CN114525413A - Method for separating copper and noble metal from copper alloy containing noble metal - Google Patents

Abstract

The invention provides a method for separating copper and precious metals from precious metal-containing copper alloys, which comprises the following steps: pyrometallurgical smelting, atomization pulverizing, selective leaching, purification and electrowinning; smelting precious metal-containing copper alloys in a smelting furnace, In the molten state, the alloy powder is made by the atomization pulverizing device, and the alloy powder is added to the reaction kettle with the leaching agent, and the selective leaching is carried out by blowing air. After solid-liquid separation, the leaching slag is separated and purified to recover precious metals. , copper powder is added to the solution to remove silver, and after silver removal, the solution is electro-deposited in an electrowinning cell to obtain cathode copper. After being treated by the method, copper and precious metals are separated and copper is recovered without loss of precious metals, which facilitates the recovery of precious metals.

Description

A method for separating copper and precious metals from precious metal-containing copper alloys

technical field

The invention relates to the technical field of hydrometallurgy of copper and precious metals, in particular to a method for separating copper and precious metals from copper alloys containing precious metals.

Background technique

The method of separating copper and precious metals from precious metal-containing copper alloys. The current mainstream process is to use electrolytic refining to separate. Specifically, the precious metal-containing copper alloys are melted and cast into copper plates and used as anodes. Copper sheets or stainless steel are used for separation. The plate is used as the cathode, the copper sulfate solution is used as the electrolyte, and copper is deposited on the cathode through electrolytic refining to obtain cathode copper with a purity of more than 99.9%. It is relatively mature and used in large and medium-sized copper smelters.

However, this separation method is suitable for the separation of copper and precious metals in precious metal-containing copper alloys with a copper content of more than 99% and a precious metal (silver and other precious metals) content of less than 0.5%. The anode passivation phenomenon occurs in the electrolysis, which makes it difficult to carry out the electrolysis. At the same time, the separation method is prone to anode polarization during the electrolysis process, resulting in overvoltage, so that a small amount of precious metal in the anode is dissolved, so that the total amount of the separated precious metal is lost, and the yield of the separated precious metal is reduced. In addition, the electrolysis cycle of this separation method is long, generally 15 days, and the anode residue needs to be re-cast in the furnace and then electrolyzed, which leads to a longer recovery cycle of precious metals, which is not conducive to the capital turnover of enterprises.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the existing methods for separating copper and precious metals from copper alloys containing precious metals by electrolytic refining, the present invention provides a new method for separating copper and precious metals from copper alloys containing precious metals. Its specific technical solutions are as follows:

A method for separating copper and precious metals from a precious metal-containing copper alloy, comprising the following steps:

(1) Fire smelting: place the precious metal-containing copper alloy material in a smelting furnace and smelt at 1200°C to melt it into a molten state;

(2) Atomization and pulverization: the precious metal-containing copper alloy material in the molten state in step (1) is atomized and solidified by an atomizing powder-making device (metal atomizer) to become precious metal-containing copper powder;

(3) Selective leaching: add the precious metal-containing copper powder of (2) into a special reaction kettle (a reaction kettle with a vent tube at the bottom), add a leaching agent, start stirring, and simultaneously pass the vent tube to the reaction kettle. Air (oxidant) is introduced into the medium, and the redox potential of the reaction kettle is controlled to be 300-400mv, and after 20-22 hours of reaction, it is filtered, and the leaching residue and leaching solution are obtained by filtration, and the leaching residue is used for the extraction and recovery of precious metals; When the oxidation-reduction potential of the reaction in this step is controlled at 300-400mv, the copper in the precious metal-containing copper powder can be completely dissolved, and a small amount of silver can be dissolved, while precious metals such as gold, platinum, palladium, and rhodium are not dissolved.

(4) Purification: the leaching solution obtained in (3) is added to another reaction kettle, stirring is started, copper powder (impurity remover) is added, and the copper powder reduces silver ions to elemental silver, and filtered to obtain relatively pure copper sulfate Solution and silver powder, silver powder is used for silver recovery;

(5) Electrowinning: the copper sulfate solution obtained in (4) is sent to an electrowinning tank, and direct current is fed into it. Under the action of the direct current, the cathode obtains a copper plate, the anode generates oxygen, and an electrowinning waste liquid is generated simultaneously.

The specific principle of the above method is as follows:

(1) Selective leaching principle: The precious metal-containing copper alloy material is smelted by fire method, and atomized into alloy powder in the molten state.

The main chemical process of selective leaching of copper:

2Cu+2H ₂ SO ₄ +O ₂ =2CuSO ₄ +2H ₂ O

(2) The principle of reduction

The copper sulfate leaching solution obtained in step (3) is added to another reaction kettle, stirring is started, and copper powder is added. The copper powder reduces the silver ions to elemental silver, and is filtered to obtain relatively pure copper sulfate solution and silver powder. The mechanism of reduction is: Cu+2Ag ⁺ →Cu ²⁺ +2Ag.

(3) The principle of electrowinning

After purification in step (4), a copper sulfate solution with a Cu ²⁺ concentration of 35-45 g/L and a H ₂ SO ₄ content of about 150-160 g/L can be obtained, and the copper sulfate solution is sent to the electrowinning cell, and the Direct current, under the action of direct current, the cathode obtains the copper plate, the anode produces oxygen, and at the same time produces the electrowinning waste liquid, in which the Cu ²⁺ concentration is 30-35g/l, the H ₂ SO ₄ content is 160-180g/L, the electrowinning waste The liquid is returned to step (3) for recycling.

The cathodic reaction produces copper, namely:

Cu ²⁺ +2e=Cu φ ^Θ Cu ²⁺ /Cu=0.34V

The anode reacts to generate oxygen, and the reaction formula is:

H ₂ O-2e=1/2O ₂ +2H ⁺ φ ^Θ O ₂ /H ₂ O=1.23V

The overall reaction formula for copper electrowinning is:

Cu ²⁺ +H ₂ O=Cu+1/2O ₂ +2H ⁺

The standard electromotive force of the electrowinning reaction is:

E ^Θ =φ ^Θ Cu ²⁺ /Cu-φ ^Θ O ₂ /H ₂ O=-0.89V

Further, the precious metal-containing copper alloy material in step (1) is a copper material containing precious metals such as gold, silver, platinum, palladium, and rhodium.

Further, the smelting furnace described in step (1) is an intermediate frequency smelting furnace.

Further, the electroplating waste liquid generated in step (5) can be returned to (3) for recycling to maximize the utilization of materials, so as to reduce the waste liquid output of the method and reduce the pollution to the environment.

Further, the leaching agent used in step (3) is sulfuric acid and/or the electroplating waste liquid produced in step (5), before the reaction, the concentration (mass percent) of sulfuric acid in the solution is 10%, and the solid-liquid ratio of the reaction is 10%. It is 1:20-24, and the reaction temperature is normal temperature, which can ensure a good selective leaching effect under the above solid-liquid ratio and sulfuric acid concentration. Further, when the concentration of sulfuric acid in the solution is higher than and close to 10%, in order to ensure that the solid-liquid ratio is 1:20-24, it can be adjusted by adding water to ensure the solid-liquid ratio and sulfuric acid concentration of the entire reaction system.

Further, the reaction temperature of step (4) is normal temperature.

Further, the current density in step (5) is 180-250A/m 2 , the content of liquid copper before electrowinning is 35-45 g/L, and the content of liquid copper after electrowinning is 30-35 g/L. Under the above conditions, it has better electrowinning effect.

Compared with the prior art, the beneficial effects of the present invention are: on the one hand, the method mainly separates the copper and the precious metal in the precious metal-containing copper alloy by selective leaching, and the method ensures that the copper is completely separated from the precious metal-containing copper alloy. In the case of , the loss of precious metals is low or even no loss, which improves the yield of precious metals obtained by separation. On the other hand, this separation method has no strict requirements on the copper content and silver content in the material. In addition, the separation period of this method is obviously shortened, and the leaching reaction time is within 24h. Generally speaking, after the treatment by this method, copper and precious metals are separated and copper is recovered without loss of precious metals, which facilitates the recovery of precious metals.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

The present invention will be further analyzed below with reference to specific embodiments. Obviously, the description is only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

The reagents or raw materials not specifically described in the following examples of the present invention are commercially available. In addition, the determination standards of copper and precious metals in the present invention are as follows: copper GB/T5121.1-2008; gold GB/T4134-2015; silver GB/T4135-2016; platinum GB/T1419-2015; palladium GB/T 15072.4-2008; Rhodium GB/T 8184-2004.

Example 1

98.32kg of precious metal-containing copper alloy raw materials were smelted in a medium-frequency furnace at a temperature of 1200°C into a molten alloy, and then atomized and solidified to obtain 90.40kg of metal powder, which was atomized into metal powder. After sampling and testing, copper and precious metals The composition content is as follows: Cu 85.71%, Au 0.13%, Pd 0.087%, Ag 4.7%, Rh 0.041%, Pt 0.004%.

The obtained atomized metal powder was added to a reactor with a vent pipe, 10% dilute sulfuric acid was added, stirring was started, the reaction temperature was room temperature, and air was introduced into the reactor to control the redox potential of the reactor to be 300- 400mv, solid-liquid ratio 1:20, reaction time 22h. The leaching solution was sampled and tested, and the data of copper and precious metal content showed that the Cu concentration was 42.3g/l, the Ag concentration was 0.717g/l, and the Cu leaching rate was 98.7%. After selective leaching, the copper in the metal powder was basically all dissolved, and the silver part Dissolved (30.51%), the precious metals gold, palladium and rhodium were not dissolved, filtered to obtain a filter residue containing precious metal rich bodies and a filtrate copper sulfate solution, and the precious metal rich bodies were extracted and recovered by precious metal separation and refining. Add the filtrate copper sulfate solution into another reaction kettle, start stirring, add copper powder to purify and remove silver, copper powder reduces silver ions to elemental silver, and filters to obtain relatively pure copper sulfate solution and silver powder, and silver powder is used for silver recovery, The copper sulfate solution enters the electrowinning step. The purified copper sulfate solution is sent to the electroplating tank, and direct current is applied. Under the action of direct current, the cathode obtains a copper plate, the cathode copper content is 99.52%, the anode generates oxygen, and the electrowinning waste liquid is generated at the same time, and the electrowinning waste liquid is returned to the leaching step. Recycling, the precious metal recovery rate is all above 99% (wherein the silver recovery in the leaching residue is 69.49%, the other part generates 1283.93g of silver powder in the purification step, and the total silver yield is 99.71%), the statistical data is shown in the following table 1 .

Table 1 Experimental results of Example 1

Example 2

The raw material of copper alloy containing precious metal 62.4kg was smelted by the intermediate frequency furnace fire method and the alloy was in a molten state at a temperature of 1200 ° C. After being atomized and solidified by an atomizing device, 59.84 kg of metal powder was obtained. The atomized metal powder was sampled and tested. The composition content is as follows: Cu 87.43%, Au 0.335%, Pd 0.18%, Ag 5.43%, Rh 0.041%, Pt 0.007%.

The obtained atomized metal powder was added to a reactor with a vent pipe, 10% dilute sulfuric acid was added, stirring was started, the reaction temperature was room temperature, and air was introduced into the reactor to control the redox potential of the reactor to be 300- 400mv, solid-liquid ratio 1:20, reaction time 20h. The leaching solution is sampled and tested, and the content of copper and precious metals shows that the Cu concentration is 43.3g/l, the Ag concentration is 0.88g/l, and the Cu leaching rate is 99.05%. After selective leaching, the copper in the metal powder is basically all dissolved, and the silver part Dissolved (36.83%), the precious metals gold, palladium and rhodium were not dissolved, filtered to obtain a filter residue containing precious metal rich bodies and a filtrate copper sulfate solution, and the precious metal rich bodies were extracted and recovered by precious metal separation and refining. Add the filtrate copper sulfate solution into another reaction kettle, start stirring, add copper powder to purify and remove silver, copper powder reduces silver ions to elemental silver, and filters to obtain relatively pure copper sulfate solution and silver powder, and silver powder is used for silver recovery, The copper sulfate solution enters the electrowinning step. The purified copper sulfate solution is sent to the electrowinning tank, and direct current is passed through. Under the action of direct current, the cathode obtains a copper plate, the cathode copper content is 99.58%, the anode generates oxygen, and the electrowinning waste liquid is generated at the same time. Recycle the electrowinning waste liquid and return it to the leaching step for recycling, and the precious metal recovery rate is all above 99% (wherein the silver recovery in the leaching residue is 63.17%, and the other part generates 1185.12g of silver powder in the purification step, and the total silver yield is 99.64% %), the statistics are shown in Table 2 below.

The experimental result of table 2 embodiment 2

Example 3

The raw material containing precious metal copper alloy 104.25kg was smelted by the intermediate frequency furnace fire method at a temperature of 1200°C to form a molten alloy, and then atomized and solidified by an atomizing device to obtain 84.24kg of metal powder, which was atomized into metal powder. The copper and precious metals were sampled and tested The composition content is as follows: Cu 92.08%, Au 0.086%, Pd 0.01%, Ag 7.072%, Rh 0.025%, Pt 0.004%.

The obtained atomized metal powder was added to a reactor with a vent pipe, 10% dilute sulfuric acid was added, stirring was started, the reaction temperature was room temperature, and air was introduced into the reactor to control the redox potential of the reactor to be 300- 400mv, solid-liquid ratio 1:24, reaction time 21h. The leaching solution was sampled and tested, and the data of copper and precious metal content showed that the Cu concentration was 37.99g/l, the Ag concentration was 0.62g/l, and the Cu leaching rate was 99.02%. After selective leaching, the copper in the metal powder was basically all dissolved, and the silver part Dissolved (21.04%), the precious metals gold, palladium and rhodium were not dissolved, filtered to obtain a filter residue containing precious metal rich bodies and a filtrate copper sulfate solution, and the precious metal rich bodies were extracted and recovered by precious metal separation and refining. Add the filtrate copper sulfate solution into another reaction kettle, start stirring, add copper powder to purify and remove silver, copper powder reduces silver ions to elemental silver, and filters to obtain relatively pure copper sulfate solution and silver powder, and silver powder is used for silver recovery, The copper sulfate solution enters the electrowinning step. The purified copper sulfate solution is sent to the electroplating tank, and direct current is applied. Under the action of direct current, the cathode obtains a copper plate, the cathode copper content is 99.52%, the anode generates oxygen, and the electrowinning waste liquid is generated at the same time, and the electrowinning waste liquid is returned to the leaching step. Recycle the electrowinning waste liquid and return it to the leaching step for recycling, and the precious metal recovery rate is all above 99% (wherein the silver recovery in the leaching residue is 78.96%, the other part generates 1235.28g of silver powder in the purification step, and the total silver yield is 99.70% %), the statistics are shown in Table 3 below.

The experimental result of table 3 embodiment 3

Comparative ratio

The copper material containing precious metals in the same batch as in Example 3 was treated by the current mainstream process (electrolytic refining method), and the content of copper and precious metals was as follows: Cu 92.08%, Au 0.086%, Pd 0.01%, Ag 7.072%, Rh0. 025%, Pt 0.004%. In the experiment, 6 kg of precious metal-containing copper material was taken and cast into a copper plate as the anode, the copper sheet was used as the cathode, and the copper sulfate solution was used as the electrolyte, which was separated by electrolytic refining. The specific experimental data are shown in Table 4.

Table 4 Experimental results of the comparative example

Using the current mainstream process, copper is deposited on the cathode to obtain 98.86% of cathode copper, and the precious metals become anode slimes during the electrolysis process. The yields of noble metals in anode slimes are shown in Table 4, and the specific yields are: Au 99.92 %, Ag 85.57%, Pt 99.25%, Pd 99.58%, Rh 81.18%. The results of Example 3 treated by the method of the present invention are shown in Table 3. The copper yield is 99.52%, the precious metal yield is Au 99.12%, Ag 99.70%, Pt 99.27%, Pd 99.38%, Rh 99.51%. By comparison, it is found that the total yield of precious metals by the method of the present invention is significantly higher than that of the comparative example, especially the yields of Ag and Rh are 14.23% and 18.33% higher than those of the comparative example, respectively. Moreover, the unit price of rhodium is relatively expensive, and the method has great economic benefits. At the same time, the electrolysis time of the comparative example reaches 135h, while the leaching time of the present application is within 24h, which provides convenience for the recovery of precious metals. In addition, by further analyzing the experimental data of the comparative example, it is found that the electrolyte and cathode copper contain precious metals. It can be seen that during the electrolysis process, the precious metals silver, rhodium and palladium in the anode are lost in the electrolyte and the cathode, which reduces the amount of precious metals in the anode slime. The recovery rate, and the precious metals lost in the electrolyte and cathode are difficult to recover. Even if it can be recovered, the cost of recovery is relatively high, which is equivalent to the use of more mainstream processes to deal with the waste of recycled raw materials to some extent, which reduces the recovery of raw materials. added value.

Generally speaking, compared with the above-mentioned methods, the method of the present invention requires high tolerance for copper purity in terms of the recovery of some precious metal-containing copper materials. From the examples, the precious metals gold, silver, platinum, palladium and rhodium are well enriched in the leaching residue, which reduces the loss rate of the precious metals, especially avoids the loss of silver and rhodium in the electrolyte and the cathode copper It cannot be recovered. In addition, the selective leaching reaction time of the present invention is generally within 24h, which greatly reduces the separation time of precious metal and copper compared with the method time of electrolytic refining, thereby shortening the precious metal recovery period.

Claims (8)

1. A method of separating copper and precious metals from a precious metal-containing copper alloy, comprising the steps of:

(1) fire smelting: smelting the alloy material containing the noble metal copper in a smelting furnace at 1200 ℃ to melt the alloy material into a molten state;

(2) atomizing to prepare powder: atomizing and solidifying the noble metal-containing copper alloy material in the molten state in the step (1) by an atomizing powder making device to obtain noble metal-containing copper powder;

(3) selective leaching: adding the copper powder containing the noble metals in the step (2) into a reaction kettle with a vent pipe, adding a leaching agent, starting stirring, introducing air into the reaction kettle through the vent pipe, controlling the oxidation-reduction potential of the reaction kettle to be 300-400mv, reacting for 20-22 hours, filtering to obtain leaching slag and leaching liquid, wherein the leaching slag is used for extracting and recovering the noble metals;

(4) purifying: adding the leachate obtained in the step (3) into another reaction kettle, starting stirring, adding copper powder, reducing silver ions into simple substance silver by the copper powder, filtering to obtain relatively pure copper sulfate solution and silver powder, and recovering the silver powder;

(5) electrodeposition: and (4) conveying the copper sulfate solution obtained in the step (4) to an electrodeposition tank, introducing direct current, obtaining a copper plate at the cathode under the action of the direct current, generating oxygen at the anode and generating electrodeposition waste liquid at the same time.

2. The method of claim 1 for separating copper and noble metals from a noble metal-containing copper alloy, wherein: the noble metal-containing copper alloy material in the step (1) is a copper material at least containing silver and/or rhodium.

3. The method of claim 1 for separating copper and noble metals from a noble metal-containing copper alloy, wherein: the smelting furnace in the step (1) is a medium-frequency smelting furnace.

4. The method of claim 1 for separating copper and noble metals from a noble metal-containing copper alloy, wherein: and (4) returning the electrodeposition waste liquid generated in the step (5) to the step (3) for recycling.

5. The method of claim 1 for separating copper and noble metals from a noble metal-containing copper alloy, wherein: the leaching agent used in the step (3) is sulfuric acid and/or electrodeposition waste liquid generated in the step (5), before reaction, the mass percentage concentration of the sulfuric acid in the solution is 10%, the solid-liquid ratio of the reaction is 1:20-24, and the reaction temperature is normal temperature.

6. The method of claim 5 for separating copper and noble metals from a noble metal-containing copper alloy, wherein: when the concentration of sulfuric acid in the solution is higher than and close to 10%, the solid-to-liquid ratio is 1:20-24, and the adjustment can be realized by adding water.

7. The method of claim 1 for separating copper and noble metals from a noble metal-containing copper alloy, wherein: the reaction temperature in the step (4) is normal temperature.

8. The method of claim 1 for separating copper and precious metals from a precious metal-containing copper alloy, wherein: the current density in the step (5) is 180-²The copper content of the liquid before electrodeposition is 35-45g/L, and the copper content of the liquid after electrodeposition is 30-35 g/L.

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