Method for extracting palladium from low-grade spent alumina carrier catalyst

Abstract

The invention discloses a method for extracting palladium from a low-grade spent alumina carrier catalyst. The method comprises the following steps of mixing the low-grade spent alumina carrier catalyst with a reducing agent, red iron oxide, a flux, a binder and water for grinding to prepare pellets, drying the pellets, and carrying out reduction smelting to obtain a metal melt and smelting slag;carrying out atomization powder spraying on the metal melt to obtain palladium-containing iron alloy powder; carrying out rust treatment on the palladium-containing iron alloy powder, then conductinggravity separation to obtain palladium concentrate and suspension liquid; filtering the suspension liquid for separating ferric oxide hydrate and rust residual liquid; roasting and dehydrating the ferric oxide hydrate to obtain the red iron oxide, and returning the ferric oxide hydrate to the mixing procedure to be used as a trapping agent; dissolving the palladium concentrate by chlorination, andcarrying out filtering to obtain a palladium-containing pregnant solution and filter residues; and purifying, precipitating and reducing the palladium-containing pregnant solution to obtain palladiumpowder. By adopting the method to extract palladium, the palladium recovery rate is greater than 97.0%, the palladium content in the palladium powder is greater than 99.95%, the trapping agent and the rust liquid can be recycled, the emission reduction effect is remarkable, the extraction cost is low, the related equipment is mature, and the industrialization prospect is good.

Description

technical field [0001] The invention belongs to the field of metallurgy of rare and precious metals, and relates to a method for extracting palladium from low-grade spent alumina carrier catalysts. Background technique [0002] The low-grade invalid alumina carrier palladium catalyst content generally does not exceed 0.05%, but the price of palladium is high, and this invalid catalyst has high value and has important recycling significance. At present, the method for extracting palladium from low-grade spent alumina carrier catalysts is as follows: [0003] Zhang Luxiang and others disclosed a method for extracting high-purity metal palladium from waste palladium-alumina catalysts (application published invention patent number: 201810178788.3). Recovery by leaching, using dilute hydrochloric acid and pro-oxidant H 2 o 2 or NaClO 3 After the leaching solution is precipitated by adding ammonia to remove impurities, butyl sodium xanthate is used as a precipitating agent to ...

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Problems solved by technology

[0012] In summary, the existing low-grade invalid alumina-supported palladium catalysts are mainly based on the all-wet method, and the wet extraction method mainly uses strong oxidizing acid to dissolve palladium. The obtained solution not only has a very low palladium content, but also generates A large amount of waste residue, waste liquid, etc., high cost of environmental protection disposal

And the pyromelting that prior art adopts, because low-grade invalidation alumina carrier palladium catalyst content is generally not more than 0.05%, wherein most carrier is the aluminum oxide of high melting point, needs to mix in a large amount of fluxes just can be in conventional smelting furnace Melting at temperatures below 1450°C will inevitably lead to higher smelting costs and poor economic benefits

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