionally, from rare earths such as cerium, and, on the other hand, one or more solutions containing the abovementioned species. The process offers very high recovery yields both for precious metals, in particular rhodium, and for cerium.