How to recycle used batteries

Abstract

The present invention provides a method for recycling waste batteries, comprising: a charging step of charging raw materials for waste batteries; a step of heating the charged raw materials; a step of cooling a heat-treated product; and a step of discharging the cooled reactants, wherein in the charging step of charging raw materials for waste batteries, a weight ratio of carbon / nickel in the charged raw materials is 20% by weight or more.

Description

[Technical Field]

[0001] The present invention relates to a method for recycling waste batteries, and more particularly to a method for high-temperature reduction heat treatment for recycling waste batteries. [Background technology]

[0002] As demand for electric vehicles grows worldwide, the disposal of waste batteries from these vehicles has become a social issue. Lithium secondary batteries, the main raw materials for these waste batteries, contain organic solvents, explosives, and heavy metals such as Ni, Co, Mn, and Fe. Ni, Co, Mn, and Li are rare and valuable metals, so the recovery and recycling process of discarded lithium secondary batteries has emerged as an important research field.

[0003] For normal recycling of the waste batteries, the end-of-life waste batteries are crushed, pulverized, gravity sorted, and magnetically sorted to extract black powder, which is a mixture of positive and negative electrode materials.

[0004] The black powder contains, for example, oxides of nickel, cobalt, manganese, lithium, aluminum, and oxygen as cathode materials, graphite and its mixture as anode materials, and some impurities such as aluminum and copper. Methods for recovering valuable metals from the black powder are broadly classified into wet processes and dry processes.

[0005] The wet process produces NiSO4, CoSO4, MnSO4, and Li2CO3 through leaching, solvent extraction, and lithium production. When the black powder is treated with the wet process, the graphite contained in the black powder, which is the negative electrode material, does not dissolve in a strong acid atmosphere, which results in an excessively long leaching process time. In addition, the black powder separates with the graphite, which results in a reduced recovery rate.

[0006] However, the dry process is a process of removing aluminum from the slag through a high-temperature dry process of the black powder, thereby producing a Ni-Co-Mn-C alloy. The dry process uses graphite and oxygen injection at high temperatures, for example, in the range of 1400 to 1600°C, to reduce the Ni-Mn-Li-Al-O oxide in the black powder, generating CO or CO2 gas, which can be removed as a Ni-Co-Mn alloy and lithium and aluminum in the slag.

[0007] The separated Ni-Co-Mn alloy can then be subjected to the same hydroprocessing process. Through the hydroprocessing leaching-solvent extraction process, NiSO4, CoSO4, and MnSO4 are produced, and because carbon is dissolved within the alloy, the leaching process time is reduced by approximately 70% compared to the hydroprocessing process.

[0008] In order to re-process the reduced alloy using a hydroprocess, the alloy particle size must be below a certain size. In the conventional process, the particle size of the silver alloy is reduced by spraying water onto the reduced molten alloy. However, the water spraying process requires a large process cost. Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the present invention proposes a method for controlling the size of Ni-based alloys when recovering valuable metals from waste batteries.

[0010] An alloy of appropriate size can be easily separated from C, and this increases the efficiency when the Ni alloy is melted in sulfuric acid or the like in the post-processing step. [Means for solving the problem]

[0011] According to one embodiment of the present invention, there is provided a method for recycling waste batteries, comprising: a charging step of charging waste battery raw materials; a heating step of charging the charged raw materials; a cooling step of a heat-treated product; and a discharging step of a cooled reactant, wherein in the charging step of charging the waste battery raw materials, a weight ratio of carbon / nickel in the charged raw materials is 20 wt % or more.

[0012] The carbon / nickel weight ratio of the charged raw material may be 50% by weight or more and 200% by weight or less.

[0013] The obtained reactant may have a particle size of 3,000 μm or less.

[0014] The obtained reactant may have a particle size of 75 to 1,000 μm.

[0015] The average particle size (D50) of the obtained reactant may be 250±50 μm.

[0016] In the step of heating the charged raw materials, the amount of oxygen in the furnace may be 0.5% by volume or less.

[0017] In the step of heating the charged raw material, the carbon weight loss rate in the raw material may be in the range of 20±5% by weight.

[0018] In the step of heating the charged and introduced raw materials, the heating temperature may be 1,050 to 1,300°C.

[0019] The reaction time of the heating step may be 30 minutes or more and 240 minutes or less. [Effects of the Invention]

[0020] According to the present invention, after crushing lithium ion batteries or vehicle batteries, the generation of a large amount of carbon dioxide, which is generated in the conventional dry process from oxidized valuable metals, can be prevented, thereby making a significant contribution to reducing global warming-related pollution.

[0021] Furthermore, the size of the alloy required for the subsequent process can be controlled, thereby reducing the overall process cost and time. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is thermodynamic data for the high capacity of nickel to carbon as a function of temperature. [Figure 2] 1 shows the grain size formation data and optical photographs of alloys depending on the C / Ni ratio. [Figure 3] 1 shows the results of evaluating the carbon weight reduction rate according to the oxygen content. [Figure 4] 1 shows particle size distribution data and optical photographs of alloys obtained as a function of reaction time. DETAILED DESCRIPTION OF THE INVENTION

[0023] The terminology used herein is merely for the purpose of referring to particular embodiments and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. As used herein, the term "comprising" refers to a particular feature, region, integer, step, operation, element, and / or component and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0024] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are additionally interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted as having an ideal or very formal meaning unless defined.

[0025] The following examples of the present invention are described in detail, but are presented by way of example only and are not intended to limit the scope of the present invention, which is defined only by the scope of the claims set forth below.

[0026] In this invention, we propose a method to control the size of Ni-based alloys when recovering valuable metals from waste batteries. Specifically, we present the C / Ni ratio of the initial input.

[0027] Ni-based alloys have almost no wettability with carbon in the molten state and are formed into spherical particles. At this time, the particle size of the alloy can be controlled by utilizing the temperature, oxygen range, and reaction time required for the high-temperature reaction.

[0028] An alloy of appropriate size can be easily separated from C, which increases the efficiency when the Ni alloy is melted in sulfuric acid or the like in the post-processing step.

[0029] Valuable metals in waste batteries include Ni, Co, Mn, Cu, Al, Li, etc., and in the present invention, the particle size of Ni-based alloys is controlled.

[0030] Ni-based alloys contain Co, Mn, Cu, and Li as their main components, with trace amounts of impurity elements such as Fe, Na, K, Mg, Cl, Si, and Ca. To produce Ni-based alloys, a reduction process is required to remove oxygen from the Ni-Co-Mn oxides present in existing waste batteries.

[0031] At this time, reduction is carried out using C as the reducing agent in the present invention.

[0032] Here, C plays three roles: it controls the particle size by utilizing the difference in wettability between the part used as a reducing agent and the C, and it penetrates into the Ni-based alloy to lower the melting point.

[0033] In the present invention, the process of generating reactants includes the steps of: charging battery raw materials → high-temperature reaction → cooling process → recovering reactants.

[0034] Here, the reactants may be Ni-based and may contain Co, Mn, C, Cu, Al, Li, etc., and may exist in the form of a compound such as an oxide containing some oxygen, a fluoride containing fluorine in the electrolyte, or carbon or a carbon compound that did not participate in the reduction.

[0035] Regarding battery raw material input, this includes all Ni-based batteries, and here C includes all input of other C other than that included as anode material. As explained earlier, C acts as a reducing agent and allows the Ni-based alloy generated at high temperature to form a sphere after melting due to the difference in wettability with C.

[0036] From the thermodynamic data in Figure 1, it can be seen that in the process of changing from the solid phase of Ni to the liquid phase, C has a thermodynamic maximum solid solubility of 0.5% in the Ni base, and at temperatures above this, it changes to the liquid phase of Ni, so it can have a larger C solid solubility.

[0037] In the present invention, since a considerable amount of C exists around Ni, particles are formed when the C / Ni ratio in the raw material is at the 20% level. After that, the C in the alloyed particles is estimated to be at the 0.1% level.

[0038] To achieve this, the C / Ni ratio must be limited from the initial battery raw materials. The table below shows the results of testing and evaluating the size of the alloy produced according to the C / Ni content.

[0039] [Table 1]

[0040] Figure 2 shows the grain size formation data and photographs of the alloys as a function of the C / Ni ratio.

[0041] In the test, the process temperature was 1,250℃, the average size of the crushed pieces was 20mm, the temperature was maintained at 1,050℃ or higher for 60 minutes, and the oxygen content was maintained at 0.5% or less.

[0042] When the C / Ni ratio was 5 wt% or less, it appeared as agglomerates of 5,000 μm or larger, and when the C / Ni ratio was 20 wt% or more, it appeared as powder-like particles.

[0043] In particular, the higher the C / Ni ratio, the smaller the powder particle size tended to be. For post-process acid treatment, the best size is formed with particles of 500 μm or less, but particles of 3,000 μm or less can also be used, so in this invention, we suggest a C / Ni ratio of 20% or more. The best C / Ni range is 50% or more.

[0044] Additionally, the amount of carbon consumed was measured by changing the amount of oxygen in the furnace over time during a high-temperature reaction at 1,250°C.

[0045] Figure 3 shows the results of evaluating the carbon weight loss rate as a function of oxygen content.

[0046] The oxygen in the alumina crucible was controlled to a level of 1% by volume, and the crushed material contained oxidized NCM, carbon, electrolyte, and separator. The ratio of the component contents was as shown in Table 2 below.

[0047] [Table 2]

[0048] In the reaction test, the weight change inside the crucible containing the reactants was measured at high temperature. The weight loss of the reactants was evaluated based on the form in which carbon and oxygen combine to convert into carbon dioxide or carbon monoxide, which is then emitted as gas.

[0049] As shown in Figure 3, when the oxygen measured at the top of the reaction test was over 1% by volume, the weight loss rate during the reaction decreased by about 40% by weight, which indicates that most of the gasifiable materials inside were converted into carbon monoxide and carbon dioxide.

[0050] At this time, the air conditions in the reactor contain, in addition to the oxygen volume percentage, carbon monoxide, carbon dioxide, nitrogen, argon, hydrocarbon gas, hydrogen fluoride, etc.

[0051] However, when the internal oxygen concentration was reduced to 0.5% by volume or less and the upper layer was filled, the weight loss rate was at the 20% level. This weight loss rate is believed to be due to the electrolyte and separator vaporizing and being converted into hydrocarbon gases.

[0052] When using this result, it was confirmed that there is no restriction on the process time when the oxygen in the furnace is 0.5% by volume or less, but if the process time in the furnace is extended when the oxygen is 1% or more, a change in C / Ni occurs due to the reaction between carbon and oxygen.

[0053] In an additional test, the duration of the process at temperatures above 1,050°C was evaluated. The results are shown in Table 3 and Figure 4.

[0054] [Table 3]

[0055] Within 10 minutes, the carbon was reduced to very small particulate metal material, but the particle size was so small that particle size and magnetic separation of the carbon from other materials was difficult.

[0056] When the process time was 30 to 240 minutes, Ni-based alloys with sizes of about 75 to 3,000 μm were formed, but after 360 minutes, most of the alloys were 5,000 μm or larger.

[0057] These results suggest that the carbon weight loss occurred over a long period of time even under low oxygen conditions, which may have resulted in a decrease in the C / Ni ratio, and that the molten alloy particles aggregated together over time, increasing the size of the alloy.

[0058] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

Claims

1. An input step of inputting waste battery raw materials; heating the raw material charged and introduced; Cooling the heat-treated product; and Discharging the cooled reactants; In the step of charging the waste battery raw material, A method for recycling waste batteries, wherein the weight ratio of carbon to nickel in the charged raw material is 20% by weight or more.

2. 2. The method for recycling waste batteries according to claim 1, wherein the weight ratio of carbon to nickel in the raw material charged is 50% by weight or more and 200% by weight or less.

3. 2. The method for recycling waste batteries according to claim 1, wherein the collected reactant has a particle size of 3,000 μm or less.

4. 2. The method for recycling waste batteries according to claim 1, wherein the collected reactant has a particle size of 75 to 1,000 μm.

5. 2. The method for recycling waste batteries according to claim 1, wherein the average particle size (D50) of the obtained reactant is 250±50 μm.

6. In the step of heating the charged and introduced raw material, 2. The method for recycling waste batteries according to claim 1, wherein the amount of oxygen in the furnace is 0.5% by volume or less.

7. In the step of heating the charged and introduced raw material, 7. The method for recycling waste batteries according to claim 6, wherein the carbon weight reduction rate in the raw material is in the range of 20±5% by weight.

8. In the step of heating the charged and introduced raw material, 2. The method for recycling waste batteries according to claim 1, wherein the heating temperature is 1,050 to 1,300°C.

9. 9. The method for recycling waste batteries according to claim 8, wherein the reaction time of the heating step is 30 minutes or more and 240 minutes or less.

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