KR20220170745A - System for Recovering Valuable Metals from Wasted Batteries - Google Patents

Abstract

The present invention relates to a method for recovering valuable metals from waste lithium ion batteries, including a step of heat-treating waste lithium ion batteries under a mixed reducing gas atmosphere of carbon dioxide (CO_2) and carbon monoxide (CO) in which log (P_CO_2/P_CO), which is the logarithm of a value obtained by calculating the partial pressure of carbon dioxide as the partial pressure of carbon monoxide, has a value within the range of -2.15 or more and 2.5 or less.

Description

System for recovering valuable metals from waste batteries {System for Recovering Valuable Metals from Wasted Batteries}

The present invention relates to a system for recovering valuable metals from waste batteries.

Lithium-ion secondary batteries are widely used in portable electronic devices due to their high energy density and low self-discharge effect. use is expected to accelerate further. As the use of lithium-ion secondary batteries accelerates, the amount of waste batteries is expected to increase, and about 5.7 million waste batteries for electric vehicles are expected to be generated before 2040.

The positive electrode of a lithium secondary battery includes a positive electrode active material layer formed on the surface of a positive electrode current collector, and the positive electrode active material includes lithium and a transition metal including nickel, cobalt, manganese, and the like. The nickel and cobalt are relatively expensive. It is a metal, and in particular, cobalt is known as a metal whose supply and demand is unstable worldwide because the number of producing countries is limited. Therefore, when valuable metals included in cathode active materials are recovered from waste batteries, particularly waste cathodes, and recycled as raw materials, price competitiveness can be secured and additional profits can be created. Recently, studies on methods for recovering and recycling valuable metals from waste batteries have been attempted.

Current battery recycling technologies include a wet method that uses a large amount of acid to recover valuable metals and a dry method that melts batteries at high temperatures to recover valuable metals. It has the disadvantage of the complexity of the treatment process and the inability to process large quantities. In the case of the dry method, indiscriminate emission of global warming gas (CO 2 ) is generated during the process, a large amount of process by-products are generated, and an additional treatment process is required.

Considering the amount of waste batteries generated at home and abroad, these long-term industries can cause environmental pollution not only in Korea but also worldwide, so eco-friendly/high-efficiency technologies must be developed.

The present invention is a method for recovering valuable metals from waste lithium ion batteries using a dry method, which prevents unnecessary energy consumption in recovering valuable metals and indiscriminate emission of global warming gas (CO2) due to oxidation of graphite, an anode material in the battery. It aims to provide a method to solve the problems of the existing dry method caused by

A method for recovering valuable metals from a waste lithium ion battery according to one aspect includes creating a mixed reducing gas atmosphere of carbon dioxide (CO ₂ ) and carbon monoxide (CO) that satisfies the partial pressure ratio of Equation 1 below; and heat-treating the waste lithium ion battery in the mixed reducing gas atmosphere.

[Equation 1]

-2.15 ≤ log(P _CO2 /P _CO ) ≤ 2.5

At this time, P _CO2 is the partial pressure value of carbon dioxide, and P _CO is the partial pressure value of carbon monoxide.

The valuable metal may be at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li).

In the heat treatment step, as the heat treatment temperature increases, the log(P _CO 2 /P _CO ) may be adjusted to decrease.

When the heat treatment temperature is greater than 500 ° C and less than 600 ° C, greater than 600 ° C and less than 700 ° C, greater than 700 ° C and less than 800 ° C, greater than 800 ° C and less than 900 ° C, or greater than 900 ° C and less than 1,000 ° C, log (P _CO2 / P _CO ) can be adjusted to a value within the range of 0.45 or more and 2.50 or less, -0.20 or more and 2.15 or less, -0.90 or more and 1.85 or less, -1.55 or more and 1.60 or less, or -2.15 or more and 1.40 or less.

The waste lithium ion battery may be a battery including lithium nickel cobalt manganese oxide or lithium cobalt oxide as a cathode active material.

The heat treatment may be performed at a temperature between 650 and 850 °C.

At the heat treatment temperature, log(P _CO 2 /P _CO ) may be performed under a mixed reducing gas atmosphere of carbon dioxide and carbon monoxide adjusted to a value within the range of -1.20 or more and 2.00 or less.

By the heat treatment, a recovered material containing at least one selected from the group consisting of Co, Ni, Mn, CoO, NiO, MnO, Li ₂ CO ₃ , and LiAlO ₂ may be obtained.

An additional heat treatment step of heat-treating the recovered product obtained by the heat treatment in an atmosphere of oxygen (O ₂ ) or carbon dioxide (CO ₂ ) at 700° C. or higher may be further included.

CO gas is generated in the additional heat treatment step, and log(P _CO 2 /P _CO ) may be adjusted by supplying the CO gas as a mixed reducing gas in the heat treatment step.

A separation step of separating valuable metal-containing materials from the recovered material obtained by the heat treatment is further included, and the separation is performed by a separation process by sieving, a separation process by magnetism, and leaching using acid or water. It may include one or more separation processes selected from the group consisting of separation processes.

CO gas is generated in the additional heat treatment step, and heat generated by an exothermic reaction by oxidation of the CO gas may be used as a heat source in the heat treatment step or the valuable metal separation step performed after the heat treatment step.

According to the present invention, valuable metals can be efficiently recovered from waste lithium ion batteries. In particular, the anode material (Graphite) in the waste lithium ion battery acts as a reducing material during the recycling process to reduce MeO-based valuable metal oxides to generate global warming gas (CO ₂ ). According to the present invention, atmospheric gas during the heat treatment process Through control, the emission of global warming gas can be minimized.

1 is an image of recovering valuable metals from a lithium ion secondary battery according to an embodiment.

Hereinafter, the present invention will be described in detail.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention. Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

In this specification, terms such as "comprise", "comprise" or "having" are intended to indicate that there is an embodied feature, number, step, component, or combination thereof, and that one or more other features or The presence or addition of numbers, steps, components, or combinations thereof is not excluded.

A method for recovering valuable metals from a waste lithium ion battery according to the present invention comprises the steps of creating a mixed reducing gas atmosphere of carbon dioxide (CO2) and carbon monoxide (CO) that satisfies the partial pressure ratio of Equation 1 below, and the mixed reducing gas and heat-treating the waste lithium ion battery in an atmosphere.

[Equation 1]

-2.15 ≤ log(P _CO2 /P _CO ) ≤ 2.5

At this time, P _CO2 is the partial pressure value of carbon dioxide, and P _CO is the partial pressure value of carbon monoxide.

According to one aspect of the present invention, the method of the present invention includes pre-treating a waste lithium ion battery, putting the pre-treated waste lithium ion battery into a heat treatment device (eg, a heat treatment furnace), the heat treatment creating a mixed gas atmosphere of CO2 and CO in the device, heat-treating the heat treatment device created in the mixed gas atmosphere, and separating valuable metals from a recovered material obtained by the heat treatment, wherein the heat treatment An additional heat treatment step may be further included under O ₂ or CO ₂ conditions at 700° C. or higher between the step and the separation step of the valuable metal.

Each step is described in more detail below.

The step of pretreating the waste lithium ion battery is performed for the purpose of preventing explosion or harmlessness of the waste lithium ion battery, removing an outer can, and the like. That is, since a waste lithium ion battery, such as a used lithium ion battery, is a closed system and has an electrolyte solution or the like inside, it is dangerous because there is a risk of explosion if the pulverization treatment is performed in the state as it is. For this reason, it is necessary to perform a discharge treatment or an electrolyte removal treatment by some method. In this way, by removing the electrolyte solution and the outer can in the waste battery pretreatment process, safety can be improved and the recovery productivity of valuable metals such as copper, nickel, and cobalt can be improved. In the case of the discharge treatment, the battery may be immersed in an aqueous solution containing alkali metal or alkaline earth metal ions.

The waste lithium ion battery pretreated as described above may undergo a pulverization process if necessary. In the pulverization step, the battery contents are pulverized to obtain a pulverized product. The crushing process may be performed for the purpose of increasing the recovery rate of valuable metals such as copper, nickel, and cobalt by increasing the reaction efficiency in the subsequent process. A specific pulverization method is not particularly limited, but can be performed by pulverizing or cutting the contents of the battery using a conventionally known pulverizer such as a cutter mixer.

Next, the waste lithium ion battery may be put into a heat treatment device, for example, a heat treatment furnace. The heat treatment furnace has a space for inserting waste batteries therein, includes a heat source inside or outside the furnace, and has an input furnace for inserting waste batteries at one side of the heat treatment furnace, As long as it has a discharge part capable of recovering the reaction product, it can be used without particular limitation; For example, any one of a muffle furnace, a hearth furnace, and a rotary kiln furnace may be used. As the heat source, a gas burner, a coal burner, a resistance heating element, or an IR lamp may be used, but may not be limited thereto. The recovery material after heat treatment is composed of Me (M=Co or Ni, or Mn) or MeO (M=Co or Ni, or Mn), Li ₂ CO ₃ and LiAlO ₂ , Graphite (C), Al, and Cu. there is.

Subsequently, the waste battery introduced into the heat treatment device is heat treated.

First, the heat treatment may be reduced in a mixed gas atmosphere of CO ₂ and CO according to the operating temperature shown in Table 1 below. The mixed gas may be adjusted so that log(PCO ₂ /PCO), which is a logarithmic value of a value calculated by calculating the partial pressure of carbon dioxide as the partial pressure of carbon monoxide, represents a value within a range of -2.15 or more and 2.5 or less. The temperature of the heat treatment is determined according to the type and shape of the battery, and can be adjusted so that log(PCO2/PCO) decreases as the temperature of the heat treatment increases in the heat treatment step. Pouch-type batteries of LCO and NMC systems undergo heat treatment at a temperature of 650 ~ 850 ° C. At this time, the heat treatment is a mixture of carbon dioxide and carbon monoxide adjusted so that log (PCO2 / PCO) is a value within the range of -1.20 or more and 2.00 or less. It may be performed under a reducing gas atmosphere. According to another embodiment, the heat treatment temperature is greater than 500 ° C and less than 600 ° C, greater than 600 ° C and less than 700 ° C, greater than 700 ° C and less than 800 ° C, greater than 800 ° C and less than 900 ° C, or greater than 900 ° C and less than 1,000 ° C In this case, log (P _CO 2 /P _CO ) may be adjusted to be a value within the range of 0.45 or more and 2.50 or less, -0.20 or more and 2.00 or less, -0.90 or more and 1.85 or less, -1.55 or more and 1.60 or less, or -2.15 or more and 1.40 or less. . By adjusting the maximum and minimum values of log (P _CO2 /P _CO ) according to the operating temperature, the CO ₂ /CO mixed gas is set to the lower limit (Min) value or higher according to each heat treatment temperature condition to suppress the precipitation of carbon , the heat treatment process time can be shortened by setting it below the upper limit (Max) value.

Temperature(℃) 500 550 600 650 700 750 800 850 900 950 1000

Max 2.50 2.30 2.12 1.97 1.83 1.70 1.58 1.48 1.38 1.29 1.21 Min 1.20 0.83 0.49 0.16 -0.17 -0.51 -0.86 -1.20 -1.53 -1.83 -2.11

After the heat treatment is completed, additional heat treatment is performed on the heat treated recovered material to remove residual carbon from the recovered material. At this time, the heat treatment temperature is set to 700 ° C or higher, and preferably, the atmosphere condition is set to O ₂ or CO ₂ at a temperature of 700 ° C to 800 ° C to remove residual carbon and generate CO gas at the same time to create an atmosphere for heat treatment. It is used for control, or the exothermic reaction by oxidation of CO is used as a heat source for the heat treatment process or separation process. The recovery material after additional heat treatment is composed of Me (M=Co or Ni, or Mn) or MeO (M=Co or Ni, or Mn), Li ₂ CO ₃ and LiAlO ₂ , Al, and Cu.

After going through the above heat treatment process, valuable metals can be recovered according to the physical properties of the recovered product, and in the case of magnetic metals, they can be separated using a magnetic field during the separation process, and in the case of ash, they are classified by size by sieving can do. In addition, among the process products, Li ₂ CO ₃ and LiAlO ₂ , which are Li-enriched phases, can be recovered by a leaching process using water or acid. The separation process can be carried out either before or after the further heat treatment, depending on the purpose.

For example, in the case of ash, the size is smaller than that of magnetic valuable metal-containing materials or non-magnetic valuable metal-containing materials in the form of flakes having a size of several mm to several cm, and sieving It can be designed to pass through a classification filter for The classification filter may be, for example, a mesh having an average pore size of 80 μm to 110 μm. According to another embodiment, the classification is performed by a centrifugal, inertial force or gravity applied to the particles in a fluidizing fluid, for example, a gas stream, a pneumatic classifier, a centrifugal separation, or a classification by physical vibration or sedimentation in a liquid. A wet polarization device using a speed difference may be applied, and the present invention is not limited thereto. In the magnetic separation, a first valuable metal-containing material having magnetism and a second valuable metal-containing material having no magnetism are separated by using a magnetic field of an electromagnet or a permanent magnet. In another embodiment, the second separation step may be performed by applying a magnetic field to the mixture of the first and second valuable metal-containing substances while applying appropriate vibration to select the first valuable metal-containing substances attached to the magnet.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1: Valuable metal recovery in a mixed reducing gas atmosphere of carbon dioxide (CO2) and carbon monoxide (CO)

=0으로 15분 처리하였다. 그 다음, 700°C 이상 800°C 이하, O₂ 또는 CO₂ 조건에서 추가 열처리를 수행하여 회수체 중 잔류 탄소를 제거하였다. 그 다음, 상기 회수체를 Sieving 하여 열처리 공정 중 생성된 Li₂CO₃와 LiAlO₂을 Ash의 형태로 회수하였다. 한편, 자성/비자성 금속은 회수체에 자장을 걸어 회수하고, Li 농축상인 Li₂CO₃와 LiAlO₂는 water leaching과 acid leaching을 통해 회수하였다.A waste lithium ion battery containing lithium nickel cobalt manganese oxide as a cathode active material was pretreated by immersing the battery in an aqueous solution containing alkaline earth metal ions and discharging for 24 hours. Then, a crushing process was performed through a crushing or cutting process so as to be well put into the heat treatment furnace. Then, as shown in Tables 1 and 2, a mixed reducing gas atmosphere of carbon dioxide (CO ₂ ) and carbon monoxide (CO) was prepared at a temperature of 850 ° C.

=0 for 15 minutes. Then, additional heat treatment was performed under conditions of 700°C or more and 800°C or less, O ₂ or CO ₂ to remove residual carbon from the recovered product. Then, the recovered material was sieved to recover Li ₂ CO ₃ and LiAlO ₂ generated during the heat treatment process in the form of ash. Meanwhile, magnetic/non-magnetic metals were recovered by applying a magnetic field to the recovery body, and Li ₂ CO ₃ and LiAlO ₂ , which are Li-enriched phases, were recovered through water leaching and acid leaching.

Comparative Example 1: Recovery of Valuable Metals in Other Gas Atmospheres

Compared with Example 1, valuable metals were recovered in various gas atmospheres as shown in Table 2 below, instead of the mixed reducing gas atmosphere of Example 1.

Experimental Example 1: Confirmation of Recovered Valuable Metals

Valuable metals were recovered according to Example 1, and the recovered valuable metals are shown in FIG.

Referring to Figure 1, (1) a metal in the form of an alloy containing Ni or Co or Mn having magnetism (2) a non-magnetic Al alloy in the case of using Al as a battery case (3) recovery using the water leaching method It can be confirmed that valuable metals can be recovered in four groups: lithium carbonate (4) MnO, LiAlO ₂ and residual carbon not oxidized in the second heat treatment.

Experimental Example 2: Analysis of Valuable Metal Recovery Depending on the Type of Reducing Gas

According to Table 2 below, valuable metals were recovered and yields of the recovered valuable metals were respectively shown.

recovered metal
atmosphere conditions Li2CO3 LiAlO2 Al dross Co Cu C Comparative Example 1 Ar 97 68 94 69 98 67 Example 1

=0

=0 97 70 98 95 98 80 Comparative Example 1 _CO2 98 70 96 95 97 52 Comparative Example 1 CO 96 69 97 95 96 83

Referring to Table 2, in the Ar atmosphere of Comparative Example 1, it was confirmed that C was used as a reducing agent and reduced to Co metal (by solid-solid reaction).

Accordingly, it was confirmed that when the valuable metal was recovered under the conditions according to Example 1, the amount of CO ₂ generated was remarkably reduced while the recovery rate of the valuable metal was high.

Experimental Example 3: Valuable metal recovery analysis according to mixed reducing gas atmosphere conditions of carbon dioxide (CO2) and carbon monoxide (CO)

According to Table 2, valuable metals were recovered and yields of the recovered valuable metals were respectively shown.

Referring to Table 2, it was confirmed that the consumption of carbon was evident in the atmosphere with only CO ₂ of Comparative Example 1, and in the atmosphere with only CO, it was confirmed that carbon precipitated and the C content increased. It can be confirmed that when CO ₂ and the CO atmosphere, which is a reducing gas, satisfy the log value, the consumption of C can be reduced by reducing the Co metal (gas-solid reaction).

Accordingly, according to each heat treatment temperature condition, the CO ₂ /CO mixed gas is set to the lower limit (Min) value or more to suppress the precipitation of carbon, and the heat treatment process time can be shortened by setting it to the upper limit (Max) value or less. point could be confirmed.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

Claims (12)

Creating a mixed reducing gas atmosphere of carbon dioxide (CO ₂ ) and carbon monoxide (CO) that satisfies the partial pressure ratio of Equation 1 below; and
A method for recovering valuable metals from a waste lithium ion battery comprising the step of heat-treating the waste lithium ion battery in the mixed reducing gas atmosphere.
[Equation 1]
-2.15 ≤ log(P _CO2 /P _CO ) ≤ 2.5
At this time, P _CO2 is the partial pressure value of carbon dioxide, and P _CO is the partial pressure value of carbon monoxide. According to claim 1,
The method, characterized in that the valuable metal is at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and lithium (Li). According to claim 1,
In the heat treatment step, as the heat treatment temperature increases, the log (P _CO 2 /P _CO ) is adjusted to decrease. According to claim 3,
When the heat treatment temperature is greater than 500 ° C and less than 600 ° C, greater than 600 ° C and less than 700 ° C, greater than 700 ° C and less than 800 ° C, greater than 800 ° C and less than 900 ° C, or greater than 900 ° C and less than 1,000 ° C,
It is characterized in that log (P _CO2 /P _CO ) is adjusted to be a value within the range of 0.45 or more and 2.50 or less, -0.20 or more and 2.15 or less, -0.90 or more and 1.85 or less, -1.55 or more and 1.60 or less, or -2.15 or more and 1.40 or less. How to. According to claim 1,
The waste lithium ion battery is a battery comprising lithium nickel cobalt manganese oxide or lithium cobalt oxide as a positive electrode active material. According to claim 5,
The method, characterized in that the heat treatment is carried out at a temperature between 650 and 850 ℃. According to claim 5,
At the heat treatment temperature, log (P _CO2 /P _CO ) is carried out in a mixed reducing gas atmosphere of carbon dioxide and carbon monoxide adjusted to a value within the range of -1.20 or more and 2.00 or less. According to claim 6,
A method characterized in that a recovered material containing at least one selected from the group consisting of Co, Ni, Mn, CoO, NiO, MnO, Li ₂ CO ₃ , and LiAlO ₂ is obtained by the heat treatment. According to claim 1,
A method characterized by further comprising an additional heat treatment step of heat-treating the recovered material obtained by the heat treatment in an atmosphere of oxygen (O ₂ ) or carbon dioxide (CO ₂ ) at 700 ° C or higher. According to claim 9,
In the additional heat treatment step, CO gas is generated, and the CO gas is supplied as a mixed reducing gas in the heat treatment step to adjust log (P _CO2 /P _CO ). According to claim 1,
Further comprising a separation step of separating valuable metal-containing materials from the recovered product obtained by the heat treatment,
The method characterized in that the separation includes at least one separation process selected from the group consisting of a separation process by sieving, a separation process by magnetism, and a separation process by leaching using acid or water. According to claim 9,
In the additional heat treatment step, CO gas is generated and the heat generated by the exothermic reaction by oxidation of the CO gas is
A method characterized in that it is provided as a heat source in the above-mentioned heat treatment step or in the valuable metal separation step performed after the heat treatment step.

Images