Process for the recovery of platinum group metals from scrap

Abstract

The application discloses a method for preparing platinum group metals from waste materials. The method comprises the following steps: high-temperature calcination of the waste materials with activated carbon and combustion-supporting agents to remove organic matters; high-temperature calcination of the waste materials with zinc powder to activate the waste materials; removal of part of impurities through subsequent oxidation leaching; preparation of a solution and a crystal corresponding to a platinum group metal compound through an oxidation-reduction process; reduction and dissolution of the platinum group metal compound with the aid of a reaction aid; purification of the platinum group metal compound through ammonium sulfide to obtain a pure iridium compound; purification of the pure iridium compound through adsorption resin to obtain a pure rhodium compound crystal; and finally, calcination and reduction to obtain a corresponding high-purity platinum group metal powder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precious metal recovery, more particularly to a method for recovering platinum group metals from waste materials. BACKGROUND

[0002] With the continuous development of technology and the continuous consumption of resources, platinum group metals have become increasingly important in modern industry. However, platinum group metal resources are scarce and expensive, so recovering platinum group metals from waste materials has important economic and environmental significance.

[0003] Currently, the main technical methods for recovering platinum group metals from waste materials include pyrometallurgy, hydrometallurgy, and biometallurgy. Pyrometallurgy recovers platinum group metals through oxidation-reduction reactions at high temperatures, with a relatively high recovery rate, but generates a large amount of waste gas and slag. Hydrometallurgy leaches platinum group metals through acid or alkaline solutions, and then separates and enriches them using ion exchange, adsorption, or precipitation, which is simple to operate and low in cost, but has a relatively low recovery rate. Biometallurgy, as an emerging technology, uses microorganisms or their metabolites to leach platinum group metals, which has the advantages of low cost and environmental friendliness, but has not yet been industrialized.

[0004] Recovering platinum group metals from waste materials has the advantages of saving resources, protecting the environment, and creating economic benefits. However, existing technical methods still face problems such as low recovery rate, environmental pollution, high energy consumption, and technical bottlenecks. Therefore, providing a method for recovering platinum group metals from waste materials with high recovery efficiency, low energy consumption, and high product purity is the focus of the present application. SUMMARY

[0005] 1. To solve the above technical problems, the technical solution provided by the present application includes the following contents:

[0006] (1) The waste material is uniformly mixed with activated carbon and combustion-supporting agent at a mass ratio of 10:6~8:2~3, and is roasted in a martensite furnace at 600℃ for 2h, then cooled to room temperature, and the powder is collected;

[0007] (2) 100 parts of the powder are uniformly mixed with 600~700 parts of zinc powder, and are roasted in a martensite furnace at 850℃ for 8h, then cooled to room temperature, and after ball milling, the mixture is passed through a 60 mesh sieve, immersed in 10% hydrochloric acid, and 10% hydrochloric acid is added while stirring until the suspended solids no longer decrease, then filtered to collect the solid, and dried to obtain active ash;

[0008] (3) The active ash is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, the temperature is raised to 60~65℃, and 25% sodium chlorate solution is slowly added to the kettle, and when the oxidation-reduction potential is greater than 970mV, the 25% sodium chlorate solution is kept stirring for 4h, then the temperature is raised to 85℃ until no gas is overflowed, then cooled to room temperature, filtered, and the filtrate is collected;

[0009] (4) The filtrate is transferred into an evaporating pan and heated to boiling. H2O2 and HNO3 are added continuously to maintain the acidity at 1.5-2.5 mol / L, and then NH4Cl is added until the precipitation no longer increases. The filtrate A is obtained after acid removal and filtration. The filtrate is washed with 15% NH4Cl solution until it is light-colored. H2O2 and HNO3 are added to the filtrate, and the filtrate is filtered until the precipitation no longer increases. The filtrate is washed with 15% NH4Cl solution until it is colorless. The washing solution of the two times of washing is combined to obtain a crude rhodium-containing solution, and the filter residues of the two times of washing are combined to obtain crude (NH4)2IrCl6;

[0010] (5) The crude (NH4)2IrCl6 is slurried with water, and the pH is adjusted to 1-1.5. The slurry is heated to boiling, and hydrazine hydrate solution 300-500 parts and an additive 0.2-0.5 parts are added with gentle stirring. After the solid no longer decreases, the pH is adjusted to 2-2.5 with ammonia water, and the slurry is boiled for 1-2 h. The filtrate is obtained after cooling and filtration to obtain an iridium-containing solution;

[0011] (6) The iridium-containing solution is adjusted to pH 1.0-1.5 with hydrochloric acid, heated to 80°C, and then ammonium sulfide 320-360 parts is added. The pH is adjusted to 2.5-3.0 and the solution is boiled for 2 h. After cooling and storage for 36 h, the solution is filtered. H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases. The filter residue is washed with 15% NH4Cl solution until it is light-colored, and then dried to obtain (NH4)2IrCl6 crystals;

[0012] (7) The crude rhodium-containing solution is pretreated with an adsorption resin using hydrochloric acid with pH 2-3 to remove impurities. H2O2 and HNO3 are continuously added, and then NH4Cl is added until the precipitation no longer increases. The filter residue is washed with 15% NH4Cl solution, and then the washing solution and the filtrate are combined. Concentration and drying are performed to obtain (NH4)3RhCl6 crystals;

[0013] (8) The (NH4)2IrCl6 crystals and the (NH4)3RhCl6 crystals are calcined and hydrogen-reduced to obtain high-purity iridium and rhodium metal powders.

[0014] 2. Further, the combustion-supporting agent is a black phosphorus / red phosphorus heterogeneous phase junction.

[0015] 3. Further, the reaction additive is modified CMK-3, and the modification steps are as follows:

[0016] (1) CMK-3, 2-methylimidazole, and ethanol are taken in a mass ratio of 3-6:2-4:30-40.

[0017] (2) The CMK-3 and 2-methylimidazole are added to the ethanol and mixed uniformly, and then ultrasonic treatment is performed for 30-40 min.

[0018] (3) the mixture is heated and evaporated in a water bath at 40 DEG C, the solid is placed in a nitrogen atmosphere, and heated to 800 DEG C at a rate of 5 DEG C / min and calcined for 3h to obtain N-CMK-3;

[0019] (4) N-CMK-3 is placed in 8-10 times the mass of ion exchange water, and 0.5w% 0.05mol / l H2PtCl6 aqueous solution is added, and ultrasonic treatment is performed for 10-20min;

[0020] (5) the mixture is heated and evaporated in a water bath at 40 DEG C, the solid is placed in a nitrogen / hydrogen mixed gas atmosphere (4:1), heated to 200 DEG C at a rate of 5 DEG C / min and calcined for 3h to obtain Pt / N-CMK-3, i.e. modified CMK-3.

[0021] 4. Further, the adsorption resin is a polyethyleneimine-tannin-based adsorption resin.

[0022] The beneficial effects of the present application are:

[0023] (1) The present application relies on activated carbon and combustion-supporting agent to more fully remove organic impurities, and a catalyst is used to improve the reduction efficiency in the oxidation-reduction purification process to separate most metal element impurities, and an adsorption resin is used to separate base metals from a rhodium-containing solution, so that high-purity iridium powder and rhodium powder can be efficiently and quickly recovered from waste materials.

[0024] (2) In the pretreatment of waste materials, organic matter in the waste materials needs to be incinerated under high-temperature conditions to remove most organic impurities, and activated carbon is used to adsorb the organic matter to separate it from the waste materials as much as possible, but even with the assistance of activated carbon, organic matter residues cannot be avoided, so an additional combustion-supporting agent is needed to provide a heat source inside the mixture to assist the combustion of organic matter during the pretreatment process, and the present application uses black phosphorus / red phosphorus heterogeneous joints as the combustion-supporting agent, which has a low ignition point and can provide a heat source inside the mixture to more fully burn the organic matter in the waste materials, the black phosphorus / red phosphorus heterogeneous joint is composed of amorphous and crystalline phases and has an overlapping structure, has excellent electron-donating ability, and can reduce metal elements in the waste materials during the pretreatment process, so that the metal elements are not excessively oxidized during calcination, thereby affecting the subsequent zinc melting efficiency and reducing the recovery efficiency of platinum group metals.

[0025] (3) The coarse (NH4)2IrCl6 contains a certain amount of base metal and other noble metal impurities, and the purity of iridium metal can be further improved only after further impurity removal, so that a further reduction dissolution and impurity removal are required, and in the process, the reduction efficiency of hydrazine hydrate is poor, so that an auxiliary agent is required to assist the dissolution of (NH4)2IrCl6, and the application selects Pt / N-CMK-3 as the reaction auxiliary agent of the reaction, and the main body is mesoporous carbon material CMK-3, which has excellent adsorption effect to make hydrazine hydrate and suspended particles fully contact, so as to improve the reaction efficiency,

[0026] (4) Pt / -CMK-3 is a common catalyst, but the Pt nanoparticles are prone to agglomeration, which reduces the promotion effect on the reaction to a certain extent, and the existence of N element in the CMK-3 modified by N doping promotes the dispersion of Pt nanoparticles and reduces the particle size of Pt, and has higher reaction catalytic activity, and the synergistic effect of Pt and N in Pt / N-CMK-3 can promote the heterogeneous cracking of hydrazine hydrate, so that the positive and negative H electron pairs can be formed in the system, and the reduction efficiency of hydrazine hydrate on (NH4)2IrCl6 in the system is promoted, so that the impurity removal effect is greatly improved, and the purity of the recovered iridium powder is greatly improved.

[0027] (5) The crude rhodium-containing solution contains various base metals, and the polyethyleneimine-tannin-based adsorption resin is used as a cation adsorption resin to further purify and remove the base metals, and the polyethyleneimine-tannin-based adsorption resin has various adaptive orbital bonding energies to adsorb various base metals in the solution, and the polyethyleneimine-tannin-based adsorption resin has a rough and irregular surface structure and many space gaps, and has excellent adsorption effect on metal ions free in the solution, and has selectivity during adsorption, and has targeted adsorption effect on the base metals existing in the solution, so that the influence of the base metals on the rhodium component during the adsorption and impurity removal process can be avoided, and the recovery efficiency of rhodium is reduced. DETAILED DESCRIPTION

[0028] The application will be further described in detail in combination with examples.

[0029] In the black phosphorus / red phosphorus heterojunction used in the application, the mass fraction of black phosphorus is 40% to 60%, and the overall particle size of the black phosphorus / red phosphorus heterojunction is 1 to 3 microns, and the particle size of the black phosphorus is 20 to 25 nanometers, which is purchased from Guangdong Small Chemical Co., Ltd., and other raw materials are obtained through conventional commercial channels unless otherwise specified.

[0030] Example 1

[0031] 1. Take CMK-3, 2-methylimidazole and ethanol, and the mass ratio is 4.5:3:35.

[0032] 2. Add CMK-3, 2-methylimidazole into ethanol and mix evenly, ultrasonic treatment for 30-40 min;

[0033] 3. The mixture is heated and evaporated in a water bath at 40°C, the solid is calcined at 800°C for 3h under nitrogen atmosphere, and N-CMK-3 is obtained;

[0034] 4. N-CMK-3 is placed in 8-10 times the mass of ionized water and 0.5w% 0.05mol / l H2PtCl6 aqueous solution is added, ultrasonic treatment for 10-20 min;

[0035] 5. The mixture is heated and evaporated in a water bath at 40°C, the solid is calcined at 200°C for 3h under nitrogen / hydrogen mixed gas atmosphere (4:1), and modified CMK-3 is obtained;

[0036] 6. The waste is stirred evenly with activated carbon and black phosphorus / red phosphorus heterophase junction at a mass ratio of 10:7:2.5, calcined at 600°C in a muffle furnace for 2h, cooled to room temperature, and the powder is collected;

[0037] 7. 100 parts of the powder are mixed evenly with 650 parts of zinc powder, calcined at 850°C in a muffle furnace for 8h, cooled to room temperature, sieved through a 60-mesh screen after ball milling, immersed in 10% hydrochloric acid, and 10% hydrochloric acid is added while stirring until the suspended solids no longer decrease, the solid is collected by filtration, dried, and active ash is obtained;

[0038] 8. The active ash is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, the temperature is raised to 60-65°C, 25% sodium chlorate solution is slowly added to the kettle, and when the oxidation-reduction potential is greater than 970mV, 25% sodium chlorate solution is continuously added and stirred for 4h, then the temperature is raised to 85°C and kept until no gas is overflowed, then the temperature is lowered to room temperature, filtered, and the filtrate is collected;

[0039] 9. The filtrate is transferred into an evaporating pan, heated and boiled, H2O2 and HNO3 are continuously added without stopping to keep the acidity at 1.5-2.5mol / L, then ammonium chloride is added until the precipitation no longer increases, the acid is removed by filtration, the filtrate A is reserved, the filter residue is washed with 15% NH4Cl solution until it is light-colored, H2O2 and HNO3 are added to the filtrate, the precipitation no longer increases, the filtrate is filtered, the filter residue is washed with 15% NH4Cl solution until it is colorless, the washing solutions of the two times are combined, and a crude rhodium-containing solution is obtained, the filter residues of the two times are combined, and a crude (NH4)2IrCl6 is obtained;

[0040] 10. The crude (NH4)2IrCl6 is slurried with water, the pH is adjusted to 1-1.5, and the mixture is heated and boiled, hydrazine hydrate solution 400 parts and modified CMK-3 0.35 parts are added while stirring gently, the solid no longer decreases, then the pH is adjusted to 2-2.5 with ammonia water, boiled for 1.5h, cooled, filtered, and the filtrate is collected, and an iridium-containing solution is obtained;

[0041] 11. The solution containing iridium is adjusted to pH = 1.0-1.5 with hydrochloric acid, heated to 80℃, 340 parts of ammonium sulfide is added, the pH is adjusted to 2.5-3.0 and boiled for 2h, and after cooling for 36h, filtration is performed, H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases, the filtrate is washed with 15% NH4Cl solution until it is light in color, and after drying, (NH4)2IrCl6 crystals are obtained;

[0042] 12. The (NH4)2IrCl6 crystals are calcined and hydrogen reduced to obtain high-purity iridium powder.

[0043] Example 2

[0044] 1. Take CMK-3, 2-methylimidazole, ethanol, mass ratio 4.5:3:35;

[0045] 2. Mix CMK-3, 2-methylimidazole into ethanol and mix uniformly, and ultrasonic treatment for 30-40min;

[0046] 3. The mixture is heated to dryness in a water bath at 40℃, the solid is calcined at 800℃ for 3h under nitrogen atmosphere, and N-CMK-3 is obtained;

[0047] 4. N-CMK-3 is placed in 8-10 times the mass of ionized water and 0.5w% 0.05mol / l H2PtCl6 aqueous solution is added, and ultrasonic treatment is performed for 10-20min;

[0048] 5. The mixture is heated to dryness in a water bath at 40℃, the solid is calcined at 200℃ for 3h under a mixed gas atmosphere of nitrogen / hydrogen 4:1, and modified CMK-3 is obtained;

[0049] 6. The waste is stirred uniformly with activated carbon and black phosphorus / red phosphorus heterophase junction at a mass ratio of 10:7:2, calcined at 600℃ in a marten furnace for 2h, cooled to room temperature, and the powder is collected;

[0050] 7. 100 parts of the powder are mixed uniformly with 650 parts of zinc powder, calcined at 850℃ in a marten furnace for 8h, cooled to room temperature, and after ball milling, passed through a 60 mesh sieve, immersed in 10% hydrochloric acid, and while stirring, 10% hydrochloric acid is added until the suspended solid no longer decreases, the solid is collected by filtration, and after drying, active ash is obtained;

[0051] 8. The active ash is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, the temperature is raised to 60-65℃, 25% sodium chlorate solution is slowly added to the kettle, and when the oxidation-reduction potential is greater than 970mV, 25% sodium chlorate solution is continuously added and stirred for 4h, then the temperature is raised to 85℃ until no gas is overflowed, and then the temperature is lowered to room temperature, filtration is performed, and the filtrate is collected;

[0052] 9. The filtrate is transferred into an evaporating pan, heated to boiling, H2O2 and HNO3 are added continuously to keep the acidity at 1.5-2.5 mol / L, then ammonium chloride is added until the precipitation no longer increases, the acid is removed by filtration, the filtrate A is reserved, the filtrate is washed with 15% NH4Cl solution until it is light-colored, H2O2 and HNO3 are added, the precipitation no longer increases, filtration is performed, the filtrate is washed with 15% NH4Cl solution until it is colorless, the washing liquid of the two times is combined, and a crude rhodium-containing solution is obtained, the filtrates of the two times are combined, and a crude (NH4)2IrCl6 is obtained;

[0053] 10. The crude (NH4)2IrCl6 is slurried with water, the pH is adjusted to 1-1.5, the mixture is heated to boiling, hydrazine hydrate solution 400 parts and modified CMK-3 0.5 parts are added, the solid no longer decreases, then the pH is adjusted to 2-2.5 with ammonia water, boiling is performed for 1.5 h, cooling and filtration are performed, and the filtrate is reserved to obtain an iridium-containing solution;

[0054] 11. The iridium-containing solution is adjusted to pH 1.0-1.5 with hydrochloric acid, heated to 80°C, ammonium sulfide 340 parts is added, the pH is adjusted to 2.5-3.0 and boiling is performed for 2 h, cooling and storage are performed for 36 h, then filtration is performed, H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases, filtration is performed, then the filtrate is washed with 15% NH4Cl solution until it is light-colored, and (NH4)2IrCl6 crystals are obtained after drying;

[0055] 12. The (NH4)2IrCl6 crystals are calcined and hydrogen-reduced to obtain high-purity iridium powder.

[0056] Example 3

[0057] 1. CMK-3, 2-methylimidazole and ethanol are taken, and the mass ratio is 4.5:3:35;

[0058] 2. The CMK-3 and 2-methylimidazole are added to the ethanol and mixed uniformly, and ultrasonic treatment is performed for 30-40 min;

[0059] 3. The mixture is heated to dryness in a water bath at 40°C, the solid is calcined at 800°C for 3 h under a nitrogen atmosphere, and N-CMK-3 is obtained;

[0060] 4. The N-CMK-3 is placed in 8-10 times the mass of ionized water, and 0.5 w% 0.05 mol / l H2PtCl6 aqueous solution is added, and ultrasonic treatment is performed for 10-20 min;

[0061] 5. The mixture is heated to dryness in a water bath at 40°C, the solid is calcined at 200°C for 3 h under a nitrogen / hydrogen mixed gas atmosphere with a ratio of 4:1, and modified CMK-3 is obtained;

[0062] 6. Waste material is stirred with activated carbon, black phosphorus / red phosphorus hetero junction in a mass ratio of 10:7:3, calcined in a muffle furnace at 600℃ for 2h, cooled to room temperature, and the powder is collected;

[0063] 7. The powder is mixed with zinc powder in a mass ratio of 100:650, calcined in a muffle furnace at 850℃ for 8h, cooled to room temperature, ground in a ball mill, and sieved through a 60 mesh sieve. The sieved powder is immersed in 10% hydrochloric acid, and 10% hydrochloric acid is added while stirring until the suspended solids no longer decrease. The solid is collected by filtration, dried, and the active ash is obtained;

[0064] 8. The active ash is placed in a titanium reaction kettle, 10% hydrochloric acid is added and stirred, and the temperature is raised to 60-65℃. A 25% sodium chlorate solution is slowly added to the kettle, and the oxidation-reduction potential is greater than 970mV. The 25% sodium chlorate solution is added and stirred for 4h, and then the temperature is raised to 85℃ until no gas is discharged. The temperature is then lowered to room temperature, and the filtrate is collected by filtration;

[0065] 9. The filtrate is transferred to an evaporating pan and boiled with continuous addition of H2O2 and HNO3 to maintain the acidity at 1.5-2.5mol / L. Ammonium chloride is then added until the precipitate no longer increases. The filtrate A is obtained by filtration after the acid is removed. The filter residue is washed with 15% NH4Cl solution until the color is light. H2O2 and HNO3 are added to the filtrate until the precipitate no longer increases. The filter residue is washed with 15% NH4Cl solution until the color is colorless. The washing solution from the two washings is combined to obtain a crude rhodium-containing solution, and the filter residue from the two washings is combined to obtain crude (NH4)2IrCl6;

[0066] 10. The crude (NH4)2IrCl6 is slurried with water, the pH is adjusted to 1-1.5, and the mixture is boiled with continuous stirring and the addition of 400 parts of hydrazine hydrate and 0.2 parts of modified CMK-3. The solid is no longer reduced, and the pH is adjusted to 2-2.5 with ammonia water. The mixture is boiled for 1.5h, cooled, and filtered to obtain an iridium-containing solution;

[0067] 11. The iridium-containing solution is adjusted to pH 1.0-1.5 with hydrochloric acid, heated to 80℃, and 340 parts of ammonium sulfide is added. The pH is adjusted to 2.5-3.0 and boiled for 2h. After cooling and storage for 36h, the mixture is filtered. H2O2 and HNO3 are added to the filtrate until the precipitate no longer increases. The filter residue is washed with 15% NH4Cl solution until the color is light, and dried to obtain (NH4)2IrCl6 crystals; 66 crystals;

[0068] 12. The (NH4)2IrCl6 crystals are calcined and hydrogen-reduced to obtain high-purity iridium powder.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that the black phosphorus / red phosphorus hetero junction in Step 1 is red phosphorus, and the rest of the implementation is the same as in Example 1.

[0071] Comparative Example 2

[0072] 1. Take CMK-3, 2-methylimidazole, ethanol, mass ratio 4.5:3:35;

[0073] 2. Mix CMK-3, 2-methylimidazole into ethanol and mix uniformly, ultrasonic treatment for 30-40 min;

[0074] 3. The mixture is heated to dryness in a water bath at 40°C, and the solid is calcined at 800°C for 3h under a nitrogen atmosphere to obtain N-CMK-3;

[0075] 4. Add 8-10 times the mass of ionized water to N-CMK-3 and add 0.5w% 0.05mol / l H2PtCl6 aqueous solution, ultrasonic treatment for 10-20 min;

[0076] 5. The mixture is heated to dryness in a water bath at 40°C, and the solid is calcined at 200°C for 3h under a nitrogen / hydrogen mixed gas atmosphere of 4:1 to obtain modified CMK-3;

[0077] 6. Stir the waste with activated carbon and black phosphorus / red phosphorus hetero-phase junction at a mass ratio of 10:7:1, and calcine in a marten furnace at 600°C for 2h, then cool to room temperature, and collect the powder;

[0078] 7. Mix 100 parts of the powder with 650 parts of zinc powder uniformly, calcine in a marten furnace at 850°C for 8h, cool to room temperature, sieve after ball milling, and then immerse in 10% hydrochloric acid while stirring and adding 10% hydrochloric acid until the suspended solids no longer decrease, filter to retain the solid, and dry to obtain active ash;

[0079] 8. Put the active ash into a titanium reaction kettle, add 10% hydrochloric acid and stir, heat to 60-65°C, slowly add 25% sodium chlorate solution into the kettle, when the oxidation-reduction potential is greater than 970mV, keep adding 25% sodium chlorate solution and stirring for 4h, then heat to 85°C until no gas is overflowed, then cool to room temperature, filter, and collect the filtrate;

[0080] 9. Transfer the filtrate into an evaporator, heat to boiling, first add H2O2 and HNO3 without stopping to keep the acidity at 1.5-2.5mol / L, then add ammonium chloride until the precipitation no longer increases, filter to remove the acid, retain the filtrate A, wash the filter residue with 15% NH4Cl solution until it is light-colored, add H2O2 and HNO3 to the filtrate, and filter when the precipitation no longer increases, wash the filter residue with 15% NH4Cl solution until it is colorless, combine the washing solutions of the two times of washing to obtain a crude rhodium-containing solution, and combine the filter residues of the two times of washing to obtain crude (NH4)2IrCl6;

[0081] 10. Coarse (NH4)2IrCl6 was slurried with water, pH was adjusted to 1-1.5, and heated to boiling with gentle stirring and addition of hydrazine hydrate solution 400 parts, modified CMK-30.35 parts. After the solid no longer decreased, the pH was adjusted to 2-2.5 with ammonia water, boiled for 1.5 h, cooled, filtered, and the filtrate was retained to obtain an iridium-containing solution;

[0082] 11. The iridium-containing solution was adjusted to pH 1.0-1.5 with hydrochloric acid, heated to 80°C, and ammonium sulfide 340 parts was added, adjusted to pH 2.5-3.0 and boiled for 2 h, cooled and stored for 36 h, and then filtered. The filtrate was added with H2O2, HNO3 until the precipitate no longer increased, and the filter residue was washed with 15% NH4Cl solution until it was light in color, dried to obtain (NH4)2IrCl6 crystals;

[0083] 12. The (NH4)2IrCl6 crystals were calcined and hydrogen reduced to obtain high-purity iridium powder.

[0084] Comparative Example 3

[0085] 1. CMK-3, 2-methylimidazole, and ethanol were taken in a mass ratio of 4.5:3:35;

[0086] 2. The CMK-3 and 2-methylimidazole were added to the ethanol and mixed uniformly, and ultrasonic treatment was performed for 30-40 min;

[0087] 3. The mixture was heated to dryness in a water bath at 40°C, and the solid was calcined at 800°C for 3 h under a nitrogen atmosphere to obtain N-CMK-3;

[0088] 4. The N-CMK-3 was placed in 8-10 times the mass of ionized water and 0.5 w% 0.05 mol / l H2PtCl6 aqueous solution was added, and ultrasonic treatment was performed for 10-20 min;

[0089] 5. The mixture was heated to dryness in a water bath at 40°C, and the solid was calcined at 200°C for 3 h under a nitrogen / hydrogen mixed gas atmosphere of 4:1 to obtain modified CMK-3;

[0090] 6. The waste material was uniformly mixed with activated carbon and black phosphorus / red phosphorus heterogeneous phase in a mass ratio of 10:7:4, calcined at 600°C in a muffle furnace for 2 h, cooled to room temperature, and the powder was collected;

[0091] 7. 100 parts of the powder were uniformly mixed with 650 parts of zinc powder, calcined at 850°C in a muffle furnace for 8 h, cooled to room temperature, and then ground through a 60-mesh sieve. The mixture was immersed in 10% hydrochloric acid while stirring, and 10% hydrochloric acid was added until the suspended solid no longer decreased. The solid was filtered and dried to obtain active ash;

[0092] 8. Put the active ash into the titanium reaction kettle, add 10% hydrochloric acid and stir, and then heat to 60-65°C. Slowly add 25% sodium chlorate solution into the kettle. When the oxidation-reduction potential is greater than 970mV, keep adding 25% sodium chlorate solution and stirring for 4h. Then heat to 85°C until no gas is overflowed, and then cool to room temperature. Filter and collect the filtrate;

[0093] 9. Transfer the filtrate into an evaporation pan, and heat to boil. First, continuously add H2O2 and HNO3 to keep the acidity at 1.5-2.5mol / L. Then, add ammonium chloride until the precipitation no longer increases. Filter, wash the filter residue with 15% NH4Cl solution until the color is light, and then filter. Add H2O2 and HNO3 to the filtrate, and filter again. Wash the filter residue with 15% NH4Cl solution until the color is colorless. Combine the washing solutions to obtain a crude rhodium-containing solution, and combine the filter residues to obtain crude (NH4)2IrCl6;

[0094] 10. Add water to the crude (NH4)2IrCl6 to slurry, adjust the pH to 1-1.5, and heat to boil. Gently stir and add 400 parts of hydrazine hydrate and 0.2-0.5 parts of modified CMK-3. When the solid no longer decreases, adjust the pH to 2-2.5 with ammonia water, and boil for 1.5h. Cool, filter, and collect the filtrate to obtain an iridium-containing solution;

[0095] 11. Add hydrochloric acid to the iridium-containing solution to adjust the pH to 1.0-1.5, heat to 80°C, add 340 parts of ammonium sulfide, adjust the pH to 2.5-3.0, and boil for 2h. Cool and store for 36h, then filter. Add H2O2 and HNO3 to the filtrate until the precipitation no longer increases, filter, and wash the filter residue with 15% NH4Cl solution until the color is light. Dry to obtain (NH4)2IrCl6 crystals;

[0096] 12. After calcination and hydrogen reduction, (NH4)2IrCl6 crystals become high-purity iridium powder.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 1 is that the Pt / N-CMK-3 in step 5 is Pt / CMK-3, and the rest of the implementation is the same as Example 1.

[0099] Comparative Example 5

[0100] 1. Take CMK-3, 2-methylimidazole, and ethanol, with a mass ratio of 4.5:3:35.

[0101] 2. Mix the CMK-3 and 2-methylimidazole into the ethanol and mix well, and then ultrasonic treat for 30-40min.

[0102] 3. The mixture is heated to dryness in a water bath at 40°C, and the solid is calcined at 800°C for 3h under a nitrogen atmosphere to obtain N-CMK-3;

[0103] 4. The N-CMK-3 is placed in 8-10 times its mass of ion exchange water and 0.5w% 0.05mol / l H2PtCl6 aqueous solution is added, and ultrasonic treatment is performed for 10-20min;

[0104] 5. The mixture is heated to dryness in a water bath at 40°C, and the solid is calcined at 200°C for 3h under a nitrogen / hydrogen mixed gas atmosphere with a ratio of 4:1 to obtain modified CMK-3;

[0105] 6. The waste is stirred uniformly with activated carbon and black phosphorus / red phosphorus heterophase junctions at a mass ratio of 10:7:2.5, and calcination is performed at 600°C in a muffle furnace for 2h, and the temperature is reduced to room temperature, and the powder is collected;

[0106] 7. 100 parts of the powder are mixed uniformly with 650 parts of zinc powder, calcination is performed at 850°C in a muffle furnace for 8h, the temperature is reduced to room temperature, and after ball milling, the mixture is passed through a 60-mesh sieve, immersed in 10% hydrochloric acid, and 10% hydrochloric acid is added while stirring until the suspended solids no longer decrease, the solid is collected by filtration, and after drying, active ash is obtained;

[0107] 8. The active ash is placed in a titanium reaction kettle, 10% hydrochloric acid is added and stirred, the temperature is increased to 60-65°C, and 25% sodium chlorate solution is slowly added to the kettle, and when the oxidation-reduction potential is greater than 970mV, the 25% sodium chlorate solution is continuously added and stirred for 4h, then the temperature is increased to 85°C and maintained until no gas is discharged, and then the temperature is reduced to room temperature, and the filtrate is collected by filtration;

[0108] 9. The filtrate is transferred to an evaporating pan and heated to boiling, H2O2 and HNO3 are continuously added without stopping to maintain the acidity at 1.5-2.5mol / L, and then ammonium chloride is added until the precipitation no longer increases, the acid is removed by filtration, the filtrate A is retained, the filter residue is washed with 15% NH4Cl solution until it is light-colored, H2O2 and HNO3 are added to the filtrate, the precipitation no longer increases, and the filter residue is washed with 15% NH4Cl solution until it is colorless, the washing solutions from the two times of washing are combined to obtain a crude rhodium-containing solution, and the combined filter residues are obtained as crude (NH4)2IrCl6;

[0109] 10. The crude (NH4)2IrCl6 is slurried with water, the pH is adjusted to 1-1.5, and the mixture is heated to boiling, hydrazine hydrate solution 400 parts and modified CMK-3 0.1 part are added while stirring gently, and when the solid no longer decreases, the pH is adjusted to 2-2.5 with ammonia water, boiling is performed for 1.5h, and the filtrate is obtained by cooling and filtration to obtain an iridium-containing solution;

[0110] 11. The iridium-containing solution is adjusted to pH = 1.0-1.5 with hydrochloric acid, heated to 80°C, 340 parts of ammonium sulfide is added, the pH is adjusted to 2.5-3.0 and boiled for 2h, and after cooling for 36h, filtration is performed, H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases, the filtrate is washed with 15% NH4Cl solution until it is light-colored, and after drying, (NH4)2IrCl6 crystals are obtained;

[0111] 12. The (NH4)2IrCl6 crystals are calcined and hydrogen-reduced to obtain high-purity iridium powder.

[0112] Comparative Example 6

[0113] 1. Take CMK-3, 2-methylimidazole, and ethanol, with a mass ratio of 4.5:3:35;

[0114] 2. The CMK-3 and 2-methylimidazole are added to the ethanol and mixed uniformly, and ultrasonic treatment is performed for 30-40 min;

[0115] 3. The mixture is heated in a water bath at 40°C, evaporated to dryness, and the solid is calcined at 800°C for 3h under a nitrogen atmosphere to obtain N-CMK-3;

[0116] 4. The N-CMK-3 is placed in 8-10 times the mass of ion exchange water and 0.5w% 0.05mol / l H2PtCl6 aqueous solution is added, and ultrasonic treatment is performed for 10-20 min;

[0117] 5. The mixture is heated in a water bath at 40°C, evaporated to dryness, and the solid is calcined at 200°C for 3h under a nitrogen / hydrogen mixed gas atmosphere with a ratio of 4:1 to obtain modified CMK-3;

[0118] 6. The waste is stirred uniformly with activated carbon and black phosphorus / red phosphorus heterophase junctions at a mass ratio of 10:7:2.5, calcined at 600°C in a muffle furnace for 2h, cooled to room temperature, and the powder is collected;

[0119] 7. 100 parts of the powder are mixed uniformly with 650 parts of zinc powder, calcined at 850°C in a muffle furnace for 8h, cooled to room temperature, and after ball milling, the mixture is passed through a 60-mesh sieve, immersed in 10% hydrochloric acid, and 10% hydrochloric acid is added while stirring until the suspended solids no longer decrease, the solid is collected by filtration, and after drying, active ash is obtained;

[0120] 8. The active ash is placed in a titanium reaction kettle, 10% hydrochloric acid is added and stirred, the temperature is increased to 60-65°C, 25% sodium chlorate solution is slowly added to the kettle, and when the oxidation-reduction potential is greater than 970mV, the 25% sodium chlorate solution is continuously added and stirred for 4h, then the temperature is increased to 85°C until no gas is discharged, and then the temperature is decreased to room temperature, the mixture is filtered, and the filtrate is collected;

[0121] 9. The filtrate is transferred into an evaporating pan and heated to boiling. H2O2 and HNO3 are added without stopping until the acidity is 1.5-2.5 mol / L, and then ammonium chloride is added until the precipitation no longer increases. The filtrate A is obtained by filtering, washing the filter residue with 15% NH4Cl solution until it is light-colored, and adding H2O2 and HNO3 until the precipitation no longer increases. The filtrate is filtered, the filter residue is washed with 15% NH4Cl solution until it is colorless, and the washing liquid of the two times is combined to obtain a crude rhodium-containing solution, and the filter residues of the two times are combined to obtain crude (NH4)2IrCl6;

[0122] 10. The crude (NH4)2IrCl6 is slurried with water, the pH is adjusted to 1-1.5, and the mixture is heated to boiling. Hydrazine hydrate solution 400 parts and modified CMK-3 0.6 parts are added with gentle stirring. After the solid no longer decreases, the pH is adjusted to 2-2.5 with ammonia water, and the mixture is boiled for 1.5 h. The filtrate is obtained by cooling and filtering to obtain an iridium-containing solution.

[0123] 11. The iridium-containing solution is adjusted to pH 1.0-1.5 with hydrochloric acid, heated to 80°C, and then ammonium sulfide 340 parts is added. The pH is adjusted to 2.5-3.0 and the mixture is boiled for 2 h. After cooling and storing for 36 h, the mixture is filtered. H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases. The filter residue is washed with 15% NH4Cl solution until it is light-colored, and dried to obtain (NH4)2IrCl6 crystals.

[0124] 12. The (NH4)2IrCl6 crystals are calcined and hydrogen-reduced to obtain high-purity iridium powder.

[0125] Product determination:

[0126] The iridium powder samples were prepared according to Examples 1-3 and Comparative Examples 1-6, respectively.

[0127] 1. Purity determination: Three 0.1 g samples were taken from each of the nine iridium powder samples, and the impurities were measured by inductively coupled plasma atomic emission spectrometry, burning loss, and calculation of the purity of the iridium powder according to GB / T 1422-2018. The average of the three sets of experiments was taken as the result, as shown in Table 1.

[0128] 2. Recovery rate determination: The waste material was used to prepare a test solution, and a standard solution was prepared to obtain a standard curve by atomic emission spectrometry (ICP-AES). The iridium content in the test solution was detected, and the average of three tests was taken as the iridium content in the waste material. Three iridium powder samples were prepared for each example, and the recovery rate of iridium (mass of iridium powder / iridium content in waste material) was calculated. The average of the results was taken as the recovery rate, as shown in Table 1.

[0129] Table 1: Test results of iridium powder

[0130] Purity (%) Recovery (%) Example 1 99.97±0.03 90.5±0.3 Example 2 99.96±0.04 90.2±0.6 Example 3 99.98±0.03 90.4±0.4 Comparative Example 1 98.41±0.04 86.7±0.5 Comparative Example 2 98.76±0.07 85.4±0.6 Comparative Example 3 99.94±0.06 88.6±0.4 Comparative Example 4 99.93±0.03 80.7±0.5 Comparative Example 5 99.94±0.07 84.3±0.3 Comparative Example 6 99.94±0.05 89.8±0.4

[0131] Example 4

[0132] 1. Waste material is stirred uniformly with activated carbon, black phosphorus / red phosphorus heterogeneous junction in a mass ratio of 10:7:2.5, calcined in a marten furnace at 600°C for 2h, cooled to room temperature, and the powder is collected;

[0133] 2. The powder is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, heated to 60-65°C, and 25% sodium chlorate solution is slowly added to the kettle. When the oxidation-reduction potential is greater than 970mV, 25% sodium chlorate solution is continuously added and stirred for 4h. Then the temperature is increased to 85°C until no gas is overflowed, and then cooled to room temperature. Filtration is performed, and the filtrate is collected;

[0134] 3. The filtrate is transferred into an evaporation pan and heated to boiling. H2O2 and HNO3 are continuously added to maintain the acidity at 1.5-2.5mol / L. Then ammonium chloride is added until the precipitation no longer increases. The filtrate A is obtained after acid removal and filtration. The filter residue is washed with 15% NH4Cl solution until it is light-colored. H2O2 and HNO3 are added to the filtrate, and the precipitation no longer increases. Filtration is performed, and the filter residue is washed with 15% NH4Cl solution until it is colorless. The washing liquid and the filtrate are combined to obtain a crude rhodium-containing solution;

[0135] 4. The crude rhodium-containing solution is pretreated with polyethyleneimine-tannin-based adsorption resin using hydrochloric acid with a pH of 2.5 to remove impurities. H2O2 and HNO3 are continuously added, and ammonium chloride is added until the precipitation no longer increases. The filter residue is washed with 15% NH4Cl solution, and the washing liquid and the filtrate are combined. Concentration and drying are performed to obtain (NH4)3RhCl6 crystals;

[0136] 5. The (NH4)3RhCl6 crystals are calcined and hydrogen-reduced to obtain high-purity rhodium powder.

[0137] Example 5

[0138] 1. Waste material is stirred uniformly with activated carbon, black phosphorus / red phosphorus heterogeneous junction in a mass ratio of 10:7:2.5, calcined in a marten furnace at 600°C for 2h, cooled to room temperature, and the powder is collected;

[0139] 2. The powder is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, heated to 60-65°C, and 25% sodium chlorate solution is slowly added to the kettle. When the oxidation-reduction potential is greater than 970mV, 25% sodium chlorate solution is continuously added and stirred for 4h. Then the temperature is increased to 85°C until no gas is overflowed, and then cooled to room temperature. Filtration is performed, and the filtrate is collected;

[0140] 3. The filtrate is transferred into an evaporating pan and heated to boiling. H2O2 and HNO3 are continuously added to maintain the acidity at 1.5-2.5 mol / L, and then NH4Cl is added until the precipitation no longer increases. The filtrate A is obtained by filtering and washing the residue with 15% NH4Cl solution until the color is light. H2O2 and HNO3 are added to the filtrate, and the filtrate is filtered until the color is colorless. The washing solution of the two times of washing is combined to obtain a crude rhodium-containing solution;

[0141] 4. The crude rhodium-containing solution is obtained by using a polyethyleneimine-tannin-based adsorption resin pretreated with HCl of pH 2 to remove impurities, continuously adding H2O2 and HNO3, and adding NH4Cl until the precipitation no longer increases. The residue is washed with 15% NH4Cl solution, and the washing solution and the filtrate are combined and concentrated and dried to obtain (NH4)3RhCl6 crystals;

[0142] 5. The (NH4)3RhCl6 crystals are calcined and hydrogen-reduced to obtain high-purity rhodium powder.

[0143] Example 6

[0144] 1. The waste is stirred with activated carbon and black phosphorus / red phosphorus heterogeneous junction at a mass ratio of 10:7:2.5, and is calcined in a marten furnace at 600°C for 2 h. The powder is collected after the temperature is reduced to room temperature.

[0145] 2. The powder is put into a titanium reaction kettle, 10% HCl is added and stirred, and the temperature is increased to 60-65°C. 25% sodium chlorate solution is slowly added to the kettle. When the oxidation-reduction potential is greater than 970 mV, 25% sodium chlorate solution is continuously added and stirred for 4 h. The temperature is then increased to 85°C until no gas is overflowed, and then the temperature is reduced to room temperature. The filtrate is collected by filtration.

[0146] 3. The filtrate is transferred into an evaporating pan and heated to boiling. H2O2 and HNO3 are continuously added to maintain the acidity at 1.5-2.5 mol / L, and then NH4Cl is added until the precipitation no longer increases. The filtrate A is obtained by filtering and washing the residue with 15% NH4Cl solution until the color is light. H2O2 and HNO3 are added to the filtrate, and the filtrate is filtered until the color is colorless. The washing solution of the two times of washing is combined to obtain a crude rhodium-containing solution;

[0147] 4. The crude rhodium-containing solution is obtained by using a polyethyleneimine-tannin-based adsorption resin pretreated with HCl of pH 2 to remove impurities, continuously adding H2O2 and HNO3, and adding NH4Cl until the precipitation no longer increases. The residue is washed with 15% NH4Cl solution, and the washing solution and the filtrate are combined and concentrated and dried to obtain (NH4)3RhCl6 crystals;

[0148] 5. The (NH4)3RhCl6 crystals are calcined and hydrogen-reduced to obtain high-purity rhodium powder.

[0149] Comparative Example 7

[0150] The difference between this comparative example and Example 4 is that the polyethyleneimine-tannin-based adsorption resin in Step 4 is a styrene cationic adsorption resin, and the rest of the implementation is the same as Example 1.

[0151] Comparative Example 8

[0152] 1. The waste material was uniformly mixed with activated carbon and black phosphorus / red phosphorus heterogeneous junctions at a mass ratio of 10:7:2.5, and was calcined in a marten furnace at 600°C for 2h, and was cooled to room temperature, and the powder was collected;

[0153] 2. The powder was put into a titanium reaction kettle, 10% hydrochloric acid was added and stirred, the temperature was raised to 60-65°C, 25% sodium chlorate solution was slowly added to the kettle, and when the oxidation-reduction potential was greater than 970mV, the 25% sodium chlorate solution was kept stirring for 4h, and then the temperature was raised to 85°C until no gas overflowed, and then it was cooled to room temperature, filtered, and the filtrate was collected;

[0154] 3. The filtrate was transferred into an evaporating pan and boiled with continuous addition of H2O2 and HNO3 to maintain the acidity at 1.5-2.5mol / L, and then ammonium chloride was added until the precipitation no longer increased, the acid was removed by filtration, the filtrate A was reserved, the filter residue was washed with 15% NH4Cl solution until it was light-colored, H2O2 and HNO3 were added to the filtrate, and the precipitation no longer increased, and then it was filtered, the filter residue was washed with 15% NH4Cl solution until it was colorless, and the washing liquid from the two times of washing was combined to obtain a crude rhodium-containing solution;

[0155] 4. The crude rhodium-containing solution was pretreated with polyethyleneimine-tannin-based adsorption resin pretreated with hydrochloric acid with a pH of 1, and then H2O2 and HNO3 were continuously added, and ammonium chloride was added until the precipitation no longer increased, and then the filter residue was washed with 15% NH4Cl, the washing liquid was combined with the filtrate, and then it was concentrated and dried to obtain (NH4)3RhCl6 crystals;

[0156] 5. The (NH4)3RhCl6 crystals were calcined and hydrogen-reduced to obtain high-purity rhodium powder.

[0157] Comparative Example 9

[0158] 1. The waste material was uniformly mixed with activated carbon and black phosphorus / red phosphorus heterogeneous junctions at a mass ratio of 10:7:2.5, and was calcined in a marten furnace at 600°C for 2h, and was cooled to room temperature, and the powder was collected;

[0159] 2. The powder is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, the temperature is raised to 60-65℃, 25% sodium chlorate solution is slowly added to the kettle, and when the redox potential is greater than 970mV, the 25% sodium chlorate solution is kept stirring for 4h, then the temperature is raised to 85℃ and kept until no gas overflow, then it is cooled to room temperature, filtered, and the filtrate is collected;

[0160] 3. The filtrate is transferred into an evaporation pan and heated to boiling, H2O2 and HNO3 are continuously added to keep the acidity at 1.5-2.5mol / L, then ammonium chloride is added until the precipitation no longer increases, the acid is removed by filtration, the filtrate A is reserved, the filter residue is washed with 15% NH4Cl solution until it is light-colored, H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases, then it is filtered, the filter residue is washed with 15% NH4Cl solution until it is colorless, and the washing liquid of the two times is combined to obtain a crude rhodium-containing solution;

[0161] 4. The crude rhodium-containing solution is pretreated with polyethyleneimine-tannin-based adsorption resin using hydrochloric acid with a pH of 4 to remove impurities, then H2O2 and HNO3 are continuously added, ammonium chloride is added until the precipitation no longer increases, the filter residue is washed with 15% NH4Cl solution after filtration, the washing liquid is combined with the filtrate, and concentration and drying are performed to obtain (NH4)3RhCl6 crystals;

[0162] 5. The (NH4)3RhCl6 crystals are calcined and hydrogen-reduced to obtain high-purity rhodium powder.

[0163] Product determination:

[0164] The rhodium powder samples are prepared according to Examples 4-6 and Comparative Examples 7-9, respectively;

[0165] 1. Three portions of each of nine rhodium powder samples, 0.1g each, are taken, and the impurities are measured by inductively coupled plasma atomic emission spectrometer and loss on ignition according to GB / T 1421-2018, the rhodium powder purity is calculated, and the average value of each of the three groups of experiments is taken as the result, as shown in Table 1.

[0166] Table 2

[0167] Purity (%) Example 4 99.95±0.02 Example 5 99.94±0.03 Example 6 99.95±0.03 Comparative Example 7 97.89±0.05 Comparative Example 8 95.71±0.04 Comparative Example 9 98.84±0.03

Claims

1. A process for the recovery of platinum group metals from scrap material, characterized in that, The preparation steps are as follows: (1) The waste material is uniformly stirred with activated carbon and combustion improver at a mass ratio of 10:6~8:2~3, calcined in a marten furnace at 600 DEG C for 2h, cooled to room temperature, and the powder is collected; (2) 100 parts of the powder are uniformly mixed with 600~700 parts of zinc powder, calcined in a marten furnace at 850 DEG C for 8h, cooled to room temperature, ball milled and sieved through a 60 mesh sieve, immersed in 10% hydrochloric acid, and 10% hydrochloric acid is added while stirring until the suspended solids no longer decrease, the solid is collected by filtration, dried, and the active ash is obtained; (3) The active ash is put into a titanium reaction kettle, 10% hydrochloric acid is added and stirred, heated to 60~65 DEG C, 25% sodium chlorate solution is slowly added to the kettle, and when the oxidation-reduction potential is greater than 970mV, 25% sodium chlorate solution is continuously added and stirred for 4h, then heated to 85 DEG C until no gas is overflowed, cooled to room temperature, filtered, and the filtrate is collected; (4) The filtrate is transferred into an evaporating pan, heated and boiled, H2O2 and HNO3 are continuously added without stopping to keep the acidity at 1.5~2.5mol / L, then ammonium chloride is added until the precipitation no longer increases, the acid is removed by filtration, the filtrate A is reserved, the filter residue is washed with 15% NH4Cl solution until it is light-colored, H2O2 and HNO3 are added to the filtrate, the precipitation no longer increases, filtered, the filter residue is washed with 15% NH4Cl solution until it is colorless, the washing liquid of the two times is combined, and the crude rhodium-containing solution is obtained, the filter residue is combined, and the crude (NH4)2IrCl6 is obtained; (5) The crude (NH4)2IrCl6 is slurried with water, the pH is adjusted to 1~1.5, heated and boiled, hydrazine hydrate solution 300~500 parts and reaction aid 0.2~0.5 parts are added while stirring, the solid no longer decreases, then the pH is adjusted to 2~2.5 with ammonia water, boiled for 1~2h, cooled, filtered, and the filtrate is collected to obtain the iridium-containing solution; (6) The iridium-containing solution is adjusted to pH=1.0~1.5 with hydrochloric acid, heated to 80 DEG C, ammonium sulfide 320~360 parts is added, the pH is adjusted to 2.5~3.0 and boiled for 2h, cooled and stored for 36h, then filtered, H2O2 and HNO3 are added to the filtrate until the precipitation no longer increases, filtered, the filter residue is washed with 15% NH4Cl solution until it is light-colored, dried, and the (NH4)2IrCl6 crystal is obtained; (7) The crude rhodium-containing solution is pretreated with the adsorption resin of hydrochloric acid with pH=2~3 to remove impurities, H2O2 and HNO3 are continuously added, ammonium chloride is added until the precipitation no longer increases, filtered, the filter residue is washed with 15% NH4Cl, the washing liquid and the filtrate are combined, concentrated and dried, and the (NH4)3RhCl6 crystal is obtained; (8) The (NH4)2IrCl6 crystal and the (NH4)3RhCl6 crystal are calcined and hydrogen reduced to obtain high-purity iridium and rhodium metal powder; The combustion improver is black phosphorus / red phosphorus heterojunction; The reaction aid is modified CMK-3, and the modification steps are as follows: (a) CMK-3, 2-methyl imidazole and ethanol are taken at a mass ratio of 3~6:2~4:30~40; (b) The CMK-3 and 2-methyl imidazole are added to the ethanol and uniformly mixed, and ultrasonic treatment is performed for 30~40min; (c) The mixture was heated to dryness in a water bath at 40℃, and the solid was calcined at 800℃ for 3h under nitrogen atmosphere to obtain N-CMK-3; (d) N-CMK-3 was added to 8-10 times its mass of deionized water and 0.5w% 0.05mol / l H2PtCl6 aqueous solution was added, and ultrasonic treatment was performed for 10-20min; (e) The mixture was heated to dryness in a water bath at 40℃, and the solid was calcined at 200℃ for 3h under a mixed gas atmosphere of nitrogen and hydrogen at a ratio of 4:1 to obtain Pt / N-CMK-3, i.e. modified CMK-3; The adsorption resin is a polyethyleneimine-tannin-based adsorption resin.