Recycling method of precious metal

Abstract

The invention relates to the technical field of precious metal recovery, in particular to a precious metal recovery method which comprises the following steps: I, crushing a waste catalyst, blending the waste catalyst with sodium carbonate according to the weight ratio of 1: (0.5-1.2), and roasting at 700-1000 DEG C for 0.5-3 hours to obtain a roasted product; and II, dispersing the roasted product and sodium hydroxide in the weight ratio of (0.2-0.5): 1 in water at the temperature of 50-90 DEG C, stirring at the rotating speed of 80-320 r / min for 5-20 min for leaching, filtering while hot after leaching is finished, and collecting, washing and drying filter residues to obtain the recovered noble metal. According to the recycling method, the precious metal is efficiently recycled from the high-carbon-content catalyst by accurately controlling parameters of all the steps, and compared with a traditional recycling method, the recycling rate is remarkably increased, the influence on the environment is reduced, and meanwhile the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of precious metal recovery, and in particular to a precious metal recovery method. Background Art

[0002] Precious metals refer to a series of metals with high economic value and unique physical and chemical properties, mainly including gold, silver and platinum group metals (such as platinum, palladium, rhodium, ruthenium, osmium, iridium), etc. These metals are highly valued for their rarity, beautiful color, good chemical stability and wide application in industry and science and technology. Since the mining of precious metals causes damage to the environment, including land destruction, water pollution and greenhouse gas emissions, and since precious metals are limited resources, recycling can extend their service life, reduce the mining of new resources, and improve the recycling rate of resources. Therefore, recycling precious metals is a major focus in the utilization of precious metals. Recycling precious metals can reduce the demand for new mineral resources, thereby reducing the pressure on the environment. If waste containing precious metals is discarded without treatment, it will not only waste resources, but also pollute the soil, water and atmosphere. Recycling can reduce the amount of these wastes and reduce the risk of environmental pollution. The precious metals recovered from waste are called "secondary resources" and can be reused as production raw materials, which is conducive to the sustainable development of resources.

[0003] At present, the recovery of precious metals generally adopts wet process and pyrometallurgical process. These two processes can recover a certain amount of precious metals from precious metal catalysts and reuse them. However, there are many types of precious metal catalysts with different compositions, and the recovery methods applicable to different catalysts are also different. Especially if you want to recover precious metals from catalysts with high carbon content, the use of wet process or pyrometallurgical process will result in high energy consumption, long time consumption, high carbon residue, and affect the recovery rate of platinum in subsequent processes, reducing the recovery rate of platinum and other problems. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a method for recovering precious metals.

[0005] The present application provides a method for recovering precious metals, comprising the following steps: 1. The spent catalyst is crushed, mixed with sodium carbonate in a weight ratio of 1:(0.5-1.2), and calcined at a temperature of 700-1000° C. for 0.5-3 h to obtain a calcined product; 2. The roasted product and sodium hydroxide in a weight ratio of (0.2-0.5):1 are dispersed in water at a temperature of 50-90°C, and stirred at a speed of 80-320r / min for 5-20min for leaching. After the leaching is completed, the residue is filtered while hot, and the residue is collected, washed, and dried to obtain the recovered metal, which is dissolved in aqua regia, and platinum, palladium, and rhodium are separated by ion exchange, and refined to obtain a platinum group metal product.

[0006] By adopting the above technical scheme, the precious metal recovery method can effectively solve the problems of high energy consumption, long time consumption, high carbon residue, etc. in the treatment of high carbon content catalysts by traditional wet and pyrometallurgical processes. Specifically, the present application first crushes the waste catalyst and mixes it with sodium carbonate in a specific proportion, and then roasts it at a temperature of 700-1000°C for 0.5-3 hours. This process can fully decompose the organic matter in the catalyst under high temperature conditions, remove a large amount of carbon deposits and other impurities, and promote the redox reaction of precious metals. This step not only improves the dissolution efficiency of platinum in the subsequent leaching process, but also significantly reduces energy consumption and operation time; next, the roasted product and sodium hydroxide are dispersed in a weight ratio (0.2-0.5): 1 in water at 50-90°C, and stirred at a speed of 80-320r / min for 5-20 minutes for leaching. Selecting an appropriate sodium hydroxide concentration and water temperature can further enhance the solubility of platinum and improve its extraction rate. At the same time, a higher stirring speed helps to evenly disperse the roasted product, ensuring that all particles can fully contact the alkali solution, thereby improving the leaching efficiency; immediately after the leaching is completed, the hot filter is collected, washed, and dried to finally obtain the recovered platinum. Hot filtration can prevent the precipitate formed after cooling from clogging the filter, ensuring the smooth operation. In addition, multiple washings can thoroughly remove residual alkalinity and other impurities, ensuring that the purity of the recovered platinum reaches a high standard.

[0007] In summary, the precious metal recovery method provided by the present invention achieves the goal of recovering platinum from high-carbon content catalysts with high efficiency and low energy consumption by precisely controlling the parameters of each step. Compared with traditional recovery methods, this method significantly improves the recovery rate of platinum, reduces the impact on the environment, and also reduces production costs, and has important application prospects and economic value.

[0008] Preferably, in step I, the crushed waste catalyst is blended with sodium carbonate in a weight ratio of 1:1.

[0009] By adopting the above technical solution, the waste catalyst and sodium carbonate are mixed in a weight ratio of 1:1 and roasted under specific conditions, which can effectively remove carbon deposits on the catalyst surface and improve the recovery rate of precious metal platinum. Specifically, the selection of this ratio makes sodium carbonate have the best effect in removing carbon deposits, avoiding the cost increase caused by incomplete carbon removal or excessive use of sodium carbonate due to improper ratio. This step significantly improves the enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product.

[0010] Preferably, in the step I, the calcination is performed at a temperature of 900°C.

[0011] By adopting the above technical solution, the mixture of spent catalyst and sodium carbonate can be roasted at a temperature of 900°C to effectively remove organic matter and some impurities in the spent catalyst while avoiding excessive energy consumption. Roasting under such conditions can better promote the release of precious metals, improve the recovery rate of platinum in the subsequent leaching step, shorten the time of the entire recovery process, and improve efficiency.

[0012] Preferably, in step I, the calcination is performed for 2 hours.

[0013] By adopting the above technical solution, the roasting time is controlled within 2 hours, which can effectively ensure that the organic matter in the waste catalyst is fully decomposed, reduce the amount of carbon residue, and thus improve the recovery rate of platinum. At the same time, the roasting time can not only ensure that the reaction is completely carried out, but also avoid the problem of increased energy consumption caused by too long a time, thereby improving the efficiency and economy of the entire recovery process.

[0014] Preferably, in step II, the weight ratio of the calcined product to sodium hydroxide is 0.3:1.

[0015] By adopting the above technical solution, the recovery rate of precious metal platinum can be effectively improved. In the leaching step, the roasting product is mixed with sodium hydroxide in a ratio of 0.3:1, and leaching is carried out under suitable temperature and stirring conditions, which can more effectively dissolve and extract precious metal platinum, further improving its recovery rate.

[0016] Preferably, in step II, the temperature of water is 80°C.

[0017] By adopting the above technical solution, the platinum recovery rate in the precious metal recovery process can be effectively improved. Specifically, in step II, the water temperature is set to 80°C, so that the solubility and reactivity of the sodium hydroxide solution reach the optimal state, which helps to better leach the platinum in the roasted product, thereby improving the final platinum recovery rate. At the same time, the operation under this temperature condition can also reduce energy consumption, shorten the reaction time, and improve the efficiency and economy of the entire recovery process.

[0018] Preferably, in step II, the rotation speed is 240 r / min.

[0019] By adopting the above technical solution, the recovery efficiency and purity of precious metals, especially platinum, can be effectively improved. The appropriate rotation speed can ensure efficient contact and reaction between sodium hydroxide and the roasting product, promote the effective separation of platinum, and avoid the problem of increased energy consumption or increased equipment wear due to excessively high rotation speed. This step optimizes the stirring effect, improves the recovery rate of platinum and the economic efficiency of operation.

[0020] Preferably, in step II, stirring is performed for 10 minutes.

[0021] By adopting the above technical solution, the roasting product is mixed with sodium hydroxide in a specific proportion and stirred at a specified temperature and speed for 10 minutes, which can effectively improve the leaching efficiency of platinum, ensure sufficient contact and reaction, reduce energy consumption and time costs, and improve the recovery rate.

[0022] In summary, this application includes the following beneficial technical effects: 1. The recovery method of the present application effectively reduces the amount of carbon deposits and improves the recovery rate of platinum by mixing the waste catalyst with sodium carbonate in an appropriate proportion and roasting at a high temperature; 2. The recovery method of the present application uses sodium hydroxide and appropriate water temperature and stirring conditions during the leaching process, which enhances the dissolution efficiency of precious metals, shortens the processing time, and reduces energy consumption; 3. In the recycling method of the present application, the entire recycling process reduces pollution to the environment, improves the recycling rate of resources, and achieves a dual improvement in economic and environmental benefits. DETAILED DESCRIPTION

[0023] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: The spent catalyst was dried in a vacuum drying oven at 120°C for 10 h and then recovered. The specific composition was: Pt, 1618 g / t, Al2O3, 47.26 wt%, C, 45.8 wt%; Sodium carbonate was purchased from Langfang Qianyao Technology Co., Ltd., with an active ingredient content of 99%; Sodium hydroxide was purchased from Yunsheng Chemical (Shandong) Co., Ltd.

[0024] The present application is further described in detail below with reference to examples and comparative examples.

[0025] Example 1.1 A method for recovering precious metals comprises the following steps: I. The spent catalyst was crushed to 80% of the size not exceeding 100 mesh, and mixed with sodium carbonate at a weight ratio of 1:0.5, and placed in a muffle furnace with a nickel tray and heated to 1000°C. During the roasting process, the furnace door was slightly opened to maintain air circulation, and the material did not need to be turned over. The material was roasted statically, and after roasting for 0.5h, it was taken out and naturally cooled to obtain a roasted product; II. Place the calcined product and sodium hydroxide in a weight ratio of 0.2:1 in a beaker, add water at a temperature of 90°C to completely disperse the calcined product and sodium hydroxide, place the beaker in a constant temperature magnetic stirrer, stir at a speed of 80r / min for 20min for leaching, and quickly vacuum filter while hot after leaching. Collect the filter residue, wash it repeatedly with hot water at 60°C for 5 times, and dry it to obtain recovered metal, dissolve it in aqua regia, separate platinum, palladium and rhodium by ion exchange, and refine it to obtain platinum group metal products.

[0026] Example 1.2 A method for recovering precious metals comprises the following steps: I. The spent catalyst was crushed to 80% of the size not exceeding 100 mesh, and mixed with sodium carbonate at a weight ratio of 1:1.2, and placed in a muffle furnace with a nickel tray and heated to 700°C. During the roasting process, the furnace door was slightly opened to maintain air circulation, and the material did not need to be turned over. The material was roasted statically, and after roasting for 3 hours, it was taken out and naturally cooled to obtain a roasted product; II. Place the calcined product and sodium hydroxide in a weight ratio of 0.5:1 in a beaker, add water at a temperature of 50°C to completely disperse the calcined product and sodium hydroxide, place the beaker in a constant temperature magnetic stirrer, stir at a speed of 320r / min for 5 minutes for leaching, and quickly vacuum filter while hot after leaching. Collect the filter residue, wash it repeatedly with hot water at 60°C for 5 times, and dry it to obtain recovered metal, dissolve it in aqua regia, separate platinum, palladium and rhodium by ion exchange, and refine it to obtain platinum group metal products.

[0027] Example 2.1 A method for recovering precious metals, which differs from Example 1.1 in that: in step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:0.6, and the rest is the same as Example 1.1.

[0028] Example 2.2 A method for recovering precious metals, which differs from Example 1.1 in that: in step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:0.7, and the rest is the same as Example 1.1.

[0029] Example 2.3 A method for recovering precious metals, which is different from Example 1.1 in that: in step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:0.8, and the rest is the same as Example 1.1.

[0030] Example 2.4 A method for recovering precious metals, which is different from Example 1.1 in that: in step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:0.9, and the rest is the same as Example 1.1.

[0031] Example 2.5 A method for recovering precious metals, which is different from Example 1.1 in that: in step I, the crushed waste catalyst is mixed with sodium carbonate at a weight ratio of 1:1.0, and the rest is the same as Example 1.1.

[0032] Example 2.6 A method for recovering precious metals, which is different from Example 1.1 in that: in step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:1.1, and the rest is the same as Example 1.1.

[0033] Example 3.1 A method for recovering precious metals, which is different from Example 2.5 in that: in step I, calcination is performed at a temperature of 800° C., and the rest is the same as Example 2.5.

[0034] Example 3.2 A method for recovering precious metals, which is different from Example 2.5 in that: in step I, calcination is performed at a temperature of 900° C., and the rest is the same as Example 2.5.

[0035] Example 3.3 A method for recovering precious metals, which is different from Example 2.5 in that: in step I, calcination is performed at a temperature of 1000° C., and the rest is the same as Example 2.5.

[0036] Example 3.4 A method for recovering precious metals, which is different from Example 2.5 in that: in step I, calcination is performed at a temperature of 1100° C., and the rest is the same as Example 2.5.

[0037] Example 4.1 A method for recovering precious metals, which is different from Example 3.2 in that: in step I, the calcination is 1 hour, and the rest is the same as Example 3.2.

[0038] Example 4.2 A method for recovering precious metals, which is different from Example 3.2 in that: in step I, the calcination is 1.5 hours, and the rest is the same as Example 3.2.

[0039] Example 4.3 A method for recovering precious metals, which is different from Example 3.2 in that: in step I, roasting is performed for 2 hours, and the rest is the same as Example 3.2.

[0040] Example 4.4 A method for recovering precious metals, which is different from Example 3.2 in that: in step I, the calcination is 2.5 hours, and the rest is the same as Example 3.2.

[0041] Example 5.1 A method for recovering precious metals, which is different from Example 4.3 in that: in step II, the weight ratio of the roasting product to sodium hydroxide is 0.3:1, and the rest is the same as Example 4.3.

[0042] Example 5.2 A method for recovering precious metals, which is different from Example 4.3 in that: in step II, the weight ratio of the roasting product to sodium hydroxide is 0.4:1, and the rest is the same as Example 4.3.

[0043] Example 6.1 A method for recovering precious metals, which is different from Example 5.1 in that: in step II, the temperature of water is 60° C., and the rest is the same as Example 5.1.

[0044] Example 6.2 A method for recovering precious metals, which is different from Example 5.1 in that: in step II, the temperature of water is 70° C., and the rest is the same as Example 5.1.

[0045] Example 6.3 A method for recovering precious metals, which is different from Example 5.1 in that: in step II, the temperature of water is 80° C., and the rest is the same as Example 5.1.

[0046] Example 7.1 A method for recovering precious metals, which is different from Example 6.3 in that: in step II, the rotation speed is 120r / min, and the rest is the same as Example 6.3.

[0047] Example 7.2 A method for recovering precious metals, which is different from Example 6.3 in that: in step II, the rotation speed is 160r / min, and the rest is the same as Example 6.3.

[0048] Example 7.3 A method for recovering precious metals, which is different from Example 6.3 in that: in step II, the rotation speed is 200 r / min, and the rest is the same as Example 6.3.

[0049] Example 7.4 A method for recovering precious metals, which is different from Example 6.3 in that: in step II, the rotation speed is 240 r / min, and the rest is the same as Example 6.3.

[0050] Example 7.5 A method for recovering precious metals, which is different from Example 6.3 in that: in step II, the rotation speed is 280r / min, and the rest is the same as Example 6.3.

[0051] Example 8.1 A method for recovering precious metals, which is different from Example 7.4 in that: in step II, stirring is performed for 10 minutes, and the rest is the same as Example 7.4.

[0052] Example 8.2 A method for recovering precious metals, which is different from Example 7.4 in that: in step II, stirring is performed for 15 minutes, and the rest is the same as Example 7.4.

[0053] Comparative Example 1.1 The difference from Example 1.1 is that in step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:0.3, and the rest is the same as Example 1.1.

[0054] Comparative Example 1.2 The difference from Example 1.1 is that in step I, the crushed waste catalyst is mixed with sodium carbonate at a weight ratio of 1:1.5, and the rest is the same as Example 1.1.

[0055] Comparative Example 2.1 The difference from Example 1.1 is that in step I, the calcination is performed at a temperature of 600° C., and the rest is the same as Example 1.1.

[0056] Comparative Example 2.2 The difference from Example 1.1 is that in step I, the calcination is performed at a temperature of 1100° C., and the rest is the same as Example 1.1.

[0057] Comparative Example 3.1 The difference from Example 1.1 is that in step II, the weight ratio of the calcined product to sodium hydroxide is 0.1:1, and the rest is the same as Example 1.1.

[0058] Comparative Example 3.2 The difference from Example 1.1 is that in step II, the weight ratio of the calcined product to sodium hydroxide is 0.6:1, and the rest is the same as Example 1.1.

[0059] Performance Testing Taking Pt as an example, the recovery effect was detected and analyzed. First, the Pt content in the recovered metal was determined, and the content was compared with the Pt content in the waste catalyst to obtain the Pt enrichment multiple, which is recorded in Table 1. Then, the Pt weight in the platinum group metal product was determined, and then compared with the Pt weight in the waste catalyst under theoretical calculation to obtain the Pt recovery rate, which is recorded in Table 1.

[0060] Table 1 Performance test table Data Analysis: As can be seen from Table 1, the enrichment multiple of Pt in the recovered metal obtained in Examples 1.1-1.2 of the present application reached 75.24-75.30, and the Pt recovery rate in the platinum group metal product reached 98.71-98.73%, proving that the precious metal recovery method provided by the present invention achieves the goal of recovering platinum from a high carbon content catalyst with high efficiency and low energy consumption by precisely controlling the parameters of each step. Compared with traditional recovery methods, this method significantly improves the recovery rate of platinum, reduces the impact on the environment, and also reduces production costs, and has important application prospects and economic value.

[0061] In Examples 2.1-2.6, the difference from Example 1.1 is that the weight ratio of the crushed waste catalyst and sodium carbonate when blended is changed, wherein the enrichment multiple of Pt in the recovered metal and the recovery rate of Pt in the platinum group metal product in Example 2.5 are greater than those in other examples, proving that the present application can effectively remove carbon deposits on the catalyst surface and improve the recovery rate of precious metal platinum by blending the waste catalyst with sodium carbonate in a weight ratio of 1:1 and roasting under specific conditions. Specifically, the selection of this ratio makes sodium carbonate have the best effect in removing carbon deposits, avoiding the cost increase caused by incomplete carbon removal or excessive use of sodium carbonate due to improper ratio. This step significantly reduces the consumption of sodium hydroxide solution in the subsequent leaching process, reduces energy consumption and time costs, and improves the efficiency of the entire recovery process.

[0062] In Examples 3.1-3.4, the difference from Example 2.5 is that the roasting temperature in step I is changed, wherein the enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Example 3.2 are greater than those in other examples, proving that the present application effectively removes organic matter and some impurities in the waste catalyst by roasting the mixture of the waste catalyst and sodium carbonate at a temperature of 900°C, while avoiding excessive energy consumption. Roasting under such conditions can better promote the release of precious metals and improve the recovery rate of platinum in the subsequent leaching step.

[0063] In Examples 4.1-4.3, the difference from Example 3.2 is that the roasting time in step I is changed. The enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Example 4.3 are greater than those in other examples, proving that the present application can effectively ensure that the organic matter in the waste catalyst is fully decomposed and the carbon residue is reduced by controlling the roasting time to 2 hours, thereby improving the recovery rate of platinum. At the same time, the roasting time can not only ensure that the reaction is completely carried out, but also avoid the problem of increased energy consumption caused by too long a time, thereby improving the efficiency and economy of the entire recovery process. In Examples 5.1-5.2, the difference from Example 4.3 is that the weight ratio of the calcined product to sodium hydroxide is changed, wherein the enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product of Example 5.1 are greater than those of other examples, proving that the present application can more effectively dissolve and extract the precious metal platinum, thereby further improving its recovery rate, by mixing the calcined product with sodium hydroxide in a ratio of 0.3:1 in the leaching step and leaching under suitable temperature and stirring conditions.

[0064] In Examples 6.1-6.3, the difference from Example 5.1 is that the temperature of water in step II is changed, wherein the enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Example 6.3 are greater than those in other examples, proving that the present application sets the water temperature to 80°C in step II, so that the solubility and reactivity of the sodium hydroxide solution reach the optimal state, which helps to better leach the platinum in the roasted product, thereby improving the final platinum recovery rate. At the same time, the operation under this temperature condition can also reduce energy consumption, shorten the reaction time, and improve the efficiency and economy of the entire recovery process.

[0065] In Examples 7.1-7.5, the difference from Example 6.3 is that the rotation speed in step II is changed, and the enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Example 7.4 are greater than those in other examples, proving that the present application can effectively improve the recovery efficiency and purity of precious metals, especially platinum, by controlling the stirring rotation speed. The appropriate rotation speed can ensure efficient contact and reaction between sodium hydroxide and the roasted product, promote the effective separation of platinum, and avoid the problem of increased energy consumption or increased equipment wear due to excessively high rotation speed. This step optimizes the stirring effect, improves the recovery rate of platinum and the economic efficiency of the operation.

[0066] In Examples 8.1-8.2, the difference from Example 7.4 is that the stirring time in step II is changed, wherein the enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Example 8.1 are greater than those in other examples, proving that the present application can effectively improve the leaching efficiency of platinum, ensure sufficient contact and reaction, reduce energy consumption and time costs, and improve the recovery rate by mixing the calcined product with sodium hydroxide in a specific proportion and stirring at a specified temperature and speed for 10 minutes.

[0067] In Comparative Examples 1.1-1.2, the difference from Example 1.1 is that the weight ratio of the crushed waste catalyst and sodium carbonate when blended is changed. The enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product of Comparative Examples 1.1-1.2 are both lower than those of Example 1.1, proving that the present application can effectively remove carbon deposits on the catalyst surface and improve the recovery rate of precious metal platinum by strictly controlling the weight ratio of the waste catalyst and sodium carbonate and roasting under specific conditions. Specifically, the selection of this ratio makes sodium carbonate have the best effect in removing carbon deposits, avoiding the cost increase caused by incomplete carbon removal or excessive use of sodium carbonate due to improper ratio. This step significantly reduces the consumption of sodium hydroxide solution in the subsequent leaching process, reduces energy consumption and time costs, and improves the efficiency of the entire recovery process.

[0068] In Comparative Examples 2.1-2.2, the difference from Example 1.1 is that the roasting temperature in step I is changed. The enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Comparative Examples 2.1-2.2 are both lower than those in Example 1.1, proving that the present application effectively removes organic matter and some impurities in the waste catalyst by strictly controlling the roasting temperature while avoiding excessive energy consumption. Roasting under such conditions can better promote the release of precious metals and improve the recovery rate of platinum in the subsequent leaching step.

[0069] In Comparative Examples 3.1-3.2, the difference from Example 1.1 is that the weight ratio of the calcined product to sodium hydroxide in step II is changed. The enrichment multiple of Pt in the recovered metal and the Pt recovery rate in the platinum group metal product in Comparative Examples 3.1-3.2 are both lower than those in Example 1.1, which proves that the present application can more effectively dissolve and extract the precious metal platinum and further improve its recovery rate by strictly controlling the weight ratio of the calcined product to sodium hydroxide in the leaching step.

[0070] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for recovering precious metals, characterized in that: The following steps are involved: The spent catalyst is crushed, mixed with sodium carbonate in a weight ratio of 1:(0.5-1.2), and calcined at a temperature of 700-1000° C. for 0.5-3 h to obtain a calcined product; The roasted product and sodium hydroxide in a weight ratio of (0.2-0.5):1 are dispersed in water at a temperature of 50-90°C, and stirred at a speed of 80-320r / min for 5-20min for leaching. After the leaching is completed, it is filtered while hot, and the filter residue is collected, washed, and dried to obtain the recovered metal, which is dissolved in aqua regia, and platinum, palladium, and rhodium are separated by ion exchange, and refined to obtain platinum group metal products.

2. A method for recovering precious metals according to claim 1, characterized in that: In the step I, the crushed waste catalyst is mixed with sodium carbonate in a weight ratio of 1:

1.

3. A method for recovering precious metals according to claim 1, characterized in that: In the step I, the sintering step is carried out at a temperature of 900°C.

4. A method for recovering precious metals according to claim 1, characterized in that: In the step I, the calcination is performed for 2 hours.

5. A method for recovering precious metals according to claim 1, characterized in that: In the step II, the weight ratio of the calcined product to sodium hydroxide is 0.3:

1.

6. A method for recovering precious metals according to claim 1, characterized in that: In step II, the temperature of water is 80°C.

7. A method for recovering precious metals according to claim 1, characterized in that: In step II, the rotation speed is 240 r / min.

8. A method for recovering precious metals according to claim 1, characterized in that: In the step II, stirring was performed for 10 min.

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