Waste battery recycling method

Abstract

The present invention relates to a waste battery recycling method, and provides a waste battery recycling method comprising: a loading step of adding a waste battery raw material; a step for heating the starting material that has been added by charging; a step of cooling the product after the heat treatment; and a step of discharging the cooled reactant, and in the charging step of adding the waste battery raw material, the weight ratio of carbon / nickel in the charged raw material is more than 20% by weight.

Description

Technical Field

[0001] The invention relates to a method for recycling waste batteries, and in particular to a high-temperature reduction heat treatment method for recycling waste batteries. Background Art

[0002] As the global demand for electric vehicles grows, how to deal with the waste batteries generated by these vehicles has become a social issue. Lithium secondary batteries, which are the main raw materials of the waste batteries, contain organic solvents, explosive substances and heavy metal substances such as Ni, Co, Mn and Fe, but Ni, Co, Mn and Li are valuable metals with great scarcity value. The recycling and reuse process of discarded lithium secondary batteries has become an important research field.

[0003] In order to conventionally recycle the waste batteries, black powder mixed with positive electrode materials and negative electrode materials is extracted through a process of crushing, pulverizing, gravity screening and magnetic screening of the waste batteries at the end of their life.

[0004] For example, the black powder contains oxides of nickel, cobalt, manganese, lithium, aluminum and oxygen as positive electrode materials and graphite as negative electrode materials and mixtures thereof, some impurities such as aluminum and copper, etc. A wet process and a dry process are mainly used as methods for recovering valuable metals from the black powder.

[0005] The wet process generates NiSO4, CoSO4, MnSO4 and Li2CO3 through leaching, solvent extraction and lithium production. If the black powder is treated by the wet process, the negative electrode material graphite contained in the black powder will not dissolve in a strong acid environment, there is a problem of excessive consumption of leaching process time, and there is a problem that the black powder is separated together with the graphite, resulting in a decrease in the actual yield.

[0006] However, the dry process is a process for removing aluminum from the slag by a high-temperature dry process of the black powder, and a Ni-Co-Mn-C alloy can be generated. For the dry process, Ni-Mn-Li-Al-O oxide in the black powder is reduced at high temperature (e.g., 1400 to 1600° C.) using graphite and oxygen blowing, thereby generating CO or CO2 gas, which can be used as Ni-Co-Mn alloy and lithium and aluminum in the slag are removed.

[0007] Then, the separated Ni-Co-Mn alloy can also be subjected to a wet process. NiSO4, CoSO4, and MnSO4 are produced by a leaching-solvent extraction process in the wet process. Since the carbon is dissolved in the alloy, the leaching process time is reduced to about 70% compared with the wet process.

[0008] In order to perform wet processing on the reduced alloy, the alloy particle size needs to be below a certain size. The existing process is to reduce the alloy particle size by water atomizing the reduced molten alloy. However, the water atomization used in this case greatly increases the process cost. Summary of the invention

[0009] Technical issues

[0010] Therefore, the present invention aims to provide a solution for controlling the size of Ni-based alloy when recovering valuable metals in waste batteries.

[0011] An alloy of appropriate size facilitates subsequent separation from C, and the efficiency becomes higher when the Ni alloy is melted in sulfuric acid or the like in the post-processing process.

[0012] Technical Solution

[0013] According to one embodiment of the present invention, a method for recycling waste batteries is provided, which comprises: a loading step of adding a raw material of waste batteries; a step of heating the raw material added by loading; a step of cooling the product after heat treatment; and a step of discharging the cooled reactants. In the loading step of adding the raw material of waste batteries, the weight ratio of carbon / nickel in the loaded raw material is 20 weight % or more.

[0014] The carbon / nickel weight ratio of the charged raw material may be 50 wt % or more and 200 wt % or less.

[0015] The obtained reactant may have a particle size of 3000 μm or less.

[0016] The resulting reactant may have a particle size of 75 to 1000 μm.

[0017] The average particle size (D50) of the obtained reactant may be 250±50 μm.

[0018] In the step of heating the raw material material added by charging, the amount of oxygen in the furnace may be 0.5% by volume or less.

[0019] In the step of heating the raw material added by charging, a weight reduction rate of carbon in the raw material may be in the range of 20±5 weight %.

[0020] In the step of heating the raw material substance added by charging, the heating temperature may be 1050 to 1300°C.

[0021] The reaction time of the heating step may be 30 minutes or more and 240 minutes or less.

[0022] Beneficial Effects

[0023] According to the present invention, it is possible to avoid the generation of a large amount of carbon dioxide in the existing dry process due to oxidation of valuable metals after pulverization of lithium-ion batteries or vehicle batteries, thereby greatly contributing to the reduction of pollution associated with global warming.

[0024] In addition, since the alloy size required for subsequent processes can be controlled, the overall process cost and time can be saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the thermodynamic data of the amount of carbon dissolved in nickel based on the temperature.

[0026] Figure 2 It is the alloy grain size formation data and optical photos according to the C / Ni ratio.

[0027] Figure 3 It is the evaluation result of the carbon weight reduction rate based on the oxygen content.

[0028] Figure 4 The particle size distribution data and optical photographs of the obtained alloys according to the reaction time are shown. DETAILED DESCRIPTION

[0029] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. Unless the context otherwise clearly indicates the opposite, the singular form used herein is also intended to include the plural form. "Including" used in the specification may specifically refer to a certain characteristic, field, integer, step, action, element and / or component, but does not exclude the existence or addition of other characteristics, fields, integers, steps, actions, elements and / or components.

[0030] Although not otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. Terms defined in dictionaries should be interpreted as having the same meaning as that disclosed in the relevant technical literature and this article, and should not be interpreted in an idealized or overly formal sense.

[0031] Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are given only as examples, and the present invention is not limited to the following embodiments, and the present invention is subject only to the scope of the claims.

[0032] The present invention aims to propose a scheme for controlling the size of Ni-based alloy when recovering valuable metals from waste batteries. Specifically, the C / Ni ratio of the initial addition is given.

[0033] The Ni-based alloy has almost no wettability with C in the molten state, and thus forms spherical particles. At this time, the particle size of the alloy can be controlled by utilizing the temperature and oxygen range and reaction time required for the high temperature reaction.

[0034] An alloy of appropriate size facilitates subsequent separation from C, and the efficiency becomes higher when the Ni alloy is melted in sulfuric acid or the like in the post-processing process.

[0035] Valuable metals in waste batteries include Ni, Co, Mn, Cu, Al, Li, etc. The present invention aims to control the particle size of the Ni-based alloy.

[0036] The Ni-based alloy contains Co, Mn, Cu, and Li as main components, and may contain Fe, Na, K, Mg, Cl, Si, Ca, etc. as trace impurity elements. In order to manufacture the Ni-based alloy, it is necessary to adopt a reduction process to remove oxygen from the Ni-Co-Mn oxide present in the existing waste batteries.

[0037] At this time, in the present invention, reduction is carried out by using C as a reducing material.

[0038] Here, C can play three roles: as mentioned above, C acts as a reducing material; the wettability difference of C is used to control the particle size; and C penetrates into the Ni-based alloy to lower the melting point.

[0039] In the present invention, the process of generating reactants is carried out in the following order: adding battery raw materials->high temperature reaction->cooling process->recovering reactants, etc.

[0040] Here, the reactants may include Co, Mn, C, Cu, Al, Li, etc. based on Ni, and may exist in the form of oxides containing partial oxygen or fluorides containing fluorine in the electrolyte, carbon or carbon compounds that do not participate in reduction, and other compounds.

[0041] The added battery raw materials include all Ni-based batteries, including C included as the negative electrode material, and all other C added. As mentioned above, C acts as a reducing material and forms a spherical shape after melting due to the difference in wettability between the Ni-based alloy generated at high temperature and C.

[0042] from Figure 1 According to the thermodynamic data, in the process of Ni changing from solid phase to liquid phase, C in Ni-based alloy has a thermodynamically maximum solid solubility rate of 0.5%. At higher temperatures, due to changes in the liquid phase of Ni, it can have a higher C solid solubility rate.

[0043] In the present invention, since a considerable amount of C exists around Ni, the C / Ni ratio in the raw material is 20% to start forming particles. It is estimated that the C content in the particles subsequently alloyed is 0.1%.

[0044] For this reason, the C / Ni ratio must be limited from the initial battery raw material. The following table shows the evaluation results of the size of the alloy produced according to the C / Ni content.

[0045] [Table 1]

[0046]

[0047] Figure 2 The data and photos of alloy grain size formation according to C / Ni ratio are shown.

[0048] During the test, the process temperature was 1250°C, the average size of the crushed material was 20 mm, the holding time above 1050°C was 60 minutes, and the oxygen was kept below 0.5%.

[0049] When the C / Ni ratio is 5 wt % or less, the material is in the form of a bulk of 5000 μm or more, and when the C / Ni ratio is 20 wt % or more, the material is in the form of particles such as powder.

[0050] In particular, the higher the C / Ni ratio is, the smaller the size of the powder particles tends to be. In the subsequent process, for acid treatment, the optimal size is to form particles of 500 μm or less, but 3000 μm or less can also be used, so the C / Ni ratio given in the present invention is 20% or more. The optimal C / Ni range is preferably 50% or more.

[0051] Furthermore, during the high temperature reaction at 1250°C, the carbon consumption was measured by changing the amount of oxygen in the furnace over time.

[0052] Figure 3 It is the evaluation result of the carbon weight reduction rate based on the oxygen content.

[0053] The oxygen in the alumina crucible is controlled to be 1 volume %, and the crushed product is in the form of oxidized NCM and carbon, electrolyte and separator. The proportion of the component contents is shown in Table 2 below.

[0054] [Table 2]

[0055]

[0056] The reaction test measures the weight change in the crucible containing the reactants at high temperature. The weight loss in the reactants is evaluated based on the carbon and oxygen being converted into carbon dioxide or carbon monoxide and discharged as gas.

[0057] like Figure 3 As shown, the weight reduction rate was 40% by weight when reacting in an oxygen atmosphere of 1% by volume or more measured at the top in the reaction test, and therefore it is considered that most of the gasifiable substances inside were converted into carbon monoxide and carbon dioxide.

[0058] At this time, the air condition in the reactor includes carbon monoxide, carbon dioxide, nitrogen, argon, hydrocarbon gas, hydrogen fluoride, etc. in addition to oxygen (volume %).

[0059] However, when the internal oxygen injected into the top layer was 0.5 volume % or less, the weight reduction rate was 20%. At this time, the weight reduction rate was considered to be caused by the conversion of the electrolyte and the separator into hydrocarbon gas.

[0060] When using this result, there is no limit on the process time when the oxygen in the furnace is 0.5 volume % or less, but when the process time in the furnace is extended at an oxygen of 1% or more, a change in C / Ni occurs due to the reaction between carbon and oxygen.

[0061] In additional tests, the process hold time above 1050°C was evaluated and the results are shown in Tables 3 and Figure 4 middle.

[0062] [Table 3]

[0063]

[0064] It is reduced to very small particles of metallic matter within 10 minutes, but because the particle size is so small, it is difficult to separate the carbon from other substances by particle size and magnetic force.

[0065] When the process time is between 30 and 240 minutes, the Ni-based alloy with a size of about 75 to 3000 μm is formed. However, when the process time exceeds 360 minutes, most of the alloys are larger than 5000 μm.

[0066] The present results suggest that even under low oxygen conditions, the weight loss of carbon occurs over a long period of time, the C / Ni ratio may decrease, and the particles of the molten alloy aggregate together over time, resulting in an increase in the alloy size.

[0067] The preferred embodiments are described in detail above, but the scope of the present invention is not limited to the above embodiments. Various modifications and improvements made by those skilled in the art using the basic concepts defined in the claims also fall within the scope of the present invention.

Claims

1. A method for recycling waste batteries, comprising: A loading step of adding waste battery raw material materials; A step of heating the raw material added by charging; A step of cooling the heat-treated product; and the step of discharging the cooled reactants, In the step of adding the waste battery raw material, The weight ratio of carbon / nickel in the charged raw material is 20 weight % or more.

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

3. The method for recycling waste batteries according to claim 1, wherein: The obtained reactant has a particle size of less than 3000 μm.

4. The method for recycling waste batteries according to claim 1, wherein: The obtained reactant has a particle size of 75 to 1000 μm.

5. 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. The method for recycling waste batteries according to claim 1, wherein: In the step of heating the raw material added by charging, The oxygen content in the furnace is 0.5 volume % or less.

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

8. The method for recycling waste batteries according to claim 1, wherein: In the step of heating the raw material substance added by charging, the heating temperature is 1050 to 1300°C.

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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