RU2357012C1 - Extraction method of noble metals from wastes of radio-electronic industry - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: invention relates to metallurgy of noble metals and can be used on enterprises of repeated metallurgy for processing of radio-electronic scrap and at extraction of gold or silver from wastes of electronic and electrochemical industries, particularly to extraction method of noble metals from wastes of radio-electronic industry. Method includes receiving from wastes of copper-nickel anodes, containing admixtures of noble metals, its electrolytic anodic dissolutionc by copper sedimentation on cathode, receiving of nickel solution and sludge with noble metals. Additionally anodic dissolution is implemented from the anode, consisting 6-10% of iron, at placement of cathode and anode in separate reticulate diaphragms for creation of cathode and anode chambers with stand in it chlorine-containing electrolyte. Received electrolyte during the process of electrolysis from cathode chamber is directed into the anode chamber. ^ EFFECT: increasing of anode dissolution rate. ^ 2 ex

Description

The invention relates to the metallurgy of noble metals and can be used in secondary metallurgy enterprises for the processing of electronic scrap and in the extraction of gold or silver from waste from the electronic and electrochemical industries.

The following methods of electrorefining metals.

A known method that relates to hydrometallurgy of precious metals, in particular to methods for the extraction of gold and silver from concentrates, waste electronic and jewelry industry. A method in which the extraction of gold and silver involves treatment with solutions of complexing salts and passing an electric current with a density of 0.5-10 A / dm ² , solutions containing thiocyanate ions, ferric ions, and the pH of the solution is 0.5-4.0. The separation of gold and silver is carried out at the cathode, separated from the anode space by a filtering membrane (RF Application No. 94005910, IPC С25С 1/20).

The disadvantages of this method are the increased loss of precious metals in the sludge. The method requires additional processing of concentrates with complexing salts.

The invention is known which relates to methods for the extraction of precious metals from spent catalysts, as well as to electrochemical processes with a fluidized or fixed bed. The processed material in the form of filling is placed in the interelectrode space of the electrolyzer, the electrochemical leaching of precious metals based on their anodic dissolution is activated by pretreating the material by reversing the electrodes in static, which turns it into a bulk multipolar electrode, providing anodic dissolution of the metal in the entire volume of the material, and electrolyte circulation through backfill from the anode to the cathode, they are provided at a speed determined from the condition of preventing contact with the cathode d hydrated anionic chloride complexes of noble metals formed during leaching in the volume of backfill, while acidified water with a hydrochloric acid content of 0.3-4.0% is used as an electrolyte. The method allows to increase the productivity of the process and simplify it (RF Patent No. 2198947, IPC С25С 1/20).

The disadvantage of this method is the increased power consumption.

A known method comprising the electrochemical dissolution of gold and silver in an aqueous solution at a temperature of 10-70 ° C in the presence of a complexing agent. Sodium ethylene diamine tetraacetate is used as a complexing agent. The concentration of EDTA Na 5-150 g / l. Dissolution is carried out at pH 7-14. The current density of 0.2-10 A / DM ² . Using the invention allows to increase the dissolution rate of gold and silver; reduce the copper content in the sludge sludge to 1.5-3.0% (RF Patent No. 2194801, IPC S25 C1 / 20).

The disadvantage of this method is the insufficiently high dissolution rate.

As a prototype of the present invention, the method of electrolytic refining of copper and nickel from copper-nickel alloys containing impurities of precious metals is selected, which includes the electrochemical dissolution of anodes from a copper-nickel alloy, deposition of copper to produce a nickel solution and sludge. Dissolution of the anodes is carried out in the anode space separated by the diaphragm, in the suspended layer of sludge, while reducing energy consumption (by 10%) and increasing the concentration of gold in the sludge. (RF patent No. 2237750, IPC С25С 1/20, publ. 04/29/2003).

The disadvantages of this invention remain the loss of noble metals in the sludge, the insufficiently high dissolution rate.

The technical result is the elimination of these disadvantages, i.e. reduction of losses of precious metals in the sludge, an increase in the dissolution rate, a decrease in the consumption of electricity.

The technical result is achieved by the fact that in the method of electrolytic sulfuric acid dissolution of copper-nickel anodes obtained from waste from the electronics industry containing impurities of precious metals, including anodic dissolution, chemical dissolution and cathodic deposition of copper, to obtain a Nickel solution and sludge with noble metals, according to the invention, the anode containing 6-10% iron and the cathode are placed in separate mesh diaphragms with a chlorine-containing electrolyte contained in them, and the percentage obtained sse electrolysis of electrolyte from the cathode to the anode space fed.

The method is implemented as follows.

In the electrolytic bath, the copper-nickel anode containing 6-10% iron, impurities of precious metals, and the cathode are placed in separate mesh diaphragms with a chlorine-containing electrolyte, creating separate anode and cathode spaces. In the cathode space, the electrolyte is enriched with ferric iron FeCl ₃ , and then it is fed into the anode space, for example, using a pump. The anode dissolution process is carried out at a current density of 2-10 A / dm ² , a temperature of 40-70 ° C and a voltage of 1.5-2.5 V. Under the influence of an electric current and the oxidative effect of ferric iron, the anode dissolution process is significantly accelerated and the content of noble metals in the sludge.

An electrolyte enriched in FeCl _{2 is} formed in the cathode space, which is sent to the anode space, where it is oxidized to FeCl ₃ , due to which the process of chemical dissolution of the anode begins.

Due to the electrolytic and chemical effects, the dissolution rate of the anode is significantly increased, the content of noble metals in the sludge is increased, the loss of gold is reduced and the dissolution time of the anode is reduced.

When the iron concentration in the anode is less than 6% in the electrolyte, a reduced content of FeCl ₃ is observed, which leads to an insufficient chemical effect of ferric iron FeCl ₃ on the anode and, as a result, a low dissolution rate of the anode.

When the iron content in the anode is from 6 to 10% in the electrolyte, a sufficient amount of ferric iron FeCl _{3 is formed} , the chemical action of which on the anode significantly accelerates the dissolution rate of the anode and allows the dissolution process to be carried out under optimal conditions.

An increase in the iron concentration in the anode of more than 10% does not contribute to a further increase in the dissolution rate of the anode, but creates additional difficulties in the processing of the electrolyte.

This method is proved by the following examples.

A copper-nickel anode containing 7% Fe and weighing 119 g was placed in the anode space and dissolved at a voltage of 2.5 V, a temperature of 60 ° C and a current density of 1000 A / m ² in an electrolyte of the following composition: CuSO ₄ · 5H ₂ O - 500 ml, H ₂ SO ₄ - 250 ml, FeSO ₄ - 60 ml, HCl - 50 ml. In the absence of electrolyte circulation, the mass of the anode in the first hour of the process decreased by 0.9 g. In two hours of electrolysis, the mass of the anode decreased by 1.8 g.

After the electrolyte was moved from the cathode to the anode space without changing the current density, the mass of the anode in the first hour of electrolysis decreased by 4.25 g, and in two hours by 8.5 g.

A copper-nickel anode containing 4% Fe and weighing 123 g was dissolved under the same conditions, and in the absence of electrolyte circulation, the anode mass decreased by 0.4 g in the first hour of the process, and the anode mass decreased by 0.8 in two hours of electrolysis g.

The movement of the electrolyte from the cathode to the anode space, without changing the current density, made it possible to reduce the mass of this anode in the first hour of electrolysis by 1.15 g, and in two hours by 2.3 g.

The Fe content of 12% in the copper-nickel anode weighing 109 g did not allow to increase the dissolution rate of the anode. Under the same conditions and in the absence of electrolyte circulation, the anode mass in the first hour decreased by 0.9 g. In two hours of electrolysis, the anode mass decreased by 1.8 g.

Under the condition of moving the electrolyte from the cathode space to the anode mass, the anode during the first hour of electrolysis decreased by 4.25 g, and in two hours - by 8.5 g.

Based on the data obtained, it can be concluded that the iron content of 6-10% in the copper-nickel anode and the movement of the electrolyte enriched in FeCl ₃ from the cathode space to the anode significantly increase the dissolution rate of the anode.

Thanks to the proposed method, effects are achieved:

1) an increase in the content of precious metals in the sludge;

2) a significant increase in the dissolution rate of the anode;

3) reducing the volume of sludge.

Claims (1)

A method for extracting precious metals from electronic industry wastes, including obtaining copper-nickel anodes from them, containing impurities of precious metals, their electrolytic anodic dissolution with deposition of copper at the cathode and obtaining a nickel solution and sludge with noble metals, characterized in that they conduct electrolytic anodic dissolution anode containing 6-10% iron, when placing the cathode and anode in separate mesh diaphragms to create a cathode and anode spaces with their chlorine-containing electrolyte, and the electrolyte obtained during the electrolysis from the cathode space is sent to the anode space.