Method for leaching platinum and palladium from waste three-way catalyst

Abstract

The invention relates to a method for leaching platinum and palladium from a waste three-way catalyst, which comprises the following steps: mixing waste three-way catalyst powder with a solvent to obtain a first mixed solution; adding a variable valence metal complex into the first mixed solution to obtain a second mixed solution; and the second mixed solution is subjected to ultrasonic treatment, and platinum and palladium in the waste three-way catalyst are leached out. According to the method, a self-circulation system is constructed through the contact electro-catalysis effect excited by ultrasonic waves and introduction of variable valence metal, high-activity free radicals can be continuously generated, and therefore efficient leaching of platinum and palladium in the waste three-way catalyst is achieved. According to the method, high-temperature and high-pressure conditions and toxic and harmful reagents are not needed, the problems of high energy consumption, potential safety hazards and environmental pollution risks are fundamentally solved, and meanwhile efficient leaching of platinum and palladium of the waste three-way catalyst is achieved.

Description

Technical Field

[0001] This invention belongs to the field of precious metal recycling technology, and relates to a method for recycling platinum group metals, particularly a method for leaching platinum and palladium from waste three-way catalytic converters. Background Technology

[0002] Platinum group metals (PGMs) are important strategic resources and play an irreplaceable role in high-tech fields such as automobiles, aerospace, and petrochemicals. Waste three-way catalytic converters serve as an "urban mine" for PGMs; their recycling can achieve the circular use of PGMs, promoting the development of a circular economy. It can also prevent the release of precious metals during landfill or incineration, reducing the risk of environmental pollution.

[0003] The main methods for recovering platinum group metals from spent three-way catalytic converters are high-temperature smelting and wet leaching. CN115354154A discloses a reduction method for smelting platinum-rhodium-palladium alloys from spent three-way catalytic converters. This method involves adding borax, quicklime powder, quartz sand, glass powder, and lead powder to the three-way catalytic converter powder at weight ratios of 35-25%, 25-15%, 20-10%, 15-5%, and 3-2%, respectively. The first stage of smelting is carried out at 2600℃, followed by a second stage smelting at 3000℃, thus recovering the platinum-rhodium-palladium alloy from the spent three-way catalytic converter. CN109207734A discloses a method for extracting precious metals from three-way catalytic converter waste. This method involves pretreatment, aqua regia leaching, platinum-palladium separation, platinum refining, and palladium refining steps, achieving the extraction of platinum and palladium from the waste.

[0004] However, high-temperature smelting usually requires high temperatures (>2500℃), which leads to problems such as high energy consumption, large equipment investment, and large emissions of waste gas, resulting in a heavy environmental burden. Wet leaching usually requires the addition of oxidants (such as Cl2, H2O2, NaClO3, HNO3 and aqua regia) to promote chlorination complexation and lower the standard potential, thereby promoting the dissolution and leaching of platinum group metals. While consuming oxidants, the strong corrosiveness and toxicity of these oxidants may also pose safety hazards and environmental pollution risks.

[0005] Therefore, developing a green, safe, low-energy-consumption, and efficient method for recycling platinum group metals from waste three-way catalytic converters is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for leaching platinum and palladium from spent three-way catalytic converters. The method provided by this invention utilizes ultrasonically excited contact electrocatalysis and a self-circulating system constructed by introducing variable-valence metals to continuously generate highly active free radicals, thereby achieving efficient leaching of platinum and palladium from spent three-way catalytic converters. The method provided by this invention eliminates the need for high-temperature, high-pressure conditions and toxic or harmful reagents, fundamentally solving the problems of high energy consumption, safety hazards, and environmental pollution risks, while simultaneously achieving efficient leaching of platinum and palladium from spent three-way catalytic converters.

[0007] To achieve this objective, the present invention employs the following technical solution:

[0008] This invention provides a method for leaching platinum and palladium from waste three-way catalytic converters, comprising the following steps:

[0009] Waste three-way catalytic converter powder is mixed with a solvent to obtain a first mixed solution; a variable valence metal complex is added to the first mixed solution to obtain a second mixed solution; the second mixed solution is subjected to ultrasonic treatment to leach platinum and palladium from the waste three-way catalytic converter.

[0010] This invention utilizes ultrasonic stimulation of the contact electrocatalytic effect and the introduction of variable-valence metals to construct a self-circulating system, which can continuously generate highly active free radicals, thereby achieving efficient leaching of platinum and palladium from spent three-way catalytic converters. This method eliminates the need for high-temperature, high-pressure conditions and toxic or harmful reagents, fundamentally solving problems such as high energy consumption, safety hazards, and environmental pollution risks, while simultaneously achieving efficient leaching of platinum and palladium from spent three-way catalytic converters.

[0011] Preferably, the variable valence metal in the variable valence metal complex includes any one or a combination of at least two of Fe, Ce, Cu, Cr, or Mn. Typical but non-limiting combinations include combinations of Fe and Ce, Cu and Cr, Fe and Mn, Fe, Ce, and Cu, Fe, Cr, and Mn, Fe, Ce, Cu, Cr, and Mn, and Fe, Ce, Cu, Cr, and Mn. Preferably, it is a combination of Fe and Mn.

[0012] Preferably, the variable valence metal complex includes any one or a combination of at least two of nitrates, sulfates, phosphates or chlorides. Typical but non-limiting combinations include combinations of nitrates and sulfates, combinations of phosphates and chlorides, combinations of nitrates, sulfates and phosphates, combinations of sulfates, phosphates and chlorides, and combinations of nitrates, sulfates, phosphates and chlorides.

[0013] Preferably, the variable valence metal complex includes any one or a combination of at least two of Fe2(SO4)3, Ce(NO3)3, CuCl2, MnCl2 or FeCl3.

[0014] Preferably, the concentration of the variable valence metal complex in the second mixed solution is 0.05 g / L to 0.60 g / L, for example, it can be 0.05 g / L, 0.10 g / L, 0.15 g / L, 0.20 g / L, 0.25 g / L, 0.30 g / L, 0.40 g / L, 0.50 g / L or 0.60 g / L, etc.

[0015] This invention achieves efficient leaching of platinum and palladium from spent three-way catalytic converters by controlling the concentration of the variable-valence metal complex in the second mixed solution to be between 0.05 g / L and 0.60 g / L. If the concentration of the variable-valence metal complex is too low, it provides insufficient active sites, failing to achieve the continuous generation of highly reactive free radicals, thus resulting in unsatisfactory platinum and palladium leaching. If the concentration of the variable-valence metal complex is too high, although it can provide sufficient active sites to ensure the continuous generation of highly reactive free radicals, thereby achieving efficient leaching of platinum and palladium, excessive addition of the variable-valence metal complex has little effect on improving the leaching rate of platinum and palladium and also wastes resources.

[0016] Preferably, the solvent is water.

[0017] Preferably, the solid-liquid ratio of the spent three-way catalytic converter powder to the solvent in the first mixed solution is 1:10 g / mL to 1:100 g / mL, for example, it can be 1:10 g / mL, 1:20 g / mL, 1:30 g / mL, 1:40 g / mL, 1:50 g / mL, 1:60 g / mL, 1:70 g / mL, 1:80 g / mL, 1:90 g / mL or 1:100 g / mL, etc.

[0018] Preferably, the power of the ultrasonic treatment is 50W to 300W, for example, it can be 50W, 80W, 100W, 150W, 200W, 250W or 300W.

[0019] This invention achieves efficient leaching of platinum and palladium from waste three-way catalytic converters by adjusting the ultrasonic treatment power to 50W~300W. If the ultrasonic treatment power is too low, the cavitation effect of the system is not significant, which will affect electron transfer and weaken the generation of free radicals, thus affecting the leaching of platinum and palladium. If the ultrasonic treatment power is too high, its strong mechanical effect will also affect electron transfer and weaken the generation of free radicals, thus affecting the leaching of platinum and palladium.

[0020] Preferably, the ultrasonic treatment time is 10 min to 60 min, for example, it can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0021] This invention enables the efficient leaching of platinum and palladium from waste three-way catalytic converters by adjusting the ultrasonic treatment time to 10-60 minutes. If the ultrasonic treatment time is too short, it cannot trigger a sustained contact electrocatalytic effect, affecting the continuous generation of highly active free radicals and thus the leaching of platinum and palladium. If the ultrasonic treatment time is too long, the temperature of the system will continue to rise, leading to a decrease in the concentration of free radicals, which will also affect the leaching of platinum and palladium.

[0022] Preferably, the frequency of the ultrasonic treatment is 10kHz to 40kHz, for example, it can be 10kHz, 15kHz, 20kHz, 25kHz, 30kHz, 35kHz or 40kHz.

[0023] Preferably, the temperature of the ultrasonic treatment is 20℃~40℃, for example, it can be 20℃, 25℃, 30℃, 35℃ or 40℃.

[0024] Preferably, the method for preparing the waste three-way catalytic converter powder includes the following steps: dismantling, crushing and dry ball milling the waste three-way catalytic converter to obtain the waste three-way catalytic converter powder.

[0025] Preferably, the dry ball milling time is 0.5h to 2h, for example, it can be 0.5h, 1h, 1.2h, 1.5h, 1.8h or 2h.

[0026] Preferably, the rotational speed of the dry ball mill is 100 r / min to 300 r / min, for example, it can be 100 r / min, 150 r / min, 200 r / min, 250 r / min or 300 r / min, etc.

[0027] Preferably, the average particle size of the waste three-way catalytic converter powder is 150μm to 850μm, for example, it can be 150μm, 180μm, 250μm, 300μm, 350μm, 400μm, 425μm, 450μm, 500μm, 550μm, 600μm, 700μm, 800μm or 850μm, etc.

[0028] As a preferred technical solution, the method includes the following steps:

[0029] The waste three-way catalytic converter is disassembled, crushed, and dry ball-milled to obtain waste three-way catalytic converter powder; the dry ball-milling time is 0.5h~2h; the dry ball-milling speed is 100r / min~300r / min; the average particle size of the waste three-way catalytic converter powder is 150μm~850μm.

[0030] Waste three-way catalytic converter powder is mixed with a solvent to obtain a first mixed solution; the solvent is water; the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:10g / mL to 1:100g / mL;

[0031] A variable valence metal complex is added to the first mixed solution to obtain a second mixed solution; the variable valence metal in the variable valence metal complex includes any one or a combination of at least two of Fe, Ce, Cu, Cr, and Mn, preferably a combination of Fe and Mn; the variable valence metal complex includes any one or a combination of at least two of nitrates, sulfates, phosphates, or chlorides; the concentration of the variable valence metal complex in the second mixed solution is 0.05 g / L to 0.60 g / L;

[0032] The second mixed solution is subjected to ultrasonic treatment to leach platinum and palladium from the waste three-way catalytic converter; the power of the ultrasonic treatment is 50W~300W; the time of the ultrasonic treatment is 10min~60min; the frequency of the ultrasonic treatment is 10kHz~40kHz; and the temperature of the ultrasonic treatment is 20℃~40℃.

[0033] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This invention utilizes ultrasonic stimulation of the contact electrocatalytic effect and the introduction of variable-valence metals to construct a self-circulating system, which can continuously generate highly active free radicals, thereby achieving efficient leaching of platinum and palladium from spent three-way catalytic converters. The method provided by this invention eliminates the need for high-temperature, high-pressure conditions and toxic or harmful reagents, fundamentally solving the problems of high energy consumption, safety hazards, and environmental pollution risks, while simultaneously achieving efficient leaching of platinum and palladium from spent three-way catalytic converters. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the principle of the method for continuously generating highly active free radicals through the leaching of platinum and palladium from a waste three-way catalytic converter provided by the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0038] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0039] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0041] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0042] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0043] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0044] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0045] Example 1

[0046] This embodiment provides a method for leaching platinum and palladium from a spent three-way catalytic converter, including the following steps:

[0047] (1) The waste three-way catalytic converter is disassembled, crushed and dry ball milled. The rotation speed of the dry ball mill is 200 r / min and the time of the dry ball mill is 1 h to obtain waste three-way catalytic converter powder. The particle size of the waste three-way catalytic converter powder is 300 μm.

[0048] (2) The waste three-way catalytic converter powder is mixed with water to obtain a first mixed solution, wherein the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:50 g / mL;

[0049] (3) Add Fe2(SO4)3 to the first mixed solution to obtain a second mixed solution, wherein the concentration of Fe2(SO4)3 in the second mixed solution is 0.50 g / L;

[0050] (4) The second mixed solution is subjected to ultrasonic treatment with a power of 100W, a time of 30min, a frequency of 20kHz, and a temperature of 30℃ to achieve the leaching of platinum and palladium in the waste three-way catalytic converter.

[0051] Example 2

[0052] This embodiment provides a method for leaching platinum and palladium from a spent three-way catalytic converter, including the following steps:

[0053] (1) The waste three-way catalytic converter is disassembled, crushed and dry ball milled. The rotation speed of the dry ball mill is 300 r / min and the time of the dry ball mill is 0.5 h to obtain waste three-way catalytic converter powder. The particle size of the waste three-way catalytic converter powder is 180 μm.

[0054] (2) The waste three-way catalytic converter powder is mixed with water to obtain a first mixed solution, wherein the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:60 g / mL;

[0055] (3) Add Ce(NH4)2(NO3)6 to the first mixed solution to obtain a second mixed solution, wherein the concentration of Ce(NH4)2(NO3)6 in the second mixed solution is 0.60 g / L;

[0056] (4) The second mixed solution is subjected to ultrasonic treatment with a power of 50W, a time of 60min, a frequency of 10kHz, and a temperature of 40℃ to achieve the leaching of platinum and palladium in the waste three-way catalytic converter.

[0057] Example 3

[0058] This embodiment provides a method for leaching platinum and palladium from a spent three-way catalytic converter, including the following steps:

[0059] (1) The waste three-way catalytic converter is disassembled, crushed and dry ball milled. The rotation speed of the dry ball mill is 200 r / min and the dry ball milling time is 2 h to obtain waste three-way catalytic converter powder. The particle size of the waste three-way catalytic converter powder is 550 μm.

[0060] (2) The waste three-way catalytic converter powder is mixed with water to obtain a first mixed solution, wherein the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:100g / mL;

[0061] (3) CuCl2 is added to the first mixed solution to obtain a second mixed solution, wherein the concentration of CuCl2 in the second mixed solution is 0.10 g / L;

[0062] (4) The second mixed solution is subjected to ultrasonic treatment with a power of 300W, a time of 45min, a frequency of 40kHz, and a temperature of 30℃ to achieve the leaching of platinum and palladium in the waste three-way catalytic converter.

[0063] Example 4

[0064] This embodiment provides a method for leaching platinum and palladium from a spent three-way catalytic converter, including the following steps:

[0065] (1) The waste three-way catalytic converter is disassembled, crushed and dry ball milled. The rotation speed of the dry ball mill is 100 r / min and the time of the dry ball mill is 1.5 h to obtain waste three-way catalytic converter powder. The particle size of the waste three-way catalytic converter powder is 250 μm.

[0066] (2) The waste three-way catalytic converter powder is mixed with water to obtain a first mixed solution, wherein the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:10 g / mL;

[0067] (3) Add MnCl2 and FeCl3 to the first mixed solution to obtain a second mixed solution. The concentration of MnCl2 in the second mixed solution is 0.10 g / L and the concentration of FeCl3 is 0.05 g / L.

[0068] (4) The second mixed solution is subjected to ultrasonic treatment with a power of 100W, a time of 10min, a frequency of 20kHz and a temperature of 20℃ to achieve the leaching of platinum and palladium in the waste three-way catalytic converter.

[0069] Example 5

[0070] This embodiment provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for replacing the concentration of Fe2(SO4)3 in step (3) with 0.01 g / L, everything else is the same as in Example 1.

[0071] Example 6

[0072] This embodiment provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for replacing the concentration of Fe2(SO4)3 in step (3) with 0.80 g / L, everything else is the same as in Example 1.

[0073] Example 7

[0074] This embodiment provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for replacing the power of ultrasonic treatment in step (4) with 20W, everything else is the same as in embodiment 1.

[0075] Example 8

[0076] This embodiment provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for replacing the power of ultrasonic treatment in step (4) with 500W, everything else is the same as in embodiment 1.

[0077] Example 9

[0078] This embodiment provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for replacing the ultrasonic treatment time in step (4) with 5 minutes, everything else is the same as in embodiment 1.

[0079] Example 10

[0080] This embodiment provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for replacing the ultrasonic treatment time in step (4) with 90 min, everything else is the same as in embodiment 1.

[0081] Comparative Example 1

[0082] This comparative example provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except that the ultrasonic treatment in step (4) is replaced with a static treatment, the static treatment time is 10 min and the temperature is 20°C, and all other steps are the same as in Example 1.

[0083] Comparative Example 2

[0084] This comparative example provides a method for leaching platinum and palladium from a waste three-way catalytic converter. Except for step (3), which does not involve the addition of Fe2(SO4)3, the method is the same as in Example 1.

[0085] The platinum and palladium leaching rates in the methods for leaching platinum and palladium from waste three-way catalytic converters provided in Examples 1 to 10 and Comparative Examples 1 to 2 are shown in Table 1.

[0086]

[0087] As can be seen from Table 1, the methods for leaching platinum and palladium from waste three-way catalytic converters provided in Examples 1 to 4 have high platinum leaching rates and palladium leaching rates.

[0088] Compared to Example 1, in Examples 5 and 6, the concentration of the variable valence metal complex in the second mixed solution was between 0.05 g / L and 0.60 g / L. The concentration of the variable valence metal complex was too low, resulting in insufficient active sites and an inability to continuously generate highly reactive free radicals, leading to unsatisfactory platinum and palladium leaching. Conversely, while a high concentration of the variable valence metal complex could provide sufficient active sites to ensure the continuous generation of highly reactive free radicals and thus achieve efficient platinum and palladium leaching, excessive addition of the variable valence metal complex did not significantly improve the platinum and palladium leaching rate and would also waste resources.

[0089] Compared to Example 1, the ultrasonic treatment power in Examples 7 and 8 is outside the range of 50W to 300W. If the ultrasonic treatment power is too low, the cavitation effect of the system is not significant, which will affect electron transfer and weaken the generation of free radicals, thereby affecting the leaching of platinum and palladium. If the ultrasonic treatment power is too high, its strong mechanical effect will also affect electron transfer and weaken the generation of free radicals, thereby affecting the leaching of platinum and palladium.

[0090] Compared to Example 1, the ultrasonic treatment time in Examples 9 and 10 is outside the range of 10 min to 60 min. If the ultrasonic treatment time is too short, it cannot induce a continuous excitation of the contact electrocatalytic effect, which affects the continuous generation of highly active free radicals and thus affects the leaching of platinum and palladium. If the ultrasonic treatment time is too long, the temperature of the system will continue to rise, which will lead to a decrease in the concentration of free radicals and thus affect the leaching of platinum and palladium.

[0091] Compared to Example 1, Comparative Example 1 did not undergo ultrasonic treatment, thus failing to achieve the contact electrocatalytic effect excited by ultrasound. The self-circulating system constructed solely by the variable valence metal could not continuously generate highly active free radicals, resulting in low leaching rates of both platinum and palladium. In Comparative Example 2, no variable valence metal complex was added, thus failing to construct a self-circulating system of the variable valence metal. The contact electrocatalytic effect excited solely by ultrasound could not continuously generate highly active free radicals, resulting in low leaching rates of both platinum and palladium.

[0092] In summary, this invention utilizes ultrasonic excitation of the contact electrocatalytic effect and the introduction of variable-valence metals to construct a self-circulating system, which can continuously generate highly active free radicals, thereby achieving efficient leaching of platinum and palladium from spent three-way catalytic converters. The method provided by this invention eliminates the need for high-temperature, high-pressure conditions and toxic or harmful reagents, fundamentally solving the problems of high energy consumption, safety hazards, and environmental pollution risks, while simultaneously achieving efficient leaching of platinum and palladium from spent three-way catalytic converters.

[0093] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for leaching platinum and palladium from a spent three-way catalytic converter, characterized in that, Includes the following steps: Waste three-way catalytic converter powder is mixed with a solvent to obtain a first mixed solution; a variable valence metal complex is added to the first mixed solution to obtain a second mixed solution; the second mixed solution is subjected to ultrasonic treatment to leach platinum and palladium from the waste three-way catalytic converter.

2. The method according to claim 1, characterized in that, The variable valence metal in the variable valence metal complex includes any one or a combination of at least two of Fe, Ce, Cu, Cr or Mn, preferably a combination of Fe and Mn; Preferably, the variable valence metal complex includes any one or a combination of at least two of nitrates, sulfates, phosphates, or chlorides.

3. The method according to claim 1 or 2, characterized in that, The concentration of the variable valence metal complex in the second mixed solution is 0.05 g / L to 0.60 g / L.

4. The method according to any one of claims 1 to 3, characterized in that, The solvent is water; Preferably, the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:10 g / mL to 1:100 g / mL.

5. The method according to any one of claims 1 to 4, characterized in that, The power of the ultrasonic treatment is 50W~300W; Preferably, the ultrasonic treatment time is 10 min to 60 min.

6. The method according to any one of claims 1 to 5, characterized in that, The frequency of the ultrasonic treatment is 10kHz~40kHz; Preferably, the temperature of the ultrasonic treatment is 20℃~40℃.

7. The method according to any one of claims 1 to 6, characterized in that, The preparation method of the waste three-way catalytic converter powder includes the following steps: dismantling, crushing and dry ball milling the waste three-way catalytic converter to obtain waste three-way catalytic converter powder.

8. The method according to claim 7, characterized in that, The dry ball milling time is 0.5h~2h; Preferably, the rotational speed of the dry ball mill is 100 r / min to 300 r / min.

9. The method according to any one of claims 1 to 8, characterized in that, The average particle size of the waste three-way catalytic converter powder is 150μm~850μm.

10. The method according to any one of claims 1 to 9, characterized in that, The method includes the following steps: The waste three-way catalytic converter is disassembled, crushed, and dry ball-milled to obtain waste three-way catalytic converter powder; the dry ball-milling time is 0.5h~2h; the dry ball-milling speed is 100r / min~300r / min; the average particle size of the waste three-way catalytic converter powder is 150μm~850μm. Waste three-way catalytic converter powder is mixed with a solvent to obtain a first mixed solution; the solvent is water; the solid-liquid ratio of the waste three-way catalytic converter powder to the solvent in the first mixed solution is 1:10g / mL to 1:100g / mL; A variable valence metal complex is added to the first mixed solution to obtain a second mixed solution; the variable valence metal in the variable valence metal complex includes any one or a combination of at least two of Fe, Ce, Cu, Cr, and Mn, preferably a combination of Fe and Mn; the variable valence metal complex includes any one or a combination of at least two of nitrates, sulfates, phosphates, or chlorides; the concentration of the variable valence metal complex in the second mixed solution is 0.05 g / L to 0.60 g / L; The second mixed solution is subjected to ultrasonic treatment to leach platinum and palladium from the waste three-way catalytic converter; the power of the ultrasonic treatment is 50W~300W; the time of the ultrasonic treatment is 10min~60min; the frequency of the ultrasonic treatment is 10kHz~40kHz; and the temperature of the ultrasonic treatment is 20℃~40℃.

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