Method for recovering and refining platinum from waste automobile platinum-containing catalyst

Abstract

The invention belongs to the technical field of platinum metal recovery and extraction, and provides a method for recovering and extracting platinum from a platinum-containing catalyst of a waste automobile in order to solve the problem that the traditional wet method is poor in platinum selectivity. A to-be-treated waste automobile platinum-containing catalyst is subjected to roasting, alkali treatment, leaching, first extraction, second extraction, reverse extraction, platinum precipitation and reduction treatment to obtain a finished product platinum, an amide imidazole extraction agent is used in the second extraction and is generated by reacting an amide derivative containing a pyridine ring with imidazole cation salt, cations of the amide imidazole extraction agent are combined with negative complex ions of platinum through electrostatic adsorption, and the platinum-containing catalyst is obtained. Negative ion pyridine ring nitrogen atoms and platinum ions form specific coordination, and selective recognition of platinum and rejection of interfering ions are realized through dual effects; meanwhile, the extraction agent improves the acid resistance through amido bonds, is matched with imidazole cations to reduce the cost, cooperates with pre-extraction impurity removal and an anti-emulsification system, enhances the separation capacity, prepares high-purity platinum and improves the recovery efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of platinum metal recovery and refining, in particular to a method for recovering and refining platinum from waste automobile platinum-containing catalysts. BACKGROUND

[0002] Platinum has become the core material of automobile exhaust purification catalysts due to its excellent catalytic activity and chemical stability. However, the reserves of platinum (Pt) are scarce, and its recovery can reduce the dependence on primary mines and reduce the environmental pressure caused by mining. The platinum content in waste automobile platinum-containing catalysts and waste electronic components is much higher than that in primary mines. Compared with primary mine exploitation, recycling and regenerating platinum can reduce carbon dioxide emissions and avoid ecological damage caused by large-scale mining, which has significant environmental benefits, low recovery cost and high resource value.

[0003] Platinum recovery technology is the core means to realize the recycling of platinum resources. Traditional technologies mainly use pyrometallurgy and hydrometallurgy. Pyrometallurgy separates platinum from the matrix through high-temperature smelting, has large processing capacity and strong adaptability to complex matrices, but has high energy consumption (smelting temperature exceeding 1200℃), is prone to produce flue gas pollution, and the purity of platinum in the product is low. Hydrometallurgy uses chemical reagents to dissolve platinum, and then separates and purifies to obtain pure products. It is the current mainstream fine recovery technology, which can realize high-purity extraction of platinum. However, common extractants such as TBP, N235, and dibutyl carbitol have poor selectivity for platinum, and the separation coefficient of platinum and palladium (Pd) is usually low, so multiple back-extractions are needed to achieve effective separation, resulting in a long extraction process. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a method for recovering and refining platinum from waste automobile platinum-containing catalysts. After the waste automobile platinum-containing catalysts to be treated are subjected to calcination, alkali treatment, leaching, first extraction, second extraction, back-extraction, platinum precipitation and reduction treatment, the finished product platinum is obtained. In the second extraction, an amide imidazole extractant is used, which is generated by the reaction of an amide derivative containing a pyridine ring and an imidazole cation salt. The cation combines with the negative complex ion of platinum through electrostatic adsorption, and the nitrogen atom of the pyridine ring forms specific coordination with the platinum ion. Through the dual action, selective recognition of platinum and exclusion of interfering ions are realized. At the same time, the extractant enhances the separation ability by improving the acid resistance with amide bond, reducing the cost with imidazole cation, and cooperating with pre-extraction impurity removal and anti-emulsion system, to prepare high-purity platinum and improve the recovery efficiency.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] The present application provides a method for recovering and refining platinum from waste automobile platinum-containing catalysts, comprising the following steps:

[0007] S1, the first intermediate is prepared by reacting di(2-ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, and the second intermediate is prepared by reacting 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride; the amide imidazole extractant is prepared by reacting the first intermediate and the second intermediate;

[0008] S2, a mixture is obtained by mixing the spent vehicle containing platinum catalyst to be treated with sodium carbonate and sodium borate, ball milling and calcining to obtain a calcined material; the pretreated platinum-containing material is obtained by twice washing the calcined material; the platinum-containing leaching solution is obtained by leaching the pretreated platinum-containing material with hydrochloric acid and NaClO3;

[0009] S3, the first extraction liquid is prepared by mixing tributyl phosphate and sulfonated kerosene, and the first extraction treatment is performed on the platinum-containing leaching solution with the first extraction liquid to obtain a platinum-containing pre-extraction liquid;

[0010] S4, the second extraction liquid is prepared by mixing the amide imidazole extractant, sulfonated kerosene, isooctanol and anti-emulsifier, and the second extraction treatment is performed on the platinum-containing pre-extraction liquid with the second extraction liquid to obtain a platinum-containing extraction liquid;

[0011] S5, the platinum-containing extraction liquid is subjected to stripping treatment to obtain a platinum-containing stripping liquid;

[0012] S6, the platinum-containing stripping liquid is treated with ammonium chloride to obtain a platinum precipitation material, water is added to the platinum precipitation material to obtain a platinum precipitation slurry, and hydrazine hydrate is added for reduction treatment to obtain a finished product platinum.

[0013] Preferably, in S1, the mass ratio of di(2-ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride is (30-32):(10.2-10.6):(20.2-20.8); the preparation reaction temperature of the first intermediate is 30-35℃, and the time is 5-7h.

[0014] The carboxyl group of di(2-ethylhexyl) phosphate and the amino group of 2-aminopyridine undergo amide reaction under the catalysis of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride (EDC·HCl) to form an amide derivative containing a pyridine ring, i.e. the first intermediate containing a pyridine ring, which provides a structural basis for specific coordination with platinum ions in the subsequent process. As a condensing agent, EDC·HCl promotes the formation of amide bond by activating the carboxyl group, reducing side reactions.

[0015] Preferably, the mass ratio of the 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride in S1 is (28-28.2):(80-82):0.1:(35-36); the preparation method of the second intermediate comprises: mixing the 1-methylimidazole, 1-bromodecane and potassium iodide, and then reacting at 80-85°C for 8-10h, then adding silver chloride, and reacting in the dark for 4-6h, then filtering, and distilling the filtrate under reduced pressure to obtain the second intermediate.

[0016] 1-methylimidazole (N atom containing a lone pair of electrons) undergoes nucleophilic substitution reaction with 1-bromodecane to generate 1-decyl-3-methylimidazole bromide salt, which then undergoes ion exchange with silver chloride (AgCl), and bromide ion combines with Ag + to generate AgBr precipitate, and chloride ion combines with 1-decyl-3-methylimidazole cation to form imidazole cation salt (1-decyl-3-methylimidazole chloride salt) containing chloride ion, which is the core cation part of the second intermediate. The cation carries a positive charge, and can combine with the negative complex ion (PtCl64- 2- ) formed by platinum in the hydrochloric acid system through electrostatic adsorption, which is one of the key structures for selective capture of platinum by the amide imidazole extractant.

[0017] Preferably, the mass ratio of the first intermediate and the second intermediate in S1 is (42-45):(30-32); the preparation reaction temperature of the amide imidazole extractant is 40-45°C, and the time is 3-5h.

[0018] The first intermediate contains a pyridine ring, which is an anion group, and combines with the second intermediate containing a cation group through electrostatic attraction to form an ionic liquid structure to obtain the amide imidazole extractant.

[0019] Preferably, the mass ratio of the waste automobile containing platinum catalyst, sodium carbonate and sodium borate in S2 is 10:(16-27):(0.4-0.8); the ball milling is grinding to a particle size of the mixture ≤50 microns, the calcination is carried out in an air atmosphere, the calcination temperature is 1300-1400°C, and the calcination time is 3-4h; the secondary washing comprises: immersing the calcined material in deionized water at a temperature of 80-85°C at a solid-liquid mass ratio of 1:(8-10), stirring for 30-40min, then filtering, immersing the filter residue in mixed acid liquid at a solid-liquid mass ratio of 1:(8-10), and soaking for 1-2h; the mixed acid liquid is obtained by mixing 15% hydrochloric acid and 10% sulfuric acid at a volume ratio of 1:1.

[0020] In the process of calcination at high temperature 1300-1400℃, the carrier of the spent car catalyst to be treated, cordierite (2MgO·2Al2O3·5SiO2), reacts with sodium carbonate and sodium borate to form sodium silicate, sodium aluminate, sodium aluminosilicate and magnesium oxide, while the platinum group metals do not react and remain in the original state; the calcination product is ground to increase the contact area, and sodium silicate and sodium aluminate are dissolved in hot water at this time, while the sodium aluminosilicate is not dissolved, and magnesium hydroxide or basic magnesium carbonate may be formed. Then the sodium aluminosilicate and other water-insoluble substances are dissolved by mixing acid solution, and after solid-liquid separation, most of the magnesium, aluminum, silicon, sodium, etc. enter the solution, and the platinum group metals enter the filter residue.

[0021] Preferably, the mass-volume ratio of the pretreated platinum-containing material, hydrochloric acid and NaClO3 in S2 is (9.8-10.2) kg:50 L:5.4 kg, the temperature of the leaching treatment is 70-75℃, and the time is 3-5h; the concentration of the hydrochloric acid is 6-8 mol / L.

[0022] Hydrochloric acid provides high-concentration Cl - , and NaClO3 as an oxidizing agent oxidizes solid Pt to soluble PtCl6 2- (3Pt+ClO3 - +6H + +11Cl - =3PtCl6 2- +3H2O), so that platinum is transferred from the solid material to the solution, realizing the preliminary leaching and selective enrichment of platinum, while Pd and Rh have a lower leaching rate due to insufficient oxidation conditions.

[0023] Preferably, the volume ratio of the tri-butyl phosphate and the sulfonated kerosene in the first extraction liquid in S3 is (20-25):(75-80), and the first extraction treatment includes: mixing the platinum-containing leaching solution with the first extraction liquid in equal volume and then standing to separate the layers, and taking the lower aqueous phase as the platinum-containing pre-extraction liquid.

[0024] Tri-butyl phosphate (TBP) as an extractant forms a neutral complex (FeCl3・3TBP) with Fe 3+ and other impurity ions (in the form of FeCl4 - ) in the leaching solution, which is extracted into the sulfonated kerosene organic phase, removing Fe 3+ and other interfering ions in the leaching solution to avoid their competition with platinum for the binding sites of the extractant.

[0025] Preferably, in S4, the mass ratio of the amide imidazole extractant, sulfonated kerosene, isooctanol and anti-emulsifier in the second extraction liquid is (5-5.2):55:40:0.5, the anti-emulsifier is Span-80; the second extraction treatment is countercurrent extraction, the volume ratio of the platinum-containing pre-extraction liquid to the second extraction liquid is (70-75):(25-30), the temperature of the countercurrent extraction is 50-55℃, the extraction time is 30-40min, and the upper organic phase after the countercurrent extraction is taken as the platinum-containing extraction liquid.

[0026] The cationic part (imidazole cation) of the amide imidazole extractant is combined with PtCl6 2- through electrostatic attraction, and the pyridine ring nitrogen atom of the anionic part is combined with the empty d orbital of Pt 4+ through a lone pair of electrons to form a specific coordination bond, so that PtCl6 2- is selectively transferred from the pre-extraction liquid to the organic phase; while PdCl4 2- and RhCl6 3- are difficult to be combined due to poor charge distribution, structure and extractant adaptability, so that platinum and other noble metals such as Pd and Rh are efficiently separated, and the enrichment degree of platinum is greatly improved. The countercurrent extraction strengthens the separation efficiency through multi-stage contact.

[0027] Preferably, in S5, the stripping treatment includes mixing the platinum-containing extraction liquid, a 0.3-0.4mol / L Na2SO3 solution and a 0.5-0.6mol / L HCl solution in a volume ratio of (6-6.2):2:1 for extraction, taking the lower liquid as the platinum-containing stripping liquid after standing and separating, the temperature of the stripping treatment is 40-45℃, and the time is 1-2h.

[0028] The SO3 2- provided by sodium sulfite (Na2SO3) forms a stable complex ion [Pt(SO3)4] 4+ with Pt 4- , replaces the combination of the extractant and platinum, and transfers platinum from the organic phase to the aqueous phase to obtain a high-concentration platinum-containing stripping liquid, so that platinum and the extractant are separated, and subsequent purification is facilitated; hydrochloric acid maintains an acidic environment to promote the complex equilibrium to move in the stripping direction.

[0029] Preferably, in S6, the amount of the ammonium chloride is 8%-15% of the mass of the platinum-containing stripping liquid; the solid content of the platinum precipitation slurry is 15%-25%; the hydrazine hydrate is a 10% hydrazine hydrate solution, the volume ratio of the platinum-containing stripping liquid to the hydrazine hydrate solution is 100:(1.25-1.67), the temperature of the reduction treatment is 30-80℃, the time is 0.5-2h, and after the reduction treatment, filtration is performed, and the filter residue is the finished product platinum.

[0030] The platinum ions in the platinum-containing stripping solution react with ammonium chloride to form ammonium chloroplatinate precipitate (H2PtCl6+2NH4Cl=(NH4)2PtCl6↓+2HCl), thereby realizing the enrichment and purification of platinum.

[0031] Preferably, hydrazine hydrate is added after the pH of the platinum deposition slurry is adjusted to 7.5-12.

[0032] In the alkaline environment with pH=7.5-12, hydrazine hydrate reduces the ammonium chloroplatinate to metallic platinum as a strong reducing agent, and high-purity finished platinum is obtained after washing and drying.

[0033] Beneficial technical effects:

[0034] The application provides a method for recovering and extracting platinum from a waste automobile platinum-containing catalyst. The extraction effect on platinum is improved by using an amide imidazole extractant. The amide imidazole extractant is introduced to carry a positive ion part, and the negative complex ion formed by platinum in a hydrochloric acid system is preliminarily combined through electrostatic adsorption, so that the capture efficiency of the platinum complex ion is improved, and the extraction is promoted. On the other hand, by introducing an anion part containing a pyridine ring structure, the lone pair electrons of the pyridine ring nitrogen atom can form a specific coordination bond with the empty d orbital of the platinum ion. This coordination has a high structure adaptability, and forms a stable combination with the platinum ion. At this time, other noble metal ions such as palladium (Pd) and rhodium (Rh) cannot form a coordination bond with the pyridine ring with the same strength, and the charge distribution and structure of the complex ion cannot be adapted, so they are effectively excluded, thereby realizing the selective separation of platinum. Through the dual action of electrostatic adsorption and specific coordination, the application realizes the selective recognition of platinum and effectively excludes interfering ions. At the same time, the amide imidazole extractant replaces the ester bond with an amide bond to improve the acid resistance, and cooperates with the imidazole cation to reduce the cost, solves the contradiction between the stability and economy of the traditional ionic liquid, and cooperates with the process design such as pre-extraction impurity removal and anti-emulsification system, significantly enhances the separation ability of platinum and other noble metals, and finally improves the extraction efficiency while considering environmental protection and practicality. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A schematic diagram of the method for recovering and extracting platinum from a waste automobile platinum-containing catalyst of the application;

[0036] Figure 2 A finished platinum product obtained by recovering and extracting platinum from a waste automobile platinum-containing catalyst according to Example 1 of the application. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in conjunction with embodiments. However, it should not be understood as a limitation on the scope of the present application only to the following examples. Without departing from the above method idea of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0038] In the present application, the terms used in the present application are merely for the purpose of describing specific embodiments, and are not intended to limit the present application.

[0039] As used in the present application, the singular forms "is", "or", "a", "any" and "the" are intended to include the plural forms, unless the context clearly indicates otherwise.

[0040] In addition, if the terms "first", "second" appear, they are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0041] The following will be specifically described in conjunction with different embodiments a method for recovering and refining platinum from waste automobile platinum-containing catalyst provided by the present application.

[0042] The waste automobile platinum-containing catalyst used in the embodiments has a particle size of <5 mm, a Pt content of 216 g / t, a Rh content of 207 g / t, a Pd content of 3021 g / t, and a cordierite carrier content of more than 90%.

[0043] Embodiment 1

[0044] As shown in Figure 1 A method for recovering and refining platinum from waste automobile platinum-containing catalyst, comprising the following steps:

[0045] 1. Add ethyl acetate, di(2-ethylhexyl) phosphate and 2-aminopyridine into the reaction container in sequence, mix uniformly, heat to 30°C, then add 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, the mass-volume ratio of ethyl acetate, di(2-ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride is 200L:31kg:10.4kg:20.5kg, to obtain a reaction system, after 6h of reaction, add 50% of the volume of deionized water to the reaction container, stir for 30min, then stand to take the organic phase, wash with 5% NaHCO3 solution for 2 times, the volume of NaHCO3 solution for each washing is 25% of the organic phase, then wash with deionized water until neutral, and obtain the first intermediate by reduced pressure distillation;

[0046] 2. Mix 95% ethanol, 1-methylimidazole, 1-bromodecane and potassium iodide, heat to 80℃ for 9h, cool to room temperature, add silver chloride, the mass-volume ratio of 95% ethanol, 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride is 500L:28.1kg:81kg:0.1kg:35.5kg, stir in the dark for 5h, then filter, take the filtrate and distill under reduced pressure to obtain the second intermediate;

[0047] 3. Stir the acetonitrile, the first intermediate and the second intermediate in a mass-volume ratio of 200L:44kg:31kg until uniform, react at 40℃ for 4h, distill under reduced pressure, wash with n-hexane for 3 times, and dry in vacuum to obtain the amide imidazole extractant;

[0048] 4. Mix the platinum-containing catalyst to be treated with sodium carbonate and sodium borate in a mass ratio of 10:16:0.8 to obtain a mixture, ball mill to a particle size of ≤50 microns, then put into a rotary kiln, calcine at 1300℃ for 4h in an air atmosphere to obtain a calcined material, immerse the calcined material in deionized water at a temperature of 80℃ in a solid-liquid mass ratio of 1:8, stir for 30min, then filter, immerse the filter residue in a mixed acid solution in a solid-liquid mass ratio of 1:8, and soak for 1h; the mixed acid solution is obtained by mixing 15% hydrochloric acid and 10% sulfuric acid in a volume ratio of 1:1, filter, wash the filter residue with deionized water until neutral, and dry to obtain a pretreated platinum-containing material;

[0049] 5. Mix the pretreated platinum-containing material with 7mol / L hydrochloric acid, then add NaClO3, the mass-volume ratio of the pretreated platinum-containing material, hydrochloric acid and NaClO3 is 10kg:50L:5.4kg, react at 70℃ for 4h, then filter to obtain a platinum-containing leaching solution;

[0050] 6. Mix tributyl phosphate and sulfonated kerosene in a volume ratio of 22:78 to obtain a first extraction liquid, mix the platinum-containing leaching solution with the first extraction liquid in equal volume, then stand to separate into layers, and take the lower aqueous phase as a platinum-containing pre-extraction liquid;

[0051] 7. Mix the amide imidazole extractant, sulfonated kerosene, isooctanol and Span-80 in a mass ratio of 5.1:55:40:0.5 to obtain a second extraction liquid, and perform countercurrent extraction of the platinum-containing pre-extraction liquid and the second extraction liquid in a volume ratio of 72:28 at 50℃, the extraction time is 35min, and take the upper organic phase to obtain a platinum-containing extraction liquid;

[0052] 8. Mix the platinum-containing extraction liquid, a 0.35mol / L Na2SO3 solution and a 0.55mol / L HCl solution in a volume ratio of 6.1:2:1, stir at 42℃ for 1.5h, stand to separate into layers, and take the lower liquid as a platinum-containing stripping liquid;

[0053] 9. Add 10% of liquid mass of ammonium chloride to the platinum-containing stripping solution, and solid-liquid separation to obtain platinum precipitation material, add water to the platinum precipitation material to obtain a platinum precipitation slurry with a solid content of 15%, adjust to pH = 9, mix with a 50% hydrazine hydrate solution, the volume ratio of the platinum-containing stripping solution to the hydrazine hydrate solution is 100:1.46, react at 30°C for 2h, after filtration, wash and dry the filter residue with deionized water to obtain the finished platinum as shown in Figure 2 .

[0054] Example 2

[0055] As shown in Figure 1 , a method for recovering and refining platinum from waste automobile platinum-containing catalysts, comprising the following steps:

[0056] 1. Add ethyl acetate, di(2-ethylhexyl) phosphate and 2-aminopyridine into the reaction container in sequence, mix uniformly, heat to 35°C, then add 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride, the mass-volume ratio of ethyl acetate, di(2-ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride is 200L:32kg:10.2kg:20.8kg, to obtain a reaction system, after reacting for 7h, add 50% of deionized water by volume of the reaction system into the reaction container, stir for 30min, then stand to take the organic phase, wash with 5% NaHCO3 solution for 2 times, the volume of NaHCO3 solution for each washing is 25% of the organic phase, then wash with deionized water until neutral, and obtain the first intermediate by distillation under reduced pressure;

[0057] 2. Mix 95% ethanol, 1-methylimidazole, 1-bromodecane and potassium iodide, heat to 85°C and react for 10h, cool to room temperature, add silver chloride, the mass-volume ratio of 95% ethanol, 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride is 500L:28.2kg:80kg:0.1kg:36kg, stir in the dark for 6h, then filter, and distill under reduced pressure to obtain the second intermediate;

[0058] 3. Stir uniformly acetonitrile, the first intermediate and the second intermediate with a mass-volume ratio of 200L:45kg:30kg, react at 45°C for 5h, distill under reduced pressure, wash with n-hexane for 3 times, and dry under vacuum to obtain the amide imidazole extractant;

[0059] 4. The platinum-containing catalyst from the waste vehicle to be treated is mixed with sodium carbonate and sodium borate at a mass ratio of 10:20:0.6 to obtain a mixture, which is ball milled to a particle size of ≤50 microns and then placed in a rotary kiln, and calcined at 1350°C for 3.5h in an air atmosphere to obtain a calcined material, which is immersed in deionized water at a temperature of 85°C at a solid-liquid mass ratio of 1:9, stirred for 35 min, and then filtered, and the filter residue is immersed in a mixed acid solution at a solid-liquid mass ratio of 1:9 for 1.5h, filtered, the filter residue is washed with deionized water until neutral, and dried to obtain a pretreated platinum-containing material;

[0060] 5. The pretreated platinum-containing material is mixed with 8 mol / L hydrochloric acid, and then NaClO3 is added, and the mass-volume ratio of the pretreated platinum-containing material, hydrochloric acid and NaClO3 is 10.2 kg:50 L:5.4 kg, and the mixture is reacted at 75°C for 5h, and then filtered to obtain a platinum-containing leaching solution;

[0061] 6. Tributyl phosphate and sulfonated kerosene are mixed at a volume ratio of 25:75 to obtain a first extraction liquid, and the platinum-containing leaching solution is mixed with the first extraction liquid at an equal volume to obtain a platinum-containing pre-extraction liquid after standing and layering;

[0062] 7. Amide imidazole extractant, sulfonated kerosene, isooctanol and Span-80 are mixed at a mass ratio of 5.2:55:40:0.5 to obtain a second extraction liquid, and the platinum-containing pre-extraction liquid is countercurrently extracted with the second extraction liquid at a volume ratio of 75:25 at 50-55°C for 40 min, and the upper organic phase is obtained as a platinum-containing extraction liquid;

[0063] 8. The platinum-containing extraction liquid, 0.4 mol / L Na2SO3 solution and 0.6 mol / L HCl solution are mixed at a volume ratio of 6.2:2:1, stirred at 45°C for 2h, and then allowed to stand and layer, and the lower liquid is taken as a platinum-containing stripping liquid;

[0064] 9. Ammonium chloride is added to the platinum-containing stripping liquid at a liquid mass of 8%, and solid-liquid separation is performed to obtain a platinum deposition material, and the platinum deposition material is slurried with water to obtain a platinum deposition slurry with a solid content of 20%, and then adjusted to pH=12, mixed with a 10% hydrazine hydrate solution, and the volume ratio of the platinum-containing stripping liquid to the hydrazine hydrate solution is 100:1.67, and the mixture is reacted at 50°C for 1h, and then filtered, and the filter residue is washed with deionized water and dried to obtain a finished platinum product.

[0065] Example 3

[0066] As shown in Figure 1 , a method for recovering and extracting platinum from a platinum-containing catalyst from a waste vehicle, comprising the following steps:

[0067] 1. Into a reaction vessel, ethyl acetate, di(2-ethylhexyl) phosphate and 2- aminopyridine were sequentially added and mixed well, then 1-(3- dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added after the temperature was raised to 35℃, the mass / volume ratio of ethyl acetate, di(2- ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3- ethylcarbodiimide hydrochloride was 200L:30kg:10.6kg:20.2kg, to obtain a reaction system, after 5h of reaction, 50% of the volume of deionized water was added to the reaction vessel, stirred for 30min, then the organic phase was separated, washed with 5% NaHCO3 solution twice, the volume of NaHCO3 solution was 25% of the volume of the organic phase, then washed with deionized water until neutral, and the first intermediate was obtained by vacuum distillation;

[0068] 2. 95% ethanol, 1-methylimidazole, 1-bromodecane and potassium iodide were mixed, the temperature was raised to 85℃ and reacted for 8h, then cooled to room temperature, silver chloride was added, the mass / volume ratio of 95% ethanol, 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride was 500L:28kg:82kg:0.1kg:35kg, stirred in the dark for 4h, then filtered, the filtrate was vacuum distilled to obtain the second intermediate;

[0069] 3. Acetonitrile, the first intermediate and the second intermediate were stirred well at a mass / volume ratio of 200L:42kg:32kg, reacted at 45℃ for 3h, washed with n-hexane 3 times, and vacuum dried to obtain the amide imidazole extractant;

[0070] 4. The platinum-containing catalyst from a waste vehicle to be treated was mixed with sodium carbonate and sodium borate at a mass ratio of 10:27:0.4 to obtain a mixture, which was ball milled to a particle size of ≤50 microns, then put into a rotary kiln, calcined at 1400℃ for 3h in an air atmosphere to obtain a calcined material, the calcined material was immersed in deionized water at a temperature of 80℃ at a solid-liquid mass ratio of 1:10, stirred for 40min, then filtered, the filter residue was immersed in a mixed acid solution at a solid-liquid mass ratio of 1:10 for 2h, the mixed acid solution was obtained by mixing 15% hydrochloric acid and 10% sulfuric acid at a volume ratio of 1:1, filtered, the filter residue was washed with deionized water until neutral, and dried to obtain a pretreated platinum-containing material;

[0071] 5. The pretreated platinum-containing material was mixed with 6mol / L hydrochloric acid, then NaClO3 was added, the mass / volume ratio of the pretreated platinum-containing material, hydrochloric acid and NaClO3 was 9.8kg:50L:5.4kg, reacted at 75℃ for 3h, then filtered to obtain a platinum-containing leaching solution;

[0072] 6. Phosphoric acid tributyl ester and sulfonated kerosene were mixed at a volume ratio of 20:80 to obtain a first extraction liquid, the platinum-containing leaching solution was mixed with the first extraction liquid at an equal volume to obtain a mixture, which was allowed to stand and separate into layers, and the lower aqueous phase was taken as a platinum-containing pre-extraction liquid;

[0073] 7. The amide imidazole extractant, sulfonated kerosene, isooctanol and Span-80 are mixed in a mass ratio of 5:55:40:0.5 to obtain a second extraction liquid, and the platinum-containing pre-extraction liquid is countercurrently extracted with the second extraction liquid at a volume ratio of 70:30 at 55°C for 30 min, and the upper organic phase is taken to obtain a platinum-containing extraction liquid;

[0074] 8. The platinum-containing extraction liquid, a 0.3 mol / L Na2SO3 solution and a 0.5 mol / L HCl solution are mixed at a volume ratio of 6:2:1, stirred at 45°C for 1 h, and then allowed to stand to separate into layers, and the lower liquid is taken as a platinum-containing stripping liquid;

[0075] 9. Ammonium chloride is added to the platinum-containing stripping liquid at a liquid mass of 15%, and solid-liquid separation is performed to obtain a platinum precipitation material, water is added to the platinum precipitation material to obtain a platinum precipitation slurry with a solid content of 25%, the pH is adjusted to 7.5, and then the platinum-containing stripping liquid is mixed with an 80% hydrazine hydrate solution at a volume ratio of 100:1.25, and the mixture is reacted at 80°C for 0.5 h, and then the filter residue is washed and dried with deionized water to obtain finished platinum.

[0076] Comparative Example 1

[0077] A method for recovering and refining platinum from a waste automobile platinum-containing catalyst, the implementation steps and parameters are the same as those of Example 1, except that TBP is used instead of amide imidazole extractant.

[0078] Comparative Example 2

[0079] A method for recovering and refining platinum from a waste automobile platinum-containing catalyst, the implementation steps and parameters are the same as those of Example 1, except that trihexylphosphine is used instead of 1-methylimidazole.

[0080] Comparative Example 3

[0081] A method for recovering and refining platinum from a waste automobile platinum-containing catalyst, the implementation steps and parameters are the same as those of Example 1, except that n-butylamine is used instead of 2-aminopyridine.

[0082] Performance test:

[0083] The purity (%) of the finished platinum obtained in Examples 1-3 and Comparative Examples 1-3 is detected, denoted as Y, and the results are shown in Table 1.

[0084] The weight of the finished platinum in Examples 1-3 and Comparative Examples 1-3 is weighed, denoted as m, the mass of platinum contained therein is calculated according to the purity Y of the finished platinum, denoted as m1, m1=m×Y×100%, the platinum content in the waste automobile platinum-containing catalyst to be treated is denoted as m0, and the Pt recovery rate (%)=(m / m0)×100%, and the results are shown in Table 1.

[0085] Table 1 Test results of purity and Pt recovery rate of finished product platinum prepared in Examples 1-3 and Comparative Examples 1-3

[0086] Final platinum purity (%) Pt recovery (%) Example 1 99.97 98.0 Example 2 99.96 96.5 Example 3 99.95 94.6 Comparative Example 1 82.55 85.3 Comparative Example 2 88.74 90.2 Comparative Example 3 85.10 88.6

[0087] As shown in Table 1, the purity of finished product platinum obtained by the method for recovering and extracting platinum from waste automobile platinum-containing catalyst provided in Examples 1-3 is greater than 99.95%, and the Pt recovery rate is 94.6%-98.0%. The purity of finished product platinum in Comparative Examples 1-3 is only 82.55%-88.74%, and the recovery rate is 85.3%-90.2%, which is significantly lower than that of the examples, indicating that the scheme of the application can prepare high-purity platinum and improve the recovery efficiency.

[0088] In Comparative Example 1, TBP is used to replace the amide imidazole extractant. TBP only has electrostatic adsorption with PtCl6 2- , lacks specific coordination, and has weak repulsion ability to PdCl4 2- and RhCl6 3- , resulting in a significant increase in the co-extraction rate of the three metals and a decrease in the purity of the finished product platinum. At the same time, TBP has weak extraction ability to Pt and is easily interfered by impurities such as Fe 3+ , resulting in a decrease in the final recovery rate to 85.3%.

[0089] In Comparative Example 2, trihexylphosphine is used to replace 1-methylimidazole. Trihexylphosphine cations have poor stability and are easily hydrolyzed to form byproducts in acidic leaching solution, resulting in a decrease in the effective concentration of the extractant. The electrostatic adsorption of trihexylphosphine with PtCl6 2- is weak, and it lacks the structural adaptability of the imidazole ring, resulting in a decrease in the selectivity to platinum, an increase in the co-extraction rate of Pd / Rh, and a decrease in the purity of the finished product platinum. At the same time, the hydrolysis products occupy the extraction sites, resulting in a decrease in the capture efficiency of platinum and a decrease in the recovery rate.

[0090] In Comparative Example 3, n-butylamine is used to replace 2-aminopyridine. n-Butylamine does not contain a pyridine ring, loses the specific coordination with Pt 4+ , and only relies on electrostatic adsorption to capture PtCl6 2- , resulting in a significant decrease in the ability to distinguish Pd and Rh and a significant decrease in the purity. In addition, the combination ability of the extractant without a pyridine ring with PtCl6 2- is reduced, resulting in the ineffective extraction of part of the platinum and a decrease in the recovery rate.

[0091] The above results show and describe the basic principles and main features of the application and the advantages of the application.

[0092] Those skilled in the art should understand that the present application is not limited by the above-mentioned embodiments, the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the equivalents of the appended claims.

Claims

1. A method for recovering and refining platinum from waste automobile platinum-containing catalysts, characterized in that: The following steps are involved: S1, reacting di(2-ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride to prepare a first intermediate, reacting 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride to prepare a second intermediate; reacting the first intermediate and the second intermediate to prepare an amide imidazole extractant; S2. Mixing the waste automobile platinum-containing catalyst to be processed with sodium carbonate and sodium borate to obtain a mixed material, ball-milling, and calcining to obtain a calcined material; washing the calcined material twice to obtain a pretreated platinum-containing material; and leaching the pretreated platinum-containing material with hydrochloric acid and NaClO3 to obtain a platinum-containing leachate; S3, preparing a first extracting solution with tributyl phosphate and sulfonated kerosene, and performing a first extraction treatment on the platinum-containing leachate with the first extracting solution to obtain a platinum-containing pre-extracting solution; S4, preparing a second extract with an amide imidazole extractant, sulfonated kerosene, isooctyl alcohol, and an anti-emulsifier, and performing a second extraction treatment on the platinum-containing pre-extract with the second extract to obtain a platinum-containing extract; S5, stripping the platinum-containing extract to obtain a platinum-containing stripping solution; S6. Treating the platinum-containing stripping solution with ammonium chloride to obtain a platinum-precipitated material, adding water to the platinum-precipitated material and mixing to obtain a platinum-precipitated slurry, and then adding hydrazine hydrate for reduction treatment to obtain a finished platinum product.

2. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The mass ratio of di(2-ethylhexyl) phosphate, 2-aminopyridine and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride in S1 is (30-32):(10.2-10.6):(20.2-20.8); the reaction temperature for the preparation of the first intermediate is 30-35°C and the time is 5-7h.

3. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The mass ratio of 1-methylimidazole, 1-bromodecane, potassium iodide and silver chloride in S1 is (28-28.2):(80-82):0.1:(35-36); the preparation method of the second intermediate comprises: mixing the 1-methylimidazole, 1-bromodecane and potassium iodide, reacting at 80-85°C for 8-10 hours, adding silver chloride, reacting in the dark for 4-6 hours, filtering, and distilling the filtrate under reduced pressure to obtain the second intermediate.

4. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The mass ratio of the first intermediate to the second intermediate in S1 is (42-45):(30-32); the preparation reaction temperature of the amide imidazole extractant is 40-45°C and the time is 3-5h.

5. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The mass ratio of the platinum-containing catalyst, sodium carbonate, and sodium borate in the waste automobile to be processed in S2 is 10:(16-27):(0.4-0.8); the ball milling is performed to grind the mixture to a particle size of ≤50 μm, and the calcination is performed in an air atmosphere at a temperature of 1300-1400° C. for 3-4 hours. The secondary washing comprises: immersing the roasted material in deionized water at a temperature of 80-85° C. at a solid-liquid mass ratio of 1:(8-10), stirring for 30-40 minutes and then filtering, and immersing the filter residue in a mixed acid solution at a solid-liquid mass ratio of 1:(8-10) for 1-2 hours; the mixed acid solution is obtained by mixing 15% hydrochloric acid and 10% sulfuric acid at a volume ratio of 1:

1.

6. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The mass volume ratio of the pretreated platinum-containing material, hydrochloric acid and NaClO3 in S2 is (9.8-10.2) kg:50 L:5.4 kg, the temperature of the leaching treatment is 70-75 ° C, and the time is 3-5 h; the concentration of the hydrochloric acid is 6-8 mol / L.

7. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The volume ratio of the tributyl phosphate and the sulfonated kerosene in the first extract in S3 is (20-25):(75-80), and the first extraction treatment includes: mixing equal volumes of the platinum-containing leachate and the first extract, then standing to separate the layers, and taking the lower aqueous phase as the platinum-containing pre-extract.

8. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: In S4, the mass ratio of the amide imidazole extractant, sulfonated kerosene, isooctyl alcohol and anti-emulsifier in the second extract is (5-5.2):55:40:0.5, and the anti-emulsifier is Span-80; the second extraction treatment is countercurrent extraction, the volume ratio of the platinum-containing pre-extract and the second extract is (70-75):(25-30), the temperature of the countercurrent extraction is 50-55°C, the extraction time is 30-40min, and the upper organic phase after the countercurrent extraction is taken to obtain the platinum-containing extract.

9. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The stripping treatment in S5 includes: mixing the platinum-containing extract, 0.3-0.4 mol / L Na2SO3 solution and 0.5-0.6 mol / L HCl solution in a volume ratio of (6-6.2):2:1 for extraction, and after standing and stratification, taking the lower layer of liquid as the platinum-containing stripping solution. The temperature of the stripping treatment is 40-45°C and the time is 1-2h.

10. The method for recovering and refining platinum from platinum-containing catalysts in scrap automobiles according to claim 1, characterized in that: The amount of ammonium chloride in S6 is 8%-15% of the mass of the platinum-containing stripping solution; the solid content of the platinum precipitated slurry is 15%-25%; the hydrazine hydrate is a 10%-80% hydrazine hydrate solution, the volume ratio of the platinum-containing stripping solution to the hydrazine hydrate solution is 100:(1.25-1.67), the temperature of the reduction treatment is 30-80°C, the time is 0.5-2h, and the reduction treatment is filtered after completion, and the filter residue is the finished platinum.

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