Zinc-containing solid waste treatment method

Abstract

The invention discloses a method for treating zinc-containing solid waste. The method comprises the following steps: (a) pretreating the zinc-containing solid waste; (b) carrying out deep leaching on the pretreated zinc-containing solid waste; removing impurities from the leachate obtained in the step (b); and (d) carrying out zinc recovery on the purified liquid obtained in the step (c). According to the method provided by the invention, the recovery rate of zinc in the zinc-containing solid waste can be effectively improved, the treatment cost is reduced, and the environmental pollution is reduced.

Description

Technical Field

[0001] The invention relates to a method for treating zinc-containing solid waste and belongs to the technical field of metallurgy. Background Art

[0002] With the development of the economy, the electronics industry has risen rapidly, and with it comes a large number of discarded electronic products, such as old mobile phones and computers. These products contain a large number of toxic and harmful substances, and if they are discarded at will, they will cause serious pollution to the environment. These wastes contain many valuable materials, such as gold, silver, copper, iron, tin, nickel, cobalt, lithium, manganese, aluminum, lead, cadmium, zinc, etc. Therefore, their reasonable recycling can not only protect the environment, but also save resources. At present, the treatment processes for zinc-containing solid waste mainly include pyrometallurgy and hydrometallurgy. Pyrometallurgy refers to a metallurgical method that separates metal elements from ores through high-temperature smelting. This method is suitable for high-grade and easily reduced ores. However, some low-grade and difficult-to-reduce ores are not suitable for using this method to extract metal elements. In addition, since a large amount of waste gas and wastewater will be generated during the pyrometallurgical process, it has a serious environmental pollution. Therefore, in actual production, people usually use hydrometallurgy instead of pyrometallurgy.

[0003] Hydrometallurgy refers to the process of dissolving metal elements in water or other solvents through chemical reactions, and then converting metal ions into elemental metals through a series of processes. The advantages of hydrometallurgy are that it can achieve continuous production and has little environmental pollution; the disadvantages are that it has high requirements for equipment and high energy consumption. Therefore, in practical applications, various factors need to be considered comprehensively to select the appropriate method to treat different types of zinc-containing solid waste.

[0004] However, the existing methods for treating zinc-containing solid waste have many shortcomings, such as: (1) The prior art discloses a method for preparing nano zinc oxide from zinc-containing solid waste, which first crushes and washes the zinc-containing solid waste to remove other impurities, then dries and roasts it, and finally uses water to perform ball milling to obtain nano zinc oxide. However, this treatment method is not only complicated to operate but also inefficient, and also produces a lot of wastewater and waste. (2) Another method is to directly put the zinc-containing solid waste into an electric furnace for smelting to obtain crude zinc ingots. Although this method is simple and convenient, a large amount of smoke and exhaust gas will be generated during the smelting process, which brings great harm to the workers; in addition, due to the large amount of impurities mixed in the raw materials, the purity of the final product is relatively low.

[0005] Therefore, it is urgent to develop a new method for treating zinc-containing solid waste to solve the above problems. Summary of the invention

[0006] In order to overcome the problems existing in the prior art, the present invention provides a method for treating zinc-containing solid waste, which can effectively improve the recovery rate of zinc in zinc-containing solid waste, reduce treatment costs, and reduce environmental pollution.

[0007] The technical solution of the present invention is as follows:

[0008] A method for treating zinc-containing solid waste comprises the following steps:

[0009] (a) pre-treating zinc-containing solid waste;

[0010] (b) deep leaching the pretreated zinc-containing solid waste;

[0011] (c) removing impurities from the leachate obtained in step (b);

[0012] (d) recovering zinc from the purified solution obtained in step (c).

[0013] Furthermore, the pretreatment includes: crushing and grinding the zinc-containing solid waste into powder so that the particle size of the zinc-containing solid waste reaches the micron level; or crushing and grinding the zinc-containing solid waste into powder so that the particle size of the zinc-containing solid waste reaches the micron level, and performing impurity removal treatment.

[0014] Furthermore, the impurity removal treatment is carried out by magnetic separation, gravity separation or screening.

[0015] Furthermore, the leaching agent used for the deep leaching is a composite acid solution composed of organic acid A, organic acid B and surfactant C, wherein organic acid A is an organic acid with a chelating effect, organic acid B is a non-chelating organic acid, and surfactant C is an anionic surfactant.

[0016] Furthermore, the organic acid A is at least one of citric acid, tartaric acid, malic acid, oxalic acid, lactic acid or pyruvic acid; the organic acid B is at least one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid or caproic acid; the surfactant C is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol polyoxyethylene ether sulfate or sodium fatty alcohol polyoxyethylene ether sulfate.

[0017] Furthermore, the step (b) also includes: before leaching, first placing the pretreated zinc-containing solid waste into a leaching device containing the leaching agent obtained in step (a), sealing the leaching device and heating it to a predetermined temperature, introducing an inert gas to replace the air until the gas composition in the leaching device meets the predetermined requirements, and stopping the introduction of the inert gas; starting the stirring system, starting the leaching program, and completing the leaching operation.

[0018] Furthermore, the predetermined temperature is any value between room temperature and 90°C.

[0019] Furthermore, the inert gas is at least one of nitrogen, helium, neon, argon, krypton or xenon.

[0020] Furthermore, the step (c) further comprises: adding a precipitant D to the leachate obtained in step (b), adjusting the pH value, and generating a precipitate of an impure metal compound; allowing the leachate obtained in step (b) to settle and remove the precipitate of the impurity metal compound; and performing solid-liquid separation on the leachate obtained in step (b) and the precipitate of the impurity metal compound to obtain a purified liquid.

[0021] Furthermore, the precipitant D is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, calcium carbonate, barium carbonate, sodium sulfide, potassium sulfide, ammonium sulfide or sodium thiosulfate.

[0022] The present invention has the following advantages:

[0023] (1) The method provided by the present invention can effectively improve the recovery rate of zinc in zinc-containing solid waste, reduce processing costs, and reduce environmental pollution.

[0024] (2) The method provided by the present invention has good adaptability and flexibility, and various parameters can be flexibly adjusted according to actual conditions to achieve the best effect.

[0025] (3) The method provided by the present invention has a simple process, is easy to operate and can be easily implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] For the purpose of the following detailed description, it should be understood that the present invention may adopt various alternative changes and step sequences, unless expressly specified to the contrary. In addition, except in any operating examples, or otherwise indicated, all numbers representing the amount of ingredients used in the specification and claims should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the attached claims are approximate values ​​that vary according to the desired performance to be obtained by the present invention. At least it is not intended to limit the application of the doctrine of equivalents to the scope of the claims, and each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0028] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0029] In addition, it should be understood that any numerical range described herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the stated minimum value of 1 and the stated maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0030] Example 1

[0031] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches micron level.

[0032] Deep leaching:

[0033] Leaching agent: a composite acid solution composed of citric acid (organic acid A), formic acid (organic acid B) and sodium dodecyl sulfate (surfactant C).

[0034] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 50°C and nitrogen is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements. Stop introducing nitrogen; start the stirring system, start the leaching program, and complete the leaching operation.

[0035] Impurity removal: adding sodium hydroxide (precipitant D) to the leachate to adjust the pH value to generate impurity metal compound precipitates; allowing the leachate to settle to remove the impurity metal compound precipitates; performing solid-liquid separation on the leachate and the impurity metal compound precipitates to obtain a purified liquid.

[0036] Zinc recovery: The purified liquid is treated for zinc recovery.

[0037] Example 2

[0038] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches the micron level, and use magnetic separation to remove impurities.

[0039] Deep leaching:

[0040] Leaching agent: a composite acid solution composed of tartaric acid (organic acid A), acetic acid (organic acid B) and sodium dodecylbenzene sulfonate (surfactant C).

[0041] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 60°C and helium is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements. Stop introducing helium, start the stirring system, start the leaching program, and complete the leaching operation.

[0042] Impurity removal: adding potassium hydroxide (precipitant D) to the leachate, adjusting the pH value, generating impurity metal compound precipitate; allowing the leachate to settle, removing the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0043] Zinc recovery: The purified liquid is treated for zinc recovery.

[0044] Example 3

[0045] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches micron level.

[0046] Deep leaching:

[0047] Leaching agent: a composite acid solution composed of malic acid (organic acid A), propionic acid (organic acid B) and sodium lauryl polyoxyethylene ether sulfate (surfactant C).

[0048] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 70°C, and neon gas is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements. Stop introducing neon gas; start the stirring system, start the leaching program, and complete the leaching operation.

[0049] Impurity removal: adding sodium carbonate (precipitant D) to the leachate, adjusting the pH value, generating impurity metal compound precipitate; allowing the leachate to settle, removing the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0050] Zinc recovery: The purified liquid is treated for zinc recovery.

[0051] Example 4

[0052] Pretreatment: crush and grind the zinc-containing solid waste into powder to make its particle size reach micron level, and use gravity separation to remove impurities.

[0053] Deep leaching:

[0054] Leaching agent: a composite acid solution composed of oxalic acid (organic acid A), butyric acid (organic acid B) and sodium sulfate of fatty alcohol polyoxyethylene ether (surfactant C).

[0055] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 80°C and argon is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements. Stop introducing argon; start the stirring system, start the leaching program, and complete the leaching operation.

[0056] Impurity removal: adding sodium bicarbonate (precipitant D) to the leachate to adjust the pH value to generate impurity metal compound precipitate; allowing the leachate to settle to remove the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0057] Zinc recovery: The purified liquid is treated for zinc recovery.

[0058] Example 5

[0059] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches micron level.

[0060] Deep leaching:

[0061] Leaching agent: a composite acid solution composed of lactic acid (organic acid A), valeric acid (organic acid B) and sodium dodecyl sulfate (surfactant C).

[0062] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 40°C and krypton gas is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements. Stop introducing krypton gas, start the stirring system, start the leaching program, and complete the leaching operation.

[0063] Impurity removal: adding calcium carbonate (precipitant D) to the leachate, adjusting the pH value, generating impurity metal compound precipitate; allowing the leachate to settle, removing the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0064] Zinc recovery: The purified liquid is treated for zinc recovery.

[0065] Example 6

[0066] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches the micron level, and use screening to remove impurities.

[0067] Deep leaching:

[0068] Leaching agent: a composite acid solution composed of pyruvic acid (organic acid A), hexanoic acid (organic acid B) and sodium dodecylbenzene sulfonate (surfactant C).

[0069] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 30°C and xenon gas is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements. Stop introducing xenon gas, turn on the stirring system, start the leaching program, and complete the leaching operation.

[0070] Impurity removal: add barium carbonate (precipitant D) to the leachate, adjust the pH value, and generate impurity metal compound precipitate; let the leachate stand for sedimentation to remove the impurity metal compound precipitate; separate the leachate and the impurity metal compound precipitate into solid-liquid state to obtain a purified liquid.

[0071] Zinc recovery: The purified liquid is treated for zinc recovery.

[0072] Example 7

[0073] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches micron level.

[0074] Deep leaching:

[0075] Leaching agent: a composite acid solution composed of citric acid and tartaric acid (organic acid A), formic acid and acetic acid (organic acid B), sodium dodecyl sulfate and sodium lauryl polyoxyethylene ether sulfate (surfactant C).

[0076] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 75°C, and a mixed gas of nitrogen and helium (volume ratio 1:1) is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements, and the introduction of the mixed gas is stopped; the stirring system is turned on, the leaching program is started, and the leaching operation is completed.

[0077] Impurity removal: adding sodium sulfide (precipitant D) to the leachate, adjusting the pH value, generating impurity metal compound precipitate; allowing the leachate to settle, removing the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0078] Zinc recovery: The purified liquid is treated for zinc recovery.

[0079] Example 8

[0080] Pretreatment: The zinc-containing solid waste is crushed and ground into powder so that its particle size reaches the micron level, and impurities are removed by combining magnetic separation and gravity separation.

[0081] Deep leaching:

[0082] Leaching agent: a composite acid solution composed of malic acid and oxalic acid (organic acid A), propionic acid and butyric acid (organic acid B), sodium dodecylbenzene sulfonate and sodium fatty alcohol polyoxyethylene ether sulfate (surfactant C).

[0083] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 65°C, and a mixed gas of neon and argon (volume ratio 2:3) is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements, and the introduction of the mixed gas is stopped; the stirring system is turned on, the leaching program is started, and the leaching operation is completed.

[0084] Impurity removal: adding potassium sulfide (precipitant D) to the leachate, adjusting the pH value, generating impurity metal compound precipitate; allowing the leachate to settle, removing the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0085] Zinc recovery: The purified liquid is treated for zinc recovery.

[0086] Example 9

[0087] Pretreatment: crush and grind the zinc-containing solid waste into powder so that its particle size reaches micron level.

[0088] Deep leaching:

[0089] Leaching agent: a composite acid solution composed of lactic acid and pyruvic acid (organic acid A), valeric acid and caproic acid (organic acid B), sodium lauryl alcohol polyoxyethylene ether sulfate and sodium fatty alcohol polyoxyethylene ether sulfate (surfactant C).

[0090] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 55°C, and a mixed gas of krypton and xenon (volume ratio 3:2) is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements, and the introduction of the mixed gas is stopped; the stirring system is turned on, the leaching program is started, and the leaching operation is completed.

[0091] Impurity removal: adding ammonium sulfide (precipitant D) to the leachate, adjusting the pH value, generating impurity metal compound precipitate; allowing the leachate to settle, removing the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified liquid.

[0092] Zinc recovery: The purified liquid is treated for zinc recovery.

[0093] Example 10

[0094] Pretreatment: The zinc-containing solid waste is crushed and ground into powder so that its particle size reaches the micron level, and impurities are removed by combining screening and magnetic separation.

[0095] Deep leaching:

[0096] Leaching agent: a composite acid solution composed of citric acid, tartaric acid and malic acid (organic acid A), formic acid, acetic acid and propionic acid (organic acid B), sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate and sodium lauryl alcohol polyoxyethylene ether sulfate (surfactant C).

[0097] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 85°C, and a mixed gas of nitrogen, helium and neon (volume ratio 1:2:3) is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements, and the introduction of the mixed gas is stopped; the stirring system is turned on, the leaching program is started, and the leaching operation is completed.

[0098] Impurity removal: Sodium thiosulfate (precipitant D) is added to the leachate to adjust the pH value to generate a precipitate of impurity metal compounds; the leachate is allowed to settle to remove the precipitate of impurity metal compounds; the leachate and the precipitate of impurity metal compounds are subjected to solid-liquid separation to obtain a purified liquid.

[0099] Zinc recovery: The purified liquid is treated for zinc recovery.

[0100] Embodiment 11

[0101] Pretreatment: The zinc-containing solid waste is crushed and ground into powder so that its particle size reaches the micron level, and impurities are removed by combining gravity separation and screening.

[0102] Deep leaching:

[0103] Leaching agent: a composite acid solution composed of oxalic acid, lactic acid and pyruvic acid (organic acid A), butyric acid, valeric acid and caproic acid (organic acid B), sodium polyoxyethylene fatty alcohol ether sulfate, sodium dodecylbenzene sulfonate and sodium lauryl alcohol polyoxyethylene ether sulfate (surfactant C).

[0104] Leaching operation: Before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After the leaching device is sealed, it is heated to 45°C, and a mixed gas of argon, krypton and xenon (volume ratio 3:1:2) is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements, and the introduction of the mixed gas is stopped; the stirring system is turned on, the leaching program is started, and the leaching operation is completed.

[0105] Impurity removal: adding a mixed solution of sodium hydroxide and potassium hydroxide (precipitant D, volume ratio 1:1) to the leachate, adjusting the pH value, and generating a precipitate of impurity metal compounds; allowing the leachate to stand and settle to remove the precipitate of impurity metal compounds; performing solid-liquid separation on the leachate and the precipitate of impurity metal compounds to obtain a purified solution.

[0106] Zinc recovery: The purified liquid is treated for zinc recovery.

[0107] Example 12

[0108] Pretreatment: The zinc-containing solid waste is crushed and ground into powder so that its particle size reaches the micron level, and impurities are removed by combining magnetic separation, gravity separation and screening.

[0109] Deep leaching:

[0110] Leaching agent: a composite acid solution composed of citric acid, tartaric acid, malic acid, oxalic acid, lactic acid and pyruvic acid (organic acid A), formic acid, acetic acid, propionic acid, butyric acid, valeric acid and caproic acid (organic acid B), sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol polyoxyethylene ether sulfate and sodium fatty alcohol polyoxyethylene ether sulfate (surfactant C).

[0111] Leaching operation: before leaching, the pretreated zinc-containing solid waste is placed in a leaching device filled with the above-mentioned leaching agent. After sealing the leaching device, it is heated to 90°C, and a mixed gas of nitrogen, helium, neon, argon, krypton and xenon (volume ratio of 1:1:1:1:1:1) is introduced to replace the air until the gas composition in the leaching device meets the predetermined requirements, and then the introduction of the mixed gas is stopped; the stirring system is turned on, the leaching program is started, and the leaching operation is completed.

[0112] Impurity removal: adding a mixed solution of sodium carbonate, sodium bicarbonate and calcium carbonate (precipitant D, volume ratio 1:1:1) to the leachate, adjusting the pH value to generate an impurity metal compound precipitate; allowing the leachate to stand for sedimentation to remove the impurity metal compound precipitate; performing solid-liquid separation on the leachate and the impurity metal compound precipitate to obtain a purified solution.

[0113] Zinc recovery: The purified liquid is treated for zinc recovery.

[0114] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for treating zinc-containing solid waste, characterized in that: The following steps are involved: (a) pre-treating the zinc-containing solid waste; (b) deep leaching the pre-treated zinc-containing solid waste; (c) removing impurities from the leaching solution obtained in step (b); and (d) recovering zinc from the purified solution obtained in step (c).

2. The method according to claim 1, characterized in that The pretreatment includes: crushing and grinding the zinc-containing solid waste into powder so that the particle size of the zinc-containing solid waste reaches the micron level; or crushing and grinding the zinc-containing solid waste into powder so that the particle size of the zinc-containing solid waste reaches the micron level, and performing impurity removal treatment.

3. The method according to claim 2, characterized in that The impurity removal treatment is carried out by magnetic separation, gravity separation or screening.

4. The method according to claim 3, characterized in that The leaching agent used for the deep leaching is a composite acid solution composed of organic acid A, organic acid B and surfactant C, wherein organic acid A is an organic acid with a chelating effect, organic acid B is a non-chelating organic acid, and surfactant C is an anionic surfactant.

5. The method according to claim 4, characterized in that The organic acid A is at least one of citric acid, tartaric acid, malic acid, oxalic acid, lactic acid or pyruvic acid; the organic acid B is at least one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid or caproic acid; the surfactant C is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol polyoxyethylene ether sulfate or sodium fatty alcohol polyoxyethylene ether sulfate.

6. The method according to claim 5, characterized in that The step (b) also includes: before leaching, first placing the pretreated zinc-containing solid waste into a leaching device containing the leaching agent obtained in step (a), sealing the leaching device and heating it to a predetermined temperature, introducing inert gas to replace the air until the gas composition in the leaching device meets the predetermined requirements, and stopping the introduction of inert gas; starting the stirring system, starting the leaching program, and completing the leaching operation.

7. The method according to claim 6, characterized in that The predetermined temperature is any value between room temperature and 90°C.

8. The method according to claim 7, characterized in that The inert gas is at least one of nitrogen, helium, neon, argon, krypton or xenon.

9. The method according to claim 8, characterized in that The step (c) further comprises: adding a precipitant D to the leachate obtained in step (b), adjusting the pH value, and generating a precipitate of an impure metal compound; allowing the leachate obtained in step (b) to settle and remove the precipitate of the impure metal compound; and performing solid-liquid separation on the leachate obtained in step (b) and the precipitate of the impurity metal compound to obtain a purified liquid.

10. The method according to claim 9, characterized in that The precipitant D is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, calcium carbonate, barium carbonate, sodium sulfide, potassium sulfide, ammonium sulfide or sodium thiosulfate.

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