High-temperature reduction device for reuse of waste batteries and heat treatment method for reuse of waste batteries

Abstract

The present invention relates to a high-temperature reduction apparatus for recycling waste batteries and a heat treatment method for recycling waste batteries, the high-temperature reduction apparatus including a loading section for loading raw materials, a heating section for heating the raw materials loaded from the loading section, a cooling section for cooling a heat-treated product, and a discharge section for discharging the cooled reactant from the cooling section, the heating section including a preliminary heat treatment section for preheating the raw materials loaded from the loading section, and a high-temperature heat treatment section for heating at a temperature higher than that of the preliminary heat treatment section, the high-temperature heat treatment section including a heat treatment section for heat-treating the raw materials in a temperature range of 1,150 to 1,400°C.

Description

[Technical Field]

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

[0002] As demand for electric vehicles grows worldwide, the disposal of waste batteries from these vehicles is becoming a social issue. Lithium secondary batteries, which are the main raw materials for such waste batteries, contain organic solvents, explosive materials, and heavy metals such as Ni, Co, Mn, and Fe. Ni, Co, Mn, and Li are highly rare and valuable metals, and therefore, the recovery and reuse processes of discarded lithium secondary batteries have emerged as an important research field.

[0003] For the normal reuse of such waste batteries, black powder, a mixture of positive and negative electrode materials, is extracted from the end-of-life waste batteries through crushing, pulverization, gravity separation, and magnetic separation processes. The black powder contains, for example, oxides of nickel, cobalt, manganese, lithium, aluminum, and oxygen, which are positive electrode materials, and graphite and its mixture, which are negative electrode materials, as well as some impurities such as aluminum and copper. Wet processes and dry processes are widely used to recover valuable metals from the black powder.

[0004] 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, graphite, which is the negative electrode material contained in the black powder, does not dissolve in a strong acid atmosphere, which causes problems such as excessive leaching time, and the black powder is separated together with the graphite, which reduces the recovery rate.

[0005] However, the dry process can produce a Ni-Co-Mn-C alloy by removing aluminum from the slag through a high-temperature dry process of the black powder. 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 is removed as a Ni-Co-Mn alloy and lithium and aluminum from the slag.

[0006] The separated Ni-Co-Mn alloy can then be subjected to the same wet process. NiSO4, CoSO4, and MnSO4 are produced through the wet process leaching-solvent extraction process, and because carbon is dissolved in the alloy, the leaching process time is reduced by approximately 70% compared to the wet process.

[0007] However, in this process, valuable metals such as lithium and aluminum are consumed as slag, and recovery of the lithium is difficult. In addition, blowing oxygen to remove graphite from the black powder introduced into the high-temperature dry process generates excessive carbon dioxide, which poses an environmental problem.

[0008] In order to solve these environmental problems, it is necessary to research a non-oxidizing dry high-temperature melting and reduction process that can minimize the generation of carbon dioxide, minimize the loss of lithium, a valuable metal, and produce Ni-Co-Mn alloys with a carbon content of 10% or less. Summary of the Invention [Problem to be solved by the invention]

[0009] According to one embodiment of the present invention, a high-temperature reduction device for recycling waste batteries is provided that is environmentally friendly and can ensure an optimal valuable metal recovery rate in the downstream valuable metal recovery process.

[0010] According to another embodiment of the present invention, a high temperature reduction apparatus having the above-mentioned advantages is utilized to provide a heat treatment method for recycling waste batteries. [Means for solving the problem]

[0011] According to one embodiment of the present invention, a high-temperature reduction apparatus for recycling waste batteries includes a loading section for loading raw materials, a heating section for heating the raw materials loaded from the loading section, a cooling section for cooling a heat-treated product, and a discharge section for discharging the cooled reactant from the cooling section, wherein the heating section includes a preliminary heat treatment section for preheating the raw materials loaded from the loading section, and a high-temperature heat treatment section for heating the raw materials at a higher temperature than that of the preliminary heat treatment section, and the high-temperature heat treatment section may include a heat treatment section for heat-treating the raw materials in a temperature range of 1,150 to 1,400° C. In one embodiment, the high-temperature heat treatment section may include two or more heat treatment sections in a vertical or horizontal direction.

[0012] In one embodiment, the high-temperature heat-treating section may include a heat absorption section that heats the raw material at a temperature higher than that of the pre-heat-treating section, and a melting section that heats the raw material at a temperature range higher than that of the heat absorption section to form at least a molten layer. In one embodiment, the heating section that heats the raw material may heat the raw material at a rate of 1 to 10°C / min.

[0013] In one embodiment, the molten portion may be formed by melting at least one of Ni, Cu, Co, and Mn to form spherical particles. In one embodiment, the weight ratio of carbon to nickel (C / Ni) of the raw material to be charged may be 20 or more.

[0014] In one embodiment, the heating unit may include a heating furnace and a heating section, and when temperatures are measured at any position in the minor axis and major axis directions of a cross section of the heating furnace with respect to a center, the temperature difference between the center and the any position may be 250° C. In one embodiment, the cross section of the heating furnace may have a length ratio of the major axis to the minor axis of 2 / 1 to 4 / 1.

[0015] In one embodiment, the heating furnace may have a bent portion on the outside of the heating furnace. In one embodiment, the bent portion may have a length of 30 mm or more. In one embodiment, the heating unit may include at least one heating unit, the heating unit may have a coil shape, and the coils may have a pitch distance that decreases as the distance from the center region of the coil increases.

[0016] In one embodiment, the heating unit may be disposed in at least a portion of the heating unit. In one embodiment, the target temperature of the pre-heating unit in the heating unit may satisfy the following formula 1:

[0017] <Expression 1> T 111 ≧0.813(x / (Cp×m)+25)

[0018] (In the above formula 1, x is the input energy [W], Cp is the specific heat [J / Kg·℃], and m is the mass transfer rate [Kg / s].)

[0019] The target temperature of the melting part in the heating part can satisfy the following formula 2.

[0020] <Expression 2> T 113 ≧0.4(x / (Cp×m)+700)

[0021] (In the above formula 2, x is the input energy [W], Cp is the specific heat [J / Kg·℃], and m is the mass transfer rate [Kg / s].)

[0022] In one embodiment, the heating unit performs heating in an atmosphere having an oxygen partial pressure of 0.1 atm or less. In another embodiment, the pre-heat treatment unit in the heating unit is heated to a temperature range of 800°C or less. In another embodiment, the endothermic unit in the heating unit may undergo an endothermic reaction through a Boudouard reaction that converts CO2 gas into 2CO.

[0023] According to another embodiment of the present invention, a heat treatment method for recycling waste batteries includes a heat treatment process performed after a crushing process of waste batteries, the heat treatment process including a step of charging raw materials, a step of heating the charged raw materials, a step of cooling a heat-treated product, and a step of discharging the cooled reactants. The step of heating the raw materials includes a step of pre-heating the charged raw materials and a high-temperature heat treatment step of heating the raw materials at a temperature higher than that of the pre-heating step. The high-temperature heat treatment step may include a heat treatment step of heat-treating the raw materials at a temperature in the range of 1,150 to 1,400°C.

[0024] In one embodiment, the high-temperature heat treatment step may include an endothermic step of heating at a temperature higher than that of the pre-heat treatment step, and a melting step of heating at a temperature range higher than that of the endothermic step to form at least a molten layer.

[0025] In one embodiment, the step of heating the charged raw material may be such that, when temperatures are measured at any position in the minor axis direction and the major axis direction of a cross section of a heating furnace, which is a heating member, based on a center point, the temperature difference between the center and the any position is 250°C or less.

[0026] In one embodiment, the cross section of the furnace may have a length ratio of the major axis to the minor axis of 2 / 1 to 4 / 1. In one embodiment, the furnace may have a bent portion on the outside of the furnace.

[0027] In one embodiment, the length of the bent portion may be 60 mm or more. In one embodiment, the step of preheating the charged raw material may be performed at a target temperature represented by the following Equation 1:

[0028] <Expression 1> T 111 ≧0.813(x / (Cp×m)+25)

[0029] (In the above formula 1, x is the input energy [W], Cp is the specific heat [J / Kg·℃], and m is the mass transfer rate [Kg / s].)

[0030] In one embodiment, the target temperature of the melting step, in which at least a portion of the melted layer is formed by heating in a temperature range higher than that of the endothermic step, may satisfy the following formula 2:

[0031] <Expression 2> T 113 ≧0.4(x / (Cp×m)+700)

[0032] (In the above formula 2, x is the input energy [W], Cp is the specific heat [J / Kg·℃], and m is the mass transfer rate [kg / s].) [Effects of the Invention]

[0033] According to one embodiment of the present invention, a high-temperature reduction device for recycling waste batteries controls the temperatures in the first to third zones in a heating section, and by incorporating structural features in the heating section, a dry high-temperature reduction device is provided that is environmentally friendly and can ensure an optimal valuable metal recovery rate in the downstream valuable metal recovery rate.

[0034] According to another embodiment of the present invention, a high temperature reduction apparatus having the above-mentioned advantages is utilized to provide a heat treatment method for recycling waste batteries. [Brief explanation of the drawings]

[0035] [Figure 1a] 1 illustrates a high temperature reduction device for waste battery recycling according to one embodiment of the present invention. [Figure 1b] 1 shows a high temperature reduction apparatus according to another embodiment of the present invention. [Figure 2a] 1 shows a photograph of grain size formation of alloys according to the C / Ni content of raw materials according to one embodiment of the present invention. [Figure 2b] 1 shows a photograph of grain size formation of alloys according to the C / Ni content of raw materials according to one embodiment of the present invention. [Figure 2c]1 shows a photograph of grain size formation of alloys according to the C / Ni content of raw materials according to one embodiment of the present invention. [Figure 3a] 1 shows the shapes of reactants according to examples and comparative examples of the present invention. [Figure 3b] 1 shows the shapes of reactants according to examples and comparative examples of the present invention. [Figure 3c] 1 shows the shapes of reactants according to examples and comparative examples of the present invention. [Figure 3d] 10 shows the temperature rise rate and edge temperature distribution according to a comparative example of the present invention. [Figure 4] 1 shows the recovery rate of the reaction product as a function of temperature in accordance with examples of the present invention and comparative examples. [Figure 5] 1 illustrates a cross section of a furnace at an arbitrary position relative to the center position, according to one embodiment of the present invention. [Figure 6] 10 shows temperature deviations in a heating furnace according to an example of the present invention and a comparative example. [Figure 7] 10 shows temperature deviations in a heating furnace according to an example of the present invention and a comparative example. [Figure 8a] 10 is a graph showing a tendency of a temperature deviation in a heating furnace decreasing depending on the length of a bent portion according to an embodiment of the present invention. [Figure 8b] The temperature deviation due to the length of the bent portion was measured by thermal analysis simulation. [Figure 9a] ~ [Figure 9c] 10 shows coil arrangements and resulting temperature distributions according to comparative examples and examples of the present invention. [Figure 9b] 10 shows coil arrangements and resulting temperature distributions according to comparative examples and examples of the present invention. [Figure 9c] 10 shows coil arrangements and resulting temperature distributions according to comparative examples and examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Thus, a first part, component, region, layer, or section described below can be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0037] The terminology used herein is for the purpose of referring to particular embodiments only 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 in this specification, the term "comprising" refers to the inclusion of specific features, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0038] When a part is referred to as being "on" or "on" another part, this means that it is directly on or above the other part, or there may be other parts between them. In contrast, when a part is referred to as being "directly on" another part, there are no other parts between them.

[0039] 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 the present invention pertains. Terms defined in commonly used dictionaries are additionally interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless otherwise defined.

[0040] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the preferred embodiments of the present invention is provided by way of example only and is not intended to limit the scope of the present invention, which is defined solely by the scope of the claims set forth below.

[0041] FIG. 1a shows a high temperature reduction device for waste battery recycling according to one embodiment of the present invention.

[0042] 1a, a high-temperature reduction apparatus 10 for recycling waste batteries according to one embodiment of the present invention includes an input unit 100 for inputting raw materials, a heating unit 110 for heating the raw materials input from the input unit 100, a cooling unit 120 for cooling the heat-treated product, and a discharge unit 130 for discharging the cooled reactants from the cooling unit 120. The high-temperature reduction apparatus 10 of the present invention refers to a furnace that is used in the step of inputting crushed battery material into the furnace and raising the temperature of the crushed battery material to above its melting point.

[0043] The high-temperature reduction device 10 crushes waste batteries and, if necessary, performs gravity separation, magnetic separation, or classification on the crushed waste batteries, and then reduces the crushed waste batteries at high temperature to produce a reaction product containing impurities such as oxides of nickel, cobalt, manganese, lithium aluminum, or oxygen, which are positive electrode materials, and a negative electrode material containing graphite and a mixture thereof, aluminum, and copper.

[0044] The loading unit 100 is a member for loading raw materials, and the raw materials may be the crushed waste batteries described above. The crushed waste batteries refer to materials that will become the base material for crushed batteries or the materials themselves after crushing. The base material for crushed batteries may include batteries that have expired, waste batteries, and waste materials generated during the manufacturing process of lithium-ion batteries.

[0045] Specifically, the waste batteries may include cathode materials such as scrap, jelly rolls, and slurry that constitute waste batteries, as well as rejected products, residues from the manufacturing process, and debris generated during the process. The base material of the crushed battery material is then crushed to produce crushed battery material. The crushed material itself may be the crushed product itself, such as black powder. By recycling waste batteries in this way, producing crushed battery material is environmentally friendly and economically advantageous.

[0046] In one embodiment, the C / Ni weight ratio in the raw material may be 20 or more. Specifically, the C / Ni weight ratio refers to the weight percent of carbon divided by the weight percent of nickel. In one embodiment, when the C / Ni weight ratio in the raw material satisfies the above range, the powder particle size is reduced, and spherical reactants are formed in the range of 500 to 3,000 μm, which is the optimal particle size ratio for acid treatment in a subsequent process. When the C / Ni weight ratio in the raw material deviates from the above range, it is difficult to form spherical fragments, and the reactants are formed in a lump state, which can result in incomplete reduction by carbon.

[0047] In one embodiment, the loading unit 100 may further include a pusher. The pusher may be configured to further facilitate the administration of the raw material loaded through the loading unit 100.

[0048] The heating unit 110 heats the raw material input from the input unit 100. The heating unit 110 inputs raw material, such as crushed waste batteries, into a furnace capable of raising the temperature of the crushed waste batteries to above their melting point. In this way, Ni-Co-Mn alloys and Li oxides containing valuable metals are produced through the heating unit 110, and the valuable metals can be recovered in a subsequent process.

[0049] In one embodiment, the heating unit 110 may be characterized by increasing the temperature of the raw material fed from the feeding unit 100 at a temperature increasing rate of 1 to 10°C / min. Specifically, the temperature increasing rate is in the range of 2.0 to 5.0°C / min.

[0050] In one embodiment, the heating unit 110 may perform heating in a temperature range of 800 to 1,300° C. By performing heating at this temperature range at this temperature increase rate, a Ni-based alloy is formed as spherical particles of 100 to 3,000 μm, thereby increasing the recovery rate of valuable metals and Li.

[0051] Specifically, the heating unit 110 may include at least one induction coil. Specifically, the heating unit 110 may include one induction coil, but more induction coils may be used. In FIG. 1a, one induction coil is used in the pre-heat treatment unit 111, and additional induction coils are used in the heat absorption unit 112 and the melting unit 113.

[0052] In one embodiment, the heating unit 110 may include a pre-heating unit 111 that pre-heats the input raw material and a high-temperature heat-treating unit (not shown) that heats the raw material at a temperature higher than that of the pre-heating unit 111. The high-temperature heat-treating unit may be a high-temperature reducing unit that reduces the raw material by heating at a temperature higher than that of the pre-heating unit 111. In one embodiment, the high-temperature heat-treating unit may include two or more heat-treating units in a vertical or horizontal direction.

[0053] In one embodiment, the high-temperature heating unit may include a heat absorption unit 112 and a melting unit 113 that forms at least a partial melt layer by heating in a temperature range higher than that of the heat absorption unit 112. The heating unit 110 has an advantage in that it can increase the recovery rate of valuable metals by including sections with different temperatures.

[0054] The pre-heat treatment section 111 is heated to a temperature range of 800° C. or less. Specifically, the pre-heat treatment section 111 is heated to a temperature range of 700° C. or less. The pre-heat treatment section 111 pre-heats the raw material, i.e., the crushed waste batteries, to the above-mentioned temperature range, with the primary purpose of removing the electrolyte and separator from the crushed waste batteries.

[0055] The heat absorption unit 112 is heated to a temperature range higher than that of the preliminary heat treatment unit 111. Specifically, an endothermic reaction can occur in the range of 700 to 1200°C, more specifically, 700 to 900°C, and even more specifically, 800 to 900°C. Specifically, in the heat absorption unit 112, an endothermic reaction can occur in the Boudouard reaction, which converts CO2 gas into 2CO gas, within the above temperature range. By including the heat absorption unit 112, the high-temperature reduction apparatus 10 can reduce carbon dioxide, thereby providing an environmentally friendly advantage.

[0056] The melting part 113 is heated to a temperature range higher than that of the heat absorption part 112. Specifically, it is heated to a temperature range of 1,400°C or less, more specifically, a temperature range of 1,150 to 1,400°C or less. In the melting part 113, any one of nickel, cobalt, manganese, and copper is melted and arranged in a spherical shape. The melting part 113 is the highest-temperature reaction zone in the heating part 110, and is a member where heat treatment is performed within the above temperature range to produce Ni-Co-Mn alloy containing valuable metals and Li oxide.

[0057] Specifically, the melting section 113 is a section where heat treatment is performed within the aforementioned temperature range, and the reduced crushed material in a stacked form of cathode, anode, or separator is reduced into spherical droplets that are easily reactive to a subsequent process for extracting valuable metals, such as a wet process.

[0058] By heating the molten zone 113 within the aforementioned temperature range, the Li recovery rate can be 40 to 70%, specifically 55 to 60%, and the Ni-Co-Mn alloy can be 55 to 95%, specifically 85 to 95%, and more specifically 85 to 90%. If the molten zone 113 deviates from the upper limit of the aforementioned range, the Li recovery rate will be excessively low. If the molten zone 113 deviates from the lower limit of the aforementioned range, the Ni-Co-Mn alloy recovery rate will be excessively low. Thus, by heating the molten zone 113 within the aforementioned temperature range, there is an advantage in that the recovery rate of the Ni-Co-Mn alloy and the Li recovery rate can be increased at the same time.

[0059] In one embodiment, the heating unit 110 includes a furnace 110_F and a heating unit 110_H. The furnace 110_F refers to a passage through which the input raw material passes through the heating unit 110. The heating unit 110_H refers to a member that applies heat energy to the furnace 110_F.

[0060] When the temperature of the cross section of the heating furnace 110_F is measured at any position in the minor and major axis directions of the cross section with the center as the reference point, the temperature difference between the center and the any position may be 250° C. or less. The cross section of the heating furnace 110_F refers to a cut taken in a direction different from the direction in which the raw material travels, for example, in a direction intersecting or perpendicular to the direction in which the raw material travels.

[0061] Specifically, the temperature difference may be the difference between the maximum temperature and the minimum temperature. If the temperature difference between the center and the arbitrary position is outside the temperature range, uniform heat transfer to the heating furnace 110_F is not easy, resulting in a problem of a decrease in valuable metal recovery rate.

[0062] In one embodiment, when a circular cross section of the same area of ​​the furnace 110_F is taken as a 100% reference, the temperature deviation between the center and the arbitrary position may be less than 10%. Specifically, the temperature deviation between the center and the arbitrary position may be less than 20% based on a 100% reference. For a detailed description of this, please refer to FIG. 4 described below.

[0063] In one embodiment, the cross section of the heating furnace 110_F may have a length ratio of the major axis to the minor axis of 2 / 1 to 4 / 1. Specifically, the length ratio of the major axis to the minor axis may be 2.5 / 1 to 3.5 / 1.

[0064] When the ratio of the length of the major axis to the length of the minor axis satisfies the above range, there is an advantage that the temperature range deviation in the heating furnace 110_F is low and uniform heat transfer is possible. If the ratio of the length of the major axis to the length of the minor axis deviates from the above range, the temperature range deviation in the heating furnace 110_F is high and uniform heat transfer is difficult, resulting in a problem of low valuable metal recovery rate in the reactants.

[0065] In one embodiment, the furnace 110_F may have a bent portion on the outside of the furnace 110_F. The bent portion refers to a corner of the rectangular cross section of the furnace 110_F that is bent. The bent portion prevents thermal energy from concentrating at the corner, thereby preventing the problem of reduced yield of reactants at the corner in the existing rectangular furnace 110_F, which occurs due to the concentration of thermal energy at the corner.

[0066] In one embodiment, the length of the bent portion may be 60 mm or more. Specifically, the length of the bent portion may be 60 mm or more and 110 mm or less, and more specifically, 75 mm or more and 100 mm or less. The length of the bent portion refers to the radius of a circle drawn around the center of a corner of the furnace. For a detailed description of this, see Figures 8a and 8b below.

[0067] In one embodiment, the heating unit 110_H may include at least one of the heating units 110, and the heating unit 110_H may apply heat energy by a method such as induction heating, gas heating, or resistance heating. In one embodiment, the heating unit 110_H may have a coil shape as a means for supplying the heat energy. In one embodiment, the wire of the coil may have any one of the following cross sections, including, but not limited to, a circle, a square, a rectangle, an oval, a triangle, a trapezoid, a diamond, and a star.

[0068] In one embodiment, the coils of the heating unit 110_H may have a pitch that decreases as the distance from the center of the coil increases. The center of the coil refers to a region including the midpoint of the length of the coil. The coil pitch refers to the distance between two effective sides of the coil when the coil is wound.

[0069] In the case of induction heating, the coil inductance is proportional to the number of turns of the coil. Specifically, the coil inductance is proportional to the number of turns of the coil. Specifically, if the coil has a large number of turns, the applied heat energy will be high, and if the coil has a small number of turns, the applied heat energy will be low.

[0070] The coils of the heating unit 110_H realized by using this principle have a smaller pitch distance as they move away from the center of the coil, which has the advantage of dispersing heat from the center where heat energy was previously concentrated. In one embodiment, the heating units 110_H are respectively arranged in the pre-heat treatment unit 111, the heat absorption unit 112, and the melting unit 113 to control the temperature of the heating unit 110.

[0071] The heating unit 110 performs heating in a gas atmosphere containing oxygen, and the oxygen may be contained in a volume fraction of 5 vol% or less. In one embodiment, the heating unit 110 performs heating in an atmosphere having an oxygen partial pressure of 0.1 atm or less. By performing heating in a gas atmosphere containing a portion of oxygen within the above range, lithium oxide for lithium recovery can be easily formed, thereby improving the recovery rate of valuable metals.

[0072] In one embodiment, the pre-heat treatment section 111 in the heating section 110 performs heat treatment at a power of 12.0 kW or more. Specifically, the pre-heat treatment section 111 performs heat treatment at a power of 12.0 to 15.0 kW. Specifically, the power is 12.0 to 14 kW.

[0073] In one embodiment, the melting zone 113 in the heating zone 110 is heat-treated at a power of 16.0 kW or more. Specifically, the power is 16.0 to 19.0 kW. Specifically, the power is 17.5 to 18.5 kW.

[0074] The power applied in the preliminary heat treatment section 111 and the melting section 113 may represent the minimum energy required to heat the reactants, and by satisfying the above range, heat treatment can be performed within the targeted temperature range.

[0075] In one embodiment, the residence time of the reactants in the heating unit 110 may be 5 to 7 hours. The residence time may refer to the total length of the heating unit 110 divided by the distance traveled by the reactants per hour. For example, in a heating unit 110 that produces reactants at 65 kg / hr per hour, if the length of the heating unit 110 is 285 cm, the reactants will travel approximately 44 cm per hour and will remain in the heating unit 110 for approximately 6.5 hours before passing through.

[0076] When heating is performed within the residence time in the heating unit 110, there is an advantage in that the recovery rate of valuable metals such as Li, Ni, Co, and Mn in the heating unit 110 is improved. When the residence time deviates from the above range, not only is Li lost, but the particle size of the reduced valuable metals increases, which increases the time required for subsequent leaching.

[0077] In one embodiment, the target temperature of the pre-heat treatment section 111 in the heating section 110 may satisfy the following formula 1:

[0078] <Expression 1> T 111 ≧0.813(x / (Cp×m)+25)

[0079] (In the above formula 1, x is the input energy [W], Cp is the specific heat [J / Kg·℃], and m is the mass transfer rate [Kg / s].)

[0080] In one embodiment, the target temperature of the melting zone 113 in the heating zone 110 may satisfy the following equation 2:

[0081] <Expression 2> T 113 ≧0.4(x / (Cp×m)+700)

[0082] (In the above formula 2, x is the input energy [W], Cp is the specific heat [J / Kg·℃], and m is the mass transfer rate [Kg / s].)

[0083] Equations 1 and 2 specifically represent the target temperatures of the preliminary heat treatment section 111 and the melting section 113 in the heating section 110 and the minimum value of the supplied energy of the reactants. By inputting the minimum energy represented by Equations 1 and 2, the target temperatures of the preliminary heat treatment section 111 and the melting section 113 can be reached. In one embodiment, x in Equation 1 may be 12,000 W or more. In one embodiment, x in Equation 2 may be 16,000 W or more.

[0084] There is an advantage in that the recovery rate of valuable metals such as Li, Ni, Co, and Mn can be improved by controlling the target temperature by the energy supplied to the reactants as in the above formulas 1 and 2. However, if heating is performed within a temperature range outside the range of the above formulas 1 and 2, there is a problem in that the recovery rate of valuable metals decreases.

[0085] The cooling unit 120 cools the reactant generated by the heating unit 110 to below 100° C. The reactant may be a reduction reactant generated by the heating unit 110. The cooling unit 120 stabilizes the reactant heated by the heating unit 110 by cooling within the above range.

[0086] The discharge unit 130 is a component through which the reactants containing valuable metals cooled through the cooling unit 120 are discharged. The reactants containing valuable metals are composed of Ni-Co based alloys, lithium compounds, carbon, and other residual impurities. The impurities may include, for example, Al, Cu, P, Na, Mg, and F.

[0087] In one embodiment, the reactants recovered from the raw materials in the high-temperature reduction device 10 may be 60% or more based on the total raw materials. Specifically, the weight of the crushed waste batteries before being fed into the heating furnace may have a recovery rate of 60-65% or more of the reactants after heat treatment. In one embodiment, Ni-Co in the reactants after heat treatment may be 40% or more of the total weight.

[0088] The high-temperature reduction apparatus 10 may include a magnetic separator that magnetically separates the alloy recovered after cooling. The magnetic separator may be disposed within the discharge section 130 or may be disposed separately from the discharge section 130.

[0089] In one embodiment, the magnetic separation unit can separate Ni-Co-based alloys using a magnetic field strength of 100 Gauss or more. By performing magnetic separation using a magnetic field strength of 100 Gauss or more, it is possible to separate magnetic Co-based alloys and increase the recovery rate of valuable metal alloys.

[0090] In one embodiment, the discharge unit 130 may further include a stepper, which may be, for example, a member having elasticity, and may be a means for more precisely and easily discharging the amount of reactant discharged from the discharge unit 130.

[0091] In one embodiment, the high-temperature reduction apparatus 10 may further include at least one suction unit. The suction unit may be a component for controlling and ventilating the gas concentration and heat in the heating furnace. For example, the suction unit may be disposed in the input unit, which is a component preceding the heating unit 110, or in the cooling unit 120, which is a component following the heating unit 110.

[0092] FIG. 1b shows a high temperature reduction apparatus 10' according to another embodiment of the present invention.

[0093] Referring to FIG. 1b, unlike FIG. 1a, the high-temperature reduction apparatus 10'' can be realized in a horizontal furnace type instead of a vertical furnace type, and the configuration of the high-temperature reduction apparatus 10' is the same as that described above to the extent that it is not inconsistent.

[0094] According to another embodiment of the present invention, a high-temperature reduction method for recycling waste batteries may include, as a heat treatment process performed after a crushing process of waste batteries, a step of charging raw materials, a step of heating the charged raw materials, a step of cooling the heat-treated product, and a step of discharging the cooled reactants.

[0095] In one embodiment, the step of heating the source material may be performed by the heating unit 110 of the high-temperature reduction apparatus 10 described above, and detailed description thereof will be the same as that described above to the extent that it does not contradict.

[0096] The step of heating the raw material may include a step of preheating the raw material charged and a high-temperature heat treatment step of heating the raw material at a temperature higher than that of the preheating step.

[0097] In one embodiment, the high-temperature heat treatment step may include the endothermic step and a melting step in which at least a portion of the molten layer is formed by heating at a temperature range higher than that of the endothermic step. The preheating step, the endothermic step, and the melting step may be performed by the preheating unit 111, the endothermic unit 112, and the melting unit 113 of the high-temperature reduction apparatus 10, respectively, and detailed descriptions thereof are the same as those described above to the extent not inconsistent.

[0098] The step of cooling the heat-treated product can be performed by the cooling unit 120 of the high-temperature reduction apparatus 10, and the detailed description thereof is the same as that described above to the extent that it does not contradict.

[0099] The step of discharging the cooled reactants can be performed by the discharge unit 130 of the high-temperature reduction apparatus 10, and the detailed description thereof is the same as that described above to the extent that it does not contradict.

[0100] Preferred examples and comparative examples of the present invention will be described below, but the following examples are merely preferred examples of the present invention and the present invention is not limited to the following examples. [Example]

[0101] <Experimental Example> <Conditions for raw materials fed into the charging section>

[0102] The crushed material charged through the charging unit 100 of the present invention uses raw materials satisfying the following components and composition ratios.

[0103] [Table 1]

[0104] Referring to Table 1 above, the crushed material composition data is a table of the components of crushed waste batteries used as an example for NCM622. Since Ni-Co-Mn in the crushed battery material is in an oxide state combined with oxygen, in order to reduce it, it must be reacted with C in the crushed material. Therefore, it was confirmed that the C / Ni ratio must be limited when inputting the initial battery raw materials. Table 2 below shows the results of evaluating the size of the alloy generated depending on the C / Ni content.

[0105] [Table 2]

[0106] Figures 2a-2c show photographs of grain size formation in alloys according to one embodiment of the present invention, depending on the C / Ni content of the raw materials. Figures 2a-2c show grain size formation data for alloys with C / Ni ratios of 100, 20, and 5, respectively. Figures 2a-2c show the process temperature of 1,250°C, the average crushed size of 20 mm, the maintenance time above 1,050°C for 60 minutes, and the oxygen content below 0.5%, while only controlling the C / Ni ratio. As shown in Figure 2c, when the C / Ni ratio was less than 5, agglomerates of 5,000 μm or larger appeared. When the C / Ni ratio was 20 or greater, as shown in Figures 2a and 2b, a powder-like particle morphology appeared.

[0107] Specifically, it was confirmed that the higher the C / Ni ratio, the smaller the powder particle size. Since the optimal particle size ratio for the acid treatment in the subsequent process is 75 to 3,000 μm, it is appropriate for the C / Ni ratio of the raw material in this invention to be 20 or more. If the ratio is less than 20, the C content in the crushed material is too low, and even if a Ni-based alloy is formed, it is difficult to form spherical crushed material of 3,000 μm or less due to wettability by the C, and the reaction product is formed in a lump state, which results in incomplete reduction by the carbon.

[0108] FIG. 2d shows the XRD data of the reduced reactant according to a comparative example of the present invention.

[0109] Referring to Figure 2d, Figure 2d shows XRD data for the reactant reduced when the C / Ni weight ratio is less than 20. In this case, it was confirmed that some materials were not reduced and some of the Ni base material remained in the form of NiO.

[0110] <Temperature rise in the center of the furnace and the shape of the reactants depending on the temperature conditions> 3a to 3c show the shapes of reactants according to an example of the present invention and a comparative example, and FIG. 3d shows the temperature rise rate and edge temperature distribution according to a comparative example of the present invention.

[0111] Figure 3a shows the shape of the reactant formed when the temperature at the center of the furnace is a low temperature of 1,150°C or less and the heating rate is 3°C / min. Figure 3b shows the shape of the reactant formed when the temperature at the center of the furnace is increased from approximately 1,200°C at a heating rate of 1°C / min. Figure 3c shows the shape of the reactant formed when the temperature at the center of the furnace is increased from approximately 1,250°C at a heating rate of 3°C / min.

[0112] Referring to Figure 3a, when the temperature inside the furnace core was low, below 1,150°C, the NCM alloy and the internal Li-Al-O formed particles coagulated together and existed in the form of flakes over 3,000 μm in size. In this case, it was not easy to separate and recover the NCM and Li-Al-O.

[0113] Referring to Figures 3b and 3c, it was confirmed that when the temperature at the center of the furnace was in the range of 1,150 to 1,400°C, which is the melting temperature of Cu or Ni, the flakes existed as powder or spherical alloy.

[0114] Specifically, referring to Figure 3b, when the temperature was increased from 1,200°C at a rate of 1°C / min or less, the flakes did not form spherical particles, but instead formed powder of 100µm or less in size.

[0115] It is believed that NCM and Li-Al-O coexist, and that Li-Al-O remains as an oxide for a long time and breaks into small particles, resulting in the NCM coexisting. This results in the NCM existing in powder form without agglomeration. If the NCM exists in powder form, there is a problem that C or Li-Al-O particles may be separated out together during the subsequent magnetic separation process, resulting in a decrease in the recovery rate.

[0116] Referring to Figure 3c, when the temperature at the center of the furnace is in the range of 1,250°C and the heating rate is 10°C / min or less, specifically about 3°C / min, it was confirmed that a Ni-based alloy is formed as spherical particles of 100 to 3,000 μm.

[0117] 3d, it was confirmed that a heating rate of 10°C / min or more requires the use of high power, which can cause the temperature at the bent portion of the heating section to rise to 1,400°C or more. As such, it was confirmed that the heating rate in the pre-heat treatment and high-temperature heat treatment sections of the present invention satisfies the above-mentioned requirements, and more specifically, that the heating rate can satisfy the above-mentioned range when the internal temperature of the heat treatment center is in the range of 700 to 1,250°C.

[0118] <Recovery rate of Li and NCM alloy from reactants depending on the internal temperature of the heating furnace> FIG. 4 shows the recovery rate of the reaction product as a function of temperature according to the examples of the present invention and the comparative examples.

[0119] Referring to Figure 4, which shows the recovery rates of Ni-Co-Mn and LiAlO2 as a function of temperature, it was confirmed that both Ni-Co-Mn and LiAlO2 have excellent recovery rates in the range of 1100-1500°C, specifically 1200-1300°C. It was also confirmed that there is a problem with the LiAlO2 recovery rate being excessively reduced in the range above 1500°C, and a problem with the Ni-Co-Mn recovery rate being excessively reduced in the range below 1100°C.

[0120] It was confirmed that the recovery rate of the main constituents, Ni-Co-Mn alloy and Li, is affected by the temperature conditions of the materials produced through heating in the high-temperature reduction device of the present invention, especially the temperature conditions in the melting section or melting stage.

[0121] Table 3 below shows the lithium recovery rate and NC alloy recovery rate depending on the temperature conditions of the molten part.

[0122] [Table 3]

[0123] Referring to Table 3, it was confirmed that when the temperature at the melting point or melting stage is in the range of 1,150 to 1,400°C, specifically in the range of 1,200 to 1,300°C, not only the recovery rate of NCM alloy, which is a valuable metal, but also the recovery rate of Li is excellent.

[0124] <Temperature deviation by position on cross section of heating furnace> FIG. 5 shows a cross section of a furnace at an arbitrary position relative to the center position, according to one embodiment of the present invention.

[0125] 5, the temperature T(X, Y) at an arbitrary position (X, Y) based on the center position (O) in the cross section of the furnace is shown. Specifically, the cross section of the furnace is cut in a direction perpendicular to the direction in which the raw material travels.

[0126] Since the furnace is heated by the external heating element, it is confirmed that the temperature at the center is the lowest in the furnace cross section and the temperature is highest at the outer periphery of the furnace closest to the heating element. Although a circular shape is the most common shape of a conventional furnace, in the furnace shape design of the present invention, the ratio of the horizontal and vertical lengths of the heating furnace is adjusted to provide a ratio that minimizes temperature deviation.

[0127] FIG. 6 shows the temperature deviation in the heating furnace according to the example of the present invention and the comparative example.

[0128] 6, the ratio of the horizontal and vertical lengths of the furnace shows the change in temperature deviation depending on the ratio of the length in the major axis direction (X) to the length in the minor axis direction (Y) on the same plane, assuming that the temperature deviation in a circular shape is 100%. Specifically, when the cross section of the furnace is square, if the length ratio in the minor axis direction is smaller than the length ratio in the major axis direction, the temperature deviation should gradually decrease, but there is a problem that the temperature is high at the corners, resulting in a low yield of the reactants at the corners.

[0129] FIG. 7 shows the temperature deviation in the heating furnace according to the example of the present invention and the comparative example.

[0130] 7, when the ratio of the major axis to the minor axis of the cross section of the furnace is 3:1, it was confirmed that the corners of the outer surface of the furnace are not sharp but have a bent portion with a predetermined angle, which prevents heat from concentrating at the corners. As a result, it was confirmed that the temperature deviation in the furnace with a 3:1 ratio of the major axis to the minor axis of the cross section of the furnace including the bent portion was even lower than that in the case of a circular furnace.

[0131] FIG. 8a is a graph showing the tendency of temperature deviation in a heating furnace to decrease depending on the length of the bent portion according to an embodiment of the present invention, and FIG. 8b is a graph showing the temperature deviation depending on the length of the bent portion measured by a thermal analysis simulation.

[0132] Referring to FIG. 8a, it can be seen that the temperature deviation decreases as the length of the bent portion increases. Specifically, when the length of the bent portion is 60 mm or more, specifically 80 mm or more, and more specifically 100 mm or more, it can be seen that the temperature difference between the outer periphery and the center converges to 200°C.

[0133] Referring to FIG. 8b, when the length of the bent portion is 50 mm or less, it can be seen that heat is concentrated near the bent portion, and when the length of the bent portion is 100 mm, it can be seen that there is no area where heat is concentrated near the bent portion and the temperature inside the heating furnace has a uniform heat distribution.

[0134] <Coil pitch control with induction heating> 9a to 9c show coil arrangements and the resulting temperature distributions according to comparative examples and examples of the present invention.

[0135] 9a, when induction heating is used as a heating unit to apply heat to a heating furnace, it was confirmed that the average temperature in the heating furnace varies depending on the pitch of the induction heating coil, and more specifically, it was confirmed that the average temperature is highest in the central region of the coil.

[0136] 9b, it can be seen that the pitch of the coils becomes narrower as the coils are further from the center of the furnace. Specifically, when comparing the central region of the coils with the outer region of the coils, it can be seen that the pitch of the coils in the outer region is denser.

[0137] As a result, it was confirmed that the pitch interval of the coils is dense in the outer region and not dense in the central region, and therefore the temperature in the central region, where the average temperature is high due to the heat concentration in FIG. 9a, is dispersed to the outer region, and the difference in the average temperatures between the central region and the outer region is small, allowing for uniform heating.

[0138] Referring to Figure 9c, it was confirmed that the problem of large differences in the average temperature of the heating part can be prevented by controlling the pattern so that the pitch interval of the coil, which is the heating part, is different in the central region and the outer region as shown in Figure 9b in the pre-heat treatment part where the heating part of the present invention is arranged, as well as the heat absorption part and the melting part.

[0139] <Energy required for heating element - minimum energy required to control the target temperature of the heating element> The target temperature Y (preheating zone: 700°C, melting zone: 1,150-1,400°C) of the reactants moving 65 kg per hour within the heating zone must be reached by satisfying the required heating element energy supply (preheating zone: 12 kW, melting zone: 18 kW) to reach that temperature. The following equation shows the correlation between the minimum energy required by the heating element when heating the furnace and the target temperature. Here, a is a constant for efficiency, which is less than 1 below 700°C, the temperature before the Boudouard reaction begins, and varies up to 0.4 for targets above the Boudouard reaction temperature. This has a coefficient of 0.2-1 depending on the target temperature condition of Y. Cp is the specific heat (J / Kg·℃), m is the mass transfer rate (Kg / s) in the range of 60 to 70 Kg / s, x is the power [W] value, which is the minimum energy required to reach the melting temperature, Ti is the initial temperature, which is room temperature in the case of preheating, and the target temperature for high-temperature heating for melting is the final temperature of preheating.

[0140] <Expression 1> Target temperature of preliminary heat treatment Y = a(x / (Cp*m)+Ti)

[0141] For example, the minimum heat input required to reach the target temperature is calculated as follows. Here, Cp is 800 J / Kg°C, m is 65 Kg / hr, and Ti is 25°C. In this case, the formula can be modified as follows. The target temperature of the preliminary heat treatment section is based on 700°C, the Boudouard reaction start temperature, and the target temperature of the melt treatment section is based on 1,150°C, the minimum temperature of the reactor.

[0142] <Expression 1> Target temperature of preliminary heat treatment section Y = 0.813(x / (Cp×m)+25);

[0143] <Expression 2> Target temperature of fusion zone Y = 0.4(x / (Cp×m)+700);

[0144] Table 4 below shows the reactant temperatures according to the minimum energy (kW) required for heating the pre-heat treatment section and the raw reactant materials. Specifically, Table 4 below shows the theoretical minimum values ​​taken into account in the heating section.

[0145] [Table 4]

[0146] Referring to Table 4 above, in the case of the preheating section, the core temperature of the reactants must be maintained at approximately 700°C as the starting temperature range for the reduction reaction. Specifically, it was confirmed that 12 kW or more of power, which is the energy required to heat the raw material (heat source), must be applied. In the case of the melting section, since the raw material contains a large amount of graphite, the endothermic reaction due to the Boudouard reaction converting carbon dioxide to carbon monoxide must be taken into consideration. Therefore, it was confirmed that at least 16 kW of power must be applied to reach the target temperature. However, this is only the minimum theoretical value required to reach the target temperature, and the actual amount of power that must be applied to the reactor must be greater than this. While the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art using the basic concept defined in the following claims are also within the scope of the present invention.

Claims

1. a charging section for charging raw materials; a heating section for heating the raw material introduced from the introduction section; a cooling section for cooling the heat-treated product; and a discharge unit that discharges the reactant cooled from the cooling unit, The heating unit is a preheating section for preheating the raw material introduced from the charging section; a high-temperature heat treatment section that heats the device at a temperature higher than that of the preliminary heat treatment section; The high-temperature heat treatment unit includes a heat treatment unit that heat-treats the raw material at a temperature in the range of 1,150 to 1,400°C.

2. The high-temperature reduction apparatus for recycling waste batteries according to claim 1 , wherein the high-temperature heat treatment section includes two or more heat treatment sections in a vertical or horizontal direction.

3. The high-temperature heat treatment section includes a heat absorption section that heats at a temperature higher than that of the preliminary heat treatment section; The high-temperature reduction device for recycling waste batteries according to claim 1 , further comprising a melting section that is heated to a temperature range higher than that of the heat absorption section to form at least a partial melted layer.

4. 2. The high-temperature reduction apparatus according to claim 1, wherein the heating unit for increasing the temperature increases the temperature of the raw material at a rate of 1 to 10° C. / min.

5. The high-temperature reduction apparatus according to claim 3 , wherein the molten portion is formed by melting at least one of Ni, Cu, Co, and Mn to form spherical particles.

6. 2. The high-temperature reduction apparatus according to claim 1, wherein the weight ratio of carbon to nickel (C / Ni) of the raw material to be charged is 20 or more.

7. the heating unit includes a heating furnace and a heating unit; When temperatures are measured at any positions in the minor axis and major axis directions of the cross section of the heating furnace with the center as the reference point, 2. The high-temperature reduction device for recycling waste batteries according to claim 1, wherein the temperature difference between the center portion and the arbitrary position is 250° C. or less.

8. The cross section of the heating furnace is 8. The high temperature reduction apparatus for recycling waste batteries according to claim 7, wherein the length ratio of the major axis to the minor axis is 2 / 1 to 4 / 1.

9. The high temperature reduction apparatus for recycling waste batteries according to claim 1 , wherein the heating furnace has a bent portion on the outside of the heating furnace.

10. 10. The high-temperature reduction apparatus for recycling waste batteries according to claim 9, wherein the length of the bent portion is 30 mm or more.

11. The heating unit includes at least one heating unit, The heating unit has a coil shape, The high-temperature reduction apparatus for recycling waste batteries according to claim 1 , wherein the coils have a pitch distance that narrows as the distance from the central region of the coils increases.

12. The high-temperature reduction apparatus for recycling waste batteries according to claim 11 , wherein the heating unit is disposed in at least a portion of the heating unit.

13. 2. The high-temperature reduction apparatus according to claim 1, wherein a target temperature of the pre-heat treatment section in the heating section satisfies the following formula 1: <Formula 1> T １１１ ≧0.813(x / (Cp×m)+25) (In the above formula 1, x is the input energy [W], Cp is the specific heat [J / Kg-°C], and m is the mass transfer rate [Kg / s].)

14. 14. The high temperature reduction apparatus according to claim 13, wherein in formula 1, x is 12,000 W or more.

15. 4. The high-temperature reduction apparatus according to claim 3, wherein a target temperature of the melting portion in the heating portion satisfies the following formula 2: <Formula 2> T １１３ ≧0.4(x / (Cp×m)+700) (In the above formula 2, x is the input energy [W], Cp is the specific heat [J / Kg-°C], and m is the mass transfer rate [Kg / s].)

16. 16. The high temperature reduction apparatus according to claim 15, wherein in formula 2, x is 16,000 W or more.

17. 2. The high-temperature reduction apparatus for recycling waste batteries according to claim 1, wherein the heating unit performs heating in an atmosphere having an oxygen partial pressure of 0.1 atm or less.

18. In the heating section, The high-temperature reduction apparatus for recycling waste batteries according to claim 1 , wherein the pre-heat treatment section is heated at a temperature range of 800° C. or less.

19. In the heating section, The heat absorption part is CO ２ 4. The high-temperature reduction device for recycling waste batteries according to claim 3, wherein an endothermic reaction occurs in the Boudouard reaction that converts gas into 2CO.

20. The heat treatment process that is carried out after the crushing process of waste batteries is as follows: charging raw materials; heating the charged and introduced raw materials; cooling the heat-treated product; and Discharging the cooled reactants; The step of heating the source material comprises: preheating the raw materials charged; and a high-temperature heat treatment step of heating at a temperature higher than that of the preheating step, The high-temperature heat treatment step includes a heat treatment step of heat treating the raw material at a temperature in the range of 1,150 to 1,400°C.

21. The high-temperature heat treatment step includes an endothermic step of heating the substrate at a temperature higher than that of the pre-heat treatment step; The heat treatment method for recycling waste batteries according to claim 20, further comprising a melting step of forming a molten portion by heating at a temperature range higher than that of the endothermic step to form at least a molten layer.

22. The step of heating the charged raw material comprises:

21. The heat treatment method for reusing waste batteries according to claim 20, wherein, when temperatures are measured at any position in the minor axis and major axis directions of a cross section of a heating furnace that is a heating member with a center point as a reference, the temperature difference between the center and the any position is 250°C or less.

23. The cross section of the heating furnace is 21. The heat treatment method for recycling waste batteries according to claim 20, wherein a length ratio of the major axis to the minor axis is 2 / 1 to 4 / 1.

24. 21. The heat treatment method for recycling waste batteries according to claim 20, wherein the heating furnace has a bent portion on the outside of the heating furnace.

25. 25. The heat treatment method for recycling waste batteries according to claim 24, wherein the length of the bent portion is 60 mm or more.

26. 21. The heat treatment method for recycling waste batteries according to claim 20, wherein the preheating of the charged raw materials is performed at a target temperature expressed by the following Equation 1: <Formula 1> T １１１ ≧0.813(x / (Cp×m)+25) (In the above formula 1, x is the input energy [W], Cp is the specific heat [J / Kg-°C], and m is the mass transfer rate [Kg / s].)

27. 22. The heat treatment method for recycling waste batteries according to claim 21, wherein a target temperature of the melting step of forming at least a portion of the melted layer by heating in a temperature range higher than that of the endothermic step satisfies the following formula 2: <Formula 2> T １１３ ≧0.4(x / (Cp×m)+700) (In the above formula 2, x is the input energy [W], Cp is the specific heat [J / Kg·°C], and m is the mass transfer rate [kg / s].)

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