Method for heat treatment of battery and method for recovering valuable material

Abstract

To heat-treat a battery at an optimal temperature by suppressing temperature rise due to thermal runaway of the battery during a heat treatment step.SOLUTION: There is provided a heat treatment method for heat-treating a battery 1 from which a valuable material is recovered, the heat treatment method including: a battery loading step of loading the battery 1 into a heating case 10 that is blocked but not sealed; and a heat treatment step of heating the heating case 10 in a heat treatment furnace 3 and heating the battery 1 inside the case through the heating case 10 to heat-treat the battery. The heat treatment step includes an exhaust step in which a fired rock 2 that is fired, porous, hydrophilic and water-absorbed is disposed inside the heating case 10, the fired rock 2 is heated in the heating case 10 so that the heated fired rock 2 heats absorption water to generate steam, and internal air in the heating case 10 is forcibly exhausted with generated steam.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for heat treating a battery to recover valuable materials from the battery, a method for recovering valuable materials by heat treating a battery, and a battery heat treatment device for recovering valuable materials from the battery. [Background technology]

[0002] Valuable materials can be recovered from batteries by heat treatment. Discarded batteries can be heat treated to remove the electrolyte and recover valuable materials. This recovery method can recover non-ferrous valuable materials such as lithium, cobalt, nickel, copper foil, and aluminum foil from lithium-ion secondary batteries, for example. Valuable materials can be recovered by heat treating the batteries, then crushing, pulverizing, and classifying them to separate each valuable material. The recovered valuable materials can be effectively reused as raw materials for batteries, so technology to recover valuable materials from batteries is extremely important in resource-poor Japan.

[0003] Batteries can be heat-treated by placing them in a heat treatment furnace and heating them to a predetermined temperature. Heat treatment of batteries involves heating the batteries to a predetermined temperature and baking them to a state where valuables can be efficiently recovered from the heat-treated batteries. If the heat treatment temperature of the batteries is too high or too low, it will hinder the efficient recovery of valuables in a high-quality state. Heat treatment of batteries involves controlling the thermal energy supplied to the heat treatment furnace to maintain the battery temperature at an appropriate value. However, heated batteries can experience thermal runaway and emit high-temperature, high-pressure exhaust gases and other emissions. The high-temperature emissions emitted from the batteries rapidly increase the internal temperature of the heat treatment furnace, raising the battery heating temperature above the desired temperature. This melts or oxidizes the valuables to be recovered from the heat-treated batteries, reducing their quality and hindering the efficient recovery of high-quality valuables. Thermal runaway in batteries is believed to be caused by heat generated by Joule heat due to short-circuit current that flows when the positive and negative electrodes are shorted. Therefore, batteries that are not fully discharged, i.e., batteries with a large remaining capacity (SOC), have the problem of being prone to thermal runaway due to the large short-circuit current.

[0004] Patent Document 1 discloses a technology in which, in order to suppress the adverse effects of thermal runaway, in a process of heat treating a lithium ion secondary battery with a voltage of 80% or more of its rated voltage, the lithium ion secondary battery is heated to 350°C or more and 430°C or less, and if the lithium ion secondary battery experiences thermal runaway and ignites during this heat treatment process, the thermal energy supplied to the heat treatment furnace is changed to 50% or less of the amount of heat supplied before the lithium ion secondary battery ignited. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-150282 Summary of the Invention [Problem to be solved by the invention]

[0006] Batteries are heat-treated, but the heat treatment process can cause thermal runaway in batteries. Therefore, it is impossible to completely eliminate thermal runaway in batteries during the heat treatment process. When a battery experiences thermal runaway, the internal temperature of the heat treatment furnace rises, but it is extremely difficult to prevent the internal temperature from rising due to thermal runaway. While the probability of thermal runaway can be reduced by lowering the set temperature during the heat treatment process, a low temperature range that heat-treats all batteries without causing thermal runaway does not allow for efficient recovery of valuable resources. Therefore, the adverse effect of random thermal runaway in unspecified batteries cannot be eliminated during the heat treatment process, and it is extremely difficult to prevent abnormal increases in the furnace temperature due to thermal runaway in batteries during the heat treatment process. Furthermore, in order to efficiently heat-treat a large number of discarded batteries, multiple batteries are placed in a heat treatment furnace and heat-treated simultaneously. Therefore, thermal runaway in a specific battery adversely affects the other batteries being heat-treated together, hindering the effective recovery of valuable resources.

[0007] The present disclosure was developed with the aim of eliminating the above-mentioned drawbacks, and one of the purposes of the present disclosure is to have the feature that even when the battery goes into thermal runaway during the heat treatment process and emits high-temperature, high-pressure exhaust, the rise in internal temperature due to the exhaust can be suppressed, the battery can be heat-treated within an optimal temperature range, and valuable materials can be efficiently recovered in high quality from the heat-treated battery. [Means for solving the problem]

[0008] A heat treatment method for batteries to recover valuable resources according to one aspect of the present disclosure is a heat treatment method for heat treating batteries to recover valuable resources, which includes a battery carrying-in process in which batteries are placed in a heating case that is closed but not sealed, and a heat treatment process in which the heating case containing the batteries in the carrying-in process is placed in a heat treatment furnace, the heating case is heated in the heat treatment furnace, and the internal batteries are heated and heat-treated through the heating case. In the heat treatment process, calcined, porous, hydrophilic, water-absorbed calcined rock is placed in the heating case that is heated in the heat treatment furnace, the calcined rock is heated in the heating case, the heated calcined rock heats the absorbed water to generate water vapor, and the generated water vapor is used to forcibly expel the air inside the heating case.

[0009] A method for recovering valuable materials from batteries according to another aspect of the present disclosure can include a heat treatment step of performing heat treatment using a heat treatment method including the above, and a recovery step of crushing the heat-treated batteries obtained in the heat treatment step to separate and recover valuable materials.

[0010] Another aspect of the present disclosure provides a battery heat treatment device for recovering valuables, which includes a closed but not sealed heating case for containing batteries, and a heat treatment furnace for heating the heating case. The heating case contains batteries and calcined, porous, hydrophilic, water-absorbed calcined rock within it. The heating case is heated by the heat treatment furnace, and the calcined rock in the heating case heats the absorbed water to generate water vapor, which then forcibly expels the air inside the heating case, thereby heat-treating the batteries. [Effects of the Invention]

[0011] The above method and apparatus have the advantage that they can suppress temperature rise due to thermal runaway of the battery during the heat treatment process, heat treat the battery within an optimal temperature range, and efficiently recover valuable materials from the battery in a high-quality state. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view of a battery heat treatment method and a battery heat treatment apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 10 is a schematic cross-sectional view showing another example of the heating case. [Figure 3] FIG. 2 is a schematic cross-sectional view showing an example of a check valve. [Figure 4] FIG. 10 is a schematic cross-sectional view showing another example of a check valve. [Figure 5] FIG. 10 is a schematic cross-sectional view showing another example of a check valve. [Figure 6] FIG. 2 is a schematic cross-sectional view showing an example of a storage section. [Figure 7] FIG. 10 is a schematic cross-sectional view showing another example of the storage section. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," and other terms including these terms) will be used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present invention. Furthermore, parts that appear with the same reference numerals in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments shown below are specific examples of the technical concept of the present invention and are not intended to limit the present invention thereto. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended as examples and are not intended to limit the scope of the present invention thereto. Furthermore, the content described in one embodiment or example can also be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated for clarity of explanation.

[0014] A battery heat treatment method according to one embodiment of the present disclosure is a heat treatment method for heat treating batteries from which valuables are recovered, comprising a battery carrying-in step of placing batteries in a closed but not sealed heating case, and a heat treatment step of placing the heating case containing the batteries in the carrying-in step into a heat treatment furnace, heating the heating case in the heat treatment furnace, and heating and heat-treating the internal batteries through the heating case. In the heat treatment step, calcined, porous, hydrophilic, water-absorbed calcined rock is placed in a heating case heated in the heat treatment furnace, and the calcined rock is heated in the heating case, causing the heated calcined rock to heat the absorbed water and generate water vapor, and the generated water vapor is used to forcibly expel the air inside the heating case.

[0015] The above-described battery heat treatment method has the advantage that it suppresses internal temperature increases due to thermal runaway in the heat treatment process, heat-treating the battery within an optimal temperature range, allowing for efficient recovery of valuables from the battery in a high-quality state. This is because the above-described battery heat treatment method includes an evacuation process, in which the absorbed water of the fired rock in the heating case is heated to generate steam. The generated steam forcibly expels the initial air, which has a high oxygen concentration and is present in the heating case before heating, thereby lowering the oxygen concentration in the heating case and enabling heat treatment of the battery. Even if the battery experiences thermal runaway and emits high-temperature, high-pressure exhaust gases or other exhaust materials, the low-oxygen state prevents ignition and prevents or suppresses a rapid rise in internal temperature due to excessive thermal energy generated by ignition of the exhaust materials. By heat-treating the battery within an optimal temperature range, valuables can be recovered from the battery in a high-quality state, allowing for efficient recovery of valuables. The above-mentioned battery heat treatment method generates water vapor in the heating case, efficiently expelling the initial internal air and lowering the oxygen concentration, allowing the battery to be heat-treated. Furthermore, in the heat treatment process, the battery is heat-treated at a temperature higher than the temperature at which water vapor is generated (100°C under atmospheric pressure). Therefore, before the temperature of the heating case heated in the heat treatment furnace rises to the battery's heat treatment temperature, water vapor is generated from the fired rock in the exhaust process, and the internal air is forcibly expelled, allowing the battery to be heat-treated with a reliably lowered oxygen concentration.

[0016] The above-described battery heat treatment method has the advantage of being able to efficiently reduce the oxygen concentration inside the heating case in a short period of time. This is because the closed heating case accommodates the batteries, allowing the range in which the oxygen concentration is reduced to be limited to the required range. This is because, compared to reducing the oxygen concentration throughout the entire heat treatment furnace, the air inside the heating case is forcibly discharged from the heating case in a narrow, required range, allowing the oxygen concentration to be reduced efficiently in a short period of time. Furthermore, the above-described battery heat treatment device is also able to prevent the adverse effects of localized heating of the batteries by housing the batteries in the heating case, allowing the entire battery to be heated and heat-treated within a temperature range favorable for recovering valuables. This is because the heating case is heated in a heat treatment furnace, and the heated heating case heats the batteries inside, preventing the heat source of the heat treatment furnace from directly and locally heating the batteries. Furthermore, the air inside the heated heating case rises along the inner surface, agitating the internal air through convection of the rising internal air, allowing the batteries inside the heating case to be effectively heated and heat-treated with minimal temperature variations. Furthermore, the above-described battery heat treatment method effectively utilizes the thermal energy of the heat treatment furnace to efficiently heat and heat-treat batteries, thereby reducing energy consumption and costs. This is because the batteries are heated in a closed heating case, and energy loss can be reduced. This is because the batteries are heated in a closed heating case, and energy loss can be reduced. The heat treatment furnace heats the heating case, which heats the batteries and sintered rock. The heat generated by heating the heating case in the evacuation process can be used to heat and heat-treat the batteries continuously, continuously, or simultaneously. Steam is generated in the evacuation process, which precedes the heat treatment process, and batteries can be heated simultaneously. No separate heating or heat source is required for the evacuation process, and there is no need to move the batteries or sintered rock or replace the containers. The evacuation process and battery heating and heat treatment can be performed in the same heating case in the heat treatment furnace. Furthermore, the water vapor generated in the heating case is further heated to produce superheated steam, which is a gas with a large heat capacity and excellent heat transfer properties, allowing for efficient heating and heat treatment of batteries. Furthermore, superheated steam has the property of preferentially condensing in low-temperature areas, suppressing temperature variations and effectively heating batteries. Superheated steam can also be used for heating in a low-oxygen atmosphere.The above-mentioned battery heat treatment method ensures and improves the safety of the work by heat treating the batteries in a low-oxygen environment, and has the advantage that even in the unlikely event of an unforeseen incident, the heating case acts as a protective barrier, preventing or minimizing danger to workers and damage to the heat treatment furnace.

[0017] The above-described battery heat treatment method allows heat treatment without removing the battery's exterior case, eliminating the time, labor, and cost required for removing the exterior case and disassembling the battery, while also avoiding potential hazards. Furthermore, the above-described battery heat treatment method also allows safe heat treatment at a desired temperature by evacuating the internal air of the heating case, including the air inside the battery's exterior case. Batteries housed in an exterior case have difficulty smoothly guiding water vapor into the interior of the exterior case, making it difficult to quickly evacuate the air inside the exterior case using water vapor. However, when a battery including the exterior case is heated in a heat treatment furnace, the air inside the exterior case expands and gradually escapes from the exterior case. The air escaping from the exterior case temporarily increases the oxygen concentration inside the heating case, potentially increasing the risk of fire. However, by evacuating the internal air, including the air escaping from the exterior case, the oxygen concentration inside the heating case can be reduced. Water vapor can efficiently heat batteries by utilizing a large amount of heat retention, not only through convective heat transfer but also through condensation and radiative heat. The water vapor heats the battery, including the exterior case, through convection and radiative heat transfer caused by condensation of the water vapor on the surfaces of the battery and exterior case, followed by evaporation of the water, which promotes the outflow of air from the exterior case and the discharge of this and other internal air to the outside, thereby reducing the oxygen concentration within the heated case.The above battery heat treatment method can be used to heat treat batteries of various types in a heated case, but there is particularly high demand for the recovery and recycling of valuable materials in batteries (battery units) that house many battery cells in a metal exterior case used as a power source for hybrid cars, electric vehicles, etc., and the above features can solve important issues.

[0018] The heat treatment method for the battery described above has the advantage that the amount and time of water vapor generated by the absorbed water can be easily determined and adjusted by adjusting the amount, size, particle size, shape, type, and arrangement of the calcined rock, as well as the amount of water supplied and the amount of water absorbed. For example, increasing the amount of water absorbed by the calcined rock increases the amount of water vapor generated and extends the time of water vapor generation, promoting the release of internal air and stably lowering the overall oxygen concentration. When the absorbed water is heated by the calcined rock and boils to steam, the absorbed water on the surface of the calcined rock boils first, followed by the absorbed water in the center, which gradually heats up and generates water vapor. The absorbed water in the center of the calcined rock generates water vapor later than the absorbed water on the surface, but the delay time for the absorbed water in the center to boil to steam increases as the particle size of the calcined rock increases. Therefore, increasing the size of the calcined rock increases the time for water vapor generation. Mixing calcined rocks of different sizes and particle sizes also allows for adjustment of the amount and time of water vapor generated by each individual sample. The amount of steam generated and the time it takes to generate it can also be adjusted by adjusting the degree of heating of the water absorbed in the fired rock. The amount of steam generated and the time it takes to generate it can be set to an optimal range, taking into account the shape of the battery and the volume of the heating case. For example, the amount of steam generated and the time it takes to generate it can be set to an optimal range, taking into account the time it takes for the air inside the battery's outer case to be discharged into the heating case. The time it takes for the battery's outer case to discharge air into the heating case is determined by the internal volume of the outer case and the thermal conductivity characteristics of the outer case, so for example, the time it takes to generate steam can be made longer for a battery with a large internal volume and an outer case with poor thermal conductivity.

[0019] The above-described battery heat treatment method has the advantages of reducing costs and avoiding the need for large-scale equipment through a simple structure and method of placing water-absorbed calcined rock in a heating case. Supplying water or steam into a heat treatment furnace during the battery heat treatment process requires complex or specialized mechanisms and structures, and fire and heat resistance to withstand the furnace temperatures is required, increasing equipment costs and increasing the size of the equipment. In contrast, the present disclosure effectively reduces oxygen concentration through an extremely simple structure and method of placing water-absorbed calcined rock in a heating case. This eliminates the need for complex or specialized mechanisms and structures for supplying water to the heat treatment furnace, thereby avoiding increased equipment costs and the need for large-scale equipment. Furthermore, the liquid used is low-cost water, which can be easily placed and supplied into the heating case in a short time, allowing the calcined rock to absorb water, thereby reducing processing and running costs. Furthermore, the above-described battery heat treatment method can be used to expand the range and types of heat treatment furnaces that can be used. This is because the heat treatment furnace does not directly heat the batteries, but instead indirectly heats the batteries and fired rock inside via the heating case, eliminating the need for a dedicated mechanism, structure, or dedicated heat treatment furnace, and preventing damage to the heat treatment furnace during battery heat treatment. The above battery heat treatment method also has the advantage that the fired rock can be safely placed in the heating case before heating. Heating can begin in the heat treatment furnace once the fired rock and batteries are placed in the heating case.

[0020] A battery heat treatment method according to another embodiment of the present disclosure can use a metal case that is closed but not sealed, and that is provided with a check valve that allows gas to pass through the heating case in the direction of exhausting the internal air but prevents gas from passing in the opposite direction. This has the advantage of preventing the inflow of external air from the outside, including backflow of the internal air that has been once exhausted, thereby reliably reducing the oxygen concentration inside the heating case and maintaining a low-oxygen state. Metal heating cases have the advantage of high thermal conductivity, allowing for efficient heating of the interior, reducing temperature variations, and reducing heating energy consumption.

[0021] In another embodiment of the present disclosure, a battery heat treatment method includes a check valve having a valve element that elastically deforms and opens under the internal pressure of the heating case. The valve element elastically closes to a valve seat and can open when the valve element is pushed away from the valve seat by the internal pressure of the heating case. The above heat treatment method provides excellent heat resistance for the check valve, allowing it to be installed in a heating case placed in a high-temperature heat treatment furnace and operate reliably to exhaust air from the heating case and prevent backflow of air within the furnace. The above heat treatment method allows the check valve opening timing to be set to an appropriate value and adjusted based on the internal pressure of the heating case. Multiple check valves can be easily opened at different times and with different time lags using different elastic deformation strengths. A check valve that opens when the internal pressure of the heating case exceeds a certain level can mitigate an increase in the internal pressure of the heating case by opening, maintaining the internal pressure within a certain range while exhausting the air from the heating case, thereby reducing and maintaining a low oxygen concentration. The above heat treatment method has the advantage of being simple in structure and low in cost.

[0022] In another embodiment of the present disclosure, a battery heat treatment method includes a check valve having a heat-resistant valve body placed on a discharge opening of a heating case, the valve body tightly contacting a valve seat under its own weight to close, and the valve body being pushed by the internal pressure of the heating case to separate from the valve seat to open. This heat treatment method allows the pressure at which the check valve opens under the weight of the valve body to be set and adjusted to an appropriate value, and also provides excellent heat resistance for the check valve, allowing it to be installed in a heating case placed in a high-temperature heat treatment furnace and operate stably and reliably. This heat treatment method also has the advantage of being simple in structure and allowing for low cost.

[0023] In another embodiment of the present disclosure, a battery heat treatment method can include placing both the battery and the water-absorbed calcined rock inside a heating case during the evacuation process, and then transporting the heating case into a heat treatment furnace. This heat treatment method has the advantage that the water-absorbed calcined rock can be placed in a heating case before being transported into the heat treatment furnace, i.e., in a heating case that is not heated by the heat treatment furnace, making it possible to simply, easily, and safely place the calcined rock in the heating case.

[0024] In another embodiment of the present disclosure, a heat treatment method for a battery can include laying calcined rock on the bottom of a heating case during the heat treatment process and placing the battery on top of the calcined rock. This heat treatment method effectively prevents ignition of exhaust gases emitted from a heat-treated battery. This is because the water vapor continuously generated from the calcined rock placed under the battery envelops the battery, displacing the internal air with the rising water vapor, effectively reducing the oxygen concentration around the battery and accelerating the heating of the battery and outer case. This heat treatment method involves laying absorbed calcined rock and then spraying water on the laid calcined rock to absorb water. This method is characterized by extremely easy placement of absorbed calcined rock on the bottom of the heating case. Furthermore, the amount of water vapor generated from the calcined rock and the duration of water vapor generation can be easily adjusted by adjusting the particle size, quantity, and water absorption of the laid calcined rock. This heat treatment method also has the advantage of reducing, mitigating, and shortening the labor, time, and burden involved, thereby improving process efficiency and reducing costs. For example, by adhering the substances melted and discharged from the heat-treated battery to the fired rock laid on the bottom of the heating case, it is possible to prevent these substances from adhering to and contaminating the bottom of the heating case, thereby reducing and shortening the effort, time, and burden required for tasks and processes such as removing the battery after heat treatment, carrying in the next battery, and cleaning the heating case. Preventing and suppressing adhesion to the heating case makes it possible to maintain a state in which batteries can be heat-treated efficiently and safely, and also makes it easier to reuse the heating case. Furthermore, fired rock that has become contaminated can be easily replaced. By placing the battery directly on the fired rock laid on the bottom of the heating case, the efficiency of heat conduction from the heating case to the battery can be improved. Furthermore, by providing a gap between the battery and the fired rock, the gap can be filled with steam, evenly enveloping the battery in steam.

[0025] In another embodiment of the present disclosure, a battery heat treatment method can include laying sintered rock over 80% or more of the bottom surface of the heating case during the heat treatment process. This heat treatment method has the advantage of effectively preventing ignition of exhaust gases emitted from the heat-treated battery. This is because laying sintered rock over 80% or more of the bottom surface of the heating case, such as the entire bottom surface or almost the entire bottom surface, allows for the generation of steam evenly over a wide area, particularly covering the bottom surface of the battery. This allows the rising steam to surround the battery, displacing the internal air and effectively reducing the oxygen concentration, and also promotes the heating of the battery and its outer case.

[0026] In another embodiment of the present disclosure, a heat treatment method for a battery includes a heat treatment step in which water is sprayed onto the laid fired rock to allow it to absorb water. This heat treatment method has the advantage of allowing the fired rock to absorb water easily and safely. This is because the fired rock can be easily laid in a heating case before heating and sprayed with water to allow it to absorb water.

[0027] Another embodiment of the present disclosure provides a method for heat-treating a battery by providing an exhaust opening for the internal air at the bottom of the heating case, and placing calcined rock at the top of the heating case during the heat-treating process. Steam generated by the heated calcined rock can be supplied to the top of the heating case. This heat-treating method has the advantage of effectively suppressing temperature increases due to thermal runaway in the battery during the heat-treating process. This is because steam, which has a lower specific gravity than the internal air, is generated upward, filling the upper part of the heating case. This increases the degree of steam accumulation at the top, expanding the area filled with high-level, high-concentration steam from top to bottom, while driving the internal air toward the exhaust opening at the bottom, allowing it to be efficiently exhausted.

[0028] In another embodiment of the present disclosure, a battery heat treatment method includes a heating case having a top lid that closes an opening for inserting a battery, the top lid having a storage compartment for fired rock, and a communication opening that connects the storage compartment to the inside of the heating case. During the heat treatment process, the fired rock in the storage compartment is heated in a heat treatment furnace, and the generated steam flows into the heating case through the communication opening, allowing the internal air to be discharged. This heat treatment method has the advantage of easily positioning the fired rock in a predetermined position. This heat treatment method also has the advantage of effectively suppressing temperature increases due to thermal runaway of the battery during the heat treatment process. This is because the fired rock is placed on the top lid of the heating case, and the steam generated by the fired rock is supplied to the heating case, expanding the area filled with high-concentration steam from top to bottom, while efficiently discharging the internal air to the outside.

[0029] In another embodiment of the present disclosure, the battery heat treatment method includes a storage section in the top cover that includes a storage recess with an upper opening in the top cover and an openable lid that can be opened and closed to freely close the upper opening of the storage recess, and the openable lid can be opened to spray water onto the fired rock in the storage recess, allowing the fired rock to absorb water.The above heat treatment method has the advantage that the openable lid can be opened to easily place the fired rock in the storage recess, and then water can be sprayed onto the fired rock to simply and easily supply a predetermined amount of absorbed water into the heating case.

[0030] In another embodiment of the present disclosure, a battery heat treatment method uses a continuous furnace as the heat treatment furnace, and batteries and water-absorbed burned rock are placed in a heating case in the continuous furnace to heat-treat the batteries. This heat treatment method has the advantage that the batteries placed in the heating cases can be efficiently heat-treated by continuously placing the heating cases in the continuous furnace one after another, and valuable materials can be efficiently recovered.

[0031] Another embodiment of the present disclosure provides a heat treatment method for batteries that allows the calcined rock to absorb water equal to or greater than the internal volume (liters) of the heating case multiplied by 0.8 cc. This heat treatment method has the advantage that the volume of water vapor generated by boiling the water absorbed by the calcined rock placed inside the heating case during the exhaust process is greater than the internal volume of the heating case, allowing the water vapor to exhaust the air inside the heating case and reduce the oxygen concentration. This is because 0.8 cc of water boils to produce 1 liter of water vapor.

[0032] A battery heat treatment method according to another embodiment of the present disclosure can convert a battery into a lithium-ion secondary battery. The heat treatment method has the advantage of suppressing an increase in the internal temperature of a heating case, heat-treating the battery within an optimal temperature range, and efficiently recovering valuable materials from the heat-treated battery in a high-quality state.

[0033] A valuable resource recovery method according to another embodiment of the present disclosure can include a heat treatment step of performing heat treatment using any of the above heat treatment methods, and a recovery step of crushing the heat-treated batteries obtained in the heat treatment step to separate and recover valuable resources. The above valuable resource recovery method has the advantage of suppressing an increase in the internal temperature of the heating case, heat-treating the batteries within an optimal temperature range, and efficiently recovering valuable resources in a high-quality state from the heat-treated heat-treated batteries.

[0034] In another embodiment of the present disclosure, the recovery method for valuable materials may include a separation step of crushing the heat-treated batteries and separating black mass containing valuable materials from the crushed material in the recovery step. The above-described recovery method for valuable materials has the advantage of being able to efficiently recover valuable materials by separating black mass containing valuable materials from the crushed material of the heat-treated batteries.

[0035] In another embodiment of the present disclosure, the black mass can contain at least one non-ferrous metal, such as cobalt, nickel, lithium, copper, or aluminum. The above-described valuable resource recovery method is characterized by being able to efficiently recover valuable resources containing any of cobalt, nickel, lithium, and aluminum by separating the black mass containing valuable resources from crushed heat-treated batteries.

[0036] In a method for recovering valuable materials according to another embodiment of the present disclosure, the battery may have a copper foil or an aluminum foil as an electrode core. The above-described method for recovering valuable materials has the advantage of being able to efficiently recover valuable materials from batteries having copper foil or aluminum foil as an electrode core.

[0037] Another embodiment of the present disclosure provides a battery heat treatment device that includes a closed but not sealed heating case that holds batteries, and a heat treatment furnace that heats the heating case. The heating case contains batteries and calcined, porous, hydrophilic, water-absorbed calcined rock inside. The heating case is heated by the heat treatment furnace, and the calcined rock in the heating case heats the absorbed water to generate steam. The generated steam forcibly expels the air inside the heating case, thereby heat-treating the batteries and recovering valuables. (Embodiment 1)

[0038] A battery heat treatment device 100 shown in the schematic diagram of Figure 1 includes a heating case 10 that is closed but not sealed and that holds batteries 1, and a heat treatment furnace 3 that heats the heating case 10. The heating case 10 contains fired rock 2, and when the heating case 10 is heated by the heat treatment furnace 3, the fired rock 2 inside the heating case 10 is heated, generating steam that expels the internal air. The heating case 10 from which the internal air has been expelled is then heated by the heat treatment furnace 3, and the batteries 1 inside the heating case 10 are heat-treated to a state in which valuables can be recovered. (Battery 1)

[0039] Battery 1 is a battery containing at least valuable materials to be recovered. Battery 1 may be, for example, a used or discarded battery, including batteries that have reached the end of their service life, defective batteries that developed a malfunction during manufacture or subsequent use, batteries discarded mid-use, batteries in devices that have reached the end of their service life, batteries in defective devices that developed a malfunction during manufacture or subsequent use, and batteries in devices that have been discarded mid-use. Because the present disclosure involves heat-treating battery 1 to recover valuable materials from its constituent materials, the present disclosure does not specify the structure, shape, size, capacity, mode, or type of battery 1 to be heat-treated. For example, the battery may include a positive electrode, a negative electrode, a separator, an electrolyte, and a battery case, cover, film, or other container that accommodates these components. Furthermore, while the present disclosure does not specify the type of battery, because valuable materials can be recovered by heat-treating the battery, batteries with excellent characteristics that are currently widely used, particularly lithium-ion secondary batteries with a large charge / discharge capacity relative to their weight and volume, are suitable for battery 1. However, the present disclosure does not limit the battery 1 to a lithium ion secondary battery, as valuable materials can be recovered from any battery that can be subjected to heat treatment to recover valuable materials.

[0040] In the present disclosure, battery 1 refers to one or more batteries. Battery 1 is not limited to a single battery cell, but is used in a broad sense to include a battery unit having multiple battery cells and even multiple battery units. A battery unit is a battery used as a power supply device, in which multiple secondary batteries, such as lithium-ion secondary batteries used to power the traction motor of an electric vehicle, are placed in a metal exterior case. Valuable materials can be recovered from a battery unit by disassembling it into battery cells or by heat treating it without disassembly. By heat treating a battery unit without disassembling it into individual battery cells, the present disclosure has the advantage of reducing the cost, effort, and time required for disassembly, preventing accidents caused by battery disassembly, and allowing for safe recovery of valuable materials. Furthermore, because a battery unit contains multiple batteries inside a metal exterior case, heat treating the battery unit to recover valuable materials has the advantage of recovering the metal materials of the exterior case in addition to the constituent materials of battery 1.

[0041] The valuables recovered in this disclosure are specified by the constituent materials of the battery 1. For example, valuables recovered from a lithium-ion secondary battery include copper foil, aluminum foil, cobalt, nickel, and lithium, which are constituent materials of the electrodes, as well as the metal material of the outer case. For example, copper foil and aluminum foil can be recovered as valuables from a battery 1 that uses copper foil or aluminum foil as the electrode core. Since the valuables recovered by heat treatment vary depending on the constituent materials of the battery 1, this disclosure does not specify the valuables recovered from the battery 1, but rather specifies them by the constituent materials of the battery 1 and the outer case. (Heating Case 10)

[0042] The heating case 10 is a container that houses the battery 1 and heat-treats the battery 1. The heating case 10 is heated in a heat treatment furnace 3, and the battery 1 inside the heating case 10 is heated and heat-treated. The heating case 10 contains calcined rock 2, which generates steam and forcibly expels the internal air, creating a low-oxygen state (low-oxygen atmosphere) inside the heating case 10. The water vapor expels the internal air in the heating case 10, creating a low-oxygen state below an oxygen concentration that effectively prevents and suppresses ignition or a sudden rise in internal temperature due to ignition. The heating case 10 forms a limited, enclosed space, which can efficiently forcibly expel the internal air of the heating case 10 and efficiently create a low-oxygen state in a short period of time. Furthermore, the heating case 10 effectively prevents and suppresses ignition and a sudden rise in internal temperature in a low-oxygen state, allowing the battery 1 to be safely heat-treated. The heating case 10 has a closed, but not sealed, structure. The heating case 10 has an opening for inserting and removing the battery 1, and the battery 1 inserted through the opening is placed in a predetermined position and posture, and is closed with a closing part such as a lid or door. The heating case 10 in FIG. 1 has an exhaust opening 11 for venting the internal air and a check valve 20, and has a non-sealed structure. The shape, size, structure, material, etc. of the heating case 10 are not specified, and any heating case that can store and place the battery 1 and the fired rock 2 inside and heat-treat the battery 1 can be used. This includes heating cases that are currently in use and those that will be developed in the future.

[0043] The heating case 10 stores one or more batteries 1 (including a battery block or battery unit having multiple battery cells) in a predetermined position and posture. By storing multiple batteries 1 in the heating case 10, the efficiency of heat treatment can be improved. The heating case 10 is shaped to match the external shape of the stored batteries 1, reducing gaps and spaces within the heating case 10, thereby improving the efficiency of internal air exhaust, shortening the time required, and uniforming the heat treatment temperature.

[0044] The heating case 10 can be made from a material with excellent heat resistance, for example, a metal such as a heat-resistant stainless steel plate. Plate-shaped cases are easy to process and can be made low cost. A metal heating case 10 has high thermal conductivity and can efficiently conduct heat to the internal batteries 1, reducing internal temperature variations and reducing and suppressing heating energy consumption. The heating case 10 has fire resistance and heat resistance strength that allows it to heat-treat the batteries 1 by heating them in the heat treatment furnace 3, and also has pressure resistance strength that can withstand increases in internal pressure. It is also preferable that the heating case have explosion-proof strength to enable safer heat treatment.

[0045] The heating case 10 in FIG. 1 is a hollow rectangular parallelepiped formed from a plate material. The heating case 10 in FIG. 1 has a top surface 10a (top plate), side surfaces 10b, and a bottom surface 10c. The heating case 10 can be shaped other than a rectangular parallelepiped, such as a cube, a cylindrical body such as a cylinder or a rectangular tube, a cone or pyramid, a polyhedron, or a shape with curved surfaces. The heating case 10 can be shaped to suit the heat treatment, valuable resource recovery, and various processes of the present disclosure, such as heating, loading, placement, and standing of the battery 1, inserting and removing the battery 1, and venting the internal air. The heating case 10 can be formed with flat surfaces, curved surfaces, or a combination of flat and curved surfaces, and can have unevenness on the outside or inside and different thicknesses. The shape (internal shape) of the heating case 10 can be shaped to allow the internal air to escape favorably. For example, it is preferable to avoid unnecessary shapes that hinder the pushing and venting of the internal air. A simple internal shape contributes to the discharge of internal air and low costs. The heating case 10 can also be shaped to enable the smooth discharge of internal air to the exhaust opening 11. A guide or the like can be provided to direct the internal air to the exhaust opening 11. The case can also be shaped to reduce the accumulation or retention of internal air. For example, if the heating case 10 has a cone shape that tapers toward the exhaust opening 11 (check valve 20) side through which the internal air is discharged, the steam can smoothly discharge the internal air toward the exhaust opening 11, making it easier to discharge the internal air to the outside.

[0046] The heating case 10 has an exhaust opening 11 for discharging the internal air to the outside. The heating case 10 is filled with steam and the internal air, including the initial air with a high oxygen concentration, is discharged to the outside through the exhaust opening 11. The exhaust openings 11 are provided with an appropriate size, shape, number, and position so that the internal air can be discharged using the steam generated from the fired rock 2. The heating case 10 can have one or more exhaust openings 11 on the top surface 10a, side surface 10b, bottom surface 10c, upper, middle, or lower portion of the heating case 10. The multiple exhaust openings 11 can discharge the internal air in the heating case 10 to the outside from multiple locations in a dispersed manner, reducing the accumulation of residual air and allowing the oxygen concentration in the heating case 10 to be reduced efficiently in a short period of time.

[0047] The exhaust opening 11 can be located close to or far from the location of the fired rock 2. For example, the exhaust opening 11 can be located away from the fired rock 2, or on the opposite side of the cell 1 from the direction of the steam generated immediately after its generation, thereby extending the residence time of the steam, efficiently displacing the internal air, and filling the heating case 10 with steam. The location of the exhaust opening 11 is determined taking into consideration the relative positions of the exhaust opening 11 and the fired rock 2, the steam-filled area, the generation of steam, and the direction of its movement, etc., and is preferably located in a position that allows the steam to easily displace the internal air and be efficiently discharged from the exhaust opening 11. It is also preferable to locate the exhaust opening 11 in a position that allows the steam to easily reside inside the heating case 10 and fill the heating case 10 with steam, thereby extending the residence time of the steam. The exhaust opening 11 can be located above, below, or at the same height as the location of the fired rock 2 in the heating case 10. The exhaust opening 11 in the heating case 10 can be located above the fired rock 2. For example, as shown in FIG. 1, the exhaust opening 11 can be provided at the top of the heating case 10. In this heating case 10, water vapor, which is lighter in density than the internal air, is continuously generated upward, repeatedly driving and pushing out the internal air from bottom to top, and the internal air can be discharged to the outside through the upper exhaust opening 11. To prevent internal air from accumulating near the exhaust opening 11, the exhaust opening 11 can be provided on the top surface 10a, the top, or a side of the upper part. The exhaust opening 11 in the heating case 10 can also be provided below the fired rock 2. For example, as shown in FIG. 2, the exhaust opening 11 can be provided at the bottom of the heating case 10. In this heating case 10, water vapor is continuously generated upward from the fired rock 2 arranged above the exhaust opening 11, filling the upper part with water vapor. As the steam concentration increases, the area filled with water vapor expands from top to bottom, driving and pushing out the internal air downward, and the internal air can be discharged to the outside through the lower exhaust opening 11.

[0048] The heating case 10 stores and places the sintered rock 2 in a predetermined position. The heating case 10 may have a storage section 13, such as a storage container, tray, stand, or storage space, for storing, arranging, or arranging the sintered rock 2. One or more storage sections 13 may be provided at the top, middle, or bottom of the heating case 10, or on the top surface 10a, side surface 10b, or bottom surface 10c of the heating case 10. They may also be provided on the inner and / or outer surface of the heating case 10, or spaced apart from either. For example, in FIG. 2, an upwardly opening storage section 13 containing the sintered rock 2 is located above the battery 1. The heating case 10 in FIG. 6 has an upper cover 12 that closes the upwardly opening opening. The upper cover 12 has a storage section 13 for the sintered rock 2 and a communication opening 14 that connects the storage section 13 to the inside of the heating case 10. The communication opening 14 allows steam generated from the fired rock 2 to flow into the heating case 10. This heating case 10 can be closed by closing the top lid 12 after storing the battery 1, and at the same time, the fired rock 2 can be placed in a predetermined position. The storage section 13 of the top lid 12 in Figure 7 has an upper opening storage recess 13a provided in the top lid 12 and an opening / closing lid 13b that can freely open and close the upper opening of the storage recess 13a, and a steam communication opening 14 is provided in the storage recess 13a. The heating case 10 in the figure can store the fired rock 2 in the storage recess 13a of the top lid 12, and the heating case 10 can be closed by closing the top lid 12. Furthermore, the top lid 12 can store and place the fired rock 2 in the storage recess 13a, and the opening / closing lid 13b can be opened to easily supply water to the fired rock 2 in the storage recess 13a by sprinkling water, etc. The amount and direction of steam inflow can be determined by the opening area, number, and position of the communication openings 14. The communication openings 14 in the figure allow steam to flow in and supply steam from the side of the storage recess 13a above the heating case 10. For example, the bottom of the storage recess 13a can be made of punched metal or a mesh, and the communication openings 14 can be provided as openings, through-holes, or slits on the bottom of the storage recess 13a so that the fired rock 2 cannot pass through or fall through. For example, the storage section 13 can be made of a metal with high thermal conductivity to promote heating of the fired rock 2. The storage section 13 can be integral with the heating case 10 or can be removable. The fired rock 2 can be placed in the storage section 13, laid inside the heating case 10, and positioned in a predetermined location. (Check valve 20)

[0049] The check valve 20 allows the internal air inside the heating case 10 to pass in the exhaust direction while preventing the external air (outside air) outside the heating case 10 from passing in the opposite direction (intake direction). The check valve 20 allows the water vapor from the fired rock 2 to pass in the direction of exhausting the internal air with a high oxygen concentration that was present inside the heating case 10. By preventing the ingress and passage of external air outside the heating case 10, the oxygen concentration inside the heating case 10 can be reliably reduced. The check valve 20 also maintains a low-oxygen state. The external air includes the exhausted internal air, and the check valve 20 can prevent the backflow of the exhausted internal air. The heating case 10 has one or more check valves 20 that exhaust the internal air to the outside and reduce the internal oxygen concentration. The heating case 10 has a check valve 20 connected or communicated with the exhaust opening. For example, the check valve 20 can be installed directly at the exhaust opening 11, eliminating the need for a communication path from the exhaust opening 11. The check valve 20 may also be provided in a communication path that connects a plurality of discharge openings 11. The structure, configuration, mechanism, etc. of the check valve 20 are not specified, but examples are shown below.

[0050] The check valve 20 includes a valve element 21 and a valve seat 23. For example, the check valve 20 can be opened and closed by an elastically deformable member of the valve element 21, and the elastically deformable member may be a member of the valve element 21, a member other than the valve element 21, or the valve element 21 itself. In the check valve 20 of Figures 3 and 4, the valve element 21 is pushed by the internal pressure of the heating case 10 and moves away from the valve seat 23 to open (indicated by the solid line in the figures), and the valve element 21 comes into close contact with the valve seat 23 to close (indicated by the dashed line in the figures). 3 has a valve element 21 that opens (moves up and down in the figure) when the internal pressure in the heating case 10 rises, a valve seat 23 with a through hole 22 that opens and closes the valve element 21, a spring 24 that is an elastically deformable member that elastically presses the plate-shaped valve element 21 against the valve seat 23, a threaded rod 25 that adjusts the valve-opening pressure by moving the spring 24 (moves up and down in the figure), and a closure plate 27 with a female threaded hole 26 into which the threaded rod 25 is screwed. This check valve 20 has the advantage that the valve-opening pressure can be adjusted by rotating an adjustment knob 28 fixed to the rear end (lower end) of the threaded rod 25 to move the threaded rod 25 up and down, thereby adjusting the pressure with which the spring 24 presses the valve element 21 against the valve seat 23 via a pressure plate 29. In the figure, when the adjustment knob 28 is turned to loosen the threaded rod 25, the force with which the spring 24 presses the valve element 21 against the valve seat 23 decreases, lowering the valve opening pressure. Conversely, when the adjustment knob 28 is turned to tighten the threaded rod 25, the valve opening pressure can be increased. The valve element 21 is set to a cracking pressure at which it opens after steam is generated from the fired rock 2. The opening pressure of the valve element 21 is set to a temperature above the boiling point of the fired rock 2, at which steam fills the heating case 10, forcibly expelling the internal air and reducing the oxygen concentration. For example, the cracking pressure at which the valve opens can be set to between 10 kPa and 100 kPa.

[0051] The check valve 20 can include a valve element 21 made of an elastic metal plate that elastically deforms under the internal pressure of the heating case 10 to open, and a valve seat 23. The cross-sectional view of Figure 4 illustrates a leaf spring 21a in which the valve element 21 itself elastically deforms. This check valve 20 opens when the leaf spring 21a is pushed away from the valve seat 23 by the internal pressure of the heating case 10 (solid line in the figure), and closes when the leaf spring 21a of the valve element 21 presses against the valve seat 23 using its own elastic restoring force (dotted line in the figure). This allows for a simple structure with a small number of parts, which allows for low costs. The check valve 20 shown in the figure has a structure in which the surface of the valve seat 23 against which the leaf spring 21a presses is an inclined surface against which the flat leaf spring 21a presses against using its elastic restoring force, allowing the leaf spring 21a to press against the surface of the valve seat 23 without any gaps to close the valve. This check valve 20 opens when the leaf spring 21a is pressed by the internal pressure of the heating case 10, so the cracking pressure is determined by the thickness, elastic deformation rate, and material of the leaf spring 21a. The cracking pressure at which this check valve 20 opens can be adjusted by replacing the leaf spring 21a; for example, the cracking pressure can be lowered by making the leaf spring 21a thinner, or higher by making it thicker.

[0052] The cross-sectional view of Figure 5 illustrates a check valve 20 in which a valve element 21 closes under its own weight. This check valve 20 includes a heat-resistant valve element 21 placed on the discharge opening 11 of the heating case 10, and the valve element 21 closes by its own weight as it comes into close contact with a valve seat 23 (dotted line in the figure), and opens when it is pushed by the internal pressure of the heating case 10 away from the valve seat 23 (solid line in the figure). The check valve 20 in this figure has a spherical valve element 21b, and closes by its own weight as the spherical valve element 21 comes into close contact with a valve seat 23 of a through hole 22 that is smaller in outer diameter than the spherical valve element 21b. The cracking pressure of this check valve 20 can be adjusted by adjusting the weight of the spherical valve element 21b and the inner diameter of the through hole 22 of the valve seat 23. The cracking pressure can be increased by making the weight of the valve element 21 heavy and the through hole 22 of the valve seat 23 small, or the cracking pressure can be adjusted to be low by making the valve element 21 light and the through hole 22 of the valve seat 23 large. The check valve 20 of this structure also has the advantage of being simple in structure and operating reliably.

[0053] The above check valve 20 opens and closes the valve body 21 by utilizing the elastic restoring force of the spring and gravity (its own weight), but the present disclosure does not limit the check valve 20 that opens by detecting pressure to the above structure, and check valves 20 of all other structures in which the valve body is opened and closed by detecting specified conditions other than pressure can be used.

[0054] The check valve 20 can be configured to open and close by detecting temperature, instead of pressure. The check valve 20 that opens and closes by detecting temperature can be a valve that opens above the boiling temperature of the fired rock 2. Because the internal pressure of the heated case 10 rises as the fired rock 2 boils, the check valve 20 that opens and closes by detecting temperature can be a valve that opens when it detects that the internal pressure of the heated case 10 is higher than the external pressure. For example, the check valve 20 can be formed into a plate shape as shown in Figure 4 and equipped with a bimetal 21c that detects the temperature of the heated case 10. A bimetal is made by bonding multiple metals with different thermal expansion coefficients together and has the property of deforming with temperature changes. This check valve 20 uses a bimetal 21c for the valve element 21, which deforms at a predetermined temperature (set temperature). When the set temperature is reached, the bimetal 21c deforms and separates from the valve seat 23, opening the valve. This check valve 20 can adjust the opening pressure by adjusting the temperature characteristics of the bimetal 21c. The bimetal 21c is made by laminating metal plates with different thermal expansion coefficients, so the temperature characteristics can be adjusted by selecting the metal plates to be laminated. The temperature characteristics of the bimetal 21c are such that it deforms at temperatures above the boiling point of the water absorbed by the fired rock 2, separating from the valve seat 23 and opening the valve. The check valve 20 that opens by detecting temperature does not necessarily use a bimetal for the temperature detection element or structure, and can also use any other mechanism that can open and close the valve body using temperature, such as a mechanism that combines a thermosensitive ferrite whose magnetic attraction force decreases at the Curie temperature with a permanent magnet.

[0055] The check valve 20, which opens and closes mechanically by utilizing the elastic restoring force of a spring, gravity, or deformation due to temperature, does not require an electronic signal, and has the advantage of being able to open reliably when the water absorbed by the burnt rock 2 is boiling, avoiding stoppage of opening and closing operation or abnormal operation due to failure of the software control surface. However, the opening and closing of the check valve 20 can also be controlled electronically. (burnt rock 2)

[0056] The calcined rock 2 is a calcined rock that has hydrophilic properties. The calcined rock 2, which has hydrophilic properties, can easily absorb water when it comes into contact with water (water absorption). For example, water can be absorbed by sprinkling water on the calcined rock 2, immersing the calcined rock 2 in water, or by spraying the calcined rock 2 evenly. The water-absorbed calcined rock 2 is heated in the heating case 10, which heats the absorbed water and generates steam. The water absorption method is not specified; for example, water can be sprinkled on the calcined rock 2 or immersed in water, allowing the calcined rock 2, which has hydrophilic properties and water retention, to easily absorb water. The water-absorbed calcined rock 2 is easy to handle without dripping, the amount and time of steam generation can be adjusted, and it can be used repeatedly. The absorbed water is a safe, secure, and low-cost liquid.

[0057] The fired rock 2 absorbs water and is placed inside the heating case 10. The amount of water absorbed by the fired rock 2 exceeds the amount of water that can be generated to forcibly expel the air inside the heating case 10 with the steam generated. Because water (liquid) evaporates and becomes steam (gas), its volume increases dramatically, so a small amount of water relative to the volume of the heating case 10 can fill the heating case 10 with steam. The fired rock 2 absorbs at least 0.8 cc of water, which is the internal volume (liters) of the heating case 10. 0.8 cc of water boils to become 1 liter of steam. Therefore, when the amount of absorbed water is more than 0.8 cc of the internal volume (liters) of the heating case 10, the volume of steam generated by boiling will be greater than the internal volume of the heating case 10, and the steam will expel the air inside the heating case 10, lowering the oxygen concentration.

[0058] The amount of water absorption of the fired rock 2 can be adjusted and specified by its particle size, size, shape, quantity, type, components, properties, composition, and mixing condition. The amount of water vapor generated can also be adjusted and specified by the amount of water supplied to the fired rock 2. The amount of water absorption can be determined by the amount of water supplied, the difference in mass between the dry state before water absorption and the dry state after water absorption, etc. The amount and time of water vapor generation can be adjusted by the amount of water absorption, water absorption rate, the amount of fired rock 2, particle size, size, shape, thickness, mixing ratio, etc. The fired rock 2 can be crushed, pulverized, processed, and sorted into crushed material, crushed stone, gravel, sand, or powder. The fired rock 2 can be made to a predetermined size and particle size, for example, 1 mm or less, 1 mm to 5 mm, 1 cm to 2 cm, 2 cm to 3 cm, 3 cm to 5 cm, or 5 cm or more, or smaller sizes (e.g., 1 μm or less) or larger sizes. It can also be made into a specific shape, such as a plate. The fired rock 2 can be made larger in size, thickness, and particle size to absorb more water per piece, generate more water vapor, and take longer to generate, while the size and particle size can be made smaller to increase the surface area per unit area.

[0059] Both the battery 1 and the water-absorbed calcined rock 2 can be placed inside the heating case 10, and the heating case 10 can then be transported into the heat treatment furnace 3. The calcined rock 2 can be placed inside the heating case 10 together with the battery 1, or can be placed inside the heating case 10 before and / or after the battery 1 is placed inside. The water-absorbed calcined rock 2 (including water-absorbed calcined rock 2 after placement) can be safely and easily placed inside the heating case 10 before heating. The method and apparatus disclosed herein do not require a separate or dedicated water or steam supply device, reducing equipment costs and allowing the use of a conventional incinerator. Water is safe and can be procured at low cost, reducing running costs. Furthermore, placing the calcined rock 2 inside the heating case 10 does not require significant space, allowing both the heating case 10 and the heat treatment furnace 3 to be made smaller and more efficient.

[0060] The fired rock 2 can be laid on the bottom surface 10c of the heating case 10. The fired rock 2 can be laid over the entire or almost entire surface of the bottom surface 10c of the heating case 10. The battery 1 can be placed on the fired rock 2 laid on the bottom surface 10c of the heating case 10 and heat-treated. By laying the fired rock 2 over almost the entire bottom surface 10c, for example, over 80% or more, preferably over 90% of the bottom surface 10c, steam can be generated evenly over a wide area, filling the heating case 10 with steam and pushing the internal air toward the exhaust opening. By laying the fired rock 2 in an area of the bottom surface 10c that covers the battery 1, steam is generated around the battery 1. The steam, which is lighter in density than the internal air, is generated upward one after another, enveloping the battery 1 in steam and pushing and driving out the internal air from below. The internal air can then be discharged to the outside through the exhaust opening 11 while reducing the oxygen concentration around the battery 1.

[0061] Calcined rock 2 is a calcined rock, stone, or rock. Rocks include igneous rocks (plutonic rocks, hypabyssic rocks, and volcanic rocks), sedimentary rocks, and metamorphic rocks. Calcined rock 2 refers to calcined rocks, stone, or rocks that are porous and hydrophilic. Calcined rock 2 can be used, for example, in the size and shape of the calcined rock, or can be processed, crushed, or pulverized after calcination, or can be calcined and sorted to a predetermined size. Calcined rock 2 is preferably natural stone crushed material, crushed material, crushed stone, gravel, sand, or powder obtained by calcining and crushing and / or pulverizing natural stone, as described in detail below. However, the present disclosure is not limited to such natural stones, and all calcined rocks, stone, and rocks can be used.

[0062] The fired rock 2 is preferably rhyolite collected in the Ishizuchi mountain range, for example, in Toon City, Ehime Prefecture, and the surrounding area. For example, a fired rhyolite contains the following components in X-ray fluorescence analysis (EZ scan): Silicon dioxide (SiO2) …………70.9% Aluminum oxide (Al2O3)...16.6% Sodium oxide (Na2O) 3.7% Potassium oxide (K2O) 2.8% Ferric oxide (Fe2O3) 2.2% Calcium oxide (CaO) 3.0% Magnesium oxide (MgO)...0.2% Titanium dioxide (TiO2) …………0.2%

[0063] Burned rhyolite can be prepared by burning selected rhyolite in an oxidizing atmosphere, crushing, and pulverizing it into a predetermined size range, such as pebbles, gravel, sand, or powder. For example, a method for burning and crushing rhyolite involves crushing the rhyolite to a particle size similar to gravel, burning it in an oxidizing atmosphere, and then pulverizing it. Gravel-like rhyolite can be burned by heating it to its interior. Burned rhyolite can be hardened by shrinking and densifying it, and it also releases carbon dioxide, becoming hard and brittle, allowing for efficient crushing. Since rhyolite contains low-melting-point potassium oxide and other elements, the low-melting-point potassium oxide and other elements are melted during the firing process, and further heating to high temperatures removes the burned components contained in the rhyolite, creating microvoids and making it porous. During the firing process, rhyolite shrinks and densifies, hardening, and the molten low-melting-point potassium oxide and other elements act as a flux, hardening it and forming porosity. Rhyolite that has become porous and hard by baking is easier to crush than unbaked rhyolite, and can be efficiently processed into a fine powder. When baked rhyolite becomes porous, the tiny voids inside become interconnected, improving its water absorption properties. When water is applied to the surface of baked rhyolite, it quickly penetrates and is absorbed, making it more absorbent than unbaked rhyolite.

[0064] The temperature at which rhyolite is fired is determined to be a temperature that allows porosity to form, or that hardens the rhyolite and makes it easier to crush and pulverize. If the firing temperature is too low, heat cannot be transferred evenly to the interior, resulting in insufficient hardness, insufficient porosity, or inability to crush and pulverize. Conversely, if the firing temperature is too high, heating costs increase and the rhyolite melts, reducing the porosity. The firing temperature for rhyolite is, for example, between 300°C and 900°C. The firing process for rhyolite involves, for example, feeding crushed rhyolite into a rotating trommel positioned downward, where it is stirred and transported by the trommel, allowing efficient and uniform heating. Low-melting-point substances contained in rhyolite (such as potassium oxide) melt and disappear, and the carbon dioxide gas generated creates tiny voids, forming porosity. It can also be baked to shrink, densify and harden, and the molten low-melting-point substance acts as a flux to improve hardness, and it can also be baked and hardened at high temperatures by sintering.

[0065] By firing rhyolite, it can be hardened, made porous, or made easier to crush into a fine powder. For example, by firing rhyolite, low-melting-point substances such as potassium oxide melt and disappear, releasing carbon dioxide, creating minute voids, forming porous rhyolite with hydrophilicity and water absorption. Porous rhyolite absorbs and retains moisture from the air, and when exposed to dry air, releases the retained moisture to regulate humidity. Further firing shrinks, densifies, and hardens the rhyolite. Some of the molten low-melting-point substances become fluxes, further solidifying and hardening, making it easier to crush efficiently by impact. After firing, the rhyolite is pulverized into powder to obtain hydrophilic and water-absorbent rhyolite porous powder 11. The rhyolite porous powder 11 obtained through the above process can be further packed into a crucible and fired in an oxidizing atmosphere, which transfers heat completely to the interior of the porous powder, resulting in a porous powder with excellent hydrophilicity and water absorption. The powder of fired rhyolite can be prepared, for example, by firing and crushing it, and then selecting particles smaller than a specific particle size. For example, fine powder of a predetermined size can be selected from the fired and crushed powder. Porous powder of rhyolite fired by the above method can be purchased from Matera Co., Ltd. (Ehime, Japan).

[0066] When the fired rock 2 was placed inside the heating case 10 and heated in the heat treatment furnace 3, it was confirmed that the oxygen concentration of 21% when the battery 1 was stored could be reduced to below the combustion limit of 10%, with ample time before the heat treatment temperature of the battery 1. The time it takes for the inside of the heating case 10 to reach a low oxygen concentration varies depending on the capacity, size, and form of the heat treatment furnace 3, heating case 10, and battery 1, but when multiple heating cases 10 measuring, for example, 110 cm long, 170 cm wide, and 90 cm high, were heated under different conditions, it was confirmed that the oxygen concentration reached below 10% 3 to 8 minutes after steam generation began, and below 3% 5 to 15 minutes later. When thermal runaway occurred in the battery 1 without placing the burnt rock 2 (comparative example), a sudden temperature rise (from about 670°C to about 1,100°C) occurred due to thermal runaway. However, when the burnt rock 2 was placed in the heating case 10, it was confirmed that the temperature rise due to thermal runaway was prevented or suppressed, and heat treatment could be carried out within an appropriate heat treatment temperature range that allows for efficient recovery of high-quality valuables. This confirmed that, for example, melting of aluminum can be prevented (the melting point of aluminum is about 660°C), and the recovery rate of high-quality valuables can be improved. (Heat treatment furnace 3)

[0067] The heat treatment furnace 3 is not particularly limited and can be appropriately selected depending on the purpose as long as it has a heat source and can heat the heating case 10 to heat the battery 1. Any heat treatment furnace currently in use or that will be developed in the future can be used as the heat treatment furnace 3.

[0068] The heat treatment furnace 3 can heat one or more heating cases 10 placed inside. The heat treatment furnace 3 can heat-treat the batteries 1 by controlling the heating temperature to a set temperature. The heat treatment furnace 3 can, for example, detect the temperature inside the heat treatment furnace 3, the external or internal temperature of the heating case 10, and the temperature of the batteries 1 and control the temperature to a set temperature. The heat treatment furnace 3 can control the set temperature by controlling thermal energy so that the detected temperature falls within a preset temperature range. The heat treatment furnace 3 can also be provided with an exhaust treatment unit to exhaust the internal air inside the furnace and discharge the thermal energy of the batteries 1, thereby adjusting the temperature inside the heat treatment furnace and limiting temperature increases. The set temperature for heat-treating the batteries 1 is set to a temperature that allows high-quality valuables to be efficiently recovered after the batteries 1 are heated and heat-treated. If the set temperature is too low, the heat-treated batteries 1 cannot be separated into a state suitable for recovering valuables by crushing or pulverization, etc. Conversely, if the set temperature is too high, valuables cannot be recovered in a high-quality state. For example, if the set temperature is too low or the heat treatment time is too short, the separator, binder, etc. may not be sufficiently sintered, resulting in inefficient recovery of valuable materials and a lower evaluation of the recovered valuable materials. Furthermore, if the set temperature is too high, aluminum may melt at temperatures above 660°C, copper may oxidize at temperatures above 800°C to 1,000°C, and lithium may evaporate at temperatures above 900°C, potentially producing cobalt oxide. This may lower the evaluation of the recovered valuable materials and make it difficult to efficiently recover high-quality valuable materials. The heat treatment temperature at which high-quality valuable materials can be efficiently recovered is determined appropriately depending on the substances contained in the battery 1 and the valuable materials to be recovered. The set temperature at which the heat treatment furnace 3 heat-treats the battery 1 is preferably between 250°C and 550°C, for example, in the case of lithium-ion secondary batteries.

[0069] The temperature and time for heating and heat-treating batteries 1 vary depending on the type and structure of the battery 1, so the heat-treated batteries 1 are crushed, pulverized, and sorted to confirm and identify a state in which valuable materials can be effectively recovered. For example, batteries with plastic exterior films, such as lithium polymer secondary batteries, can be heat-treated with short heating times, while batteries with metal exterior cans can be heat-treated for longer heating times. Furthermore, the heat treatment time for batteries 1 separated into individual units differs from that for battery units in which multiple batteries 1 are housed in a metal exterior case. Individual batteries 1 can be heat-treated in a short time because they are heated directly, but batteries 1 housed in an exterior case require a longer heat treatment time because they are heated through the exterior case.

[0070] A continuous furnace capable of efficiently heat-treating batteries 1 is suitable for the heat treatment furnace 3. A continuous furnace can continuously transport heating cases 10, efficiently heat-treat the batteries 1 placed in the heating cases 10, and efficiently recover valuable resources. A continuous furnace can heat-treat batteries 1 stored in heating cases 10 while transporting them, for example, on a heat-resistant belt conveyor. This continuous furnace has a closed structure that allows batteries 1 to pass through the inlet and outlet, and can maintain the internal temperature at a set temperature to continuously heat-treat batteries 1. Furthermore, a continuous furnace can also heat-treat one or more heating cases 10 while transporting them in a container such as a pallet or tray. The pallet can be configured to have an opening at the top so that the batteries 1 can be exposed and heated and fired in the heat treatment furnace 3. This continuous furnace allows the pallet to be pushed and moved into the continuous furnace to heat-treat batteries 1. Furthermore, the pallet or heating case 10 can be moved, for example, by placing it on a cart, or by providing heat-resistant wheels on the bottom surface 10c of the pallet or heating case 10, or by arranging multiple heat-resistant rollers in a parallel position to allow smooth movement.

[0071] The heat treatment method for heat treating batteries from which valuables are recovered includes a battery loading step of placing batteries 1 in a heating case 10, and a heat treatment step of heating the heating case 10 in a heat treatment furnace 3 and heating the internal batteries 1 through the heating case 10 to perform heat treatment. The method for recovering valuables from batteries further includes a recovery step of separating and recovering the valuables. The heat treatment step includes an exhaust step in which the burned rock 2 heats the absorbed water to generate steam, and the generated steam is used to forcibly exhaust the air inside the heating case 10. [Battery 1 delivery process]

[0072] In the battery 1 carrying-in step, the battery 1 is carried in and housed in the heating case 10. The battery 1 is placed in the heating case 10 through the opening thereof, and is then placed in a predetermined position within the heating case 10. The water-absorbed calcined rock 2 is placed in the heating case 10 at the same time as the battery 1, or before or after the battery 1 is placed therein, or the calcined rock 2 is absorbed after it is placed in the heating case 10. For example, after the battery 1 and calcined rock 2 are placed in the heating case 10, the opening is closed with the top lid 12. Inside the heating case 10, which has been closed and sealed with the top lid 12, there is internal air (initial air) with an oxygen concentration similar to that of the outside air (e.g., 21%). The battery 1 loading process can be carried out easily, safely, and securely in a short time at room temperature and normal pressure, ensuring low cost and safety. The heating case 10 containing the battery 1 and calcined rock 2 is loaded into the heat treatment furnace 3. [Heat treatment process]

[0073] In the battery 1 carrying-in process, the heating case 10 containing the battery 1 is placed in the heat treatment furnace 3, and the heating case 10 is heated in the heat treatment process. In the heat treatment process, the heating case 10 is heated in the heat treatment furnace 3, and the battery 1 contained inside is heated and heat-treated through the heating case 10. In the heat treatment process, the heat treatment furnace 3 heats the heating case 10, and the battery 1 and the fired rock 2 inside the heating case 10 are heated. The heat treatment process includes an exhaust process in which the air inside the heating case 10 is forcibly exhausted. In the exhaust process, the fired rock 2 that has absorbed water is placed inside the heating case 10. In the exhaust process, the air inside the heating case 10 is forcibly exhausted using water vapor generated by the fired rock 2. In the heat treatment process, the water-absorbed calcined rock 2 is placed in the heating case 10, and the heating case 10 and the calcined rock 2 inside it are heated in the heat treatment furnace 3. The calcined rock 2 heats the absorbed water, generating steam. The generated steam fills the heating case 10, driving out the air inside the heating case 10 and forcibly discharging the air from the exhaust opening (exhaust process). As the oxygen-rich air is discharged through the check valve 20, the amount of oxygen-rich air remaining in the heating case 10 decreases, and the oxygen concentration drops. The exhaust process creates and maintains a low-oxygen atmosphere below the combustion limit. Therefore, in the heat treatment process of the battery 1, the battery 1 is heated and heat-treated via the heating case 10 in a state in which the internal air has been discharged in the exhaust process and the oxygen concentration has been reduced. Even if the battery 1 heated in the heating case 10 experiences thermal runaway and ejects discharged materials, it is possible to prevent an increase in internal temperature due to excessive thermal energy generated when the discharged materials ignite, and the battery 1 can be heat-treated within a set temperature range that is preferable for recovering valuable materials. In the heat treatment process, the water vapor in the heating case 10 is further heated to generate superheated steam, which can efficiently heat and heat-treat the battery 1. The superheated steam can heat-treat the battery 1 even in a low-oxygen atmosphere. [Recovery process]

[0074] The recovery process recovers valuable materials from the heat-treated batteries obtained by the heat treatment process. After the exhaust process, which forcibly exhausts the internal air from the heating case 10, the heat-treated batteries 1 are heat-treated at an optimal temperature range, preventing abnormal temperature increases in the batteries 1 due to thermal runaway. This creates a favorable recovery condition, allowing valuable materials to be recovered in a high-quality and efficient state in the recovery process. The recovery process can be appropriately selected depending on the purpose, such as the valuable materials to be recovered and the battery's configuration, form, and condition. For example, in the recovery process, after the batteries 1 are heat-treated in the heat treatment process, the heat-treated batteries are removed from the heating case 10, and valuable materials are recovered using a dry or / and wet method. For example, specific valuable materials can be recovered from the heat-treated batteries (batteries 1) by crushing, pulverizing, sorting, separating, or classifying them, or a combination thereof. Furthermore, other processes can be added as needed, and one or more processes can be performed in stages. The present disclosure is characterized in that the heat treatment process of the battery includes an exhaust process in which the air inside the heating case 10 is forcibly exhausted using water vapor generated by the fired rock 2. It does not specify a method or device for recovering valuable materials from the heat-treated battery 1, and all other methods and devices that can recover valuable materials from the heat-treated battery can be used. Not only currently used methods but also methods that will be developed in the future can be used.

[0075] The recovery process can include a crushing process and a separation process. Heat-treated batteries that have been heat-treated within the optimal temperature range are in a state suitable for crushing, separation, and recovery, and can be easily crushed and separated to recover valuable materials. This allows for high-quality valuable materials to be recovered, improving the efficiency of valuable material recovery. In the crushing process, the heat-treated batteries are crushed to obtain crushed material. The crushing process can be performed in stages, and the crushed material can be crushed into finer particles to obtain a pulverized material. In the separation process, valuable materials or materials containing valuable materials (e.g., black mass) are separated from the crushed material. In the separation process, black mass containing valuable materials or valuable materials are sorted, separated, and classified using, for example, sieves, magnetic force, wind force, centrifugal force, suction force, etc. The separation process can be performed in stages and can be appropriately selected depending on the purpose. For example, crushed materials such as coarse products and fine products can be classified according to size, and sorting can be performed using wind force, magnetic force, sieves, etc., or a combination of these, depending on the valuable materials to be recovered. The separation process can efficiently recover valuable materials from black mass containing at least one of non-ferrous metals, i.e., cobalt, nickel, lithium, copper, and aluminum, and can also efficiently recover these or any of them as valuable materials from batteries having copper foil or aluminum foil as the electrode core. [Industrial Applicability]

[0076] The present disclosure can be suitably used as a method for heat-treating a battery at an optimal temperature by suppressing a temperature rise due to thermal runaway of the battery during the heat treatment process, and as a valuable resource recovery method that can efficiently recover valuable resources in a high-quality state by heat-treating the battery using this heat treatment method. [Explanation of symbols]

[0077] 100...Battery heat treatment device 1...Battery 2...Burned rock 3...Heat treatment furnace 10...Heating case 10a…Top surface 10b...side 10c…Bottom surface 11...Exhaust opening 12...Top lid 13...Storage area 13a...Storage recess 13b…Opening / closing lid 14…Communication opening 20...Check valve 21...Valve body 21a...leaf spring 21b…spherical 21c...Bimetal 22...Valve seat 22a...Through hole 23…Discharge port 24...Spring 25...Threaded rod 26...Female screw hole 27...Blocking plate 28...Adjustment knob 29...Pressure plate

Claims

1. a battery loading step in which the batteries are placed in a closed but not sealed heated case; The heating case containing the battery in the carrying-in step is placed in a heat treatment furnace, Heating the heating case in the heat treatment furnace, a heat treatment step of heating the battery inside through the heating case, A heat treatment method for heat treating the battery from which valuable materials are recovered, comprising: In the heat treatment step, The heating case heated in the heat treatment furnace is A fired, porous, hydrophilic, absorbent fired rock is placed; Heating the fired rock in the heating case, the heated calcined rock heats the absorbed water to produce steam; The method for heat treatment of a battery includes an exhaust step in which the generated water vapor is used to forcibly exhaust the air inside the heating case.

2. The method for heat treating a battery according to claim 1, The heating case includes: The internal air is passed through the exhaust direction, A check valve is provided to prevent gas from passing in the opposite direction. A method of heat treating batteries using a closed but not sealed metal case.

3. The method for heat treating a battery according to claim 2, The check valve is a valve body that is elastically deformed by the internal pressure of the heating case to open, The valve body elastically contacts the valve seat to close the valve, The method for heat treatment of a battery, wherein the valve body is pushed by the internal pressure of the heating case and separates from the valve seat to open the valve.

4. The method for heat treating a battery according to claim 2, The check valve is a heat-resistant valve body placed on the discharge opening of the heating case; The valve body comes into close contact with the valve seat by its own weight to close the valve, The method for heat treatment of a battery, wherein the valve body is pushed by the internal pressure of the heating case and separates from the valve seat to open the valve.

5. The method for heat treating a battery according to claim 1, In the exhaust step, The battery and the water-absorbed fired rock are both placed inside the heating case, The battery heat treatment method includes carrying the heating case into the heat treatment furnace.

6. The method for heat treating a battery according to claim 1, In the heat treatment step, The fired rock is laid on the bottom surface of the heating case, A method for heat treating a battery, comprising placing the battery on the fired rock.

7. The method for heat treating a battery according to claim 6, In the heat treatment step, A method for heat treating a battery, wherein the fired rock is laid on at least 80% of the bottom surface of the heating case.

8. The method for heat treating a battery according to claim 6, A heat treatment method for batteries in which water is sprinkled on the laid fired rock to cause it to absorb water.

9. The method for heat treating a battery according to claim 1, A discharge opening for internal air is provided at the bottom of the heating case, In the heat treatment step, The fired rock is placed on top of the heating case, The method for heat treatment of a battery includes heating the fired rock to generate steam, which is supplied to the upper part of the heating case.

10. The method for heat treating a battery according to claim 9, the heating case has a top lid that closes an opening for inserting the battery, The top cover is A storage section for the fired rock is provided, a communication opening is provided that communicates the storage section with the inside of the heating case, In the heat treatment step, Heating the fired rock in the storage section in the heat treatment furnace; The method for heat treatment of a battery includes flowing the generated water vapor into the heating case through the communication opening to discharge the internal air.

11. The method for heat treating a battery according to claim 10, The storage section of the top cover is a storage recess with an upper opening provided in the upper cover; an opening / closing cover that can be freely opened and closed to close an upper opening of the storage recess, A heat treatment method for a battery, in which the open / close lid is opened and water is sprayed onto the fired rock in the storage recess, causing the fired rock to absorb the water.

12. The method for heat treating a battery according to claim 11, The heat treatment furnace is a continuous furnace, The method for heat treating a battery includes placing the battery and the heating case containing the water-absorbed fired rock in the continuous furnace, and heat-treating the battery.

13. The method for heat treating a battery according to claim 1, The fired rock, A method for heat treating a battery, comprising absorbing water in an amount of at least 0.8 cc x the internal volume (liters) of the heating case.

14. The method for heat treating a battery according to claim 1, The method for heat treatment of a battery, wherein the battery is a lithium ion secondary battery.

15. a heat treatment step of performing heat treatment according to the heat treatment method for a battery according to any one of claims 1 to 14; The heat-treated battery obtained in the heat treatment step is A method for recovering valuable materials from batteries, including a recovery step of crushing the batteries to separate and recover the valuable materials.

16. A method for recovering valuable materials from the battery according to claim 15, In the recovery step, Crushing the heat-treated battery A method for recovering valuable materials from batteries, comprising a separation step of separating black mass containing valuable materials from crushed material.

17. A method for recovering valuable materials from the battery according to claim 16, The black mass is A method for recovering valuable materials from batteries containing at least one non-ferrous metal selected from the group consisting of cobalt, nickel, and lithium.

18. A method for recovering valuable materials from the battery according to claim 15, The battery A method for recovering valuable materials from batteries that use copper foil or aluminum foil as the electrode core.

19. A closed but not sealed heated case for the battery; a heat treatment furnace for heating the heating case, The heating case has therein: the battery; and a calcined, porous, hydrophilic, water-absorbed calcined rock; The heating case is heated by the heat treatment furnace, and the calcined rock in the heating case heats the absorbed water to generate steam; A heat treatment device for heat treating a battery from which valuable resources are recovered, forcibly discharging the air inside the heating case with the generated steam.

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