Process for recovering valuable metals from waste secondary batteries using supercritical carbon dioxide process

Abstract

The present invention relates to an apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, which can improve the recovery rate of valuable metals while minimizing the input amount of ammonium carbonate in the recovery of valuable metals from spent secondary batteries through a wet process using an alkaline solution. The apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process according to the present invention comprises: a supercritical reactor that induces the conversion of valuable metals contained in black powder into valuable metal complex compounds through a combination of a wet process using an alkaline solution and a supercritical carbon dioxide process; a carbon dioxide supply device that supplies carbon dioxide to the supercritical reactor; a black powder supply device that supplies black powder to the supercritical reactor; a chemical supply device that supplies a reducing agent, a complexing agent, and a pH adjusting agent to the supercritical reactor; and a gas-liquid separation device that receives a mixture of liquid phase substances and gaseous phase substances among the reaction products of the supercritical reactor and separates it into a liquid phase substance in which valuable metal complex compounds are dissolved and gaseous carbon dioxide. It is characterized by comprising a valuable metal recovery tank that receives a liquid phase substance in which a valuable metal complex is dissolved from a gas-liquid separation device and recovers the valuable metal.

Description

Technology Field

[0001] The present invention relates to a process for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, and more specifically, to a process for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process that can minimize the amount of ammonium carbonate input and improve the recovery rate of valuable metals while recovering valuable metals from spent secondary batteries through a wet process using an alkaline solution. Background Technology

[0002] The secondary battery recycling market is gradually expanding, and in response to this trend, the European Union is legislating mandatory recycling of battery materials to achieve carbon neutrality and manage raw material supply. Lithium-ion batteries, a representative type of secondary battery, contain large amounts of valuable metals such as Li, Co, Ni, Mn, Cu, Al, and Fe. Furthermore, NCM-based lithium-ion batteries contain high concentrations of Ni, Co, and Mn.

[0003] Recycling methods for lithium-ion batteries are broadly classified into dry processes, wet processes, and direct regeneration processes. The dry process involves melting spent lithium-ion batteries into an alloy and then recovering valuable metals in the form of metal compounds through wet treatment; however, it has the disadvantages of high process costs and limited recovery of valuable metals (see Non-Patent Literature 1). The direct regeneration process involves separating the positive and negative active materials from spent lithium-ion batteries and then regenerating the positive electrode through heat treatment, etc. While applicable to some LFP positive active materials, it is difficult to apply to NCM-based positive active materials due to their mixed nature.

[0004] The wet process is a process for recovering valuable metals within the cathode active material by leaching black powder obtained by crushing spent lithium-ion batteries into an acidic solution, and it has the advantage of recovering valuable metals with high purity and having lower process costs compared to the dry process.

[0005] Meanwhile, in carrying out the wet process, acidic solutions, organic acid solutions, alkaline solutions, etc., may be used to leach valuable metals from black powder. Until now, methods using inorganic acidic solutions such as sulfuric acid have been widely used; however, when using inorganic acids, large amounts of wastewater and gypsum sludge are generated, increasing wastewater treatment costs, Mn and Fe are leached together, requiring additional purification processes, and the lifespan of equipment is shortened due to strong corrosiveness (see Patent Document 1). In addition, when using organic acids such as malic acid, high-purity valuable metals can be recovered, but there is a problem of increased process costs due to the high cost of the organic acid (see Non-Patent Document 2).

[0006] The method using an alkaline solution has advantages such as the ability to selectively leach Ni, Co, etc. (excluding Mn) and relatively low process costs; however, it has disadvantages in that the recovery rate of valuable metals is lower compared to the organic acid process, and it requires pH control and a continuous supply of ammonium carbonate ((NH4)2CO3) to induce the leaching of valuable metals. Prior art literature

[0007] Korean Patent Publication No. 2012-0037736 (Published April 20, 2012)

[0008] Resources Recycling Vol. 31, No. 3, 2022, 27-39J. of Korean Inst. of Resources Recycling Vol. 23, no. 4, 2014, 21-29 The problem to be solved

[0009] The present invention was devised to solve the above-mentioned problems, and aims to provide a process for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process that can minimize the input amount of ammonium carbonate and improve the recovery rate of valuable metals when recovering valuable metals from spent secondary batteries through a wet process using an alkaline solution.

[0010] In addition, another objective of the present invention is to provide a technology capable of recycling carbon dioxide and ammonia used in the recovery of valuable metals. means of solving the problem

[0011] The apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process according to the present invention for achieving the above objective comprises: a supercritical reaction vessel that induces the conversion of valuable metals contained in black powder into valuable metal complex compounds through a combination of a wet process using an alkaline solution and a supercritical carbon dioxide process; a carbon dioxide supply device that supplies carbon dioxide to the supercritical reaction vessel; a black powder supply device that supplies black powder to the supercritical reaction vessel; a chemical supply device that supplies a reducing agent, a complexing agent, and a pH adjusting agent to the supercritical reaction vessel; a gas-liquid separation device that receives a mixture of liquid phase material and gas phase material among the reaction products of the supercritical reaction vessel and separates it into a liquid phase material in which valuable metal complex compounds are dissolved and gaseous carbon dioxide; and a valuable metal recovery vessel that receives the liquid phase material in which valuable metal complex compounds are dissolved from the gas-liquid separation device and recovers the valuable metals.

[0012] When black powder and a reducing agent, complexing agent, and pH adjusting agent in the form of aqueous solutions are supplied to a supercritical reactor, and carbon dioxide is supplied, and supercritical conditions of a certain pressure and temperature are applied to the supercritical reactor, the formation and dissolution of valuable metal complex compounds by a wet process using an alkaline solution and the promotion of the dissolution of valuable metal complex compounds by a supercritical carbon dioxide process are carried out simultaneously or sequentially.

[0013] The formation and dissolution of valuable metal complexes by a wet process using an alkaline solution proceeds through a process in which valuable metal oxides present in black powder react with a reducing agent to be reduced to valuable metal ions, a process in which valuable metal ions react with a complexing agent to be converted into valuable metal complexes, and a process in which the valuable metal complexes dissolve in the liquid phase. The promotion of dissolution of valuable metal complexes by a supercritical carbon dioxide process is that, due to the permeability characteristics of supercritical carbon dioxide, valuable metal oxides present in black powder are additionally detached, thereby promoting the reduction reaction of valuable metal oxides, and due to the dissolution characteristics of supercritical carbon dioxide, the solubility of the valuable metal complexes in the liquid phase is increased.

[0014] Ammonium carbonate ((NH4)2CO3) is produced by the reaction of water (H2O), carbonic acid (CO3), and ammonia (NH3) in a supercritical reactor.

[0015] The reducing agent is ammonium sulfite ((NH4)2SO3), the complexing agent is ammonia (NH3), and the pH adjusting agent is ammonium carbonate ((NH4)2CO3).

[0016] The apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process according to the present invention receives a liquid phase material from a gas-liquid separation device and the ammonium ions (NH4) dissolved in the liquid phase material + It further includes an electrochemical membrane device that converts and recovers ) into ammonia gas (NH3).

[0017] The electrochemical membrane device is an ammonium ion (NH4 + An ammonia recovery reaction tank filled with a liquid phase substance containing ), and ammonium ions (NH4) in water when power is applied +It comprises an ammonia recovery membrane module that converts ) into ammonia gas (NH3) and recovers the converted ammonia gas (NH3), an ammonia recovery chamber that is closely attached to one side of the ammonia recovery membrane module and finally recovers the ammonia gas (NH3) that has passed through the ammonia recovery membrane module, and a cathode to which power is applied.

[0018] The ammonia recovery membrane module has a structure in which a membrane heating layer, an ammonia separation layer, and an ammonia conversion induction layer are sequentially stacked on an ammonia recovery layer; the membrane heating layer and the ammonia conversion induction layer are electrically connected to act as an anode and form a porous structure, while the ammonia separation layer and the ammonia recovery layer function as gas separation membranes capable of facilitating the movement of ammonia gas.

[0019] When power is applied to the separator heating layer, the ammonia conversion inducing layer, and the cathode, hydroxide ions (OH) on the surface of the ammonia conversion inducing layer - ) is generated, and hydroxide ions (OH) - Ammonium ions (NH4) near the surface of the ammonia conversion-inducing layer due to ) generation + This is converted into ammonia gas (NH3), and the converted ammonia gas (NH3) sequentially passes through the porous structure ammonia conversion inducing layer, the pores of the ammonia separation layer, the porous structure separation membrane heating layer, and the pores of the ammonia recovery layer.

[0020] When power is applied, the temperature of the membrane heating layer rises due to Joule heating, and the heat from the membrane heating layer is transferred to the ammonia separation layer and ammonia recovery layer adjacent to the membrane heating layer, causing the temperature of the ammonia separation layer and ammonia recovery layer to rise, and the speed of movement of ammonia gas passing through the ammonia separation layer and ammonia recovery layer increases due to the rise in temperature of the ammonia separation layer and ammonia recovery layer.

[0021] The ammonia recovery chamber is provided with a collection space for ammonia gas (NH3) and has a three-dimensional structure with one side open. The open portion is provided in close contact with one side of the ammonia recovery layer. Ammonia gas (NH3) generated on the surface of the ammonia conversion induction layer and passing through the ammonia separation layer, the membrane heating layer, and the ammonia recovery layer in sequence is finally recovered in the ammonia recovery chamber. The pressure inside the ammonia recovery chamber is set to be lower than the pressure acting on the ammonia recovery membrane module. Effects of the invention

[0022] The process for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process according to the present invention has the following effects.

[0023] In recovering valuable metals from black powder of spent secondary batteries through a wet process using an alkaline solution, the recovery rate of valuable metals can be improved by combining a supercritical carbon dioxide process. Furthermore, as the supercritical carbon dioxide process is combined, ammonium carbonate is self-generated, allowing the input amount of ammonium carbonate required for the reaction to be minimized. In addition, the ammonia and carbon dioxide used in the valuable metal recovery process can be recovered and recycled. Brief explanation of the drawing

[0024] FIG. 1 is a schematic diagram of a device for recovering valuable metals from waste secondary batteries using a supercritical carbon dioxide process according to one embodiment of the present invention. Figure 2 is a diagram showing the configuration of an electrochemical membrane device. Figure 3 is a schematic diagram of an ammonia recovery membrane module. Figure 4 is a photograph of an electrochemical membrane device manufactured according to one embodiment of the present invention. Figure 5 is a photograph showing the temperature change of the ammonia recovery membrane module according to the application of power. Figure 6 is an experimental result showing the amount of raw water evaporated according to the temperature of the ammonia recovery membrane module. Specific details for implementing the invention

[0025] The present invention provides a technology for recovering valuable metals from spent secondary batteries that can increase the recovery rate of valuable metals and minimize the input amount of ammonium carbonate ((NH4)2CO3) by combining a wet process using an alkaline solution with a supercritical carbon dioxide process. In addition, the present invention provides a technology for recycling carbon dioxide (CO2) and ammonia (NH3) used in the recovery of valuable metals.

[0026] In this specification, 'discarded secondary battery' refers to a used secondary battery, and while the type of secondary battery is not particularly limited, it may include lithium-based secondary batteries such as lithium-ion batteries.

[0027] As described above in 'Technology forming the background of the invention,' when recovering valuable metals from black powder of spent secondary batteries, the wet process, particularly the wet process using an alkaline solution, has the advantages of a high recovery rate of valuable metals compared to the dry process, selective leaching of Ni, Co, etc., and low process costs, but it has the disadvantages of a lower recovery rate of valuable metals compared to the wet process using an organic acid and the requirement for a continuous supply of ammonium carbonate.

[0028] Combination of supercritical carbon dioxide process and wet process

[0029] The present invention provides a technology that can overcome the disadvantages of a wet process using an alkaline solution. By combining a supercritical carbon dioxide process with a wet process using an alkaline solution, the disadvantages of a wet process using an alkaline solution can be overcome.

[0030] The principle of recovering valuable metals from black powder through a wet process using an alkaline solution is that the valuable metal oxides (MO) present in the black powder x ) valuable metal ions (M +The valuable metal ions are reduced to a valuable metal complex (M-NH3) by reacting the reduced valuable metal ions with ammonia, and then the valuable metal complex dissolved in the liquid phase is recovered. Finally, the valuable metal complex is purified into a valuable metal by a known smelting process.

[0031] Under this principle, to increase the recovery rate of valuable metals, their solubility in the liquid phase must be increased, and the reason for converting valuable metals into the form of valuable metal complexes is to increase their solubility in the liquid phase. Therefore, for the recovery rate of organometallics to improve, the solubility of valuable metal complexes in the liquid phase must be increased.

[0032] In the present invention, the supercritical carbon dioxide process serves to increase the solubility of valuable metal complex compounds. As is known, supercritical carbon dioxide is a supercritical fluid that exhibits liquid characteristics in terms of its involvement in the interaction between solvent and solute molecules, and gas characteristics in terms of its excellent substrate permeability.

[0033] When supercritical carbon dioxide, which has such excellent solubility and permeability characteristics, is applied to black powder sludge containing valuable metal complexes, the black powder sludge is separated into liquid and solid phases, and the dissolution of the valuable metal complexes into the liquid phase is promoted. In this way, by combining a supercritical carbon dioxide process with a wet process using an alkaline solution, the solubility of the valuable metal complexes can be increased, thereby ultimately improving the recovery rate of the valuable metals.

[0034] In addition, the present invention can minimize the input amount of ammonium carbonate by combining a supercritical carbon dioxide process. Ammonium carbonate is an essential component in a wet process using an alkaline solution. As described above, in the principle of a wet process using an alkaline solution, valuable metal oxides (MO x ) valuable metal ions (M +The reduction to ) and the conversion of valuable metal ions into valuable metal complexes (M-NH3) proceed, and ammonium carbonate ((NH4)2CO3) plays a role in stabilizing the reaction and maintaining the pH of the liquid phase as alkaline to prevent the leaching of Mn. Therefore, a continuous supply of ammonium carbonate is required for the formation of valuable metal complexes and the maintenance of pH. For reference, Mn leaches out if the pH of the liquid phase is neutral or acidic.

[0035] In the case of the present invention, ammonium carbonate ((NH4)2CO3) is self-generated by a supercritical carbon dioxide process, and accordingly, even if the amount of ammonium carbonate input is minimized, the amount of ammonium carbonate required for the wet process—that is, the amount of ammonium carbonate required for the formation of valuable metal complexes and pH maintenance—can be maintained at a constant level.

[0036] The reaction mechanism for the production of ammonium carbonate ((NH4)2CO3) by the supercritical carbon dioxide process is as shown in Equations 1 and 2 below. That is, when water (H2O) and carbon dioxide (CO2) are supplied to black powder in the reaction vessel, and ammonia (NH3), etc. are supplied for the wet process, and supercritical conditions are applied to the reaction vessel, ammonium carbonate ((NH4)2CO3) is produced by the reaction of Equations 1 and 2 below.

[0037] (Equation 1) CO2+ H2O ↔ H2CO3↔ HCO3 - + H + ↔ CO3 2- + 2H +

[0038] (Equation 2) 2NH3+ H2CO3↔ (NH4)2CO3

[0039] Hereinafter, an apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0040] Precious metal recovery device

[0041] Referring to FIG. 1, a device for recovering valuable metals from a waste secondary battery using a supercritical carbon dioxide process according to one embodiment of the present invention comprises a supercritical reaction tank (110), a carbon dioxide supply device (20), a black powder supply device (10), a chemical supply device (30), a gas-liquid separation device (120), a valuable metal recovery tank (130), and an electrochemical separation membrane device (140).

[0042] The supercritical reaction vessel (110) provides a space in which a reaction proceeds in which valuable metals contained in black powder are dissolved in a liquid phase by a supercritical carbon dioxide process and a wet process.

[0043] The carbon dioxide supply device (20) supplies carbon dioxide to the supercritical reaction tank (110), and the carbon dioxide supplied to the supercritical reaction tank (110) is converted into supercritical carbon dioxide when supercritical conditions are applied. The black powder supply device (10) supplies black powder to the supercritical reaction tank (110), and the black powder refers to crushed waste secondary batteries.

[0044] The chemical supply device (30) is a device that supplies chemicals to the supercritical reaction vessel (110), and the chemicals may refer to a reducing agent, a complexing agent, and a pH adjusting agent, or may refer to a reducing agent and a complexing agent. That is, through the chemical supply device (30), a reducing agent, a complexing agent, and a pH adjusting agent may be supplied to the supercritical reaction vessel (110), or a reducing agent and a complexing agent excluding the pH adjusting agent may be supplied.

[0045] Reducing agents, complexing agents, and pH adjusters are chemicals used to leach valuable metals contained in black powder during a wet process using an alkaline solution, and the reducing agent [removes] valuable metal oxides (MO₂) existing in the black powder in the form of metal oxides x ) valuable metal ions (M + It plays the role of reducing to ), and the complexing agent is a valuable metal ion (M +It serves to convert the valuable metal complex (M-NH3) into a valuable metal complex, and the pH adjuster maintains the pH of the liquid phase as alkaline during the conversion reaction of the valuable metal oxide into the valuable metal complex, thereby allowing the reaction to proceed stably. The reducing agent, complexing agent, and pH adjuster can be supplied to the supercritical reactor (110) in the form of aqueous solutions.

[0046] The type of chemical is not particularly limited. In one embodiment, ammonium sulfite ((NH4)2SO3) may be used as the reducing agent, ammonia (NH3) as the complexing agent, and ammonium carbonate ((NH4)2CO3) as the pH adjusting agent, and the following description will be based on this. When ammonium carbonate is used as the pH adjusting agent, the supply of the pH adjusting agent to the supercritical reaction vessel (110) may be omitted or the amount of the agent may be minimized, because ammonium carbonate is generated within the supercritical reaction vessel (110), and this will be described later.

[0047] Taking the case where the valuable metals contained in the black powder are Ni, Co, and Mn as an example, the reduction of valuable metal oxides and the conversion of valuable metal ions into valuable metal complexes are exemplified by Equations 3 and 4 below. Equation 3 represents the reaction in which a valuable metal oxide is reduced to a valuable metal ion by the reducing agent ammonium sulfite ((NH4)2SO3), and Equation 4 represents the reaction in which a valuable metal ion is converted into a valuable metal complex by the complexing agent ammonia (NH3).

[0048] (Equation 3)

[0049] NiO + (NH4)2SO3 + 2H + → Ni 2+ + (NH4)2SO3 + H2O

[0050] Co3O4 + (NH4)2SO3 + 2H + → 3Co 2+ + (NH4)2SO3 + H2O

[0051] MnO2+ (NH4)2SO3+ 2H + → Mn2+ + (NH4)2SO3 + H2O

[0052] (Equation 4)

[0053] Ni 2+ + 6NH3→ [Ni(NH3)6] 2+

[0054] Co 2+ + 6NH3→ [Co(NH3)6] 2+

[0055] Mn 2+ + 6NH3→ [Mn(NH3)6] 2+

[0056] The reasons for applying reducing agents and complexing agents to recover valuable metals present in black powder are as follows. The valuable metals in black powder must ultimately be recovered in metallic form, but these metals exist in the form of metal oxides. Therefore, it is necessary to reduce the valuable metal oxides existing in the form of metal oxides into valuable metal ions. Furthermore, since valuable metal complexes have higher solubility in the liquid phase than valuable metal ions, the valuable metal ions are converted into valuable metal complexes. During the wet process using an alkaline solution, the pH of the liquid phase must be maintained in an alkaline state, so a pH adjuster is used.

[0057] When black powder and a reducing agent, complexing agent, and pH adjusting agent in the form of an aqueous solution are supplied to the supercritical reactor (110), and carbon dioxide is supplied, and supercritical conditions of a certain pressure and temperature are applied to the supercritical reactor (110), <formation and dissolution of valuable metal complex compounds by a wet process using an alkaline solution> and <promotion of dissolution of valuable metal complex compounds by a supercritical carbon dioxide process> are carried out simultaneously or sequentially. At this time, the process conditions of the supercritical reactor (110) for converting gaseous carbon dioxide into supercritical carbon dioxide can be set to a pressure of 74 to 300 bar and a temperature of 35 to 200°C.

[0058] Specifically, valuable metal oxides (NiO, CO3O4, MnO2, etc.) present in black powder react with ammonium sulfite ((NH4)2SO3) to produce valuable metal ions (Ni 2+ , Co 2+ , Mn 2+ It is reduced to (etc.), and the valuable metal ions react with ammonia (NH3) to form a valuable metal complex ([Ni(NH3)6] 2+ , [Co(NH3)6] 2+ , [Mn(NH3)6] 2+ It is converted into (etc.), and the valuable metal complex is dissolved in the liquid phase.

[0059] During the wet process using such an alkaline solution, the reduction of valuable metal oxides and the dissolution of valuable metal complexes are promoted by supercritical carbon dioxide. Specifically, due to the permeability characteristics of supercritical carbon dioxide, valuable metal oxides present in the black powder are additionally detached, thereby promoting the reduction reaction of valuable metal oxides, while the solubility of valuable metal complexes in the liquid phase is increased due to the dissolution characteristics of supercritical carbon dioxide. The promotion of the reduction of valuable metal oxides and the dissolution of valuable metal complexes by supercritical carbon dioxide can be confirmed through the valuable metal recovery rate of the experimental examples described later.

[0060] When the reaction combining a wet process using an alkaline solution and a supercritical carbon dioxide process is completed, solid, liquid, and gaseous substances exist within the supercritical reaction vessel (110). The solid substance is black powder from which valuable metals have been removed, the liquid substance is an aqueous solution in which a valuable metal complex is dissolved, and the gaseous substance is gaseous carbon dioxide converted from supercritical carbon dioxide upon release of the supercritical conditions. At this time, the liquid substance contains the chemicals used to form the valuable metal complex. For example, ammonium ions (NH4 + ) exists in the liquid phase substance.

[0061] In addition, when the reaction combining the wet process using an alkaline solution and the supercritical carbon dioxide process is completed, the remaining liquid and gaseous substances, excluding the solid substances, are transferred to the gas-liquid separation device (120). The solid substances remaining in the supercritical reaction tank (110) are discharged from the supercritical reaction tank (110) through a separate process and disposed of.

[0062] Meanwhile, in the process of forming and dissolving valuable metal complex compounds through a combination of a wet process using an alkaline solution and a supercritical carbon dioxide process within the supercritical reactor (110), the generation of ammonium carbonate ((NH4)2CO3) occurs in parallel. The reaction mechanism for the generation of ammonium carbonate is based on Equations 1 and 2 as previously explained. That is, to proceed with the wet process using an alkaline solution and the supercritical carbon dioxide process within the supercritical reactor (110), water (H2O), carbon dioxide (CO2), and a chemical (reducing agent, complexing agent, and pH adjuster) containing ammonium ions are supplied, and H2CO3 is formed by the reaction between H2O and CO2 (see Equation 1), and ammonium carbonate ((NH4)2CO3) is formed by the reaction between H2CO3 and NH3 (see Equation 2).

[0063] The fact that ammonium carbonate ((NH4)2CO3) is generated spontaneously within the supercritical reactor (110) means that the supply of ammonium carbonate can be omitted or minimized. In order for a valuable metal complex to be stably formed by a wet process using an alkaline solution, ammonium carbonate must be continuously supplied as a pH regulator to maintain reaction stability and the pH of the liquid phase as alkaline, in addition to the reducing agent (ammonium sulfite) and the complexing agent (ammonia). However, as ammonium carbonate is generated through a spontaneous reaction within the supercritical reactor (110), the amount of ammonium carbonate supplied can be minimized.

[0064] Above, the formation of valuable metal complex compounds, the promotion of dissolution by the combination of a wet process using an alkaline solution in a supercritical reaction vessel (110), and the minimization of the amount of ammonium carbonate input due to the self-generation of ammonium carbonate in the supercritical reaction vessel (110) have been explained.

[0065] Meanwhile, the gas-liquid separation device (120) separates the mixture of liquid and gaseous substances supplied from the supercritical reaction tank (110) into liquid and gaseous substances. The separated gaseous substance is carbon dioxide, which is transferred to the carbon dioxide supply device (20) for recycling, and the separated liquid substance is transferred to the valuable metal recovery tank (130) or transferred to the valuable metal recovery tank (130) after passing through the electrochemical separation membrane device (140).

[0066] The valuable metal recovery tank (130) is for recovering the valuable metal complex from the liquid phase in which the valuable metal complex is dissolved, and the valuable metal can be finally recovered by precipitating the valuable metal complex through pH adjustment, etc. and applying a known wet smelting process to the precipitated valuable metal complex.

[0067] The electrochemical separation membrane device (140) is an ammonium ion (NH4) dissolved in a liquid substance supplied from a gas-liquid separation device (120). + It is a device that converts and recovers ) into ammonia gas (NH3). The ammonia gas (NH3) recovered by the electrochemical separation device (140) can be supplied to the chemical supply device (30) and recycled.

[0068] The detailed configuration of the electrochemical separation device (140) is as follows.

[0069] Referring to FIG. 2, the electrochemical membrane device (140) is configured to include an ammonia recovery reaction tank (210), an ammonia recovery membrane module (220), an ammonia recovery chamber (230), and a cathode (240).

[0070] The ammonia recovery reaction tank (210) is provided with a space in which the liquid phase material separated from the gas-liquid separation device (120) is stored, and the ammonia recovery membrane module (220) and the cathode (240) are provided in a form that is immersed in the liquid phase material of the ammonia recovery reaction tank (210). Although not shown in the drawing, a power supply device is provided on one side of the ammonia recovery reaction tank (210) to supply power to the ammonia recovery membrane module (220) and the cathode (240).

[0071] The ammonia recovery membrane module (220) recovers ammonium ions (NH4) present in the liquid phase substance when power is applied. + It serves to convert the ammonia gas (NH3) into ammonia gas (NH3) and recover the converted ammonia gas (NH3). As shown in FIG. 3, this ammonia recovery membrane module (220) has a structure in which a membrane heating layer (222), an ammonia separation layer (223), and an ammonia conversion induction layer (224) are sequentially stacked on an ammonia recovery layer (221).

[0072] The ammonia conversion induction layer (224) and the membrane heating layer (222) are made of a conductive material and are physically in contact with each other and electrically connected. In one embodiment, an ammonia separation layer (223) is interposed between the ammonia conversion induction layer (224) and the membrane heating layer (222). By making the area of ​​the ammonia separation layer (223) relatively small, physical contact and electrical connection between the ammonia conversion induction layer (224) and the membrane heating layer (222) can be induced.

[0073] The ammonia conversion inducing layer (224) and the separator heating layer (222), which are made of a conductive material and are electrically connected to each other, serve as the anode in the electrochemical separator device (140) of the present invention. That is, power from the power supply device is applied to the cathode (240) and the ammonia conversion inducing layer (224) and the separator heating layer (222).

[0074] When power is applied to the ammonia conversion inducing layer (224) and the membrane heating layer (222), hydroxide ions (OH) on the surface of the ammonia conversion inducing layer (224) are produced by a hydrogen generation reaction. - ) is generated. Hydroxide ions (OH) - Due to the generation of ), the pH is locally raised near the surface of the ammonia conversion-inducing layer (224). For example, the pH of the liquid phase material near the surface of the ammonia conversion-inducing layer (224) rises to 11 or higher. As is known, ammonium ions (NH4) in water + ) has the characteristic of being converted into ammonia gas (NH3) at a pH of 11 or higher, so hydroxide ions (OH) on the surface of the ammonia conversion inducing layer (224) - As the pH rises above 11 due to the generation of ), ammonium ions (NH4) in the water + ) is converted into ammonia gas (NH3).

[0075] At this time, hydroxide ions (OH - ) is generated on the surface of the ammonia conversion-inducing layer (224), and the pH increase occurs locally near the surface of the ammonia conversion-inducing layer (224), along with ammonium ions (NH4 + The conversion of ) into ammonia gas (NH3) also occurs near the surface of the ammonia conversion inducing layer (224), so the generated ammonia gas (NH3) is easily recovered by the ammonia recovery membrane module (220).

[0076] The ammonia conversion inducing layer (224), which acts as an anode together with the separator heating layer (222), may be made of a conductive polymer in one embodiment. Any one of polyaniline (PANI), polypyrrole (PPy), polythiophene (PT), or PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) may be used as the conductive polymer. This conductive polymer is coated in a form applied to the entire surface of the ammonia recovery layer (221), including the ammonia separation layer (223), to form a porous structure.

[0077] The ammonia separation layer (223), which is provided in a form interposed between the ammonia conversion induction layer (224) and the membrane heating layer (222), is a thin film with pores formed to enable the movement of ammonia gas (NH3), and the ammonia gas (NH3) generated near the surface of the ammonia conversion induction layer (224) moves toward the ammonia recovery layer (221) through the pores of the ammonia separation layer (223).

[0078] In one embodiment, the ammonia separation layer (223) may be a porous polymer separation membrane or a porous ceramic separation membrane, and in the case of a porous polymer separation membrane, any one of polydimethylsiloxane, polyethylene, polypropylene, polycarbonate, or polyamide may be used.

[0079] As described above, the separator heating layer (222) is electrically connected to the ammonia conversion induction layer (224) to perform the role of an anode, and also induces joule heating when power is applied to promote the movement of ammonia gas (NH3). The separator heating layer (222) is composed of a material with excellent electrical and thermal conductivity, and in one embodiment, it may be composed of carbon fiber. When using carbon fiber, the separator heating layer (222) may be formed by applying a solution in which carbon fiber is dispersed onto the ammonia recovery layer (221) to form a coating, or by electrospinning carbon fiber onto the ammonia recovery layer (221). In this case, the carbon fiber is provided in a network form, so even if the carbon fiber is stacked, the surface of the ammonia recovery layer (221) is partially exposed.

[0080] With an ammonia separation layer (223) provided on one side of the membrane heating layer (222) and an ammonia recovery layer (221) provided on the other side, when power is applied to the membrane heating layer (222), the temperature of the membrane heating layer (222) is raised by Joule heating, and the heat of the membrane heating layer (222) is transferred to the ammonia separation layer (223) and the ammonia recovery layer (221). As a result, the temperature of the ammonia gas (NH3) moving through the pores of the ammonia separation layer (223) and the ammonia recovery layer (221) is raised, and since the rise in the temperature of the ammonia gas (NH3) means an increase in the movement speed of the ammonia gas (NH3), the recovery efficiency of the ammonia gas is increased by the Joule heating effect of the membrane heating layer (222). Figure 5 shows the temperature change of the ammonia recovery membrane module according to the power application, and Figure 6 shows the experimental results of the amount of raw water evaporated according to the temperature of the ammonia recovery membrane module. Through the results of Figures 5 and 6, it can be confirmed that the temperature rise is caused by the membrane heating layer (222), and thus the ammonia gas recovery efficiency can be improved.

[0081] In addition to the role of an anode and a role of inducing Joule heating as described above, the separator heating layer (222) additionally serves as a medium to spatially connect the pores of the ammonia separation layer (223) and the pores of the ammonia recovery layer (221). The ammonia separation layer (223) and the ammonia recovery layer (221), described later, perform the function of a gas separation membrane to induce the movement of ammonia gas (NH3). If the separator heating layer (222) is not present, the ammonia separation layer (223) is stacked on the ammonia recovery layer (221), and in this case, the ammonia recovery layer (221) and the ammonia separation layer (223) can block each other's pores.

[0082] On the other hand, as a separation membrane heating layer (222) is provided between the ammonia recovery layer (221) and the ammonia separation layer (223) with a certain thickness and in a form that partially exposes the surface of the ammonia recovery layer (221), the pores of the ammonia recovery layer (221) and the pores of the ammonia separation layer (223) are spatially connected to each other through the separation membrane heating layer (222).

[0083] The ammonia recovery layer (221) is formed on the surface of the ammonia conversion induction layer (224) and serves to finally recover the ammonia gas (NH3) that has passed sequentially through the ammonia separation layer (223) and the separation membrane heating layer (222), and performs the function of a gas separation membrane together with the ammonia separation layer (223). As an example, a porous polymer separation membrane or a porous ceramic separation membrane may be applied as the ammonia recovery layer (221), and in the case of a porous polymer separation membrane, it may be made of any one of polypropylene, polyethylene, polydimethylsiloxane, polycarbonate, or polyamide.

[0084] The ammonia recovery chamber (230) has a three-dimensional structure with one side open and a space for collecting ammonia gas (NH3), and the open portion is in close contact with one side of the ammonia recovery layer (221). In addition, to facilitate the recovery of ammonia gas (NH3) passing through the ammonia recovery layer (221) into the ammonia recovery chamber (230), it is preferable that the pressure inside the ammonia recovery chamber (230) be set lower than the pressure acting on the ammonia recovery membrane module (220). That is, it is preferable to maintain the pressure inside the ammonia recovery chamber (230) in a negative pressure state, and in one embodiment, the inside of the ammonia recovery chamber (230) can be set to a vacuum state. To set the negative pressure of the ammonia recovery chamber (230), a pressure pump may be provided on one side of the ammonia recovery chamber (230).

[0085] Meanwhile, the ammonia gas (NH3) recovered through the ammonia recovery layer (221) may be recovered in the form of salt. In this case, an acidic solution tank is provided on one side of the ammonia recovery reaction tank (210) to replace the ammonia recovery chamber (230), and the ammonia gas (NH3) that has passed through the ammonia recovery layer (221) is supplied to the acidic solution of the acidic solution tank. The acidic solution of the acidic solution tank is one of nitric acid solution, sulfuric acid solution, or phosphoric acid solution, and when ammonia gas (NH3) is supplied to the acidic solution, the ammonia gas (NH3) reacts with one of nitric acid, sulfuric acid, or phosphoric acid to form one of ammonium nitrate, ammonium sulfate, or ammonium phosphate within the acidic solution, thereby forming a dissolved state. Ammonium nitrate, ammonium sulfate, ammonium phosphate, etc. in the acidic solution can be used as fertilizer, etc. FIG. 4 shows an electrochemical separation membrane device (140) manufactured according to one embodiment of the present invention.

[0086] The detailed configuration of the electrochemical separation membrane device (140) has been described above. The ammonium ions (NH4) contained in the liquid phase material separated by the gas-liquid separation device (120) through the electrochemical separation membrane device (140) described above +It can remove and recover ) and ammonium ions (NH4) from liquid phase substances + As ) is removed, the concentration of valuable metal complexes in the liquid phase material increases. In addition, ammonium ions (NH4 + The liquid phase material from which ) has been removed is transferred to a valuable metal recovery tank (130), and within the valuable metal recovery tank (130), the valuable metal can be finally recovered through the precipitation of the valuable metal complex and a known wet smelting process.

[0087] For the above, an apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process according to one embodiment of the present invention has been described. Below, the present invention will be explained in more detail through experimental examples.

[0088] Experimental Example 1: Combination of Wet Process and Supercritical Process Using Inorganic Acid

[0089] In recovering valuable metals (Li, Ni, Co, Mn) contained in black powder through a wet process using an inorganic acid, the recovery rates of valuable metals were compared depending on whether a supercritical process was combined. Table 1 below lists the experimental conditions for the wet process experiment using an inorganic acid (Comparative Example 1) and the experiment combining a wet process using an inorganic acid with a supercritical process (Example 1), respectively, and Table 2 shows the experimental results indicating the recovery rates of each valuable metal according to the experimental conditions in Table 1. A reaction time of 120 minutes was applied for Comparative Example 1, and a reaction time of 30 minutes was applied for Example 1. In addition, sulfuric acid (H2SO4) was applied as the inorganic acid, and hydrogen peroxide (H2O2) was applied as the reducing agent.

[0090] division H2SO4 molar ratio H2O2 molar ratio Sample (g) High liquid ratio (g / L) Temperature (°C) Reaction time (min) Stirring speed (rpm) pressure (bar) Comparative Example 1 2.5 2.07 20 153.846 75 120 200 - Example 1 2.5 2.07 20 153.846 75 30 200 85

[0091] division Li leaching rate Ni leaching rate Co leaching rate Mn leaching rate pH change (before reaction → after reaction) Comparative Example 1 92.79 90.85 90.07 83.36 3.5 → 3.0 Example 1 95.62 93.43 91.11 90.30 3.8 → 3.4

[0092] Referring to the experimental results in Table 2, it can be seen that the leaching rate of all valuable metals is improved in Example 1, which is an experiment in which a supercritical process is combined with a wet process, compared to Comparative Example 1. However, in the case of this experiment, it can be seen that Mn is leached together with Li, Ni, and Co as an inorganic acid is applied, which means that a separate purification process is required for the leached Mn.

[0093] Experimental Example 2: Combination of Wet Process and Supercritical Process Using an Alkaline Solution

[0094] In recovering valuable metals (Li, Ni, Co, Mn) contained in black powder through a wet process using an alkaline solution, the recovery rates of valuable metals were compared depending on whether a supercritical process was combined. Table 3 below lists the experimental conditions for the wet process experiment using an alkaline solution (Comparative Example 2) and the experiment combining a wet process using an inorganic acid with a supercritical process (Examples 2, 3, and 4), respectively, and Table 4 shows the experimental results indicating the recovery rates of each valuable metal according to the experimental conditions in Table 3. A reaction time of 60 minutes was applied for Comparative Example 2, while a reaction time of 30 minutes was applied for Examples 2, 3, and 4. In addition, ammonium sulfite ((NH4)2SO3) was used as a reducing agent, water ammonia (NH4OH) as a complexing agent, and ammonium carbonate ((NH4)2CO3) as a pH adjusting agent.

[0095] division Ammonia water concentration (M) (NH4)2CO3 concentration (M) (NH4)2SO3 concentration (M) Sample (g) High liquid ratio (g / L) Temperature (°C) Reaction time (min) Stirring speed (rpm) pressure (bar) Comparative Example 2 3M 1.5M 3M 20 153.846 room temperature 60 200 - Example 2 3M 1.5M 3M 20 153.846 75 30 200 85 Example 3 3M 1.0M 3M 20 153.846 75 30 200 85 Example 4 3M 0.5M 3M 20 153.846 75 30 200 85

[0096] division Li leaching rate Ni leaching rate Co leaching rate Mn leaching rate pH change (before reaction → after reaction) Comparative Example 2 75.18 80.35 76.65 Non-detectable 9.4 → 8.9 Example 2 88.60 96.75 93.84 Non-detectable 9.4 → 8.9 Example 3 85.33 90.03 88.41 Non-detectable 9.5 → 9.0 Example 4 81.22 86.27 78.83 Non-detectable 9.3 → 9.0

[0097] Referring to the experimental results in Table 4, it can be seen that compared to Comparative Example 2, Examples 2, 3, and 4 increased the leaching rate of each valuable metal (Li, Co, Co) by 10 to 20 percent even though half the reaction time was applied.

[0098] In addition, from the results of Examples 2 to 4, it can be seen that the higher the concentration of ammonium carbonate, the better the leaching rate of valuable metals. This result demonstrates that the concentration of ammonium carbonate is a factor that directly influences the formation of valuable metal complexes.

[0099] In addition, it can be confirmed that Mn is not leached out by applying a wet process using an alkaline solution, and it can be seen that the pH remains stable after the completion of the process in all of Examples 2 to 4. Explanation of the symbols

[0100] 10 : Black powder dispenser 20 : Carbon dioxide dispenser 30 : Pharmaceutical supply device 110: Supercritical reactor 120: Gas-liquid separator 130: Valuable metal recovery tank 140: Electrochemical membrane separator 210: Ammonia recovery reactor 220: Ammonia recovery membrane module 221: Ammonia recovery layer 222: Membrane heating layer 223 : Ammonia separation layer 224 : Ammonia conversion induction layer 230: Ammonia recovery chamber 240: Cathode

Claims

Claim 1 A supercritical reactor that induces the conversion of valuable metals contained in black powder into valuable metal complex compounds through a combination of a wet process using an alkaline solution and a supercritical carbon dioxide process; a carbon dioxide supply device that supplies carbon dioxide to the supercritical reactor; a black powder supply device that supplies black powder to the supercritical reactor; a chemical supply device that supplies a reducing agent, a complexing agent, and a pH adjuster to the supercritical reactor; and a gas-liquid separation device that receives a mixture of liquid and gaseous substances among the reaction products of the supercritical reactor and separates it into a liquid substance in which valuable metal complex compounds are dissolved and gaseous carbon dioxide. An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, comprising: a valuable metal recovery tank that receives a liquid phase material in which a valuable metal complex compound is dissolved from a gas-liquid separation device and recovers the valuable metal; wherein the reducing agent, the complexing agent, and the pH adjusting agent are substances containing ammonium ions, and ammonium carbonate ((NH4)2CO3) is generated by the reaction of water (H2O), carbonic acid (CO3), and ammonia (NH3) in a supercritical reaction tank. Claim 2 An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, characterized in that, in claim 1, when black powder and a reducing agent, complexing agent, and pH adjusting agent in the form of aqueous solutions are supplied to the supercritical reactor and carbon dioxide is supplied, supercritical conditions of a certain pressure and temperature are applied to the supercritical reactor, thereby simultaneously or sequentially forming and dissolving valuable metal complex compounds by a wet process using an alkaline solution and promoting the dissolution of valuable metal complex compounds by a supercritical carbon dioxide process. Claim 3 An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, wherein, in claim 2, the formation and dissolution of a valuable metal complex by a wet process using an alkaline solution proceeds in the following steps: a process in which a valuable metal oxide present in black powder reacts with a reducing agent to be reduced to a valuable metal ion; a process in which the valuable metal ion reacts with a complexing agent to be converted into a valuable metal complex; and a process in which the valuable metal complex dissolves in a liquid phase; and the promotion of the dissolution of the valuable metal complex by a supercritical carbon dioxide process is characterized by the fact that, due to the permeability characteristics of supercritical carbon dioxide, the valuable metal oxide present in black powder is additionally detached to promote the reduction reaction of the valuable metal oxide, and due to the dissolution characteristics of supercritical carbon dioxide, the solubility of the valuable metal complex into the liquid phase is increased. Claim 4 delete Claim 5 An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, characterized in that, in claim 1, the reducing agent is ammonium sulfite ((NH4)2SO3), the complexing agent is ammonia (NH3), and the pH adjusting agent is ammonium carbonate ((NH4)2CO3). Claim 6 In claim 1, the ammonium ions (NH4) dissolved in the liquid substance are supplied from a gas-liquid separation device. + A device for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, characterized by further including an electrochemical separator that converts and recovers ) into ammonia gas (NH3). Claim 7 In claim 6, the electrochemical membrane device comprises ammonium ions (NH4 + An ammonia recovery reaction tank filled with a liquid phase substance containing ), and ammonium ions (NH4) in water when power is applied + An apparatus for recovering valuable metals from a spent secondary battery using a supercritical carbon dioxide process, characterized by comprising: an ammonia recovery membrane module that converts ) into ammonia gas (NH3) and recovers the converted ammonia gas (NH3); an ammonia recovery chamber that is closely attached to one side of the ammonia recovery membrane module and finally recovers the ammonia gas (NH3) that has passed through the ammonia recovery membrane module; and a cathode to which power is applied. Claim 8 An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, wherein the ammonia recovery membrane module has a structure in which a membrane heating layer, an ammonia separation layer, and an ammonia conversion induction layer are sequentially stacked on an ammonia recovery layer, the membrane heating layer and the ammonia conversion induction layer are electrically connected to perform the role of an anode and form a porous structure, and the ammonia separation layer and the ammonia recovery layer perform the function of a gas separation membrane capable of moving ammonia gas. Claim 9 In claim 8, when power is applied to the membrane heating layer, the ammonia conversion inducing layer, and the cathode, hydroxide ions (OH) on the surface of the ammonia conversion inducing layer - ) is generated, and hydroxide ions (OH) - Ammonium ions (NH4) near the surface of the ammonia conversion-inducing layer due to ) generation + An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process characterized in that ) is converted into ammonia gas (NH3), and the converted ammonia gas (NH3) sequentially passes through the pores of a porous structured ammonia conversion inducing layer, an ammonia separation layer, a porous structured separator heating layer, and an ammonia recovery layer. Claim 10 An apparatus for recovering valuable metals from spent secondary batteries using a supercritical carbon dioxide process, characterized in that, in claim 9, when power is applied, the temperature of the separator heating layer is raised by Joule heating, and the heat from the separator heating layer is transferred to the ammonia separation layer and ammonia recovery layer adjacent to the separator heating layer, thereby raising the temperature of the ammonia separation layer and ammonia recovery layer, and the velocity of ammonia gas passing through the ammonia separation layer and ammonia recovery layer is increased due to the temperature rise of the ammonia separation layer and ammonia recovery layer. Claim 11 An apparatus for recovering valuable metals from a spent secondary battery using a supercritical carbon dioxide process, characterized in that, in claim 8, the ammonia recovery chamber has a three-dimensional structure with one side open and a space for collecting ammonia gas (NH3), the open portion is provided in close contact with one side of the ammonia recovery layer, the ammonia gas (NH3) generated on the surface of the ammonia conversion induction layer and passing through the ammonia separation layer, the membrane heating layer, and the ammonia recovery layer in sequence is finally recovered in the ammonia recovery chamber, and the pressure inside the ammonia recovery chamber is set to be lower than the pressure acting on the ammonia recovery membrane module.

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