Separation method of palladium from silver electrolyte

Abstract

The invention relates to a wet metallurgic method for effectively separating palladium from silver electrolyte by adopting modified polyacrylonitrile resin, and the process is free from pollution. The method adopts a technical scheme that: polyacrylonitrile resin is modified by adopting a hydroxyl amine hydrochloride solution to obtain a novel chelating resin namely amidoxime polyacrylonitrile resin; silver electrolyte which is roughly purified to remove heavy metal impurities is adsorbed by adopting the amidoxime polyacrylonitrile resin, so that palladium in the solution is loaded onto the resin, and the resin is subjected to primary desorption by adopting an acidic thiourea solution to obtain a palladium-containing desorption liquid; the resin is subjected to secondary desorption by adopting a high-concentration hydrochloric acid solution to obtain a silver-containing desorption liquid; and the resin which is subjected to twice desorption is regenerated by adopting a hydroxyl amine hydrochloride solution, and is returned to adsorb the palladium-containing silver electrolyte. According to the method, palladium and silver can be effectively separated, the adsorbed solution can be directly returned to silver electrolysis, the operation is simple, the purification time is short, the recovery rate of noble metals is high, and the practicality is strong.

Description

technical field [0001] The invention relates to the separation of precious metals in the field of hydrometallurgy, in particular to a method for effectively separating palladium from silver electrolytes. Background technique [0002] The refining of silver mainly adopts electrolytic refining method, and its electrolyte is silver nitrate solution. With the progress of electrolytic refining, the heavy metals in the silver anode plate will continue to dissolve, resulting in Cu 2+ , Pb 2+ 、 Bi 3+ , Sb 3+ Plasma accumulates in the silver electrolyte; on the other hand, precious metals (such as platinum and palladium) in the silver anode plate will also partially dissolve into the electrolyte during the electrolysis process, making the Pd 2+ 、Pt 2+ Accumulate continuously in the electrolyte, when the Pd in ​​the silver electrolyte 2+ 、Pt 2+ When it reaches a certain concentration, it will be precipitated at the cathode together with silver, resulting in a decrease in the qu...

AI Technical Summary

Problems solved by technology

However, the saturated adsorption capacity of activated carbon for palladium is low, only 23 mg g -1 , the demand for activated carbon is large during the adsorption process; silver and palladium are adsorbed and desorbed at the same time, and complete separation has not been achieved; moreover, the activated carbon used for adsorption needs to be oxidized with high-concentration nitric acid, and a high-concentration nitric acid solution is also used for desorption, which is easy to release nitrogen oxides gas, causing environmental pollution

In addition, activated carbon activated by thiourea is used to adsorb and separate metal palladium from silver electrolyte, and its saturated adsorption capacity can reach 50-70 mg·g -1 , but it is easy for thiourea to enter the silver electrolyte during the adsorption process, so that the electrolyte after the adsorption of palladium cannot be directly returned to the silver electrolyte

[0008] The above methods can separate the platinum group metal palladium from the silver electrolyte to a certain extent, but the separation process is not thorough enough, and the silver-containing solution after separation cannot be directly returned to the silver electrolysis process, making the follow-up treatment process cumbersome

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