阅读说明：本技术 从含粘结剂的正极材料中回收有价金属的方法和有价金属 (Method for recovering valuable metal from positive electrode material containing binder and valuable metal ) 是由 张勤俭 肖超 李攀 赵思佳 罗进爱 邓海龙 王磊 于 2021-10-25 设计创作，主要内容包括：本申请提供一种从含粘结剂的正极材料中回收有价金属的方法和有价金属,涉及锂离子电池领域。从含粘结剂的正极材料中回收有价金属的方法,包括：将所述含粘结剂的正极材料与浓硫酸进行混合,熟化后将体系与水进行浆化；在浆化后的体系内加入双氧水,然后在保护气氛下进行加压浸出,再固液分离得到有价金属浸出液。有价金属,使用所述的从含粘结剂的正极材料中回收有价金属的方法制得。本申请提供的从含粘结剂的正极材料中回收有价金属的方法,能够有效提升有价金属的浸出率,安全性高,设备成熟,操作简单,易于推广。(The application provides a method for recovering valuable metals from a positive electrode material containing a binder and the valuable metals, and relates to the field of lithium ion batteries. A method of recovering a metal value from a binder-containing cathode material, comprising: mixing the anode material containing the binder with concentrated sulfuric acid, curing, and slurrying the system with water; adding hydrogen peroxide into the slurried system, then carrying out pressure leaching under a protective atmosphere, and carrying out solid-liquid separation to obtain valuable metal leaching liquid. Valuable metals are obtained by the method for recovering valuable metals from the cathode material containing the binder. The method for recovering the valuable metals from the cathode material containing the binder can effectively improve the leaching rate of the valuable metals, and is high in safety, mature in equipment, simple to operate and easy to popularize.)

1. A method for recovering a valuable metal from a binder-containing positive electrode material, comprising:

mixing the anode material containing the binder with concentrated sulfuric acid, curing, and slurrying the system with water;

adding hydrogen peroxide into the slurried system, then carrying out pressure leaching under a protective atmosphere, and carrying out solid-liquid separation to obtain valuable metal leaching liquid.

2. The method according to claim 1, wherein the binder-containing positive electrode material is subjected to a pretreatment before use, the pretreatment comprising:

and crushing the positive electrode material containing the binder, and screening to obtain powder.

3. The method of claim 2 wherein said powder has a particle size of 100 mesh or less.

4. The method of claim 1, wherein the mixing comprises: adding concentrated sulfuric acid into the anode material containing the binder, and stirring until the system is in a rheological phase;

preferably, the speed of adding the concentrated sulfuric acid is 0.6-1.2L/h.

5. The method according to claim 1, wherein the mass ratio of the binder-containing cathode material to concentrated sulfuric acid is 1: (1-1.2).

6. The method according to claim 1, wherein the curing is carried out at a temperature of 90-110 ℃ for 1-2 hours.

7. The method according to claim 1, wherein in the slurried system, the concentration of concentrated sulfuric acid is 2-2.5mol/L, and the liquid-solid ratio is (5-6) ml: 1g of a compound;

preferably, the slurrying is carried out under stirring at a speed of 250-350 r/min.

8. The method according to claim 1, wherein the amount of hydrogen peroxide added is 110-120% of the theoretical amount.

9. A method according to any one of claims 1-8, characterized in that the pressure leaching is performed at a pressure of 0.5-0.8MPa, at a temperature of 90-120 ℃ and for a time of 2-3 h.

10. A valuable metal, which is produced by the method for recovering a valuable metal from a binder-containing positive electrode material according to any one of claims 1 to 9.

Technical Field

The application relates to the field of lithium ion batteries, in particular to a method for recovering valuable metals from a positive electrode material containing a binder and the valuable metals.

Background

Cobalt and nickel are one of the key raw materials of the lithium battery, the realization of the recycling of the retired ternary lithium battery has important significance for solving the problems that resources required by lithium battery manufacturing and key mineral resources are restricted by people, and meanwhile, environmental benefits and social benefits are brought.

The current mainstream process for lithium battery recovery mainly comprises a pyrogenic process and a wet process, wherein the wet recovery process comprises the steps of disassembling a battery shell, crushing and screening to obtain positive active powder, leaching valuable metals in the positive active powder in acid liquor to obtain leachate rich in the valuable metals, and treating a binder in the positive active powder before leaching to solve the problems of low metal leaching rate and difficulty in filtering after acid leaching.

The separation methods mainly used at present include a heat treatment method and an organic solvent method. The heat treatment method utilizes a high-temperature pyrolysis method to decompose the binder in the positive active powder so as to achieve the purpose of separation, and the method can effectively remove the residual conductive agent and the binder, but the high-temperature treatment has the problems of higher energy consumption, the installation of a matched waste gas treatment facility for the generated waste gas and the like; the organic solvent method is to soak the anode active powder in an organic solvent with excellent binder solubility, and to separate the binder from the anode active powder after filtration, but the organic solvent is viscous, has low filtration speed when being separated from the anode active powder, has high cost, needs to be matched with an organic solvent recovery facility, and the like, and limits further industrial application.

Therefore, it is necessary to find a method for leaching the positive active powder with low cost, simple operation and high recovery rate of valuable metals.

Disclosure of Invention

An object of the present application is to provide a method for recovering valuable metals from a binder-containing positive electrode material and valuable metals, so as to solve the above problems.

In order to achieve the purpose, the following technical scheme is adopted in the application:

a method of recovering a valuable metal from a binder-containing cathode material, comprising:

mixing the anode material containing the binder with concentrated sulfuric acid, curing, and slurrying the system with water;

adding hydrogen peroxide into the slurried system, then carrying out pressure leaching under a protective atmosphere, and carrying out solid-liquid separation to obtain valuable metal leaching liquid.

Preferably, the binder-containing cathode material is subjected to pretreatment before use, the pretreatment including:

and crushing the positive electrode material containing the binder, and screening to obtain powder.

Preferably, the particle size of the powder is less than or equal to 100 meshes.

Preferably, the mixing comprises: and adding concentrated sulfuric acid into the anode material containing the binder, and stirring until the system is in a rheological phase.

Preferably, the speed of adding the concentrated sulfuric acid is 0.6-1.2L/h.

Preferably, the mass ratio of the binder-containing cathode material to concentrated sulfuric acid is 1: (1-1.2).

Preferably, the curing temperature is 90-110 ℃ and the curing time is 1-2 h.

Preferably, in the slurried system, the concentration of concentrated sulfuric acid is 2-2.5mol/L, and the liquid-solid ratio is (5-6) ml: 1g of a compound;

preferably, the slurrying is carried out under stirring at a speed of 250-350 r/min.

Preferably, the addition amount of the hydrogen peroxide is 110-120% of the theoretical amount.

Preferably, the protective atmosphere comprises an inert gas.

Preferably, the pressure of the pressure leaching is 0.5-0.8MPa, the temperature is 90-120 ℃, and the time is 2-3 h.

The application also provides a valuable metal prepared by the method for recovering the valuable metal from the cathode material containing the binder.

Compared with the prior art, the beneficial effect of this application includes:

according to the method for recovering valuable metals from the cathode material containing the binder, the concentrated sulfuric acid curing and pressure leaching are adopted to reinforce the leaching process, the viscosity of the binder is reduced after the concentrated sulfuric acid is cured at a high temperature, the leaching rate of the valuable metals (the valuable metals are converted into sulfate which is easier to leach) is improved, and the leaching rate of the valuable metals (nickel, cobalt and manganese) can reach more than 97%; the binder in the positive active powder is removed without high-temperature heat treatment or an organic solvent method, so that the working procedure is simplified, and the cost and the energy consumption are reduced;

compared with normal pressure leaching, the pressure leaching can ensure that the leaching process is carried out at a temperature far higher than the boiling point of normal pressure liquid, and the leaching rate of metal can be improved by improving the leaching temperature; the pressure leaching can effectively inhibit the high-temperature decomposition of the hydrogen peroxide during the reduction leaching, and the addition amount and the cost of the hydrogen peroxide are reduced;

different from the common pressurized oxygen leaching of the pressurized leaching process, the process adopts inert gas for evacuation and pressurization, the inert gas does not participate in the reaction, the reduction leaching is favorably carried out, the possibility of explosion caused by the reaction of oxygen and organic matters under the condition of high temperature and high pressure is avoided, and the safety is high;

the method can be completed in one high-pressure reaction kettle, and has the advantages of mature equipment, simple operation and easy popularization.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments are briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope of the present application.

Fig. 1 is a process flow diagram illustrating a method for recovering valuable metals from a binder-containing cathode material according to example 1.

Detailed Description

The terms as used herein:

"prepared from … …" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of … …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of … …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when the range "1 ~ 5" is disclosed, the ranges described should be construed to include the ranges "1 ~ 4", "1 ~ 3", "1 ~ 2 and 4 ~ 5", "1 ~ 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

In these examples, the parts and percentages are by mass unless otherwise indicated.

"part by mass" means a basic unit of measure indicating a mass ratio of a plurality of components, and 1 part may represent any unit mass, for example, 1g or 2.689 g. If we say that the part by mass of the component A is a part by mass and the part by mass of the component B is B part by mass, the ratio of the part by mass of the component A to the part by mass of the component B is a: b. alternatively, the mass of the A component is aK and the mass of the B component is bK (K is an arbitrary number, and represents a multiple factor). It is unmistakable that, unlike the parts by mass, the sum of the parts by mass of all the components is not limited to 100 parts.

"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).

A method of recovering a valuable metal from a binder-containing cathode material, comprising:

mixing the anode material containing the binder with concentrated sulfuric acid, curing, and slurrying the system with water;

adding hydrogen peroxide into the slurried system, then carrying out pressure leaching under a protective atmosphere, and carrying out solid-liquid separation to obtain valuable metal leaching liquid.

In an alternative embodiment, the binder-containing cathode material is pretreated before use, and the pretreatment includes:

and crushing the positive electrode material containing the binder, and screening to obtain powder.

In an alternative embodiment, the powder has a particle size of 100 mesh or less.

The phrase "particle size of 100 mesh or less" as used herein means that the size of the powder is 100 mesh or less.

In an alternative embodiment, the mixing comprises: and adding concentrated sulfuric acid into the anode material containing the binder, and stirring until the system is in a rheological phase.

Concentrated sulfuric acid is added into the positive electrode material containing the binder, so that a large amount of dense smoke is prevented from being generated by violent reaction; stirring is also required to be performed slowly to avoid that the stirring is so fast that the binder-containing positive electrode material is stirred up to generate dust.

In an alternative embodiment, the concentrated sulfuric acid is added at a rate of 0.6 to 1.2L/h.

The adding speed of the concentrated sulfuric acid is controlled mainly to avoid the generation of a large amount of dense smoke in the feeding process.

Optionally, the rate of adding the concentrated sulfuric acid may be any value of 0.6L/h, 0.7L/h, 0.8L/h, 0.9L/h, 1.0L/h, 1.1L/h, 1.2L/h, or 0.6-1.2L/h.

In an optional embodiment, the mass ratio of the binder-containing cathode material to concentrated sulfuric acid is 1: (1-1.2).

The concentrated sulfuric acid is less, the enhanced leaching effect is poor, and the concentrated sulfuric acid is changed into a sticky wet mud shape when more concentrated sulfuric acid is added, so that the operation is difficult.

Optionally, the mass ratio of the binder-containing cathode material to concentrated sulfuric acid may be 1: 1. 1: 1.1, 1: 1.2 or 1: (1-1.2).

In an alternative embodiment, the temperature of the aging is 90-110 ℃ and the time is 1-2 h.

Optionally, the curing temperature can be any value between 90 ℃, 100 ℃, 110 ℃ or 90-110 ℃, and the curing time can be any value between 1h, 1.5h, 2h or 1-2 h.

In an alternative embodiment, in the slurried system, the concentration of concentrated sulfuric acid is 2 to 2.5mol/L, and the liquid-solid ratio is (5 to 6) ml: 1g of a compound;

in an alternative embodiment, the slurrying is carried out under stirring at a rate of 250-.

Optionally, in the slurried system, the concentration of the concentrated sulfuric acid may be any value between 2mol/L, 2.1mol/L, 2.2mol/L, 2.3mol/L, 2.4mol/L, 2.5mol/L, or 2 to 2.5mol/L, and the liquid-solid ratio may be 5 ml: 1g, 5.5 ml: 1g, 6 ml: 1g or (5-6) ml: any value between 1 g; the stirring speed can be any value between 250r/min, 300r/min, 350r/min or 250-350 r/min.

In an optional embodiment, the addition amount of the hydrogen peroxide is 110-120% of the theoretical amount.

The excess coefficient of hydrogen peroxide in the conventional acid leaching is 1.5-1.8, and in the scheme, the excess coefficient of hydrogen peroxide can be 1.1-1.2.

Optionally, the addition amount of the hydrogen peroxide can be any value between 110%, 115%, 120% or 110% and 120% of the theoretical amount.

In an alternative embodiment, the protective atmosphere comprises an inert gas.

In an alternative embodiment, the pressure leaching is carried out at a pressure of 0.5-0.8MPa, a temperature of 90-120 ℃ and a time of 2-3 h.

The pressure of the pressure leaching is selected to ensure that the system pressure is at least greater than the saturated vapor pressure of water and the oxygen partial pressure of 0.1MPa at the reaction temperature.

Optionally, the pressure of the pressure leaching may be any value between 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa or 0.5-0.8MPa, the temperature may be any value between 90 ℃, 100 ℃, 110 ℃, 120 ℃ or 90-120 ℃, and the time may be any value between 2h, 2.5h, 3h or 2-3 h.

The application also provides a valuable metal prepared by the method for recovering the valuable metal from the cathode material containing the binder.

The term "a valuable metal" as used herein means a mixed solution of valuable metals or a valuable metal obtained by post-treatment.

Embodiments of the present application will be described in detail below with reference to specific examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Firstly, raw materials are explained, and the details are as follows:

crushing the positive electrode material containing the binder PVDF, and screening by using a 100-mesh sieve to obtain powder; the detection shows that the contents of main metals such as nickel, cobalt, manganese and lithium in the powder are 36.72%, 4.29%, 0.64% and 4.55% respectively.

The binder referred to herein mainly refers to PVDF and a binder having properties similar to PVDF.

Example 1

Referring to fig. 1, the present embodiment provides a method for recovering valuable metals from a binder-containing cathode material, which specifically includes the following steps:

1) 100.13g of the above powder was weighed into a reaction vessel, and 65mL of concentrated sulfuric acid was added at a flow rate of 0.78L/h with stirring and mixed uniformly (wet sludge state).

2) The reaction kettle is sealed, and the temperature is raised to 105 ℃ and kept stand for 2 h.

3) And (3) stopping heating, starting stirring, adding 550mL of pure water for slurrying, wherein in a slurried system, the concentration of concentrated sulfuric acid is 2mol/L, and the liquid-solid ratio is 6 mL: 1g of a compound;

then adding 50g of 30 wt% hydrogen peroxide, introducing nitrogen to exhaust air in the reaction kettle, adjusting the kettle pressure to 0.5MPa, starting to heat up, heating to 105 ℃, and then carrying out heat preservation reaction for 2 hours.

4) And after the reaction is finished, cooling the temperature of the reaction kettle to room temperature, releasing the pressure, discharging the feed liquid, and performing suction filtration to obtain leaching solution containing nickel, cobalt, manganese and lithium and leaching slag.

The test shows that the leaching rates of nickel, cobalt, manganese and lithium are respectively 97.88%, 98.53%, 97.31% and 99.75%.

Example 2

The embodiment provides a method for recovering valuable metals from a positive electrode material containing a binder, which specifically comprises the following steps:

1) 200.28g of the above powder was weighed into a reaction vessel, and 135mL of concentrated sulfuric acid was added at a flow rate of 0.8L/h with stirring and mixed uniformly (wet sludge state).

2) The reaction kettle is sealed, and the temperature is raised to 105 ℃ and kept stand for 2 h.

3) And (3) stopping heating, starting stirring, adding 950mL of pure water for slurrying, wherein in a slurried system, the concentration of concentrated sulfuric acid is 2.4mol/L, and the liquid-solid ratio is 5.25 mL: 1g of a compound;

then adding 104g of 30 wt% hydrogen peroxide, introducing nitrogen to exhaust air in the reaction kettle, adjusting the kettle pressure to 0.7MPa, starting to heat up, heating to 115 ℃, and then carrying out heat preservation reaction for 2 hours.

4) And after the reaction is finished, cooling the temperature of the reaction kettle to room temperature, releasing the pressure, discharging the feed liquid, and performing suction filtration to obtain leaching solution containing nickel, cobalt, manganese and lithium and leaching slag.

Through detection, the leaching rates of nickel, cobalt, manganese and lithium are 98.24%, 98.99%, 98.45% and 99.83% respectively.

Example 3

The embodiment provides a method for recovering valuable metals from a positive electrode material containing a binder, which specifically comprises the following steps:

1) 200.61g of the above powder was weighed into a reaction vessel, and 135mL of concentrated sulfuric acid was added at a flow rate of 0.8L/h with stirring and mixed uniformly (wet sludge state).

2) The reaction kettle is sealed, and the temperature is raised to 120 ℃ and kept stand for 1 h.

3) And (3) stopping heating, starting stirring, adding 950mL of pure water for slurrying, wherein in a slurried system, the concentration of concentrated sulfuric acid is 2.4mol/L, and the liquid-solid ratio is 5.25 mL: 1g of a compound;

then adding 104g of 30 wt% hydrogen peroxide, introducing nitrogen to exhaust air in the reaction kettle, adjusting the kettle pressure to 0.8MPa, starting to heat up, heating to 115 ℃, and then carrying out heat preservation reaction for 2 hours.

4) And after the reaction is finished, cooling the temperature of the reaction kettle to room temperature, releasing the pressure, discharging the feed liquid, and performing suction filtration to obtain leaching solution containing nickel, cobalt, manganese and lithium and leaching slag.

Through detection, the leaching rates of nickel, cobalt, manganese and lithium are respectively 98.33%, 98.76%, 98.38% and 99.79%.

Comparative example 1

Weighing 100.09g of the powder, adding the powder into 600mL of sulfuric acid solution with the concentration of 2mol/L, reacting at 90 ℃ for 2h, and performing suction filtration to obtain leaching solution containing nickel, cobalt, manganese and lithium and leaching residues, wherein the leaching rates of nickel, cobalt, manganese and lithium are 58.75%, 60.29%, 62.81% and 68.6% respectively.

Comparative example 1 the leaching results show that: the PVDF as the binder has hydrophobicity, so that poor contact between acid liquor and materials is caused during direct acid leaching, and on the other hand, a small part of nickel and cobalt in the positive active powder exists in the form of a high-valence compound which is difficult to leach, so that the direct acid leaching effect is poor.

Comparative example 2

Weighing 100.1g of the powder, adding the powder into 600mL of 2mol/L sulfuric acid solution, adding 72.5g of 30 wt% hydrogen peroxide, reacting at 90 ℃ for 2h, and performing suction filtration to obtain leaching solution and leaching residue containing nickel, cobalt, manganese and lithium, wherein the leaching rates of nickel, cobalt, manganese and lithium are 86.12%, 82.54%, 84.71% and 88.5% respectively.

Comparative example 2 the leaching results show that: the reduction leaching can reduce a small part of trivalent cobalt nickel into easily leached divalent cobalt nickel, so that the leaching rate is improved; the hydrogen peroxide is easy to decompose at 60 ℃, so that excessive hydrogen peroxide is required to be added during reduction leaching, and the excessive coefficient of the hydrogen peroxide is 1.6, namely 1.6 times of the theoretical dosage; therefore, the method can reduce the usage amount of hydrogen peroxide, improve the leaching rate and further reduce the production cost.

Comparative example 3

Weighing 100.62g of the powder, adding 65mL of concentrated sulfuric acid while stirring, uniformly mixing (wet mud-like), placing the mixture in an oven at 105 ℃, standing for 2h, taking out the mixture, sequentially adding 550mL of pure water and 72.5g of 30 wt% hydrogen peroxide, reacting at 90 ℃ for 2h, and performing suction filtration to obtain leaching solution and leaching residue containing nickel, cobalt, manganese and lithium, wherein the leaching rates of nickel, cobalt, manganese and lithium are 83.94%, 82.88%, 82.31% and 88.19% respectively.

Comparative example 3 the leaching results show that: when concentrated sulfuric acid is aged and leached, the PVDF binder is corroded to a certain extent by high-concentration sulfuric acid, so that the performance of the PVDF binder is reduced, the PVDF binder can more easily penetrate through the obstruction of the PVDF binder to react with valuable metal compounds in powder materials, the PVDF binder is converted into easily-leached sulfate, and the leaching rate is effectively improved.

Comparative example 4

Weighing 100.02g of the powder, adding the powder into 600mL of 2mol/L sulfuric acid solution, adding 72.5g of 30 wt% hydrogen peroxide (the excess coefficient of the hydrogen peroxide is 1.6), transferring the mixed solution into a reaction kettle, sealing the reaction kettle, introducing nitrogen to exhaust the air in the reaction kettle, adjusting the kettle pressure to 0.5MPa, starting heating, heating to 105 ℃, and carrying out heat preservation reaction for 2 hours. After the reaction is finished, cooling the temperature of the reaction kettle to room temperature, releasing the pressure, discharging the feed liquid, and performing suction filtration to obtain leaching liquid and leaching residues containing nickel, cobalt, manganese and lithium, wherein the leaching rates of nickel, cobalt, manganese and lithium are 93.4%, 92.65%, 91.67% and 97.42% respectively.

Comparative example 4 the leaching results show that: the metal leaching rate is effectively improved after the reaction temperature is increased by pressure reduction leaching.

Comparative example 5

100.07g of the powder is weighed and added into 600mL of sulfuric acid solution with the concentration of 2mol/L, 50g of 30 wt% hydrogen peroxide (the excess coefficient of the hydrogen peroxide is 1.1) is added, the mixed solution is transferred to a reaction kettle, the reaction kettle is sealed, nitrogen is introduced to exhaust the air in the reaction kettle, the kettle pressure is adjusted to 0.5MPa, then the temperature is raised, and the temperature is raised to 105 ℃ and then the reaction is kept for 2 hours. After the reaction is finished, cooling the temperature of the reaction kettle to room temperature, releasing the pressure, discharging the feed liquid, and performing suction filtration to obtain leaching liquid and leaching residues containing nickel, cobalt, manganese and lithium, wherein the leaching rates of nickel, cobalt, manganese and lithium are 92.72%, 91.82%, 91.56% and 97.9% respectively.

Comparative example 5 the leaching results show that: the metal leaching rate is almost the same as the result when the excessive coefficient of hydrogen peroxide is 1.6, which shows that the decomposition of hydrogen peroxide can be effectively inhibited during the pressure reduction leaching, the use efficiency is improved, and the consumption of hydrogen peroxide is reduced.

Table 1 shows the reaction parameters and leaching rates of examples 1 and 2 and comparative examples 1 to 5.

TABLE 1 reaction parameters and Leaching Rate

As can be seen from the above table 1, the method provided by the application is obviously superior to the method provided by the comparative example, and the leaching rate of valuable metals is obviously improved to more than 97%.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Moreover, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.