Method for non-destructive recovery of waste catalyst carrier and noble metal

Abstract

The invention relates to the technical field of catalyst recovery, and discloses a method for non-destructively recovering a waste catalyst carrier and noble metal. The present invention uses a noble metal leaching agent comprising an oxidizing agent, a ligand precursor, and water for recovering spent catalyst supports and noble metals. The method comprises the following steps: after roasting and reducing the waste catalyst, leaching the waste catalyst in the precious metal leaching agent, and carrying out first solid-liquid separation and washing to respectively obtain a waste catalyst carrier and precious metal. According to the method, a form of firstly reducing and then oxidizing is adopted, a compound leaching system is used for replacing a traditional leaching system based on hydrochloric acid, acid gas volatilization during leaching reaction is reduced, environmental pollution is reduced, and the operation environment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst recovery, and in particular to a method for non-destructively recovering waste catalyst carriers and precious metals. Background Art

[0002] With the rapid development of the chemical industry, the emission of chemical solid waste has also increased. Among them, catalysts are the core of the chemical industry. Due to catalyst poisoning, loss of active components, sintering, carbon accumulation on the surface, etc. during the reaction process, the annual waste catalysts produced have exceeded tens of thousands of tons and are in urgent need of treatment. Precious metals are often used in active centers to synthesize various catalysts. Since the content of precious metals in waste catalysts far exceeds that extracted from natural ores, and the carrier is expensive, the development of alternative resources such as waste catalysts is imperative to reduce the supply risk of precious metals and carriers and establish the concept of circular economy.

[0003] Currently, the methods for precious metal recovery are mainly divided into two categories: pyrometallurgy and hydrometallurgy.

[0004] Pyrometallurgy is the process of reducing precious metals and converting them into alloys through high-temperature smelting reduction, which is beneficial for their subsequent recovery. CN 220520576U reports a pyrometallurgical ruthenium recovery device, which is equipped with a stirring component and a switch component in a heating reaction chamber, which is beneficial for realizing the stirring, heating and roasting of ruthenium-containing waste catalysts. Although this method has high output, it also has high energy consumption.

[0005] Hydrometallurgy is the process of converting secondary resources containing precious metals into liquid phase through dissolution or chemical reaction. Precious metals in the liquid phase are enriched and separated by adsorption, extraction, precipitation, ion exchange and electrolysis. Commonly used leaching agents include aqua regia, cyanide, halide and thiosulfate.

[0006] CN 116440942A reports a process for wet treatment of hydrogenation waste catalysts by oxidation leaching - concentration precipitation of tungsten - addition of ammonia precipitation of molybdenum - neutralization precipitation of aluminum - carbonization precipitation of nickel - calcium salt precipitation of tungsten and molybdenum. This process can not only comprehensively recover valuable metals such as tungsten, molybdenum, and nickel, but also eliminate the problem of flue gas pollution in the existing roasting process. Although the operation is simple, a large amount of waste water and waste residue will be generated during the leaching process, which is easy to pollute the environment and increase the cost of subsequent treatment.

[0007] In addition, the current waste catalyst recycling process only focuses on the recovery of precious metals, while the carrier is severely damaged, ignoring its economic value and being downgraded. Therefore, it is urgent to develop a new green and pollution-free waste catalyst recycling technology that can achieve a higher precious metal recovery rate without destroying the carrier. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems existing in the prior art and provide a precious metal leaching agent and application thereof.

[0009] The precious metal leaching agent provided by the present invention can be used for non-destructive recovery of waste catalyst carriers and precious metals, achieving a higher precious metal leaching rate without destroying the carrier, and has the characteristics of simple process, low processing cost, etc.

[0010] In order to achieve the above-mentioned object, the first aspect of the present invention provides a precious metal leaching agent, wherein the precious metal leaching agent comprises an oxidant, a ligand precursor and water.

[0011] The second aspect of the present invention provides the use of the precious metal leaching agent described in the first aspect in recovering spent catalyst carriers and precious metals.

[0012] The third aspect of the present invention provides a method for recovering spent catalyst carriers and precious metals using the precious metal leaching agent described in the first aspect.

[0013] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0014] (1) The precious metal leaching agent provided by the present invention replaces the traditional aqua regia dissolution method without destroying the carrier, adopts a mild, efficient and simple technology, and realizes efficient leaching of precious metals by in-situ generation of ligands.

[0015] (2) The present invention adopts the form of reduction followed by oxidation, and utilizes a compound leaching system to replace the traditional hydrochloric acid-based leaching system, thereby reducing the volatilization of acid gas during the leaching reaction, reducing environmental pollution, and improving the operating environment. By adjusting the ratio of the oxidant to the coordination precursor, the properties of the leaching system can be adjusted to control the leaching reaction of the precious metal.

[0016] (3) The process route of the method for recovering precious metals from waste catalysts provided by the present invention is as follows: roasting-reduction-acid-free leaching, which shortens the process cycle, reduces the recovery cost, does not damage the carrier, and has a high precious metal leaching rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The XRD pattern of the waste catalyst used in the present invention;

[0018] Figure 2 XRD patterns of the spent catalyst, the carrier recovered from Example 1 and Example 3;

[0019] Figure 3 Optical photographs of the spent catalyst and the alumina carrier recovered from Example 1;

[0020] Figure 4 The crushing strength of the spent catalyst, the carrier recovered from Example 1 and Example 3;

[0021] Figure 5 The nitrogen adsorption-desorption curves of the spent catalyst, the carrier recovered from Example 1 and Example 3;

[0022] Figure 6 The pore size distribution of the spent catalyst, Example 1 and Example 3 recovered carrier;

[0023] Figure 7 Silver content of the spent catalyst, Example 1 and the recovered carrier of Example 3;

[0024] Figure 8 The palladium content of the spent catalyst, Example 1 and the recovered carrier of Example 3. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] A first aspect of the present invention provides a precious metal leaching agent, wherein the precious metal leaching agent comprises an oxidant, a ligand precursor and water.

[0027] In one embodiment of the present invention, the oxidant is selected from at least one of peroxymonosulfate, peroxydisulfate and hydrogen peroxide, and is preferably a potassium peroxymonosulfate complex salt.

[0028] In one embodiment of the present invention, the ligand precursor is selected from at least one of acetonitrile, propionitrile, valeronitrile and capronitrile.

[0029] In one embodiment of the present invention, the concentration of the oxidant is 0.5-5 mol / L, preferably 1 mol / L.

[0030] In one embodiment of the present invention, the concentration of the ligand precursor is 5-15 mol / L, preferably 9-10 mol / L.

[0031] The second aspect of the present invention provides the use of the precious metal leaching agent described in the first aspect in recovering spent catalyst carriers and precious metals.

[0032] In one embodiment of the present invention, the precious metal in the spent catalyst is selected from at least one of gold, silver, ruthenium, rhodium, palladium, osmium, iridium and platinum, preferably palladium and / or silver.

[0033] The noble metal leaching agent provided by the present invention is suitable for supported catalysts.

[0034] The third aspect of the present invention provides a method for recovering waste catalyst carriers and precious metals using the precious metal leaching agent described in the first aspect, wherein the method comprises: roasting and reducing the waste catalyst, leaching it in the precious metal leaching agent and performing a first solid-liquid separation and washing to obtain the waste catalyst carrier and the precious metal respectively.

[0035] In the present invention, the solid part obtained by the first solid-liquid separation is used to obtain the carrier, and the liquid part is used to obtain the precious metal.

[0036] The recycling process provided by the present invention has a short process cycle time, low price, is green and has a high metal leaching rate. More importantly, it does not damage the carrier and can be reused. The purpose of roasting is to remove organic matter and carbon deposits.

[0037] In one embodiment of the present invention, the calcination conditions include: heating to 300-800° C. at a heating rate of 1-20° C. / min and calcining for 1-4 hours.

[0038] In one embodiment of the present invention, the heating rate is 5-10°C / min.

[0039] In one embodiment of the present invention, the temperature at the end point of the heating is 600-800°C.

[0040] In one embodiment of the present invention, the calcination time is 3-4 hours.

[0041] In one embodiment of the present invention, the reduction conditions include: normal pressure; stirring in a water bath; and a temperature of 20-80°C, preferably 40-60°C.

[0042] In one embodiment of the present invention, the reducing agent used in the reduction is selected from at least one of sodium borohydride, hydrazine hydrate, ascorbic acid and formaldehyde.

[0043] In one embodiment of the present invention, the concentration of the reducing agent is 1-20 mol / L, preferably 8-10 mol / L.

[0044] In one embodiment of the present invention, the mixture obtained after the reduction is subjected to a second solid-liquid separation, and the solid portion is subjected to a first drying.

[0045] In one embodiment of the present invention, the first drying conditions include: temperature of 60-80° C.; time of 6-12 hours.

[0046] In one embodiment of the present invention, the leaching conditions include: normal pressure; water bath; temperature of 20-120°C, preferably 40-60°C; time of 0.5-6h, preferably 3-4h.

[0047] In one embodiment of the present invention, the liquid-to-solid ratio of the leaching is 0.5-20:1, preferably 1-1.5:1.

[0048] In the present invention, the liquid-to-solid ratio refers to the ratio of the volume of the leaching agent to the mass of the waste catalyst, and its unit is mL / g or its magnified or abbreviated multiple (L / Kg, etc.). For example, a liquid-to-solid ratio of 10 means that the volume of the leaching agent to the mass of the waste catalyst is 10mL:1g.

[0049] In one embodiment of the present invention, the solid part obtained by the first solid-liquid separation is washed and dried to obtain the carrier. The purpose of washing is to separate the precious metal attached to the carrier into the washing liquid.

[0050] In one embodiment of the present invention, the second drying conditions include: temperature of 60-80° C.; time of 6-12 hours.

[0051] In the present invention, the system after leaching can be treated in the following manner:

[0052] After the first solid-liquid separation, a filtrate (containing precious metals) and a solid part (waste catalyst carrier) are obtained; the obtained filtrate is heated and evaporated to obtain a concentrated mother liquor; the obtained steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10-80 cm; the separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation; the washing operation is repeated 8-20 times, and the concentrated liquid remaining after evaporation is discharged and combined with the concentrated mother liquor to extract the precious metals, and the carrier can be reused after drying.

[0053] According to a particularly preferred embodiment of the present invention, a method for non-destructively recovering spent catalyst carriers and precious metals comprises the following steps:

[0054] (1) calcining the spent catalyst: placing the spent catalyst in a muffle furnace, calcining at 300-800°C for 1-4h at a heating rate of 1-20°C / min, and cooling naturally;

[0055] (2) dispersing the particles obtained in step (1) in a solution containing a reducing agent, and vigorously stirring in a water bath at 20-80° C. under normal pressure; the reducing agent is selected from at least one of sodium borohydride, hydrazine hydrate, ascorbic acid and formaldehyde; then, the obtained mixture is allowed to stand for 12-24 hours, filtered, and dried at 60-80° C. for 6-12 hours to obtain a dry and reduced spent catalyst;

[0056] (3) dispersing the particles obtained in step (2) in an aqueous solution containing an oxidant and a ligand precursor; reacting vigorously in a water bath at 20-120° C. for 0.5-6 h at normal pressure; the oxidant is selected from at least one of peroxymonosulfate, peroxydisulfate and hydrogen peroxide; the ligand precursor is selected from at least one of acetonitrile, propionitrile, valeronitrile and capronitrile;

[0057] (4) The system obtained in step (3) is subjected to solid-liquid separation to obtain a filtrate (containing precious metals) and a solid portion (waste catalyst carrier); the obtained filtrate is heated and evaporated to obtain a concentrated mother liquor and steam; the steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10-80 cm; the separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation, and the washing operation is repeated 8-20 times, and the concentrated liquid remaining after evaporation is discharged and combined with the concentrated mother liquor to extract the precious metals, and the carrier can be reused after drying.

[0058] The present invention will be described in detail below through examples.

[0059] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0060] The leaching rate calculation formula in the following examples is as follows:

[0061] R%=W1 / W2*100%

[0062] Wherein, W1 is the metal ion content in the waste catalyst after the reaction, and W2 is the metal ion content in the raw material.

[0063] In the following examples, the XRD patterns of the spent catalysts used are as follows: Figure 1 As shown. The diffraction peaks at 25.58°, 35.15°, 37.78°, 43.36°, 52.56°, 57.51°, 66.52°, 68.21° and 76.89° correspond to α-Al2O3 (PDF78-2427). The characteristic peaks at 16.22°, 19.59°, 31.21°, 31.61°, 31.70°, 32.78°, 36.68°, 38.88°, 40.05°, 44.80°, 47.59°, 59.90°, 63.93°, 67.42° and 67.57° correspond to θ-Al2O3 (PDF 86-1410). The results show that the spent catalyst is composed of α-Al2O3 and θ-Al2O3. In addition, no obvious diffraction patterns of Pd and Ag species were detected, which may be due to the low content or high dispersion of Pd and Ag.

[0064] Example 1

[0065] This example is used to illustrate a method for recovering spent catalyst carriers and precious metals using a precious metal leaching agent.

[0066] (1) 100 g of spent catalyst was placed in a muffle furnace, heated to 600 °C at a heating rate of 10 °C / min, calcined in an air atmosphere at 600 °C for 4 h, and cooled naturally;

[0067] (2) collecting the spent catalyst particles obtained in step (1), dispersing them in a solution containing sodium borohydride (10 mol / L), and vigorously stirring them in a water bath at 40° C. under normal pressure; standing the mixture for 24 hours after the reaction, washing the particles with ethanol and deionized water three times; and drying them in an oven at 60° C. for 6 hours to obtain the reduced spent catalyst;

[0068] (3) Under normal pressure, 10 g of the reduced spent catalyst obtained in step (2) was added to a water (5 mL) solution containing potassium persulfate complex salt (10 mmol) and acetonitrile (5 mL), and the mixture was vigorously reacted in a water bath at 40° C. for 3 h;

[0069] (4) The system obtained in step (3) is subjected to solid-liquid separation to obtain a filtrate and a solid portion; the obtained filtrate is introduced into a heater for heating and evaporation to obtain a concentrated mother liquor and steam; the steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10 cm; the obtained separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation, and this operation is repeated 8 times, and the concentrated liquid remaining from the evaporation is discharged and combined with the concentrated mother liquor to extract precious metals, and the carrier can be reused after drying.

[0070] Example 2

[0071] This example is used to illustrate a method for recovering spent catalyst carriers and precious metals using a precious metal leaching agent.

[0072] (1) 100 g of spent catalyst was placed in a muffle furnace, heated to 700 °C at a heating rate of 10 °C / min, calcined in an air atmosphere at 700 °C for 3 h, and cooled naturally;

[0073] (2) collecting the spent catalyst particles obtained in step (1), dispersing them in a solution containing hydrazine hydrate (8 mol / L), and vigorously stirring them at 60° C. under normal pressure; standing them for 24 hours after the reaction, washing the particles with ethanol and deionized water three times; and drying them in an oven at 60° C. for 6 hours to obtain the reduced spent catalyst;

[0074] (3) Under normal pressure, 10 g of the reduced spent catalyst obtained in step (2) was added to a water (5 mL) solution containing hydrogen peroxide (10 mmol) and propionitrile (5 mL), and the mixture was vigorously reacted in a water bath at 60° C. for 4 h;

[0075] (4) The system obtained in step (3) is subjected to solid-liquid separation to obtain a filtrate and a solid portion; the obtained filtrate is introduced into a heater for heating and evaporation to obtain a concentrated mother liquor and steam; the steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10 cm; the obtained separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation, and this operation is repeated 8 times, and the concentrated liquid remaining from the evaporation is discharged and combined with the concentrated mother liquor to extract precious metals, and the carrier can be reused after drying.

[0076] Example 3

[0077] This example is used to illustrate a method for recovering spent catalyst carriers and precious metals using a precious metal leaching agent.

[0078] (1) 100 g of spent catalyst was placed in a muffle furnace, heated to 800 °C at a heating rate of 10 °C / min, calcined in an air atmosphere at 800 °C for 4 h, and cooled naturally;

[0079] (2) collecting the spent catalyst particles obtained in step (1), dispersing them in a solution containing ascorbic acid (10 mol / L), and vigorously stirring them at 40° C. under normal pressure; standing them for 24 hours after the reaction, washing the particles with ethanol and deionized water three times; and drying them in an oven at 60° C. for 6 hours to obtain the reduced spent catalyst;

[0080] (3) Under normal pressure, 10 g of the reduced spent catalyst obtained in step (2) was added to a water (5 mL) solution containing hydrogen peroxide (10 mmol) and butyronitrile (10 mL), and the mixture was vigorously reacted in a water bath at 60° C. for 4 h;

[0081] (4) The system obtained in step (3) is subjected to solid-liquid separation to obtain a filtrate and a solid portion; the obtained filtrate is introduced into a heater for heating and evaporation to obtain a concentrated mother liquor and steam; the steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10 cm; the obtained separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation, and this operation is repeated 8 times, and the concentrated liquid remaining from the evaporation is discharged and combined with the concentrated mother liquor to extract precious metals, and the carrier can be reused after drying.

[0082] Example 4

[0083] This example is used to illustrate a method for recovering spent catalyst carriers and precious metals using a precious metal leaching agent.

[0084] (1) 100 g of spent catalyst was placed in a muffle furnace, heated to 800 °C at a heating rate of 10 °C / min, calcined in an air atmosphere at 800 °C for 4 h, and cooled naturally;

[0085] (2) Collect the spent catalyst particles obtained in step (1), disperse them in a solution containing hydrazine hydrate (10 mol / L), and vigorously stir them at 40° C. under normal pressure; let them stand for 24 hours after the reaction, wash the particles with ethanol and deionized water three times; and dry them in an oven at 60° C. for 6 hours to obtain the reduced spent catalyst;

[0086] (3) Under normal pressure, 10 g of the reduced spent catalyst obtained in step (2) was added to a water (5 mL) solution containing potassium persulfate complex salt (10 mmol) and acetonitrile (10 mL), and the mixture was vigorously reacted in a water bath at 60° C. for 4 h;

[0087] (4) The system obtained in step (3) is subjected to solid-liquid separation to obtain a filtrate and a solid portion; the obtained filtrate is introduced into a heater for heating and evaporation to obtain a concentrated mother liquor and steam; the steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10 cm; the obtained separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation, and this operation is repeated 8 times, and the concentrated liquid remaining from the evaporation is discharged and combined with the concentrated mother liquor to extract precious metals, and the carrier can be reused after drying.

[0088] Example 5

[0089] This example is used to illustrate a method for recovering spent catalyst carriers and precious metals using a precious metal leaching agent.

[0090] (1) 100 g of spent catalyst was placed in a muffle furnace, heated to 800 °C at a heating rate of 10 °C / min, calcined in an air atmosphere at 800 °C for 4 h, and cooled naturally.

[0091] (2) Collect the spent catalyst particles obtained in step (1), disperse them in a solution containing hydrazine hydrate (10 mol / L), and vigorously stir them at 40° C. under normal pressure; let them stand for 24 hours after the reaction, wash the particles with ethanol and deionized water three times; and dry them in an oven at 60° C. for 6 hours to obtain the reduced spent catalyst;

[0092] (3) Under normal pressure, 10 g of the reduced spent catalyst obtained in step (2) was added to a water (5 mL) solution containing potassium persulfate complex salt (10 mmol) and propionitrile (10 mL), and the mixture was vigorously reacted at 60° C. for 4 h;

[0093] (4) The system obtained in step (3) is subjected to solid-liquid separation to obtain a filtrate and a solid portion; the obtained filtrate is introduced into a heater for heating and evaporation to obtain a concentrated mother liquor and steam; the steam is introduced into a washing column for condensation and directly used for washing the waste catalyst carrier, and solid-liquid separation is performed when the condensed water covers the waste catalyst carrier by 10 cm; the obtained separated liquid is heated and evaporated, and the steam is introduced into a washing column for condensation, and this operation is repeated 8 times, and the concentrated liquid remaining from the evaporation is discharged and combined with the concentrated mother liquor to extract precious metals, and the carrier can be reused after drying.

[0094] Test Example 1

[0095] Figure 1 The XRD patterns of the spent catalyst raw material, and the recovered carriers of Example 1 and Example 3 are shown. The results show that the crystal structure of the recovered carriers of Example 1 and Example 3 is consistent with the crystal structure of the original untreated spent catalyst, and no changes have occurred. This indicates that the crystal structure of the alumina carrier treated by the method of the present invention is not destroyed.

[0096] In addition, from Figure 2 It can be seen that the appearance structure of the alumina carrier recovered in Example 1 also remains intact, and its spherical structure has not been damaged in any way.

[0097] Test Example 2

[0098] The crushing strength test was performed on the waste catalyst raw material and the recovered carriers of Example 1 and Example 3:

[0099] The sample is placed in the center of the press, and the load is evenly applied to 100N at a speed of 1N / s and kept stable for 5s, then unloaded to display the crushing strength. This method is repeated 12 times, and the average value is taken after removing the maximum and minimum values.

[0100] from Figure 3 It can be seen that the crush strength of the spent catalyst is 64 N, while the crush strengths of the recovered supports of Example 1 and Example 3 are 63 N and 62 N, respectively. The retention of the crush strength indicates that the macroscopic and microscopic structures of the recovered alumina supports have hardly changed.

[0101] Test Example 3

[0102] Figure 4 and Figure 5 Nitrogen adsorption-desorption curves and corresponding pore size distributions of the spent catalyst, the carrier recovered from Example 1 and Example 3.

[0103] Comparing the recovered carrier and the waste catalyst in Example 1, it can be seen that the specific surface area and pore structure have not changed significantly. However, the specific surface area of ​​Example 3 has increased from 23.9564 m2 g -1 Increased to 25.6447m2 g -1, the average pore size decreased from 29.8225nm to 24.8924nm. However, in general, the pore size structure of the waste catalyst treated by the present invention did not change significantly. This is conducive to retaining the structure of the alumina carrier and is also conducive to the secondary use of the alumina carrier.

[0104] Test Example 4

[0105] Figure 6 and Figure 7 Palladium and silver content of the recovered support for the spent catalyst, Example 1 and Example 3 (ICP test).

[0106] The results show that the waste catalyst contains 1.895 mg / g of Ag and 0.223 mg / g of Pd. However, the carrier recovered in Example 1 only contains 0.035 mg / g of Ag and 0.003 mg / g of Pd. The leaching rate of Pd and Ag in this process can reach 99%, and the leaching rate of Ag can reach 98%. However, the carrier recovered in Example 3 only contains 0.026 mg / g of Ag and 0.002 mg / g of Pd, and the leaching rate of Pd and Ag can reach 99%. It shows that the present invention can effectively remove Pd and Ag in a gentle way without destroying the carrier alumina.

[0107] The precious metal leaching agent of the present invention can effectively leach precious metals without damaging the carrier. The treated carrier can be recovered and reused.

[0108] The method for recovering precious metals from waste catalysts provided by the present invention only requires four steps to effectively leach precious metals. The process is gentle and efficient, and the operation is simple, which provides a new idea for developing a green, low-cost and efficient waste catalyst recovery process.

[0109] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A precious metal leaching agent, characterized in that: The noble metal leaching agent comprises an oxidant, a ligand precursor and water.

2. The precious metal leaching agent according to claim 1, wherein: The oxidant is selected from at least one of peroxymonosulfate, peroxydisulfate and hydrogen peroxide, preferably potassium peroxymonosulfate composite salt; Preferably, the ligand precursor is selected from at least one of acetonitrile, propionitrile, valeronitrile and capronitrile.

3. The precious metal leaching agent according to claim 1 or 2, wherein: The concentration of the oxidant is 0.5-5 mol / L, preferably 1 mol / L; Preferably, the concentration of the ligand precursor is 5-15 mol / L, preferably 9-10 mol / L.

4. Use of the precious metal leaching agent according to any one of claims 1 to 3 in recovering spent catalyst carriers and precious metals.

5. The use according to claim 4, wherein: The precious metal in the spent catalyst is selected from at least one of gold, silver, ruthenium, rhodium, palladium, osmium, iridium and platinum, preferably palladium and / or silver.

6. A method for recovering spent catalyst carriers and precious metals using the precious metal leaching agent according to any one of claims 1 to 3, characterized in that: The method comprises: roasting and reducing the waste catalyst, leaching it in the precious metal leaching agent, and performing a first solid-liquid separation and washing to obtain the waste catalyst carrier and the precious metal respectively.

7. The method according to claim 6, wherein: The calcination conditions include: heating to 300-800°C at a heating rate of 1-20°C / min and calcining for 1-4h; Preferably, the heating rate is 5-10°C / min; Preferably, the temperature at the end of the heating period is 600-800°C; Preferably, the calcination time is 3-4 hours.

8. The method according to claim 6 or 7, wherein: The reduction conditions include: normal pressure; stirring in a water bath; a temperature of 20-80°C, preferably 40-60°C; Preferably, the reducing agent used in the reduction is selected from at least one of sodium borohydride, hydrazine hydrate, ascorbic acid and formaldehyde; Preferably, the concentration of the reducing agent is 1-20 mol / L, preferably 8-10 mol / L; Preferably, the mixture obtained after the reduction is subjected to a second solid-liquid separation, and the solid portion is subjected to a first drying; Preferably, the first drying conditions include: temperature of 60-80° C.; time of 6-12 h.

9. The method according to any one of claims 6 to 8, wherein: The leaching conditions include: normal pressure; water bath; temperature of 20-120°C, preferably 40-60°C; time of 0.5-6h, preferably 3-4h; Preferably, the liquid-to-solid ratio of the leaching is 1-20:1, preferably 1-1.5:

1.

10. The method according to any one of claims 6 to 9, wherein: The solid part obtained by the first solid-liquid separation is washed and dried to obtain a carrier; Preferably, the second drying conditions include: temperature of 60-80° C.; time of 6-12 h.

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