EXTRACTION OF PLATINUM METALS FROM AUTOMOBILE CATALYSTS

摘要

The bulk of raw materials in metallurgy of secondary platinum metals are the wastes suchas multilayered ceramic-metal systems, e.g. the spent catalysts of the chemical andpetrochemical industry, automobile catalysts, etc. Due high chemical resistance of a ceramicbasis the extraction of platinum metals by leaching even at very fine crushing is poor.The study of sorption leaching of platinum and a palladium from the spent automobilecatalysts are carried out.The average content of PGM is 0.5%. A few methods of raw materials sampling werecompared:1) direct hydrometallurgical leaching of platinum metals from the fine-grained catalyst andatomic absorption analysis of the obtained solutions;2) fusion to a metal or sulphidic collector of precious metals with the alloy analysis by directspectrometry;3) fusion with dissolution of a precious metals collector and atomic absorption analysis of PGMin solutions.Leaching allows detecting out no more than 90% of a palladium and 80% of platinum. Fusion toa collector gives the best results at the chemical ending.Researches on sorption leaching are executed. Under optimum conditions the extraction ofplatinum metals to concentrates is comparable with similar indicators of collector fusion.The large part of raw materials in metallurgy of secondary platinum metals are the multilayeredor tridimensional ceramic-metal systems, in particular the spent catalysts of the chemical andpetrochemical industry, automobile catalysts, ceramic-metal condensers, etc. The content of thesum of PGMs can be from hundreds grams per ton to several percent. For processing of suchmaterials the hydrometallurgical methods of platinum metals leaching by various reagents areused commonly. High chemical resistance of the ceramic basis covering the metal particlescauses low recovery even at very fine grinding.Other fundamentally different method of catalysts opening includes dissolution of the ceramicbasis in the solutions of hydrofluoric acid and the subsequent recovery of platinum metals frominsoluble residue. Application of this method is associated to use of corrosive medias andappropriate equipment.Fusion of the specified materials with collecting of PGM by copper, nickel or lead at thespecialized enterprises provides higher extraction in semiproduct. At the same time, complexityand duration of the subsequent extraction of platinum metals concentrates causes high total costper unit. Thereby this method is economically acceptable only for rather poor raw materials (nomore than 0,1%). Undoubtedly, that the raw materials with the high content of PGM arereasonable to process by individual technology.In the present work the processing of some kinds of ceramic-metal raw materials, particularlyautomobile catalysts (neutralizers) with various collectors at the conditions of a target fusion areinvestigated.