: Received: 24 January 2018 / Approved: 24 January 2018 / Online: 24 January 2018 (16:31:27 CET)
: Received: 22 February 2018 / Approved: 22 February 2018 / Online: 22 February 2018 (15:46:53 CET)
Małecki, S.; Gargul, K. Low-Waste Recycling of Spent CuO-ZnO-Al2O3 Catalysts. Metals2018, 8, 177.
Małecki, S.; Gargul, K. Low-Waste Recycling of Spent CuO-ZnO-Al2O3 Catalysts. Metals 2018, 8, 177.
CuO-ZnO-Al2O3 catalysts are designed for the low-temperature shift conversion in the process of hydrogen and ammonia synthesis gas production. The paper presents the results of research on recovery of copper and zinc from spent catalysts using pyrometallurgical and hydrometallurgical methods. Under reducing conditions, at high temperature, having appropriately selected the composition of the slag, more than 66% of copper in metallic form and about 70% of zinc in the form of ZnO can be extracted from this material. Hydrometallurgical processing of the catalysts was carried out using two leaching solutions: alkaline and acidic. Almost 62% of the zinc contained in the catalysts has been leached to the alkaline solution and about 98% of copper has been leached to the acidic solution. After the hydrometallurgical treatment of the catalysts, insoluble residue was also obtained in the form of pure ZnAl2O4. This compound can be reused to produce catalysts, or it can be processed under reducing conditions at high temperature to recover zinc. The recovery of zinc and copper from such a material is consistent with the policy of sustainable development and helps to reduce the environmental load of stored wastes.
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