Silver anode mud treatment process

Abstract

The invention relates to a silver anode mud treatment process. The process is characterized by leaching silver anode mud with nitric acid, wherein silver, palladium and base metals enter into solution while gold and platinum remain in residue; after roasting the leaching residue and removing impurities, using a cast gold anode plate to electrolyze the leaching residue to obtain gold No. 1 and using electrolyte for recycling platinum; regulating the pH value of leachate and adding mixed precipitator A solution to selectively precipitate palladium to obtain palladium precipitate residues; solution after palladium precipitation mainly being AgNO3 solution and returning the AgNO3 solution to undergo silver electrolysis; dissolving the palladium precipitate residues with aqua regia and filtering the dissolved solution to obtain the filter residue which is mainly AgCl, reducing the filter residue with hydrazine hydrate to obtain crude silver powder and returning the crude silver powder to a cast silver anode plate; and concentrating and carrying out ammonium on the solution after dissolution to obtain (NH4)2PdCl6 precipitate, dissolving the (NH4)2PdCl6 precipitate with ammonia and acidizing the (NH4)2PdCl6 precipitate with hydrochloric acid to obtain Pd(NH3)2Cl2 precipitate, then reducing the Pd(NH3)2Cl2 precipitate with hydrazine hydrate and then drying the reduction product to obtain spongy palladium, wherein the produced filtrate is returned to the concentration process. The invention has the advantages of less precious metal loss, low cost, strong practicability, high comprehensive recoverability and obvious economic benefit.

Description

technical field [0001] The invention relates to a treatment process of silver anode slime, which belongs to the field of nonferrous metal hydrometallurgy. Background technique [0002] Electrolytic refining is a common method for preparing high-purity metals. For example, the electrolytic refining process of silver uses crude silver as the anode, titanium plate as the cathode, and silver nitrate aqueous solution as the electrolyte, with a DC voltage of 1.5-3.5V and a current of 250-300A / m 2 Refining under certain conditions can obtain 99.99% silver. [0003] Before electrolysis, crude silver generally contains various impurities such as Au, Pt, Pd and base metals Pb, Cu, Bi. During the electrolysis process, most of the gold and platinum group metals whose electrode potential is higher than that of silver will not dissolve and precipitate, and some base metal impurities with a lower electrode potential than silver will form oxides or basic salts and also precipitate. The m...

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Problems solved by technology

However, this method has problems such as difficult control of leaching conditions, high price of leaching reagents, difficult separation of precious metals and base metals, difficult separation of platinum and palladium, and low recovery rate.

And this method is difficult to miniaturize, the amount of silver anode slime in general smelting enterprises is limited, it cannot be processed by the above method, so it has to be sold outside, but the precious metals in it are not recycled and the value is greatly reduced, causing huge economic losses to the enterprise

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