Method for efficiently recovering palladium from waste palladium / resin catalyst

Abstract

The invention relates to the technical field of palladium recovery, and particularly discloses a method for efficiently recovering palladium from a waste palladium / resin catalyst, and the method comprises the steps of oxygen-enriched roasting, vacuum roasting, synergistic oxidation leaching and the like, and can achieve the following effects that under the oxygen-enriched condition, on one hand, decomposition and combustion of macromolecular organic matter are accelerated, and the decomposition rate of a resin carrier is increased; under the conventional roasting condition, the resin decomposition rate is 70-80% within 1-2 h, the organic matter decomposition rate is increased to 85-95% after oxygen is blown in, and subsequent leaching of palladium is facilitated. And meanwhile, the temperature required by roasting is reduced, and efficient decomposition of organic matters can be realized at 500-650 DEG C. Through vacuum roasting, palladium oxide is reduced under the high-temperature condition, the reduction process is shortened, and the efficiency is improved. Hydrochloric acid, hydrogen peroxide and ozone are adopted for synergistic leaching, and the leaching rate is increased; the bivalent palladium in the ozone oxidation solution is adopted, compared with systems such as nitric acid and chlorine, the method is more environmentally friendly, and pollution is reduced.

Description

Technical Field

[0001] The invention relates to a palladium recovery method, in particular to a method for efficiently recovering palladium from a waste palladium / resin catalyst, belonging to the technical field of palladium recovery. Background Art

[0002] Palladium is a scarce platinum group metal, and its usage has been increasing annually, making it the world's most consumed platinum group metal. According to industry statistics, my country's demand for palladium catalysts accounts for over 90% of total palladium demand. In the petrochemical industry, palladium catalysts are used in the production of organic chemical raw materials such as selective hydrogenation, acetaldehyde, and vinyl acetate. The use of palladium catalysts reduces pollution in the production process and maximizes energy conservation and consumption reduction. Research on palladium catalysts has created favorable conditions for the development of new reaction routes and processes in the petrochemical industry. However, my country's palladium mineral resources are limited and far from meeting the development needs of various industries. Spent palladium / resin catalysts used in the petrochemical and pharmaceutical industries are a key palladium-containing secondary resource, with an annual domestic production of nearly 100 tons, containing Pd content ranging from 1.5% to 2%. Recycling and reusing these waste catalysts is crucial for resolving the imbalance between supply and demand for palladium resources in my country.

[0003] At present, the industrial recovery of palladium / resin waste catalysts mainly adopts the process route of roasting-reduction-leaching-purification.

[0004] Calcination decomposes the resin carrier, generating volatilization gases such as carbon dioxide and water vapor. This prevents insufficient contact between the palladium and hydrochloric acid during subsequent leaching, which can affect the leaching reaction speed and efficiency. Calcination temperatures that are too low or for too short a time will result in incomplete carrier decomposition, while calcinations that are too high or for too long may cause severe oxidation of the palladium, hindering palladium leaching.

[0005] During the roasting process, some palladium oxidizes to form palladium oxide. Palladium oxide is extremely resistant to acids and alkalis, and even aqua regia cannot dissolve it. Therefore, the calcined material requires a reduction pretreatment before leaching to reduce the palladium oxide to palladium, thereby improving the palladium leaching rate in the subsequent acid leaching process. Currently, the most common method uses hydrazine hydrate as a reducing agent to reduce palladium oxide. However, hydrazine hydrate is expensive, increasing production costs. After reduction, the reducing agent must be rinsed clean with a large amount of water; otherwise, the amount of hydrochloric acid and oxidant required in the subsequent leaching process will be significantly increased. The hydrazine hydrate washing process generates a large amount of wastewater, which, with increasing environmental protection requirements, increases processing costs. Furthermore, palladium metal adhering to the surface of the waste material is lost with the wash water, reducing metal recovery. Furthermore, the hydrazine hydrate washing process is time-consuming, reducing production efficiency and increasing production costs.

[0006] After calcination, the catalyst is leached by wet method. The leaching processes mainly include aqua regia dissolution method, chloride dissolution method, etc., so that palladium enters the solution in the form of ions.

[0007] The aqua regia dissolution method is currently a common method for recovering spent palladium-containing resin catalysts due to its simple process equipment, low cost, and easily controlled operating conditions. However, the aqua regia dissolution process produces large amounts of nitrogen oxides, which seriously pollute the environment and increase the cost of treating wastewater and exhaust gases.

[0008] The chlorination dissolution method is stable and reliable, has a high leaching rate and high economic benefits, but the chlorine used in the chlorination method is highly toxic, and the equipment must be sealed to a certain extent. At the same time, the system is highly acidic and oxidizing, which places high demands on the equipment and has high investment costs.

[0009] Palladium is generally purified using ammonium chloride precipitation. Tetravalent palladium reacts with ammonium chloride to form a (NH4)2PdCl6 precipitate, separating the palladium from impurities. Divalent palladium and ammonium chloride cannot form a precipitate, making separation impossible. However, because tetravalent palladium is unstable and easily converts to divalent, an oxidant must be added to the solution before adding ammonium chloride to oxidize the divalent palladium to tetravalent palladium to ensure the ammonium chloride precipitation effect. Commonly used oxidants are nitric acid and chlorine. Oxidation with nitric acid produces nitrogen-containing waste gas and wastewater, which are difficult to handle. Oxidation with chlorine, on the other hand, creates a poor operating environment.

[0010] Patent CN201810562151.4 discloses a method for recovering palladium from palladium-containing waste catalysts. The method uses a fully wet process to recover palladium, and a large amount of organic waste liquid is generated during the elution process, which is difficult to treat subsequently.

[0011] Patent CN202010905956.1 discloses a method for recovering palladium from spent palladium resin catalysts. The method mainly adopts a pyrometallurgical capture process and includes the following steps: (1) mixing the spent palladium resin catalyst with a binder and metallic iron oxide in proportion and vacuum carbonizing the mixture; (2) smelting the carbonized product in a high-temperature furnace to reduce the metallic iron oxide to metallic iron and capture palladium to obtain a molten metallic palladium-iron alloy product, which is then atomized to obtain palladium-iron alloy powder; (3) adding sulfuric acid to selectively dissolve the iron. After the dissolution reaction is completed, the product is filtered and washed to obtain a palladium concentrate and an iron-containing filtrate; (4) dissolving the palladium concentrate in a ferric chloride solution, filtering to obtain a palladium chloride solution, and reducing the solution with hydrazine hydrate to obtain a crude palladium powder. This method uses a pyrometallurgical capture process to recover palladium, introduces a large amount of additives, and has a smelting temperature of up to 1400°C, resulting in relatively high processing costs. After obtaining the alloy concentrate, it is necessary to perform powder spraying, iron dissolution, and liquid preparation again, which is a long process with low efficiency. Summary of the Invention

[0012] In view of the problems in the prior art, the present invention provides a method for efficiently recovering palladium from waste palladium / resin catalyst.

[0013] The purpose of the present invention can be achieved through the following technical solutions: A method for efficiently recovering palladium from a waste palladium / resin catalyst comprises the following steps: Step 1: Take a preset amount of waste palladium / resin catalyst and perform oxygen-enriched roasting; Step 2: After step 1, nitrogen is introduced, and then the temperature is raised and roasting is continued, maintaining the preset vacuum degree in the furnace; after roasting, the temperature is lowered, and nitrogen protection is continuously introduced during the cooling process; Step 3: Take the palladium / resin catalyst calcined in step 2, add hydrochloric acid and water, and begin to heat up. After reaching a preset temperature, add hydrogen peroxide. After the reaction time is preset, add ozone to continue the reaction. After the reaction is completed, solid-liquid separation is performed to obtain a filtrate and a filter residue. Step 4: The filtrate obtained in step 3 is subjected to ozone oxidation, followed by palladium precipitation with ammonium chloride to obtain ammonium chloropalladate; Step 5: Ammonium chloropalladate is purified by ammoniation with ammonia water and acidification with hydrochloric acid, and finally reduced with hydrazine hydrate to obtain qualified palladium powder.

[0014] Optionally, the oxygen-enriched roasting conditions in step 1 are as follows: an oxygen concentration in the furnace of 25-50%, a roasting temperature of 500-650° C., and a roasting time of 1-2 h.

[0015] Optionally, the chemical reaction formulas in the oxygen-enriched roasting process are C8H8+10O2=8CO2+4H2O, C3H4O2+3O2=3CO2+2H2O.

[0016] Optionally, in step 2, the vacuum calcination temperature is 750-850° C., the calcination time is 2-3 h, and the vacuum degree is 100-1000 Pa; during the nitrogen protection process, the nitrogen supply is stopped until the temperature drops below 100° C.

[0017] Optionally, in step 3, the temperature of the hydrogen peroxide solution when added is 80-95° C., the dropping time is 1-2 h, the dropping speed is 20 ml / h, and the ozone addition time is 1-2 h.

[0018] Optionally, in step 3, the ratio of catalyst: water: hydrochloric acid: hydrogen peroxide: ozone is 100 g: (200-300) ml: (50-100) ml: (20-40) ml: (10-20) ml.

[0019] Optionally, the temperature is room temperature and the duration is 20 to 40 minutes.

[0020] Beneficial effects of the present invention: The present invention performs oxygen-enriched roasting, supplementing a certain amount of oxygen during the roasting process to maintain the oxygen content in the roasting atmosphere between 25% and 50%. This can achieve the following effects: 1. Improving the resin decomposition rate under the same time conditions. Oxygen-enriched conditions accelerate the decomposition and combustion of high-molecular organic matter, thereby increasing the decomposition rate of the resin carrier. Under conventional roasting conditions, the resin decomposition rate is 70% to 80% in 1-2 hours. After the introduction of oxygen, the organic matter decomposition rate increases to 85% to 95%, which is beneficial for the subsequent leaching of palladium. 2. Lowering the required roasting temperature. Efficient decomposition of organic matter can be achieved at 500-650°C.

[0021] After the oxygen-enriched roasting is completed, oxygen supplementation is stopped and nitrogen is introduced instead to maintain the absence of oxygen in the system. The temperature is then raised to 750-850°C, and the vacuum is maintained at 100-1000 Pa. At this time, palladium oxide decomposes palladium and oxygen. The decomposition temperature of palladium oxide under normal pressure and aerobic conditions is 900-950°C. By supplementing nitrogen and maintaining a certain vacuum, the oxygen partial pressure is effectively reduced, which promotes the decomposition of palladium oxide. The temperature for complete decomposition of palladium oxide can be reduced to 750-850°C, reducing energy consumption. Nitrogen protection is then applied during the cooling process to prevent palladium from oxidizing again.

[0022] The leaching process uses hydrogen peroxide + ozone synergistic oxidation leaching. First, hydrochloric acid + hydrogen peroxide is used for leaching. After leaching, ozone is continued to be added, and oxidation leaching is carried out again for a period of time, which can increase the palladium leaching rate to more than 99%.

[0023] The leachate is then precipitated with ammonium chloride for palladium precipitation. Due to the instability of divalent palladium, conventional processes involve oxidizing the solution prior to precipitation, typically with nitric acid or chlorine. This process utilizes ozone, a more potent oxidant than chlorine, for oxidation, significantly improving palladium precipitation. The palladium concentration in the precipitation tail solution is less than 0.01 g / L, the palladium precipitation rate is greater than 99.9%, and the recovery rate exceeds 99.6%. Furthermore, the ozone oxidation process produces no waste gas, reducing waste gas and wastewater pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0025] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] See also Figure 1 As shown, a method for efficiently recovering palladium from a waste palladium / resin catalyst comprises the following steps: Step 1: Take a preset amount of waste palladium / resin catalyst and perform oxygen-enriched roasting; Step 2: After step 1, nitrogen is introduced, and then the temperature is raised and roasting is continued, maintaining the preset vacuum degree in the furnace; after roasting, the temperature is lowered, and nitrogen protection is continuously introduced during the cooling process; Step 3: Take the palladium / resin catalyst calcined in step 2, add hydrochloric acid and water, and begin to heat up. After reaching a preset temperature, add hydrogen peroxide. After the reaction time is preset, add ozone to continue the reaction. After the reaction is completed, solid-liquid separation is performed to obtain a filtrate and a filter residue. Step 4: The filtrate obtained in step 3 is subjected to ozone oxidation, followed by palladium precipitation with ammonium chloride to obtain ammonium chloropalladate. This method allows the palladium concentration in the tail liquid to be less than 0.01 g / L.

[0028] Step 5: Ammonium chloropalladate is purified by ammoniation with ammonia water and acidification with hydrochloric acid, and finally reduced with hydrazine hydrate to obtain qualified palladium powder.

[0029] Specifically, the oxygen-enriched roasting conditions in step 1 are as follows: an oxygen concentration in the furnace of 25-50%, a roasting temperature of 500-650° C., and a roasting time of 1-2 hours.

[0030] Specifically, the chemical reaction formulas in the oxygen-enriched roasting process are C8H8+10O2=8CO2+4H2O, C3H4O2+3O2=3CO2+2H2O.

[0031] Specifically, in step 2, the vacuum calcination temperature is 750-850° C., the calcination time is 2-3 hours, and the vacuum degree is 100-1000 Pa; during the nitrogen protection process, the nitrogen supply is stopped until the temperature drops below 100° C.

[0032] Specifically, in step 3, the temperature of the hydrogen peroxide solution when added is 80-95° C., the dropping time is 1-2 hours, the dropping speed is 20 ml / h, and the ozone addition time is 1-2 hours.

[0033] Specifically, in step 3, the ratio of catalyst: water: hydrochloric acid: hydrogen peroxide: ozone is 100g: (200-300)ml: (50-100)ml: (20-40)ml: (10-20)ml.

[0034] Specifically, in the process of oxidizing the filtrate with ozone in step 4, the amount of ozone injected is 15-30% of the liquid volume, the temperature is room temperature, and the duration is 20-40 minutes.

[0035] Palladium / resin catalysts are palladium-supported catalysts on a resin support. They are commonly used in hydrogenation, dehydrogenation, and coupling reactions. Resin supports are typically high-molecular-weight polymers (such as polystyrene and polyacrylic acid), which exhibit high chemical stability and controllable surface functional groups. When polystyrene decomposes in air, oxygen participates in the reaction, leading to oxidative decomposition and combustion. Generally, it decomposes into carbon dioxide, water, and other small molecules at around 600°C. The reaction is as follows: C8H8 + 10O2 = 8CO2 + 4H2O. The decomposition behavior of polyacrylic acid in air is closely related to its molecular structure, molecular weight, and heating conditions. Because polyacrylic acid contains carboxyl groups (-COOH), it undergoes thermal oxidative degradation and combustion during heating. Generally, it decomposes into carbon dioxide, water, and other small molecules at around 600°C. The reaction is as follows: C3H4O2 + 3O2 = 3CO2 + 2H2O. However, resin carriers generally use high molecular weight or cross-linked polystyrene or polyacrylic acid, which contains additives or stabilizers. They are usually unable to be completely decomposed at 600°C, and the decomposition rate in the actual treatment process is 70-80%. Due to incomplete resin decomposition, a small amount of palladium remains in the resin structure, making subsequent leaching difficult, and the leaching rate is generally 90-95%. The present invention performs oxygen-enriched roasting, supplementing a certain amount of oxygen during the roasting process to maintain the oxygen content in the roasting atmosphere between 25-50% (conventional roasting does not add additional oxygen, and the oxygen content is basically the same as that in the atmosphere, at around 21%). This accelerates the decomposition and combustion of high-molecular organic matter and improves the decomposition rate of the resin carrier. The decomposition rate of the carrier can reach 85-95%, and the palladium leaching rate reaches above 99.8%. Compared with the conventional roasting-leaching process, the palladium leaching rate is increased by 5-10%.

[0036] During the calcination process, some palladium oxidizes to form palladium oxide. Traditionally, the calcined material is reduced with hydrazine hydrate or other reducing agents to convert the palladium oxide to palladium before leaching. However, the wet reduction process is costly (reduction costs 2 to 3 yuan per kg of material), inefficient (the entire process of reduction, filtration, and washing takes at least 24 hours), and prone to palladium loss (the reduction solution removes 0.5 to 1% of the palladium). The present invention employs vacuum calcination of the calcined material, decomposing the palladium oxide in the material into palladium and oxygen in an oxygen-free, vacuum environment. The calcined material can then be leached directly, eliminating the need for a reduction step. The equipment used is a vacuum induction melting furnace. Vacuum calcination is performed directly after oxygen-enriched calcination using the same equipment, achieving efficient thermal energy utilization, shortening the production process, improving production efficiency, and reducing metal loss. Furthermore, the oxygen-free, vacuum environment lowers the decomposition temperature of palladium oxide. By adopting the method of the present invention, palladium oxide is decomposed into palladium, thereby reducing costs, improving production efficiency, and reducing palladium loss. The processing cost of each kilogram of material in this method is 1 to 1.5 yuan, the entire process takes 6 to 7 hours, and there is no palladium loss.

[0037] Traditional acid leaching processes use highly oxidizing aqua regia and chlorine systems, which result in poor operating environments and severe equipment corrosion. The present invention utilizes a "hydrogen peroxide + ozone synergistic oxidation" leaching system, which reduces equipment corrosion, is environmentally friendly, and offers excellent leaching results, ensuring a palladium leaching rate of over 99.8%.

[0038] The obtained palladium-containing solution is first oxidized to oxidize the divalent palladium in the solution to tetravalent palladium. Ammonium chloride can then be added to obtain ammonium chloropalladate, which can be purified. The traditional ammonium chloride palladium precipitation process uses nitric acid or chlorine for oxidation, which has a poor operating environment and produces nitrogen-containing waste gas and wastewater that are difficult to treat. The present invention uses ozone for oxidation, which generates oxygen after ozone oxidation and is environmentally friendly.

[0039] In summary, the present invention adopts a first stage of oxygen-enriched roasting to improve the decomposition rate of the resin, and a second stage of vacuum roasting to reduce the decomposition temperature of palladium oxide, eliminating the traditional material reduction process and improving production efficiency. The leaching process innovatively proposes the use of a "hydrogen peroxide + ozone" synergistic oxidation leaching system to synergistically leach palladium and improve the leaching rate of palladium. The ammonium chloride palladium precipitation process adopts ozone oxidation to reduce the difficulty of waste liquid and waste gas treatment. A variety of processes are combined to achieve short-process continuous and efficient operation, overcoming the low decomposition rate of the carrier in the roasting process of the traditional process, the large amount of water washing in the reduction process, the large loss of palladium metal, the low work efficiency, and the serious environmental pollution in the leaching process and purification process. The problems of improving the palladium recovery rate and improving production efficiency are overcome.

[0040] In the present embodiment, the palladium, resin, and other metal contents in the waste palladium / resin catalyst are 1.5%, 97.5%, and 1%, respectively. This is demonstrated in detail in the following examples.

[0041] Example 1: This example provides a method for recovering palladium from a waste palladium / resin catalyst. The method comprises the following steps: Step 1: Take 1000g of waste palladium / resin catalyst and put it into a calcination furnace, blow in oxygen, maintain the oxygen concentration in the furnace at 25%, heat it to 650℃, and keep it warm for 1h.

[0042] Step 2: After step 1, nitrogen is introduced to evacuate all air. The temperature is then raised while maintaining a vacuum of 100 Pa. After reaching 750°C, the temperature is maintained for 2 hours. The temperature is then lowered, with nitrogen continuously introduced.

[0043] Step 3: Place 150g of the product from Step 2 into a beaker, add 100ml of hydrochloric acid and 300ml of water, and begin heating. Once the temperature reaches 80°C, add 40ml of hydrogen peroxide dropwise over 1 hour to initiate leaching. Then, bubble in 30ml of ozone over 2 hours to continue leaching. After the reaction is complete, solid-liquid separation is performed to obtain 600ml of filtrate. The resulting residue is 130g, containing 0.02% palladium and achieving a palladium leaching yield of 99.82%.

[0044] Step 4: Ozone was bubbled into the filtrate at room temperature for 20 minutes to oxidize the filtrate. Palladium was then precipitated with ammonium chloride. The palladium concentration in the tail liquid was detected to be 0.005 g / L.

[0045] Step 5: Ammonium chloropalladate is then purified until 14.96 g of qualified palladium powder is obtained, with a palladium recovery rate of 99.73%.

[0046] Example 2 includes the following steps: Step 1: Take 1000g of waste palladium / resin catalyst and put it into a calcination furnace, blow oxygen into it, maintain the oxygen concentration in the furnace at 35%, heat it to 550℃, and keep it warm for 1.5h.

[0047] Step 2: After step 1, nitrogen is introduced to evacuate all air. The temperature is then raised while maintaining a vacuum of 500 Pa. After reaching 800°C, the temperature is maintained for 2.5 hours. The temperature is then lowered, with nitrogen continuously introduced.

[0048] Step 3: Place 100g of the product from Step 2 into a beaker, add 100ml of hydrochloric acid and 300ml of water, and begin heating. Once the temperature reaches 90°C, add 40ml of hydrogen peroxide dropwise over 1.5 hours to initiate leaching. Then, bubble in 20ml of ozone over the same 1.5 hours to continue leaching. After the reaction is complete, solid-liquid separation yields 580ml of filtrate. The resulting residue weighs 85g, containing 0.03% palladium and achieving a palladium leaching yield of 99.83%.

[0049] Step 4: Ozone was bubbled into the filtrate at room temperature for 30 minutes to oxidize the filtrate. Palladium was then precipitated with ammonium chloride. The palladium concentration in the tail liquid was 0.007 g / L.

[0050] Step 5: Ammonium chloropalladate is then purified until 14.97 g of qualified palladium powder is obtained, with a palladium recovery rate of 99.80%.

[0051] Example 3 includes the following steps: Step 1: Take 1000g of waste palladium / resin catalyst and put it into a calcination furnace, blow oxygen into it, maintain the oxygen concentration in the furnace at 50%, heat it to 500℃, and keep it warm for 2h.

[0052] Step 2: After step 1, nitrogen is introduced to evacuate all oxygen. The temperature is then raised while maintaining a vacuum of 1000 Pa. After reaching 850°C, the temperature is maintained for 3 hours. The temperature is then lowered, with nitrogen continuously introduced.

[0053] Step 3: Place 50g of the product from Step 2 into a beaker, add 50ml of hydrochloric acid and 150ml of water, and begin heating. Once the temperature reaches 95°C, add 20ml of hydrogen peroxide dropwise over 1 hour to initiate leaching. Subsequently, 5ml of ozone is bubbled in over 1 hour to continue leaching. After the reaction is complete, solid-liquid separation is performed to obtain 350ml of filtrate. The leached residue is 43g, containing 0.07% palladium, for a palladium leaching yield of 99.80%.

[0054] Step 4: Ozone (52.5 ml) was bubbled into the filtrate at room temperature for 40 minutes for oxidation. Palladium was then precipitated with ammonium chloride. The palladium concentration in the tail liquid was 0.006 g / L.

[0055] Step 5: Ammonium chloropalladate is then purified until 14.96 g of qualified palladium powder is obtained, with a palladium recovery rate of 99.67%.

[0056] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for efficiently recovering palladium from a waste palladium / resin catalyst, characterized in that: The method comprises the following steps: Step 1: Take a preset amount of waste palladium / resin catalyst and perform oxygen-enriched roasting; Step 2: After step 1, nitrogen is introduced, and then the temperature is raised and roasting is continued, maintaining the preset vacuum degree in the furnace; after roasting, the temperature is lowered, and nitrogen protection is continuously introduced during the cooling process; Step 3: Take the palladium / resin catalyst calcined in step 2, add hydrochloric acid and water, and begin to heat up. After reaching a preset temperature, add hydrogen peroxide. After the reaction time is preset, add ozone to continue the reaction. After the reaction is completed, solid-liquid separation is performed to obtain a filtrate and a filter residue. Step 4: The filtrate obtained in step 3 is subjected to ozone oxidation, followed by palladium precipitation with ammonium chloride to obtain ammonium chloropalladate; Step 5: Ammonium chloropalladate is purified by ammoniation with ammonia water and acidification with hydrochloric acid, and finally reduced with hydrazine hydrate to obtain qualified palladium powder.

2. A method for efficiently recovering palladium from a waste palladium / resin catalyst according to claim 1, characterized in that: The oxygen-enriched roasting conditions in step 1 are as follows: an oxygen concentration in the furnace of 25-50%, a roasting temperature of 500-650° C., and a roasting time of 1-2 hours.

3. A method for efficiently recovering palladium from a waste palladium / resin catalyst according to claim 1, characterized in that: The chemical reaction formulas in the oxygen-enriched roasting process are C8H8+10O2=8CO2+4H2O, C3H4O2+3O2=3CO2+2H2O.

4. A method for efficiently recovering palladium from a waste palladium / resin catalyst according to claim 1, characterized in that: In step 2, the vacuum calcination temperature is 750-850° C., the calcination time is 2-3 hours, and the vacuum degree is 100-1000 Pa. During the nitrogen protection process, the nitrogen supply is stopped until the temperature drops below 100° C.

5. A method for efficiently recovering palladium from a waste palladium / resin catalyst according to claim 1, characterized in that: In step 3, the temperature of hydrogen peroxide when added is 80-95° C., the addition time is 1-2 h, the addition speed is 20 ml / h, and the ozone addition time is 1-2 h.

6. A method for efficiently recovering palladium from a waste palladium / resin catalyst according to claim 1, characterized in that: In step 3, the ratio of catalyst: water: hydrochloric acid: hydrogen peroxide: ozone is 100 g: (200-300) ml: (50-100) ml: (20-40) ml: (10-20) ml.

7. A method for efficiently recovering palladium from a waste palladium / resin catalyst according to claim 1, characterized in that: In the step 4, during the oxidation of the filtrate by ozone, the amount of ozone injected is 15-30% of the liquid volume, the temperature is room temperature, and the duration is 20-40 minutes.

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