Method for enriching and recycling platinum group metal in waste catalyst by using carbonylation alloy

Abstract

The invention discloses a method for enriching and recovering platinum group metal in a waste catalyst by using carbonylation alloy, which comprises the following steps: uniformly mixing nickel-copper-containing carbonylation alloy as a trapping agent with a waste catalyst (automobile exhaust ternary, medical catalyst and the like), a slag former, a fluxing agent and a reducing agent according to a ratio, and melting at high temperature; nickel-copper-based alloy rich in precious metal can be obtained after slag sulfonium separation, and then the purposes of separation of precious metal and base metal and re-enrichment of the precious metal are achieved through acid dissolution. A traditional iron matte trapping and lead matte trapping method is abandoned, a slag matte trapping method is adopted, the slag type is stable, the content of precious metal in slag is low, the enrichment and recovery rate of the precious metal is high, precious metal alloy enrichment is easy to treat, and the cost is low; the method is free of heavy metal pollution, wide in application field and suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of precious metal pyrometallurgical enrichment and recovery, and relates to a method for enriching and recovering platinum group metals in waste catalysts by utilizing carbonyl alloy. Background Art

[0002] Platinum, palladium and rhodium in the platinum group of precious metals have excellent purification capabilities for automobile exhaust. According to statistics, the annual consumption of platinum, palladium and rhodium metals for the production of catalysts remains at around 60%. Although new energy vehicles have gradually replaced the oil vehicle market in recent years, with the increase in the number of vehicles and the improvement of environmental protection standards, the demand for precious metals will further increase. Therefore, a large number of catalysts that have been scrapped due to failure are considered to be the secondary resources of platinum group metals with the most development value and potential in the future. Therefore, extensive research has been conducted at home and abroad on the extraction technology and process of platinum group metals from secondary resources represented by failed catalysts. At present, the recovery of platinum group metals from waste catalysts is divided into hydrometallurgical and pyrometallurgical processes.

[0003] Wet process: The general process of wet treatment of honeycomb catalysts with cordierite as the carrier is to dissolve the active components of the platinum group metals. The general process flow is: after the spent catalyst is ground, it is treated with an acid solution to dissolve the platinum group metals into the solution and separate them from the carrier. The core of this process is the leaching process, which can be divided into normal pressure chemical dissolution method and pressurized chemical dissolution method according to the leaching pressure.

[0004] Pyrometallurgical process: Due to the low grade of precious metals and the difficulty in dissolving and removing impurities of cordierite and Al2O3 carriers when wet-processing automobile exhaust three-way catalysts, pharmaceutical catalysts or rhodium-containing organic catalysts, it is not conducive to wet refining. Many researchers tend to use pyrometallurgical process to enrich platinum group metals in automobile exhaust waste catalysts. Many internationally renowned precious metal companies also use pyrometallurgical process to enrich platinum group metals. The pyrometallurgical process uses molten lead, copper, iron, nickel and other capture metals or uses copper sulfide, nickel sulfide, and iron sulfide to have a special affinity for platinum group metals to achieve the transfer and enrichment of platinum group metals. The general process includes crushing, batching, granulation, smelting and slag making, blowing and other processes. Finally, the alloy or matte containing platinum group metals is treated by wet method to achieve the recovery of platinum group metals. Among them, the iron collector is cheap, but it is easy to form high temperature and acid-alkali resistant ferrosilicon alloy with Si in the main raw material or slag-making agent during the smelting process. The inclusion of metal mattes in ferrosilicon alloys causes a decrease in the yield of platinum group metals during the smelting process and increases the difficulty of later alloy matte treatment; lead volatilizes during smelting and has insufficient affinity with rhodium, resulting in a deterioration of the working environment and a rhodium yield of less than 60%.

[0005] Invention patent CN200910094112.7 relates to a method for recovering precious metals from spent automobile catalysts. The method comprises the following steps: (1) mixing spent automobile catalysts with a reducing agent, an additive and a collector; (2) placing the mixed material in a clay graphite crucible and smelting it in an electric furnace or in an electric arc furnace to obtain a precious metal phase; (3) selectively leaching base metals from the precious metal phase to obtain a precious metal concentrate, which is then refined to produce platinum, palladium and rhodium products.

[0006] Invention patent CN200910094317.5 relates to a method for recovering precious metals from spent automobile catalysts, the process of which is as follows: (1) wet leaching of precious metals from spent automobile catalysts, replacement of leaching liquid to obtain precious metal concentrate; (2) pyrometallurgical capture of precious metals in the residue to obtain precious metal phase, selectively leaching base metals therein to obtain precious metal concentrate; (3) combining the precious metal concentrates from the above two steps for refining to produce platinum, palladium and rhodium products. The process of invention patent CN200910094112.7 has a short process and high efficiency for extracting platinum group metals, but cannot recover other base metals throughout the process, resulting in a large amount of wastewater. The process of invention patent CN200910094317.5 uses hydrochloric acid leaching, which results in a poor on-site environment, strong corrosion, and a high equipment failure rate. The leached slag is smelted, resulting in a long precious metal recovery process and high cost. Summary of the invention

[0007] The purpose of the present invention is to address the above-mentioned technical problems existing in the current pyrometallurgical enrichment and recovery of precious metals in waste catalysts, and to provide a method for enriching and recovering platinum group metals in waste catalysts using carbonyl alloys. The method can effectively improve the recovery rate of platinum, palladium and rhodium in waste catalysts and reduce the difficulty of handling alloy mattes.

[0008] To achieve its purpose, the present invention adopts the following technical solution: A method for enriching and recovering platinum group metals from waste catalysts using carbonyl alloys, wherein the method uses a carbonyl alloy containing nickel and copper as a collector, and mixes it with waste catalysts (automobile exhaust ternary, pharmaceutical catalysts, etc.), slag-making agents, fluxing agents and reducing agents according to a ratio and melts them at high temperature, and then obtains a nickel-copper-based alloy enriched with precious metals after separation of slag and matte, and then separates the precious and base metals by acid dissolution to obtain a precious metal concentrate (concentrate), and finally purifies the precious metal concentrate to obtain platinum group metals. Specifically, the following steps are included: (1) mixing carbonyl alloy, waste catalyst, slag-forming agent, flux and reducing agent uniformly to obtain a mixture; in the mixture, the amount of carbonyl alloy added is 25-100wt% of the waste catalyst, the amount of slag-forming agent added is 5-35wt% of the waste catalyst, the amount of flux added is 3-5wt% of the waste catalyst, and the amount of reducing agent added is 5-35wt% of the waste catalyst; (2) smelting the mixture in step (1) at a high temperature, and separating the slag and matte to obtain a copper-nickel alloy and smelting slag; (3) acid dissolving the copper-nickel alloy in step (2), filtering and separating, and obtaining precious metal-enriched concentrate and base metal acid solution; wherein the acid dissolution conditions are: acid concentration 0.1-2.5 mol / L, solution pH 0.1-3.0, dissolution temperature 25-85°C; Cu in the base metal acid solution 2+ Ion concentration 10~20g / L, Ni 2+ Concentration 10~45g / L; (4) purifying the precious metal-enriched concentrate in step (3) to obtain platinum group precious metals; (5) Vacuum evaporation and water cooling crystallization are used to remove the Cu in the base metal acid solution in step (3). 2+ , using electric evaporation and water-cooled crystallization or frozen crystallization to remove Ni from base metal acid solution 2+ .

[0009] As a further preferred embodiment of the technical solution of the present invention, in step (1), the carbonyl alloy is any one of the carbonyl alloy produced by nickel smelting, the nickel-copper alloy in the carbonylation process, or the nickel-copper slag in the carbonylation process, or a combination of any two or more thereof.

[0010] Furthermore, in step (1), the waste catalyst is any one of automobile exhaust three-way catalyst, pharmaceutical catalyst or rhodium-containing organic catalyst or a combination of any two or more thereof.

[0011] Furthermore, in step (1), the reducing agent is any one of coke powder, coal powder or charcoal powder, or a combination of any two or more thereof.

[0012] Furthermore, in step (1), the flux is any one of sodium carbonate or borax or a combination of two of them; the slag-forming agent is one of calcium oxide, silicon oxide, calcium fluoride, aluminum oxide or magnesium oxide or a combination of two or more of them.

[0013] Furthermore, in step (2), the smelting furnace is a muffle furnace, a medium frequency furnace, an arc furnace or a plasma furnace, the smelting temperature is 1200-1550° C., and the smelting time is 0.5-5.0 h.

[0014] Furthermore, in step (3), the copper-nickel alloy is crushed and ground to a particle size of 10-300 mesh, sulfuric acid is added, and the mixture is stirred and dissolved in acid for 2-10 hours and then filtered and separated to obtain a precious metal-enriched concentrate and a base metal acid solution.

[0015] Furthermore, in step (4), the purification operation of the precious metal-enriched concentrate is to first dissolve by chlorination, and then separate and extract the precious metals by copper powder replacement, extraction or ion exchange.

[0016] Furthermore, in the vacuum evaporation and water-cooling crystallization decoppering process in step (5), the Cu 2+ The concentration is 70~120g / L, the temperature of the acid solution is 75~100℃, and the acidity is 120~200g / L; during the water-cooled crystallization process, the acidity of the acid solution is adjusted to 50~75g / L, the temperature is lower than 45℃, and crystallization is carried out by mechanical stirring.

[0017] Furthermore, in the process of electroevaporation and water-cooling crystallization denickeling in step (5), Ni 2+ The concentration is 90~200g / L, the acidity is 900~1300g / L, and the temperature of the acid solution is 95~110℃; during the water-cooled crystallization process, the acidity of the acid solution is adjusted to 150~350g / L, the temperature is lower than 45℃, and mechanical stirring is used to allow the crystals to nucleate and grow.

[0018] The innovation of the present invention lies in that the slag type of the slag matte capture method is stable, the slag contains low precious metals, and the precious metal enrichment recovery rate is high. Its beneficial effects are: a process for carbonylation alloy pyrometallurgical enrichment and recovery of platinum group metals in waste catalysts has been developed, and the traditional iron matte capture and lead matte capture methods have been abandoned. There is no heavy metal pollution, and it has the advantages of wide application fields, high precious metal yield, easy treatment of precious metal alloy enrichments, low cost, etc., and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and are not used to restrict or limit the present invention.

[0021] In other words, the present invention covers any substitutions, modifications, equivalent methods and schemes made within the spirit and scope of the present invention as defined by the claims.

[0022] The present invention provides a method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloys, such as Figure 1 As shown, the method uses a nickel-copper carbonyl alloy as a collector, and mixes it with waste catalysts (automobile exhaust ternary, pharmaceutical catalysts, etc.), slag-forming agents, fluxing agents and reducing agents in a proportion and melts them at a high temperature. After separation of slag and matte, a nickel-copper based alloy enriched with precious metals can be obtained, and then acid dissolution is used to achieve the purpose of separating precious and base metals and enriching precious metals again. By controlling the temperature, acidity and nickel-copper ion concentration of the acid hydrolysis solution in steps, nickel and copper are gradually precipitated using a water-cooled crystallization method.

[0023] In the following examples of the present invention, the parts of each reagent are all parts by weight.

[0024] Example 1 Mix 100 parts of waste automobile exhaust three-way catalyst, 25 parts of carbonyl alloy (Ni: 8%, Cu: 15%, S: 3%, Pt: 300g / t, Pd: 450g / t), 10 parts of calcium oxide, 5 parts of silicon oxide, 5 parts of sodium carbonate and 10 parts of coke evenly. Pour the mixture into a clay crucible and place it in a muffle furnace for smelting. The smelting temperature is 1250℃ and the smelting time is 3.5h. The melt is separated from the slag by natural sedimentation cooling to obtain a copper-nickel alloy enriched in precious metals and smelting slag. The copper-nickel alloy is crushed and ground into 50 mesh particles, and then acid-dissolved with 3mol / L sulfuric acid solution at 55℃. The solution pH is 4, and filtered to separate to obtain precious metal-enriched concentrate and base metal acid solution. Cu in the base metal acid solution 2+ Ion concentration is 70g / L, Ni 2+ The concentration is 20g / L. Referring to a method for treating waste automobile exhaust catalyst by pyrolysis (CN111575489B), the precious metal enriched concentrate is separated and purified, and the extraction rates of Pt, Pd and Rh are 95.34%, 95.35% and 90.79% respectively. The base metal acid solution of step (3) is heated under vacuum to concentrate the solution volume by 45%, the sulfuric acid concentration is increased to 120g / L, and the copper ion concentration is increased to 127.27g / L. Then, water-cooled crystallization is used to precipitate the copper in the concentrated solution as CuSO4.5H2O crystals, and the copper ion extraction rate can reach 70.42%. The copper-removed solution is subjected to an electric evaporation process to make the nickel ions supersaturated under electric energy conditions, the sulfuric acid concentration is increased to 900g / L, and the nickel ion concentration is increased to 95g / L. Then, NiSO4•7H2O is precipitated from the high-concentration acid solution under water-cooled conditions, and the nickel ion extraction rate can reach 95.07%.

[0025] Example 2 Mix 100 parts of waste pharmaceutical catalysts, 45 parts of carbonyl alloy (Ni: 8%, Cu: 15%, S: 3%, Pt: 300g / t, Pd: 450g / t), 7 parts of calcium oxide, 10 parts of silicon oxide, 15 parts of sodium carbonate, and 15 parts of coke. Pour the mixture into a clay crucible and place it in a muffle furnace for smelting at a smelting temperature of 1350°C for 4 hours. The melt is separated from the slag by natural sedimentation cooling to obtain a copper-nickel alloy enriched in precious metals and smelting slag. The copper-nickel alloy is crushed and ground into 150 mesh particles, then acid-dissolved at 70°C with a 4 mol / L sulfuric acid solution. The solution pH is 3, filtered and separated to obtain precious metal-enriched concentrate and base metal acid solution. Cu in the base metal acid solution 2+ Ion concentration is 80g / L, Ni 2+The concentration is 45g / L. Referring to a method for jointly extracting platinum group metals from primary and secondary resources (CN106244812A), the precious metal enriched concentrate is purified to obtain platinum group metal products, and the extraction rates of Pt, Pd, and Rh are 98.45%, 98.33%, and 96.75%, respectively. Vacuum evaporation is used in sequence to heat the base metal acid solution in step (3) under vacuum to concentrate the solution volume by 60%, increase the sulfuric acid concentration to 150g / L, and increase the copper ion concentration to 200g / L. Then, water-cooled crystallization is used to precipitate the copper in the concentrated solution as CuSO4.5H2O crystals, and the copper ion extraction rate can reach 85.12%. The copper-removed liquid is subjected to an electric evaporation process to make the nickel ions supersaturated under electric energy conditions, the sulfuric acid concentration is increased to 1150g / L, the nickel ion concentration is increased to 145g / L, and then NiSO4•7H2O is precipitated from the high-concentration acidic solution under water cooling conditions, achieving a nickel ion removal rate of 97.33%.

[0026] Example 3 Mix 100 parts of rhodium-containing organic catalyst, 100 parts of carbonyl alloy (Ni: 8%, Cu: 15%, S: 3%, Pt: 300g / t, Pd: 450g / t), 35 parts of calcium oxide, 10 parts of silicon oxide, 5 parts of borax, and 15 parts of coke. Pour the mixture into a clay crucible and place it in a muffle furnace for smelting at a smelting temperature of 1300°C for 3 hours. The melt is separated from the slag by natural sedimentation cooling to obtain a copper-nickel alloy enriched in precious metals and smelting slag. The copper-nickel alloy is crushed and ground into 300 mesh particles, then acid-dissolved with a 4 mol / L sulfuric acid solution at 95°C. The solution pH is 2, filtered and separated to obtain precious metal-enriched concentrate and base metal acid solution. Cu in the base metal acid solution 2+ Ion concentration is 120g / L, Ni 2+ The concentration is 65g / L. Referring to a method for separating and extracting platinum group metals (CN105441693A), the precious metal enriched concentrate is separated and purified, and the extraction rates of Pt, Pd, and Rh are 98.02%, 98.11%, and 96.05%, respectively. Vacuum evaporation is used in sequence to heat the base metal acid solution in step (3) under vacuum to concentrate the solution volume by 50%, increase the sulfuric acid concentration to 200g / L, and increase the copper ion concentration to 240g / L. Then, water-cooled crystallization is used to precipitate the copper in the concentrated solution as CuSO4.5H2O crystals, and the copper ion extraction rate can reach 87.35%. The copper-de-copperized solution is subjected to an electric evaporation process to make the nickel ions supersaturated under electric energy conditions, increase the sulfuric acid concentration to 1200g / L, and increase the nickel ion concentration to 180g / L. Then, NiSO4·7H2O is precipitated from the high-concentration acid solution under water-cooled conditions, and the nickel ion extraction rate can reach 98.69%.

Claims

1. A method for enriching and recovering platinum group metals from waste catalysts using carbonyl alloys, characterized in that: The method comprises the following steps: (1) mixing carbonyl alloy, waste catalyst, slag-forming agent, flux and reducing agent uniformly to obtain a mixture; in the mixture, the amount of carbonyl alloy added is 25-100wt% of the waste catalyst, the amount of slag-forming agent added is 5-35wt% of the waste catalyst, the amount of flux added is 3-5wt% of the waste catalyst, and the amount of reducing agent added is 5-35wt% of the waste catalyst; (2) smelting the mixture in step (1) at a high temperature, and separating the slag and matte to obtain a copper-nickel alloy and smelting slag; (3) acid dissolving the copper-nickel alloy in step (2), filtering and separating, and obtaining precious metal-enriched concentrate and base metal acid solution; wherein the acid dissolution conditions are: acid concentration 0.1-2.5 mol / L, solution pH 0.1-3.0, dissolution temperature 25-85°C; Cu in the base metal acid solution 2+ Ion concentration 10~20g / L, Ni 2+ Concentration 10~45g / L; (4) purifying the precious metal-enriched concentrate in step (3) to obtain platinum group precious metals; (5) Vacuum evaporation and water cooling crystallization are used to remove the Cu in the base metal acid solution in step (3). 2+ , using electric evaporation and water-cooled crystallization or frozen crystallization to remove Ni from base metal acid solution 2+ .

2. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 1, characterized in that: In step (1), the carbonyl alloy is any one of the carbonyl alloy produced by nickel smelting, the nickel-copper alloy in the carbonylation process, or the nickel-copper slag in the carbonylation process, or a combination of any two or more thereof.

3. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 2, characterized in that: In step (1), the waste catalyst is any one of automobile exhaust three-way catalyst, pharmaceutical catalyst or rhodium-containing organic catalyst or a combination of any two or more thereof.

4. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 3, characterized in that: In step (1), the reducing agent is any one of coke powder, coal powder or charcoal powder, or a combination of any two or more thereof.

5. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 4, characterized in that: In step (1), the flux is any one of sodium carbonate or borax or a combination of two of them; the slag-forming agent is one of calcium oxide, silicon oxide, calcium fluoride, aluminum oxide or magnesium oxide or a combination of any two or more of them.

6. A method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to any one of claims 1 to 5, characterized in that: In step (2), the smelting furnace is a muffle furnace, a medium frequency furnace, an arc furnace or a plasma furnace, the smelting temperature is 1200-1550° C., and the smelting time is 0.5-5.0 h.

7. A method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloys according to claim 6, characterized in that: In step (3), the copper-nickel alloy is crushed and ground to a particle size of 10-300 mesh, sulfuric acid is added, and the mixture is stirred and dissolved in acid for 2-10 hours and then filtered to separate, thereby obtaining a precious metal-enriched concentrate and a base metal acid solution.

8. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 7, characterized in that: In step (4), the purification operation of the precious metal-enriched concentrate is to first dissolve by chlorination, and then separate and extract the precious metals by copper powder replacement, extraction or ion exchange.

9. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 8, characterized in that: In the vacuum evaporation and water-cooling crystallization decoppering process in step (5), the Cu in the base metal acid solution after vacuum evaporation is 2+ The concentration is 70~120g / L, the temperature of the acid solution is 75~100℃, and the acidity is 120~200g / L; during the water-cooled crystallization process, the acidity of the acid solution is adjusted to 50~75g / L, the temperature is lower than 45℃, and crystallization is carried out by mechanical stirring.

10. The method for enriching and recovering platinum group metals in waste catalysts by using carbonyl alloy according to claim 9, characterized in that: In the process of electroevaporation and water-cooling crystallization denickeling in step (5), Ni 2+ The concentration is 90~200g / L, the acidity is 900~1300g / L, and the temperature of the acid solution is 95~110℃; during the water-cooled crystallization process, the acidity of the acid solution is adjusted to 150~350g / L, the temperature is lower than 45℃, and mechanical stirring is used to allow the crystals to nucleate and grow.

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