Method for high-efficiency separation of palladium from silver electrolyte

Abstract

The invention provides a method for high-efficiency separation of palladium from a silver electrolyte. The method comprises the following steps: allowing the mass volume concentration of free nitric acid in the silver electrolyte to accord with requirements and heating the silver electrolyte; weighing a high-efficiency palladium removing agent, adding the high-efficiency palladium removing agent into the heated silver electrolyte and successively carrying out a reaction with stirring and vacuum filtration so as to obtain a palladium-removed liquid and a palladium complex; washing the palladium complex; adding the palladium-removed liquid into a silver electrolytic tank and carrying out silver electrolysis so as to obtain silver powder; when the mass volume concentration of palladium in a solution in the silver electrolytic tank is more than or equal to 0.4 g / L, separating palladium from the solution and returning palladium-removed liquid to the procedure of silver electrolysis for refining and cyclic utilization; and when the concentrations of a variety of other impurity ions in the solution in the silver electrolytic tank exceed prescribed limits of the silver electrolyte, extracting out the silver electrolyte, separating palladium out and carrying out treatment of a waste silver electrolyte. With the method, high-efficiency high-selectivity one-step separation of palladium from a complex silver electrolyte can be realized, the deposition rates of metals like silver and copper are extremely low, properties of the solution are not destroyed, the solution can be returned to the silver electrolytic tank for cyclic utilization, and purifying and palladium removal efficiency of the electrolyte can be improved.

Description

technical field [0001] The invention belongs to the technical field of rare and precious metal hydrometallurgy, and relates to a method for separating palladium from a silver electrolyte, in particular to a method for efficiently separating palladium from a silver electrolyte. Background technique [0002] In the process of producing high-purity silver powder by silver electrolytic refining, the main impurity element that affects the quality of silver powder is palladium. For example, in the process of producing IC-Ag99.99 silver products, the maximum allowable content of palladium is less than 10g / t. Since the standard electrode potentials of palladium and silver are close, in the process of electrolytic refining of high-purity silver powder in nitric acid system, the dissolution rate of palladium element is as high as 40-75%. When it enters the silver electrolyte, part of palladium is deposited on the cathode, and the electrolytic silver powder contains up to 50g of palladi...

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Problems solved by technology

Many of the above methods have the following problems: 1) The co-precipitation rate of silver is relatively high, which is not suitable for the removal of impurities and recovery of palladium in the silver electrolysis production process; 2) The treatment of palladium precipitates is cumbersome and the cost is high; 3) The separation effect of palladium is poor , the palladium content in the silver electrolyte after palladium separation is still high, and it cannot be returned to the silver electrolysis for recycling; 4) The palladium enters the intermediate product, causing dispersion again, and the recovery rate is not high; 5) The properties and composition of the silver electrolyte are affected to a certain extent. Changes and damages, or the introduction of impurities that affect the quality of silver powder products, can not be used again as silver electrolyte

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