KR101314635B1 - Method of recycling cobalt from cobalt containing wastes - Google Patents

Abstract

The present invention relates to a method for recovering cobalt from wastes containing a large amount of expensive cobalt, such as waste lithium ion batteries, waste cemented carbide tools, and waste catalysts. It also relates to a cobalt recovery method that is environmentally friendly and can significantly reduce the risk of work.
The cobalt recovery method according to the present invention is characterized in that it comprises a leaching step of putting the pulverized waste containing cobalt into the leachate containing malic acid, formic acid and water and pressurized.

Description

Cobalt recovery method of cobalt containing waste {METHOD OF RECYCLING COBALT FROM COBALT CONTAINING WASTES}

The present invention relates to a method for recovering cobalt from wastes containing a large amount of expensive cobalt, such as waste lithium ion batteries, waste cemented carbide tools, and waste catalysts. In addition, the present invention relates to a cobalt recovery method that can be environmentally friendly and significantly lower the risk of work compared to conventional methods.

Lithium-ion battery is a rechargeable battery that can be used as a rechargeable battery. It is lighter, has a higher energy density / weight ratio than any other battery, has a low power loss due to self-discharge, and does not exhibit a memory effect. It is widely used in electronic devices such as phones and laptops.

Commercially available lithium ion batteries include a positive electrode using lithium oxide as a positive electrode active material, a negative electrode using carbon, and an electrolyte disposed between the positive electrode and the negative electrode.

Among them, lithium cobalt (LiCoO ₂ ) is typically used as the positive electrode active material. Since cobalt contained in lithium cobalt is an expensive rare metal, recovery of cobalt is very important in view of efficient use of resources.

Further, a so-called cemented carbide (WC-Co) composed of tungsten carbide and cobalt metal is widely used as a material for cutting tools, and it is also important to efficiently recover cobalt from expensive pulverized tools.

On the other hand, as a representative method for recovering cobalt from waste containing cobalt, a wet method including a waste crushing process, an acid leaching process of valuable metals, and a separation process using caustic soda to separate the cobalt hydroxide from the leachate is used. have.

In addition, the leachate containing hydrogen peroxide (H ₂ O ₂ ) added to hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ) or nitric acid (HNO ₃ ) And is widely used for dissolving cobalt from batteries.

However, hydrochloric acid, sulfuric acid or nitric acid contained in the leach solution is very toxic, and the operation risk is high. In addition, when the hydrogen peroxide which is a reducing agent is added to improve the leaching efficiency, the risk of the operation is further increased, There is a problem in that environmental pollutants are discharged.

In addition, a cobalt extraction process in which cobalt hydroxide is separated from the cobalt leach liquor using caustic soda may also complicate the process and reduce productivity.

The present invention is to solve the problems of the prior art described above, in the recovery of cobalt from the waste lithium ion battery, waste cemented carbide, waste catalyst, environmentally friendly and low operating risks, while the leaching efficiency of the equivalent level or more compared to sulfuric acid leaching solution The problem to be solved is to provide a cobalt recovery method that can be obtained.

In addition, another object of the present invention is to provide a cobalt recovery method that can produce a simple yet excellent cathode active material precursor from the cobalt leach solution.

As a means for solving the above problems, the present invention provides a cobalt recovery method comprising a leaching step of injecting cobalt to the leachate containing malic acid, formic acid and water, and then pressurized cobalt. .

In addition, in the method according to the invention, the concentration of the malic acid is preferably 0.2 ~ 5M, which is low leaching efficiency when the concentration of malic acid is less than 0.2M, the organic acid is not sufficiently dissolved when more than 5M, This is because the leaching efficiency does not improve.

In the method according to the invention, the leaching pressure is preferably 0.5 to 5 bar.

In addition, in the method according to the present invention, the formic acid is preferably contained in the leaching solution by 5 to 20% by volume, which is low when the concentration of the formic acid is less than 5%, more than 20% This is because the leaching efficiency does not improve and remains as it is.

In addition, in the method according to the invention, the temperature of the leaching step is preferably 60 ~ 180 ℃.

In addition, the method according to the present invention may further include the step of precipitating cobalt malate by leaving the leachate from which cobalt is extracted as it is or by additionally adding malic acid. And it is preferable that the additional amount of malic acid is finally up to 5M, because when it exceeds 5M, malic acid is no longer dissolved.

In addition, the method according to the invention may further comprise the step of heat-treating the cobalt malate to produce cobalt oxide.

In addition, the method according to the present invention may further comprise the step of preparing LiCoO ₂ by heat treatment by mixing the cobalt malate and LiCO ₂ .

In addition, the waste used in the method according to the present invention may include a waste lithium ion battery, waste cemented carbide or waste catalyst.

The cobalt recovery method according to the present invention is equivalent to the conventional method using a leaching solution containing sulfuric acid having a strong toxicity as a main component by applying a leaching step using a leaching solution containing malic acid which is a natural organic acid and some formic acid as a reducing agent. With the above leaching efficiency, the working risk can be lowered and environmental pollution can be reduced.

In addition, the cobalt leachate used in the cobalt recovery method according to the present invention has a high tendency to selectively react with cobalt, and precipitates and separates cobalt of the leachate with cobalt malic acid through a step of adding malic acid to the leachate. Because of this, the process of separating the cobalt through the conventional separate cobalt extraction process is significantly simplified to increase the productivity and reduce the recovery cost.

In addition, the cobalt malate produced by the cobalt recovery method according to the present invention can be produced as a positive electrode active material having excellent characteristics through a simple heat treatment.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing explaining the process of collect | recovering cobalt from a waste lithium ion battery.
FIG. 2 is a photograph showing a waste lithium ion battery used in an embodiment of the present invention and a state in which the waste cathode active material is separated from the waste lithium ion battery.
3 is a scanning electron micrograph of the pulmonary anode active material powder.
Figure 4 is a view showing the XRD analysis of the waste positive electrode active material powder.
5 is a graph showing the results of measuring leaching efficiency when sulfuric acid and various organic acids are used as a leaching solution.
6 is a graph showing a difference in leaching efficiency according to the amount of H ₂ O ₂ added as a reducing agent.
7 is a graph showing the leaching efficiency of malic acid and citric acid when leaching without using a reducing agent, when using formic acid as a reducing agent, using formic acid as a reducing agent and leaching in an autoclave.
Fig. 8 is a photograph of a precipitate obtained by further adding cobalt as a malic acid leaching solution, a leaching liquid after 1 hour, a leaching liquid after 6 hours, and malic acid.
9 shows the results of XRD analysis after pyrolysis of comal malate in the atmosphere.
Figure 10 shows the results of XRD analysis of Examples 1, 2, 3 and commercial LiCoO ₂ of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should also be understood that the terms or words used in the present specification and claims should not be construed in a conventional and dictionary sense and that the inventors may properly define the concept of the term to best describe its invention And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical idea of the present invention, various equivalents that may be substituted for them at the time of the present application There may be modified examples and the scope of the present invention is not limited to the embodiments described below.

In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Waste Bipolar Active Material  Powder manufacturing

As shown in Figure 1, the cobalt recovery method according to an embodiment of the present invention is largely divided into a pre-treatment step (S100), leaching step (S200) and cobalt separation step (S300) of the waste lithium ion battery, The pre-treatment step (S100) of the ion battery is further divided into a first heat treatment step (S110), a cutting and sorting step (S120), a second heat treatment step (S130), and a calcining step (S140) of the waste lithium ion battery.

In the first heat treatment step (S110) of the waste lithium ion battery, the unit cell is fixed by heating the unit cell fixed in the case made of synthetic resin to a constant temperature in the air to volatilize the adhesive component of the adhesive, thereby reducing the adhesive force. To be easily separated from the process. At this time, the heating conditions are preferably maintained for 1 hour or more at 100 ~ 200 ℃ temperature, the left picture of Figure 2 shows a state in which the battery is separated from the case.

The cutting and sorting process (S120) is a pre-step process for disassembling the unit cell separated from the case to separate the positive electrode active material. The cutting and sorting process is performed by cutting a predetermined size using a cutter, and then pulverizing the positive electrode active material in a powder form. It is a process of separating it from the material. On the other hand, the rapid oxidation reaction by the metal lithium generated by the abnormal reduction can be alleviated through the dehumidification atmosphere applied during the first low temperature heating and cutting process.

The second heat treatment step (S130) is a step of heat treating waste cut to about 500 ℃, through the second heat treatment, the separation membrane and the electrolyte can be removed by the volatilization, it is possible to easily separate the positive electrode active material of relatively weak adhesion from the metal plate To be.

The calcination step (S140) is a step of heating the electrode material consisting of LiCoO ₂ , carbon and organic materials as the cathode active material to a temperature of approximately 900 ℃ in the air or oxygen atmosphere, the organic material contained in the electrode material, CO, CO ₂ It is a process of converting and removing them.

Through the above process, the waste positive electrode active material powder as shown on the right side of FIG. 2 was obtained. 3 and 4 show the scanning electron micrograph and the XRD analysis results of the waste cathode active material powder of FIG. 2, there is no change in crystal structure before and after heat treatment, and the average particle size of the waste cathode active material powder is less than 10 μm. As a result of component analysis, the components of the powder of the positive electrode active material were confirmed to be as shown in Table 1 below.

The analysis results of the metal components of the pulverulent cathode active material powder (% by mass%) Co Ni Mn Li Fe Cu Al 48.51% 1.81% 1.06% 6.68% 0.03% 0.002% 0.28%

As confirmed in Table 1, about 48.51% by mass of Co is contained in the waste positive electrode active material powder prepared according to the embodiment of the present invention.

On the other hand, any method different from the embodiment of the present invention may be used as long as it is possible to obtain LiCoO ₂ in the form of a concentrated positive electrode active material powder form a spent lithium ion battery.

Preparation of Cobalt Leachate

As the leachate for dissolving cobalt contained in the waste positive electrode active material powder obtained as described above, the present inventors do not use highly toxic substances such as sulfuric acid or nitric acid, and are eco-friendly and toxic to human body with natural ingredients included in fruits or plants. A leaching liquid containing no organic acid as a main component was considered.

On the other hand, the organic acid include malic acid, citric acid, malonic acid, with glycolic acid, lactic acid, ascorbic acid, acrylic acid, glutaric acid, tartaric acid, etc. may be used. However, the concentration 2M, a reducing agent of an organic acid, as shown in Fig. 5 H ₂ O ₂ As a result of leaching the waste cathode active material at the temperature of 80 ° C using an organic acid leaching solution added with 5% by volume, the leaching efficiency of malic acid and citric acid was 86.7% and 89.9%, respectively, lower than that of sulfuric acid (95.8%). Although the level was shown, the leaching efficiency of other organic acids was found to be relatively low.

And, as a result of confirming the difference in the leaching efficiency according to the content of H ₂ O ₂ reducing agent, as shown in Figure 6, when the content of H ₂ O ₂ to 10%, the leaching efficiency of malic acid and citric acid is 92.0%, respectively And the leaching efficiency of malic acid and citric acid is 95.9% and 94.3%, respectively, when the H ₂ O ₂ content is 15%, but the leaching efficiency is still lower than that of sulfuric acid. It can be seen.

The present inventors considered formic acid (formic acid) which is toxic but little harmful to the human body when diluted to increase the leaching efficiency of malic acid or citric acid as a reducing agent, in order to confirm the effect of formic acid, Table 2 The leaching process was performed under the same conditions.

Kinds Leachate Components Leaching condition Mountain type density
(M) Formic acid
(volume%) Temperature
(℃) Stirring speed
(rpm) Reaction time
(H) Leaching Method Comparative Example 1 Malian 2 - 80 300 2 Reflux Comparative Example 2 Citric acid 2 - 80 300 2 Reflux Comparative Example 3 Malian 2 10 80 300 2 Reflux Comparative Example 4 Citric acid 2 10 80 300 2 Reflux Comparative Example 5 Citric acid 2 10 120 - 2 Autoclave Example Malian 2 10 120 - 2 Autoclave

As confirmed in FIG. 7, the leaching efficiency of malic acid and citric acid without using a reducing agent was only 44.1% and 57.6%, respectively, but the addition of formic acid at 10% by volume of leaching efficiency of malic acid and citric acid was 70.5, respectively. %, 62.9%, especially when leaching from autoclave to high temperature and pressurized environment, the leaching efficiency increased to 99.9% for malic acid compared to sulfuric acid, while the leaching efficiency was 19.9% for citric acid. On the contrary, it was confirmed that the leaching efficiency was lowered.

That is, when the leaching liquid according to the embodiment of the present invention is used for high temperature and pressure leaching, it is possible to reduce the environmental pollution and at the same time significantly reduce the work risk, while cobalt leaching of sulfuric acid leaching liquid is equivalent to or better than that.

Isolation of Cobalt Components

Meanwhile, as shown in FIG. 8, when the cobalt leachate produced according to the embodiment of the present invention is left, malic acid combines with a cobalt component to form a red series cobalt compound, and when malic acid is further added thereto, Formation of the cobalt compound is promoted, producing a precipitate as shown on the right side of FIG.

As a result of analyzing the components of this precipitate, it was confirmed that the cobalt component contained 70.3% by mass and contained a very small amount of other metal components. That is, by adding malic acid to the leachate according to the embodiment of the present invention, the cobalt component can be easily separated, and there is no need to perform a separate cobalt separation process as in the prior art.

On the other hand, in the embodiment of the present invention, the amount of malic acid added to the leach solution was 3M, in addition to 2M of the initial leach solution was finally to 5M.

In addition, as a result of analyzing the precipitate in detail through XRD and FT-IR, the precipitate was analyzed as Co (C ₄ H ₆ O ₅ ) ₂ 4H ₂ O, which is cobalt maleate.

LiCoO ₂ Manufacturing

Two methods were used in the examples of the present invention to prepare LiCoO ₂ with the cobalt maleate prepared in the above step.

First, cobalt malate was heat-treated in the air at a temperature of 300 ° C., 500 ° C., 700 ° C. and 900 ° C. for 7 hours, thereby forming cobalt oxide, that is, Co ₃ O ₄ . Figure 9 shows the results of XRD analysis of the samples heat-treated at each temperature, as confirmed in Figure 9, from about 500 ℃ it was confirmed that the cobalt oxide is completely removed from the organic component is formed. Among them, 3.7 g of Co ₃ O ₄ prepared at 700 ° C. and 20.8 g of Li ₂ CO ₃ were mixed, followed by heat treatment at 800 ° C. to prepare LiCoO ₂ (Example 1), and Co ₃ O ₄ prepared at 900 ° C. LiCoO ₂ (Example 2) was prepared by mixing 3.7 g and 20.8 g of Li ₂ CO ₃ , followed by heat treatment at 800 ° C.

Next, 4.0 g of cobalt malate and 0.35 g of Li ₂ CO ₃ were mixed and then heat-treated at 800 ° C., thereby directly preparing LiCoO ₂ (Example 3) without undergoing a step of forming cobalt oxide.

As a result of analyzing LiCoO ₂ of Example 1, Example 2 and Example 3, crystallization and ordering aspects of Examples 1 and 2 made of oxide and then made of lithium cobalt as shown in FIG. In comparison to Example 3.

hybrid Capacitor  Produce

Table 3 below shows the results of conducting a 20 mm coin cell test to prepare a hybrid capacitor in order to evaluate the properties of LiCoO ₂ prepared according to Examples 1, 2 and 3 of the present invention.

cathode anode Voltage
(V) DC
(F / g) PD
(W / kg) ED
(Wh / kg) PpyCNT Commercial LiCoO ₂ 1.5 66.87 75 20.90 PpyCNT LiCoO ₂
(Example 3) 1.5 92.14 75.1 28.87 PpyCNT LiCoO ₂
(Example 1) 1.5 80.39 75.25 25.29 PpyCNT LiCoO ₂
(Example 2) 1.5 50.96 75.25 16.03

As confirmed in Table 3, in Examples 2 and 3 of the present invention, it exhibits excellent properties compared to commercial LiCoO ₂ (manufacturer Johnson Matthey Company) products, in particular, heat treatment in which cobalt malate and Li ₂ CO ₃ are mixed In the case of Example 3 produced by the present invention exhibits superior characteristics as compared to Example 1, as well as commercial LiCoO ₂ , it can be seen that can be suitably used as a cathode active material precursor of a lithium secondary battery.

Claims (10)

A cobalt recovery method comprising a leaching step in which a pulverized waste containing cobalt is added to a leachate containing malic acid, water and formic acid as a reducing agent, and pressurized. The method of claim 1,
The concentration of malic acid is 0.2 ~ 5M cobalt recovery method of the waste, characterized in that. The method of claim 1,
The cobalt recovery method of the waste, characterized in that the pressure of the leaching process is 0.5 ~ 5.0 bar. The method of claim 1,
The formic acid is cobalt recovery method of the waste, characterized in that 5 to 20% by volume contained in the leachate. The method of claim 1,
Cobalt recovery method of the waste, characterized in that the temperature of the leaching process is 60 ~ 180 ℃. The method of claim 1,
Cobalt recovery method of the waste further comprising the step of precipitating cobalt malate by further adding malic acid to the cobalt extracted leachate. The method according to claim 6,
Cobalt recovery method of the waste, characterized in that further comprising the step of heat-treating the cobalt maleate to produce cobalt oxide. The method according to claim 6,
Cobalt recovery method further comprises the step of preparing LiCoO ₂ by heat treatment by mixing the cobalt maleate and LiCO ₂ . The method according to claim 6,
The additional amount of malic acid is 5M or less cobalt recovery method, characterized in that. The method according to any one of claims 1 to 8,
The waste is a cobalt recovery method, characterized in that the waste lithium ion battery, waste cemented carbide or waste catalyst.

Images