Method for leaching platinum group metals from spent catalyst by UV-vis

A method for leaching platinum group metals from spent catalyst by UV-vis, which uses a platinum group metal lixiviant for extracting platinum group metals from spent catalyst under the condition of UV-vis to obtain platinum group metal lixivium, so as to recover platinum group metals from spent catalyst, comprising the following steps:

• (1) shearing spent catalyst, crushing to 80-200 meshes, and sieving;
• (2) preparing the platinum group metal lixiviant:
• uniformly mixing ferric oxalate complex with chloride salt solution at a liquid-to-solid ratio of 40:1 to 10:1, adding 30 wt % aqueous hydrogen peroxide solution with a volume fraction of 0.1-4 vol. % of the system, and mixing uniformly;
• wherein the chloride salt is at least one of sodium chloride, potassium chloride and ammonium chloride;
• (3) leaching platinum group metals:
• adding the spent catalyst sieved in step (1) to the platinum group metal lixiviant obtained in step (2) at a liquid-to-solid ratio of 20:1 to 5:1, and stirring under the condition of UV-vis for 10-120 min at a speed of 200-600 r/min to obtain a mixture, wherein the wavelength range of the UV-vis is 200-760 nm;
• (4) carrying out solid-liquid separation:
• carrying out solid-liquid separation of the mixture obtained in step (3), the liquid phase obtained is a mixture of platinum group metal lixivium and ferric oxalate complex, and the solid phase is solid catalyst;
• (5) separating the platinum group metals:
• placing the liquid phase obtained in step (4) under UV-vis for 2-24 h to obtain a solid-liquid mixture, the solid phase is ferrous oxalate solid, and the liquid phase is platinum group metal lixivium;
• (6) stirring the platinum group metal lixivium obtained in step (5) at 40-80° C. for 2-8 h at a speed of 200-600 r/min to obtain a solid substance enriched with platinum group metals;
• (7) recycling iron:
• collecting the ferrous oxalate solid obtained in step (5), washing with deionized water, drying at 40-80° C. for 12-24 h, and roasting at 300-700° C. for 4-8 h to obtain ferric oxide;
• (8) the ferric oxide obtained in step (7) can be recycled as a reactant for preparing ferric oxalate complex.