CN102943180A - Method for recycling gold and silver from silver separating residues of copper anode slime - Google Patents

Abstract

The invention relates to a method for recovering gold and silver in waste slag, in particular to a method for recovering gold and silver from copper anode slime and silver slag by wet method. The specific method is: the copper anode slime is divided into silver slag and sodium thiosulfate for mixing and ball milling to obtain ball abrasive; put the ball abrasive and reaction solvent into a hydrothermal reaction kettle for hydrothermal reaction; filter the hydrothermal product to obtain Thiourea dioxide is added to the hydrothermal solution for reduction reaction to obtain coarse gold and silver powder. Compared with the prior art, since the present invention adopts ball milling and hydrothermal reaction, the leaching rate of gold and silver is greatly improved. The invention has the characteristics of simple and easy process, relatively common and cheap raw materials, no pollution and the like.

Description

A kind of method for recovering gold and silver from copper anode slime and silver slag

the

technical field

The invention relates to a method for recovering gold and silver in waste slag, in particular to a method for wet recovery of gold and silver from copper anode slime and silver slag.

the

Background technique

Silver separation slag is the residue after extracting precious metals such as gold, silver, platinum, palladium and copper, selenium, tellurium and other valuable elements from copper anode slime. Copper anode slime is composed of elements with higher potential than copper and various substances insoluble in electrolyte during the electrolytic refining process. Its composition mainly depends on the composition of copper anode, casting quality and electrolysis technical conditions, and its yield is generally It is 0.2~0.8%; it usually contains Au, Ag, Cu, Pb, Se, Te, As, Sb, Bi, Ni, Fe, S, Sn, SiO ₂ , A1 ₂ O ₃ , platinum group metals and water. Anode slime derived from copper sulfide concentrate contains more Cu, Se, Ag, Pb, Te and a small amount of Au, Sb, Bi, As and gangue minerals, and few platinum group metals; while copper-nickel sulfide The anode slime of the mine contains more Cu, Ni, S, Se, the precious metals are mainly platinum group metals, and the content of Au, Ag, Pb is less; the output rate of silver-separated slag is generally 50-60% of that of copper anode slime , a smelter with an annual output of 100,000 tons of electric copper produces about 750 tons of anode slime and 350-450 tons of silver slag. The anode slime produced by copper electrolysis contains relatively high Pb and Sn, and the precious metals are mainly Ag, Au and platinum group metals; the silver-separated slag obtained after the extraction of precious metals contains high Pb and Sn, and the gold content is about 10g/t. The silver is about 200g/t to 2000g/t, the content of platinum and palladium is about 5g/t to 15g/t, and the content of precious metals is several to hundreds of times higher than that of the generally mined precious metal ores. Recycling is very necessary. However, compared with anode slime, the content of precious metals in silver-separated slag is low, and it is more difficult to recover precious metals.

There are not many domestic studies on gold and silver recycling of silver-separated slag. Some smelters use oxygen bottom-blown smelting to continuously redox smelt the silver-separated slag (patent application 200810049459.5), and obtain precious lead and high-lead slag. Lead is refined to obtain precious metal alloys, and silver and gold are obtained by electrolysis, which causes smelting pollution, and the process is long and the recovery rate is low. Therefore, most manufacturers now temporarily store the silver slag aside for further development and utilization. A small number of manufacturers sell it to some specialized precious metal recycling companies for processing and recycling, and extract some precious metal elements (patent applications 90103200.X, 97105925.X, 200710303815.7). This extensive recycling wastes some valuable metals in the slag , and environmental protection is not considered in the process, which not only wastes resources but also causes new environmental pollution.

As a mature gold leaching process, the cyanidation method has been used by people for a long time, but because the traditional cyanidation method produces a large amount of cyanide-containing wastewater, it causes great harm to the staff and the environment, and the gold dissolution rate is relatively low. Slow, long production cycle. The sodium thiosulfate method has the characteristics of non-toxic reagents, small amount of leaching agent, cheap and easy to obtain, fast leaching speed, and easy recovery of gold. In the presence of _O2 , sodium thiosulfate and gold can form a stable complex:

4Au+8S ₂ O ₃ ^2- +2H ₂ O+O ₂ =4Au(S ₂ O ₃ ) ₂ ^3- + ^4OH-

When Cu ²⁺ , NH ₃ , and S ₂ O ₃ ^2- exist in the solution, sodium thiosulfate is more likely to form a stable complex with gold.

The methods of leaching silver mainly include ammonia leaching method and sodium sulfite leaching method, which are mainly suitable for situations with high silver content. Sodium thiosulfate and silver ions can form a stable complex, which has a good leaching effect on silver chloride, silver sulfide and metallic silver, and has a higher leaching rate at a lower concentration of sodium thiosulfate. At the same time, thiosulfate has fast leaching speed, high leaching rate, non-toxicity, and low leaching rate to other base metals, so it has good selectivity and is a good low-grade silver leaching agent. It is suitable for leaching Ag, Ag ₂ O , AgCl and other forms of silver.

4Ag +8S ₂ O ₃ ^2- +2H ₂ O+O ₂ =4Ag(S ₂ O ₃ ) ₂ ^3- +4OH ^-

Ag ₂ O+4S ₂ O ₃ ^2- +H ₂ O=2Ag(S ₂ O ₃ ) ₂ ^3- + ^2OH-

AgCl +S ₂ O ₃ ^2- =Ag(S ₂ O ₃ ) ₂ ^3- +Cl ^-

Contents of the invention

The purpose of the present invention is to solve the problem of recovering gold and silver from the silver-separated slag of copper anode slime, which can not only ensure the effective recovery of the gold and silver precious metals in the silver-separated slag, but also has a short process flow and simple equipment.

The copper anode slime of the present invention separates the silver slag and reclaims the method for gold and silver as follows:

According to the design requirements, the silver slag of copper anode slime and sodium thiosulfate are mixed and ball milled, wherein sodium thiosulfate: silver slag of copper anode slime = 1:10~3:10 (mass ratio), and the ball milling time is 1 ～3 hours, obtain ball mill; Ball mill and reaction solvent are packed in hydrothermal reaction kettle and carry out hydrothermal reaction, wherein ball mill: reaction solvent (mass ratio)=1:1～1:3, and reaction solvent is made of copper sulfate Composed of ammonia water solution, the concentration of copper sulfate is 3~8g/L, the concentration of ammonia water is: 50~100mL/L (20% ammonia water), the ball mill and the reaction solvent account for 20~40% of the volume of the entire reaction kettle, hydrothermal reaction The temperature is 140-180°C, and the reaction time is 1-4 hours; the hydrothermal product is filtered to obtain hydrothermal slag and hydrothermal liquid, and the hydrothermal slag is treated centrally; thiourea dioxide is added to the hydrothermal liquid for reduction reaction, in which thiourea dioxide is added The amount is 5~10g/L, the reduction temperature is 30~60°C, and the reduction time is 1~3 hours; the reduction product is filtered to obtain coarse gold and silver powder and the reduced liquid, and the reduced liquid is concentrated for treatment.

The beneficial effect of the present invention is that: compared with the prior art, the present invention greatly improves the leaching rate of gold and silver due to the adoption of ball milling and hydrothermal reaction. The invention has the characteristics of simple and easy process, relatively common and cheap raw materials, no pollution and the like.

the

Description of drawings

Fig. 1 shows the flow chart of gold and silver recovery from copper anode slime and silver slag

Detailed ways

Example 1

The silver slag and sodium thiosulfate of the copper anode slime are mixed and ball milled, wherein the mass ratio of the silver slag and sodium thiosulfate of the copper anode slime is 10:1, and the ball milling time is 1 hour to obtain a ball mill; The material and the reaction solvent are loaded into the hydrothermal reaction kettle, wherein the mass ratio of the ball mill material and the reaction solvent is 1:1, the total volume of the ball mill material and the reaction solvent accounts for 20% of the volume of the hydrothermal reaction kettle, and the hydrothermal reaction temperature is 140°C , the reaction time is 1 hour, wherein the reaction solvent is composed of copper sulfate and aqueous ammonia solution, the concentration of copper sulfate is 3g/L, and the concentration of 20% ammonia water is 50mL/L (20% ammonia water); the hydrothermal product is filtered to obtain hydrothermal slag and Hydrothermal liquid, hydrothermal slag centralized treatment; add thiourea dioxide to the hydrothermal liquid for reduction reaction, so that the concentration of thiourea dioxide is 5g/L, the reduction temperature is 30°C, and the reduction time is 1 hour; the reduction product is filtered to obtain crude Gold and silver powder and reduced liquid, the reduced liquid is concentrated. The gold recovery rate is 95.2%, and the silver recovery rate is 97.3%.

Example 2

The silver slag of copper anode slime and sodium thiosulfate are mixed and ball milled, wherein the mass ratio of silver slag and sodium thiosulfate of copper anode slime is 10:3, and the ball milling time is 2 hours to obtain ball mill; ball mill The material and the reaction solvent are loaded into the hydrothermal reaction kettle, wherein the mass ratio of the ball mill material and the reaction solvent is 1:1.5, the total volume of the ball mill material and the reaction solvent accounts for 25% of the volume of the hydrothermal reaction kettle, and the hydrothermal reaction temperature is 180°C , the reaction time is 4 hours, wherein the reaction solvent is composed of copper sulfate and aqueous ammonia solution, the concentration of copper sulfate is 8g/L, and the concentration of 20% ammonia water is 100mL/L (20% ammonia water); the hydrothermal product is filtered to obtain hydrothermal slag and Hydrothermal liquid, hydrothermal slag centralized treatment; add thiourea dioxide to the hydrothermal liquid for reduction reaction, so that the concentration of thiourea dioxide is 10g/L, the reduction temperature is 60°C, and the reduction time is 3 hours; the reduction product is filtered to obtain crude Gold and silver powder and reduced liquid, the reduced liquid is concentrated. The gold recovery rate is 95.5%, and the silver recovery rate is 98.1%.

Example 3

The silver slag and sodium thiosulfate of the copper anode slime are mixed and ball milled, wherein the mass ratio of the silver slag and sodium thiosulfate of the copper anode slime is 10:2, and the ball milling time is 1.5 hours to obtain a ball mill; The material and the reaction solvent are loaded into the hydrothermal reaction kettle, wherein the mass ratio of the ball mill and the reaction solvent is 1:3, the total volume of the ball mill and the reaction solvent accounts for 40% of the volume of the hydrothermal reaction kettle, and the hydrothermal reaction temperature is 160°C , the reaction time is 2 hours, wherein the reaction solvent is composed of copper sulfate and aqueous ammonia solution, the concentration of copper sulfate is 5g/L, and the concentration of 20% ammonia water is 70mL/L (20% ammonia water); the hydrothermal product is filtered to obtain hydrothermal slag and Hydrothermal liquid, hydrothermal slag centralized treatment; Add thiourea dioxide to the hydrothermal liquid for reduction reaction, so that the concentration of thiourea dioxide is 8g/L, the reduction temperature is 40°C, and the reduction time is 2 hours; the reduction product is filtered to obtain crude Gold and silver powder and reduced liquid, the reduced liquid is concentrated. The gold recovery rate is 95.1%, and the silver recovery rate is 98.4%.

Example 4

The silver slag of copper anode slime and sodium thiosulfate are mixed and ball milled, wherein the mass ratio of silver slag and sodium thiosulfate of copper anode slime is 10:1.5, and the ball milling time is 3 hours to obtain ball mill; ball mill The material and the reaction solvent are loaded into the hydrothermal reaction kettle, wherein the mass ratio of the ball mill material and the reaction solvent is 1:2, the total volume of the ball mill material and the reaction solvent accounts for 30% of the volume of the hydrothermal reaction kettle, and the hydrothermal reaction temperature is 170°C , the reaction time is 2.5 hours, wherein the reaction solvent is composed of copper sulfate and aqueous ammonia solution, the concentration of copper sulfate is 6g/L, and the concentration of 20% ammonia water is 85mL/L (20% ammonia water); the hydrothermal product is filtered to obtain hydrothermal slag and Hydrothermal liquid, hydrothermal slag centralized treatment; Add thiourea dioxide to the hydrothermal liquid for reduction reaction, so that the concentration of thiourea dioxide is 7g/L, the reduction temperature is 50°C, and the reaction time is 2.5 hours; the reduction product is filtered to obtain crude Gold and silver powder and reduced liquid, the reduced liquid is concentrated. The gold recovery rate is 97.1%, and the silver recovery rate is 98.6%.

Claims (2)

1. the method that the silver separating residue of copper anode slime gold and silver reclaims is characterized in that, described method steps is as follows:

(1) silver separating residue of copper anode slime and Sulfothiorine are carried out batch mixing and ball milling, wherein Sulfothiorine: silver separating residue of copper anode slime mass ratio=1:10 ~ 3:10, Ball-milling Time is 1 ~ 3 hour, obtains the ball milling material;

(2) ball milling material and reaction solvent are packed into carry out hydro-thermal reaction in the hydrothermal reaction kettle, ball milling material wherein: reaction solvent mass ratio=1:1 ~ 1:3, reaction solvent is comprised of copper sulfate and ammonia aqueous solution, wherein concentration of copper sulfate is 3 ~ 8g/L, ammonia concn is: 50 ~ 100mL/L(20% ammoniacal liquor), hydrothermal temperature is 140 ~ 180 ℃, and the reaction times is 1 ~ 4 hour;

(3) the hydrothermal product filtration is obtained hydro-thermal slag and hydro-thermal liquid, the hydro-thermal slag focuses on; Add thiourea peroxide in the hydro-thermal liquid and carry out reduction reaction, wherein the thiourea peroxide add-on is 5 ~ 10g/L, and reduction temperature is 30 ~ 60 ℃, and the recovery time is 1 ~ 3 hour;

(4) the reduzate filtration is obtained thick metal(lic)powder and the rear liquid of reduction, the rear liquid of reduction focuses on.

2. method according to claim 1, it is characterized in that: in the described step (2), ball milling material and reaction solvent account for 20 ~ 40% of whole reactor volume.

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