A method for extracting precious metals from waste supported composite catalysts

Abstract

The present invention belongs to the field of precious metal recovery, and in particular to a method for extracting precious metals from waste loaded composite catalysts. The method comprises the steps of: pre-treating the waste loaded composite catalyst to remove organic matter in the waste loaded composite catalyst to obtain an intermediate waste catalyst; subjecting the intermediate waste catalyst to oxygen pressure acid leaching to obtain an acid-leached system; washing and filtering the acid-leached system to obtain a filter residue; subjecting the filter residue to alkali melting-oxidation distillation to obtain a ruthenium-containing absorption liquid, refining the ruthenium-containing absorption liquid to produce sponge ruthenium, and calcining the sponge ruthenium in a hydrogen reducing gas atmosphere to obtain ruthenium metal. The method combines oxygen pressure acid leaching with a precious metal enrichment process, can recover precious metals from waste catalysts, has the characteristics of strong process selectivity, high recovery rate, simple operation, low energy consumption, etc., and the output precious metal powder contains few impurities and has good quality, and is directly used as a product in the fields of catalysts, medicines, etc.

Description

Technical Field

[0001] The invention belongs to the field of precious metal recovery, and in particular relates to a method for extracting precious metals from waste supported composite catalysts. Background Art

[0002] A supported composite catalyst is a catalyst in which the active components and the co-catalyst are uniformly dispersed and supported on a specially selected carrier. Supported composite catalysts for hydrogenation reduction are mostly used for the hydrogenation reduction of various substances such as aromatic rings and heterocyclic rings. The supported active metals usually include elements of Group VIII of the periodic table such as cobalt, nickel, ruthenium, rhodium, palladium, platinum and iridium, and also contain co-catalysts such as copper, silver, gold, zinc, tin, bismuth or antimony. The carrier material used is often metal, metal oxide, carbon fiber or polymer.

[0003] Precious metals are important basic raw materials with low reserves, high value, and difficult extraction processes. Recycling and refining precious metals through discarded supported composite catalysts can not only reduce the mining and processing of precious metal ores, but also avoid water pollution and greenhouse gas emissions. Therefore, the recycling of precious metal renewable resources in discarded supported composite catalysts will surely produce very important economic and social benefits.

[0004] At present, the methods for recovering precious metals from waste supported composite catalysts mainly include pyrometallurgical recovery and wet recovery. The pyrometallurgical method is to smelt the waste containing precious metals at high temperature to enrich the precious metals in general metals, and then recover them by traditional methods. However, this method is cumbersome to operate, complex in process, high in operating cost, and low in precious metal yield. The most widely used method is wet recovery, which is to leach the precious metals into the solution to form an ion state, and then extract them from the solution, thus forming a variety of different extraction processes.

[0005] Chinese patent CN112342397A (publication date: February 9, 2021) discloses a method for recovering metallic platinum from a platinum-carbon catalyst. Aqua regia is added during the recovery process. Although it has a high recovery rate, the acid consumption is large, the solution ion concentration is high, and the tail liquid treatment process is complicated.

[0006] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for extracting precious metals from waste supported composite catalysts, aiming to solve the problems of complex operation and serious environmental pollution in existing precious metal recovery methods.

[0008] A method for extracting precious metals from waste supported composite catalysts, comprising the following steps:

[0009] Providing a waste supported composite catalyst, the waste supported composite catalyst comprises an active metal, the active metal comprises a noble metal, and the noble metal comprises a ruthenium metal and a palladium metal;

[0010] Pre-treating the waste supported composite catalyst to remove organic matter in the waste supported composite catalyst to obtain an intermediate waste catalyst;

[0011] The intermediate waste catalyst is subjected to oxygen pressure acid leaching to obtain an acid-leached system;

[0012] Washing and filtering the acid-leached system to obtain a filter residue;

[0013] The filter residue is subjected to alkaline melting-oxidation distillation treatment to obtain a ruthenium-containing absorption liquid, the ruthenium-containing absorption liquid is subjected to purification treatment to obtain sponge ruthenium, and the sponge ruthenium is calcined in a hydrogen reducing gas atmosphere to obtain ruthenium metal.

[0014] Optionally, while obtaining the ruthenium-containing absorption liquid, a steam residue is also obtained. After obtaining the steam residue, the process further includes the steps of: adding hydrochloric acid and NaClO3 to the steam residue, then washing and filtering, adding aluminum powder to the filtrate to react, filtering after the reaction is completed, washing with hot water until the pH value of the filtrate is neutral, and drying at 120-150°C for 1-2 hours to obtain palladium metal.

[0015] Optionally, the amount of aluminum powder added is 1 to 3 times the theoretical consumption, and the reaction temperature is 37 to 50°C.

[0016] Optionally, the waste supported composite catalyst further comprises a carrier and a co-catalyst, and the active metal and the co-catalyst are supported on the carrier;

[0017] The carrier is one of aluminum oxide, silicon dioxide, alumina, silicon dioxide-alumina, zeolite, and activated carbon;

[0018] The waste supported composite catalyst is used for aromatic ring hydrogenation reaction.

[0019] Optionally, the step of pretreating the waste supported composite catalyst specifically comprises:

[0020] The waste loaded composite catalyst is crushed, and the crushed waste loaded composite catalyst is successively ground, cleaned, dried and calcined in stages.

[0021] Optionally, the step of pretreating the waste supported composite catalyst specifically comprises:

[0022] The waste supported composite catalyst is broken into small pieces, the broken waste supported composite catalyst is ground into 100-200 meshes, washed with water for 3-5 times, and dried at 170-250°C for 0.5-1h after washing;

[0023] After drying, the first calcination is carried out at an oxygen content of 7.0-14.0v% and 200-300°C for 1-2h, and then the second calcination is carried out at an oxygen content of 12.0-19.0v% and 400-500°C for 1-2h; wherein the oxygen content of the second calcination is greater than that of the first calcination.

[0024] Optionally, the step of subjecting the intermediate waste catalyst to oxygen pressure acid leaching treatment specifically comprises:

[0025] The intermediate waste catalyst is placed in a high-pressure reactor, and sulfuric acid with a mass concentration of 20-60% and a FeCl3 solution with a mass concentration of 50-80% are added to the high-pressure reactor according to a solid-liquid mass ratio of 1:3-8 and a solid-liquid mass ratio of 1:5-10, respectively, and oxygen is introduced until the oxygen partial pressure is 0.3-1.5MPa, and then an acid leaching reaction is carried out at 80-90°C for 1-2h.

[0026] Optionally, the step of washing and filtering the acid-leached system to obtain filter residues specifically comprises:

[0027] The acid-leached system is washed with hot water at 95-100° C., filtered, and leached residue is obtained;

[0028] The leached residue is washed 2 to 3 times with hot water having a solid-liquid mass ratio of 1:2 to 4, and filtered to obtain the filter residue.

[0029] Optionally, the step of subjecting the filter residue to alkali fusion-oxidation distillation treatment to obtain a ruthenium-containing absorption liquid specifically comprises:

[0030] The filter residue is heated to 70-90° C., the pH value is adjusted to 8-9 with an alkaline solution, sodium sulfide is added under stirring for precipitation, and after filtering, a filtrate and a filter residue are obtained;

[0031] Concentrating the filtrate for 1 to 2 hours to obtain a concentrated solution;

[0032] The concentrated solution and the filter residue are mixed and heated to 100° C., and a NaClO 3 solution is added thereto for distillation to obtain the ruthenium-containing absorption solution.

[0033] Optionally, the step of calcining the ruthenium sponge in a hydrogen reducing gas atmosphere specifically includes: calcining the ruthenium sponge in an inert atmosphere at 300-400°C for 2-3 hours, and then introducing hydrogen to reduce it at 700-900°C for 2 hours to obtain ruthenium powder.

[0034] Beneficial effects: The present invention provides a method for extracting precious metals from waste loaded composite catalysts, which method consists of pretreatment, oxygen pressure acid leaching, filtration and washing, and precious metal purification. The present invention combines oxygen pressure acid leaching, alkali fusion-oxidation distillation and precious metal enrichment technology to simultaneously recover precious metals ruthenium and palladium from waste loaded composite catalysts. The palladium is reduced by aluminum powder, and the recovery rate of palladium can reach up to 97.08%. The method combines oxygen pressure acid leaching with precious metal enrichment technology, and can recover precious metals ruthenium and palladium from waste loaded composite catalysts. It has the characteristics of strong process selectivity, high recovery rate, simple operation, low energy consumption, etc. The output precious metal powder contains less impurities and has good quality. It can be directly used as a product in the fields of catalysts, medicines, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic flow chart of a method for extracting precious metals from waste supported composite catalysts provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention provides a method for extracting precious metals from a waste supported composite catalyst. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] Please combine Figure 1 The present invention provides a method for extracting precious metals from a waste supported composite catalyst, comprising the following steps:

[0038] S1. providing a waste supported composite catalyst, wherein the waste supported composite catalyst comprises an active metal, wherein the active metal comprises a noble metal, and wherein the noble metal comprises a ruthenium metal and a palladium metal;

[0039] S2, pre-treating the waste supported composite catalyst to remove organic matter in the waste supported composite catalyst to obtain an intermediate waste catalyst;

[0040] S3, subjecting the intermediate waste catalyst to oxygen pressure acid leaching to obtain an acid-leached system;

[0041] S4, washing and filtering the acid-leached system to obtain a filter residue;

[0042] S5. Subjecting the filter residue to alkaline melting-oxidation distillation treatment to obtain a ruthenium-containing absorption liquid, subjecting the ruthenium-containing absorption liquid to a refining treatment to obtain a ruthenium sponge, and calcining the ruthenium sponge in a hydrogen reducing gas atmosphere to obtain ruthenium metal.

[0043] In one embodiment, while obtaining the ruthenium-containing absorption liquid, a steam residue is also obtained. After obtaining the steam residue, the steps further include: adding hydrochloric acid and NaClO3 to the steam residue, then washing and filtering, slowly adding aluminum powder to the filtrate to react, filtering after the reaction is completed, washing with hot water until the pH value of the filtrate is neutral, and drying at 120-150°C for 1-2 hours to obtain palladium metal.

[0044] The traditional process of extracting precious metal palladium adopts a fire-wet combined process of pyrometallurgical enrichment-precipitation of precious and base metals-precipitation of precious metals-reduction precipitation-refining and purification to obtain sponge palladium. The catalyst is smelted by fire to obtain palladium concentrate, and then the metal palladium is recovered through aqua regia dissolution, ammonia complexation, hydrochloric acid precipitation of palladium, and hydrazine hydrate reduction. The process is cumbersome and complicated. Although hydrazine hydrate has strong reduction properties, it reacts violently, releases a large amount of gas, is difficult to control, and hydrazine hydrate itself is toxic and carcinogenic, causing environmental pressure.

[0045] This embodiment combines oxygen pressure acid leaching, alkali fusion-oxidation distillation and precious metal enrichment process, and simultaneously recovers precious metals ruthenium and palladium from the waste supported composite catalyst. The palladium is reduced by aluminum powder, and the recovery rate of palladium can reach up to 97.08%. This method combines oxygen pressure acid leaching with precious metal enrichment process, and can recover precious metals ruthenium and palladium from the waste supported composite catalyst. It has the characteristics of strong process selectivity, high recovery rate, simple operation, low energy consumption, etc. The output precious metal powder contains less impurities and has good quality. As a product, it can be directly used in the fields of catalysts, medicines, etc.

[0046] Furthermore, the amount of aluminum powder added is 1 to 3 times the theoretical consumption, and the reaction temperature is 37 to 50°C.

[0047] In this embodiment, the waste supported composite catalyst is pretreated, oxygen pressure acid leached, filtered and washed, and the precious metal is purified, and finally the precious metal is recovered. In this embodiment, the oxygen pressure acid leaching method is combined with the precious metal enrichment process, which can effectively remove the base metal elements in the waste supported composite catalyst. The whole process has a mild reaction and little pollution to the environment.

[0048] In one embodiment, the waste supported composite catalyst further comprises a carrier and a promoter, and the active metal and the promoter are supported on the carrier;

[0049] The active metal may also include one or more of aluminum, nickel, and copper;

[0050] The carrier may be one of aluminum oxide, silicon dioxide, alumina, silicon dioxide-alumina, zeolite, and activated carbon.

[0051] In one embodiment, the spent supported composite catalyst is used for aromatic ring hydrogenation reaction.

[0052] In one embodiment, the step of pretreating the waste supported composite catalyst specifically comprises:

[0053] The waste loaded composite catalyst is crushed, and the crushed waste loaded composite catalyst is successively ground, cleaned, dried and calcined in stages.

[0054] This embodiment adopts a staged roasting method to pretreat the waste supported composite catalyst, so that the carbon deposits on the waste supported composite catalyst are burned more thoroughly, which is beneficial to the subsequent recovery of precious metals and improves the recovery rate of precious metals.

[0055] In a specific embodiment, the step of pretreating the waste supported composite catalyst specifically comprises:

[0056] The waste supported composite catalyst is broken into small pieces, the broken waste supported composite catalyst is ground into 100-200 meshes, washed with water for 3-5 times, and dried at 170-250°C for 0.5-1h after washing;

[0057] After drying, a first calcination is carried out at an oxygen content of 7.0-14.0v% and 200-300°C for 1-2h (e.g. 1h), and then a second calcination is carried out at an oxygen content of 12.0-19.0v% and 400-500°C for 1-2h (e.g. 1h); wherein the oxygen content of the second calcination is greater than that of the first calcination.

[0058] In the pretreatment process of this embodiment, a two-stage roasting method is used to fully remove harmful impurities such as organic matter and volatile substances, which can avoid the occurrence of reduction, adsorption, encapsulation, complexation and other reactions during decomposition, and avoid the loss of precious metals caused by splashing during dissolution.

[0059] In one embodiment, the step of subjecting the intermediate waste catalyst to oxygen pressure acid leaching treatment specifically comprises:

[0060] The intermediate waste catalyst is placed in a high-pressure reactor, and sulfuric acid with a mass concentration of 20-60% and a FeCl3 solution with a mass concentration of 50-80% are added to the high-pressure reactor according to a solid-liquid mass ratio of 1:3-8 and a solid-liquid mass ratio of 1:5-10, respectively, and oxygen is introduced until the oxygen partial pressure is 0.3-1.5MPa, and then an acid leaching reaction is carried out at 80-90°C for 1-2h.

[0061] Through the above oxygen pressure acid leaching treatment, the carrier in the intermediate waste catalyst can be completely dissolved.

[0062] In one embodiment, the step of washing and filtering the acid-leached system specifically comprises:

[0063] The acid-leached system is washed with hot water at 95-100° C., filtered, and leached residue is obtained;

[0064] The leached residue is washed 2 to 3 times with hot water having a solid-liquid mass ratio of 1:2 to 4, and filtered to obtain the filter residue.

[0065] After the above washing and filtering treatment, the precious metals enter the filter residue, and impurities such as aluminum and nickel enter the filtrate.

[0066] In one embodiment, the step of subjecting the filter residue to alkali fusion-oxidation distillation to obtain a ruthenium-containing absorption liquid specifically comprises:

[0067] The filter residue is heated to 70-90° C., the pH value is adjusted to 8-9 with an alkaline solution, sodium sulfide is added under stirring for precipitation, and after filtering, a filtrate and a filter residue are obtained;

[0068] Concentrating the filtrate for 1 to 2 hours to obtain a concentrated solution;

[0069] The concentrated solution and the filter residue are mixed and heated to 100° C., and a NaClO 3 solution is added thereto for distillation to obtain the ruthenium-containing absorption solution.

[0070] In the process of extracting ruthenium by the alkaline fusion-oxidation distillation method in this embodiment, sodium sulfide precipitation is used to completely precipitate the precious metal. The waste water and waste gas generated by this can be recycled by the factory after post-treatment without causing secondary pollution.

[0071] In one embodiment, the step of calcining the ruthenium sponge in a hydrogen reducing gas atmosphere specifically includes: calcining the ruthenium sponge in an inert atmosphere at 300-400°C for 2-3 hours, and then introducing hydrogen to reduce it at 700-900°C for 2 hours to obtain ruthenium powder.

[0072] The present invention is further described in detail below in conjunction with specific embodiments.

[0073] Example 1

[0074] A method for extracting precious metals from a waste supported composite catalyst containing precious metals ruthenium, nickel, palladium and copper, the specific steps are as follows:

[0075] S1, pretreatment: first, 80g of the waste loaded composite catalyst (containing 6.4g of ruthenium, 2.4g of palladium, 0.8g of nickel and 0.8g of copper) was broken into small pieces, and then the broken waste loaded composite catalyst was ground to 100 mesh, washed with appropriate amount of clean water for 3 times, and dried at 170°C for 0.5h; then the oxygen content was increased to 7.0v%, and calcined at 200°C for 1h; then the oxygen content was increased to 12.0v%, and calcined at 400°C for 1h to remove organic matter in the waste loaded composite catalyst to obtain an intermediate waste catalyst.

[0076] S2. Oxygen pressure acid leaching: Place the intermediate waste catalyst in a high-pressure reactor, add 20% sulfuric acid and 50% FeC13 solution in a solid-liquid mass ratio of 1:3 and 1:5 respectively, introduce oxygen to reach an oxygen partial pressure of 0.3 MPa, and react at a temperature of 80°C for 1 hour to completely dissolve the carrier in the intermediate waste catalyst to obtain a system after acid leaching.

[0077] S3, filtration and washing: the system after acid leaching is washed and filtered with hot water at 95°C to obtain leaching residue; it is washed twice with hot water at a solid-liquid mass ratio of 1:2 to the leaching residue, and the solid-liquid separation allows the precious metals to enter the filter residue, and impurities such as aluminum and nickel to enter the filtrate.

[0078] S4. Purification of precious metals: heat the filter residue to 70°C, adjust the pH value to 8 with an alkaline solution, add sodium sulfide under stirring for precipitation, and filter to obtain a filtrate and a filter residue; concentrate the filtrate for 1 hour, heat the obtained concentrated solution and the filter residue to 100°C together, add a 50% NaClO3 solution by mass concentration for distillation, and the added amount is 3 times the theoretical consumption to obtain a ruthenium-containing absorption liquid and a steam residue; the evaporated ruthenium-containing absorption liquid is absorbed by an acid solution, and then refined to produce sponge ruthenium, which is calcined at 350°C for 2 hours in a nitrogen atmosphere, and then reduced at 800°C for 2 hours by passing hydrogen to prepare 6.299g of ruthenium powder. To the steam residue, add 5 mol / L hydrochloric acid and NaClO3 in an amount three times the theoretical consumption, filter and wash, slowly add aluminum powder to the palladium-containing filtrate in an amount three times the theoretical consumption, react, control the reaction temperature at 37°C, generate palladium powder, hot filter and wash with hot water until the pH value is neutral, dry at 120°C for 1h, and finally obtain 2.31g of palladium powder.

[0079] Calculated based on the weight of the above-produced products, the recovery rate of ruthenium is 98.42% and the recovery rate of palladium is 96.25%.

[0080] Example 2

[0081] A method for extracting precious metals from a waste supported composite catalyst containing precious metals ruthenium, nickel, palladium and copper, the specific steps are as follows:

[0082] 1. Pretreatment: First, 80g of the waste loaded composite catalyst (containing 6.4g of ruthenium, 2.4g of palladium, 0.8g of nickel and 0.8g of copper) was broken into small pieces, and then the broken waste loaded composite catalyst was ground to 150 mesh, washed with an appropriate amount of clean water for 4 times, and dried at 210°C for 0.8h; then the oxygen content was increased to 10.0v%, and calcined at 250°C for 1h; then the oxygen content was increased to 15.0v%, and calcined at 450°C for 1h to remove organic matter in the waste loaded composite catalyst to obtain an intermediate waste catalyst.

[0083] 2. Oxygen pressure acid leaching: Place the intermediate waste catalyst in a high-pressure reactor, add 60% sulfuric acid and 80% FeC13 solution at a solid-liquid mass ratio of 1:8 and 1:10 respectively, introduce oxygen to reach an oxygen partial pressure of 1.5MPa, react at a temperature of 90°C for 2h, dissolve the carrier in the intermediate waste catalyst completely, and obtain a system after acid leaching.

[0084] 3. Filtration and washing: The acid-leached system is washed and filtered with hot water at 100°C to obtain leached residue; it is washed three times with hot water at a solid-liquid mass ratio of 1:4 to the leached residue, and the solid-liquid separation allows the precious metals to enter the filter residue, and impurities such as aluminum and nickel to enter the filtrate.

[0085] 4. Purification of precious metals: heat the filter residue to 90°C, adjust the pH value to 9 with an alkaline solution, add sodium sulfide under stirring for precipitation, and filter to obtain a filtrate and a filter residue; concentrate the filtrate for 2 hours, heat the obtained concentrated solution and the filter residue to 100°C together, add a 50% NaClO3 solution by mass concentration for distillation, and the added amount is 3 times the theoretical consumption to obtain a ruthenium-containing absorption liquid and a steam residue; the evaporated ruthenium-containing absorption liquid is absorbed by an acid solution, and then refined to produce sponge ruthenium, which is calcined at 350°C for 3 hours in a nitrogen atmosphere, and then reduced at 900°C for 2 hours by passing hydrogen to prepare 6.13g of ruthenium powder. After adding 5 mol / L hydrochloric acid and NaClO3 to the steam residue in an amount three times the theoretical consumption, filter and wash, slowly add aluminum powder to the palladium-containing filtrate in an amount three times the theoretical consumption, react, control the reaction temperature to 50°C, react to generate palladium powder, hot filter and wash with hot water until the pH value is neutral, dry at 150°C for 2h, and finally obtain 2.25g of palladium powder.

[0086] Calculated based on the weight of the above-produced products, the recovery rate of ruthenium is 95.78%, and the recovery rate of palladium is 93.75%.

[0087] Example 3

[0088] A method for extracting precious metals from a waste supported composite catalyst containing precious metals ruthenium, nickel, palladium and copper, the specific steps are as follows:

[0089] 1. Pretreatment: First, 80g of the waste loaded composite catalyst (containing 6.4g of ruthenium, 2.4g of palladium, 0.8g of nickel and 0.8g of copper) was broken into small pieces, and then the broken waste loaded composite catalyst was ground to 200 mesh, washed with an appropriate amount of clean water for 5 times, and dried at 250°C for 1h; then the oxygen content was increased to 14.0v%, and calcined at 300°C for 1h; then the oxygen content was increased to 19.0v%, and calcined at 500°C for 1h to remove organic matter in the waste loaded composite catalyst to obtain an intermediate waste catalyst.

[0090] 2. Oxygen pressure acid leaching: Place the intermediate waste catalyst in a high-pressure reactor, add 40% sulfuric acid and 65% FeC13 solution in a solid-liquid mass ratio of 1:5 and 1:8 respectively, introduce oxygen to reach an oxygen partial pressure of 1.0 MPa, and react at a temperature of 80°C for 1.5 hours to completely dissolve the carrier in the intermediate waste catalyst to obtain a system after acid leaching.

[0091] 3. Filtration and washing: The acid-leached system is washed and filtered with hot water at 95°C to obtain leached residue; it is washed three times with hot water at a solid-liquid mass ratio of 1:3 to the leached residue, and the solid-liquid separation allows the precious metals to enter the filter residue and impurities such as aluminum and nickel to enter the filtrate.

[0092] 4. Purification of precious metals: heat the filter residue to 80°C, adjust the pH value to 8 with an alkaline solution, add sodium sulfide under stirring for precipitation, and filter to obtain a filtrate and a filter residue; concentrate the filtrate for 1.5 hours, heat the obtained concentrated solution and the filter residue to 100°C together, add a 50% NaClO3 solution by mass concentration for distillation, and the added amount is 3 times the theoretical consumption to obtain a ruthenium-containing absorption liquid and a steam residue; the evaporated ruthenium-containing absorption liquid is absorbed by an acid solution, and then refined to produce sponge ruthenium, which is calcined at 400°C for 2 hours in a nitrogen atmosphere, and then reduced at 800°C for 2 hours by passing hydrogen to prepare 6.32g of ruthenium powder. After adding 5 mol / L hydrochloric acid and NaClO3 to the steam residue in an amount three times the theoretical consumption, filter and wash, slowly add aluminum powder to the palladium-containing filtrate in an amount three times the theoretical consumption, react, control the reaction temperature to 50°C, and generate palladium powder. After hot filtration, wash with hot water to a neutral pH value, and dry at 130°C for 1h to finally obtain 2.33g of palladium powder.

[0093] Calculated based on the weight of the above-produced products, the recovery rate of ruthenium is 98.75%, and the recovery rate of palladium is 97.08%.

[0094] In summary, the present invention provides a method for extracting precious metals from waste supported composite catalysts, which method consists of pretreatment, oxygen pressure acid leaching, filtration and washing, and precious metal purification. The method combines oxygen pressure acid leaching with precious metal enrichment technology, and can recover precious metals such as ruthenium and palladium from waste supported composite catalysts. It has the characteristics of strong process selectivity, high recovery rate, simple operation, low energy consumption, etc. The output precious metal powder contains less impurities and has good quality, and can be directly used as a product in the fields of catalysts, medicines, etc.

[0095] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for extracting precious metals from waste supported composite catalysts, characterized in that: The steps include: (1) Pretreatment: First, 80 g of the waste loaded composite catalyst was broken into small pieces, wherein the waste loaded composite catalyst contained 6.4 g of ruthenium, 2.4 g of palladium, 0.8 g of nickel and 0.8 g of copper. The broken waste loaded composite catalyst was then ground into 200 meshes, washed with an appropriate amount of clean water for 5 times, and dried at 250°C for 1 hour. Then, the oxygen content was increased to 14.0 v%, and the mixture was calcined at 300°C for 1 hour. The oxygen content was increased to 19.0 v%, and the mixture was calcined at 500°C for 1 hour to remove organic matter from the waste loaded composite catalyst, thereby obtaining an intermediate waste catalyst. (2) Oxygen pressure acid leaching: Place the intermediate waste catalyst in a high-pressure reactor, add 40% sulfuric acid and 65% FeCl3 solution at a solid-liquid mass ratio of 1:5 and 1:8 respectively, introduce oxygen to reach an oxygen partial pressure of 1.0 MPa, and react at a temperature of 80°C for 1.5 hours to completely dissolve the carrier in the intermediate waste catalyst to obtain a system after acid leaching; (3) Filtration and washing: The acid-leached system is washed and filtered with hot water at 95°C to obtain leached residue; the residue is washed three times with hot water at a solid-liquid mass ratio of 1:3 to the leached residue, and the solid-liquid separation allows the precious metals to enter the filter residue and the aluminum and nickel impurities to enter the filtrate; (4) Purification of precious metals: heating the filter residue to 80°C, adjusting the pH value to 8 with an alkaline solution, adding sodium sulfide under stirring for precipitation, filtering, and obtaining a filtrate and a filter residue; concentrating the filtrate for 1.5 hours, heating the obtained concentrated solution and the filter residue together to 100°C, adding a 50% mass concentration NaClO3 solution for distillation, the added amount being 3 times the theoretical consumption, to obtain a ruthenium-containing absorption liquid and a distillation residue; absorbing the distilled ruthenium-containing absorption liquid with an acid solution, and then refining to produce sponge ruthenium, calcining the sponge ruthenium at 400°C for 2 hours in a nitrogen atmosphere, and then introducing hydrogen to reduce it at 800°C for 2 hours to obtain a ruthenium powder 6 .32g, add 5mol / L hydrochloric acid and NaClO3 to the steam residue, the amount of hydrochloric acid and NaClO3 added is 3 times the theoretical consumption, filter and wash, slowly add aluminum powder to the palladium-containing filtrate, the amount of aluminum powder added is 3 times the theoretical consumption, react, control the reaction temperature to 50°C, react to generate palladium powder, filter and wash with hot water until the pH value is neutral, dry at 130°C for 1h, and finally obtain 2.33g of palladium powder; Calculated based on the weight of the above-produced products, the recovery rate of ruthenium is 98.75%, and the recovery rate of palladium is 97.08%.

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