A hydrometallurgical method was studied for platinum extraction from spent auto-catalyst in an autoclave,and then a process flowsheet was suggested for efficiently recovering platinum group metals from spent auto-catalyst with low energy consumption and low waste emission.Spent auto-catalyst pretreated with oxygen and hydrogen was put into a glass bottle together with hydrochloric acid,sodium chloride and sodium chlorate.And then the bottle was put into an autoclave filled with 145℃ water to extract Pt at1 013.25 kPa oxygen pressure(1 418.55 kPa total pressure).The possible reactions were proposed of platinum extraction in the autoclave.Effects were emphatically studied of redox pretreatment of spent catalyst successively with oxygen and hydrogen on Pt extraction.The results show that the platinum extraction rate of non-pretreated spent catalyst is 82%.Pretreated with O2 and H2,the spent catalyst has increased platinum extraction rate by 10% and 6%,respectively,showing that the effect of O2 pretreatment was better than that of H2 pretreatment.The optimal conditions of O2 pretreatment are 300-400 ℃ pretreatment temperature,2.0hpretreatment duration and 150-200mL/min O2 flow.The optimal conditions of H2 pretreatment are 300-600 ℃ pretreatment temperature,2.0hduration and 150-250mL/min H2 flow.The Pt extraction rate is 99% under the optimal conditions.
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