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The method is applied in the manufacturing of copper-zinc-chromium-aluminium based catalysts. Accordingly a solution is obtained containing copper and zinc as well as small amounts of chromium and aluminium, purified by removing unwanted impurities such as sulphur and iron and offering high utilization of copper and zinc. The used catalyst containing copper-zinc-aluminium or copper-zinc-chromium-aluminium is washed with hot chemically purified water and treated with nitric acid in the presence of chromium anhydride. After removing the insoluble residue the obtained solution containing copper, zinc and small amounts of chromium and aluminium is treated with metallic copper for the reduction of chromium (VI) ions which have not reacted into chromium (III). Then the pH of the solution is increased to 3.0-3.5 using solution and the iron (III) hydroxide precipitate is removed by filtration.
BG9004689A1989-10-171989-10-17Method for recuperation of copper and zinc from waste copper-zinc-aluminium and copper-zinc-chromium-aluminium catalysts
BG51863A1
(en)
A method for producing an aqueous solution of high phosphorous content, recovering iron compounds constituting precipitating agents, and separating heavy metals in a sewage-water or raw-water purification plant