Lithium recovery device and lithium recovery method

Abstract

To provide an apparatus and method for collecting lithium, capable of efficiently collecting lithium ions from a lithium ion extraction liquid extracted from the treatment member of a lithium secondary battery.SOLUTION: An apparatus for collecting lithium includes: a predetermined lithium selection permeable membrane; a first mesh-like electrode fixed on one main surface side of the lithium selection permeable membrane; a second mesh-like electrode fixed on the other main surface side of the lithium selection permeable membrane; and temperature control means selected from temperature control means A for controlling the temperature of the lithium ion extraction liquid and temperature control means B for controlling the temperature of the lithium selection permeable membrane, and the like. A method for collecting lithium from the lithium ion extraction liquid comprises: using the lithium selection permeable membrane; controlling the temperature of the lithium ion extraction liquid to 30°C or more and 100°C or less; and moving lithium ions to a collected liquid being an aqueous solution to collect lithium in the collected liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lithium recovery device and a lithium recovery method. [Background technology]

[0002] Lithium secondary batteries and the like are used in large quantities as secondary batteries for various portable devices, and the development of a technology for efficiently recovering the metal ions used in these secondary batteries is eagerly awaited. Lithium secondary batteries are also used in hybrid cars and electric vehicles, which have been developed to comply with carbon dioxide emission regulations. While many recycling technologies for these lithium secondary batteries have been developed, there is a strong demand for the development of a highly efficient lithium recovery technology. Known lithium recovery technologies include those described in Patent Documents 1 and 2, for example.

[0003] Patent Document 1 describes a method for recovering lithium from a lithium ion extract extracted from a processing component of a lithium secondary battery, using a lithium permselective membrane and adjusting the pH of the lithium ion extract to 12 or more and 14 or less, and transferring lithium ions to a recovery solution that is an aqueous solution, thereby recovering lithium in the recovery solution. Patent Document 2 describes a Li extraction method in which a partition wall mainly made of a perovskite-type Li ion conductive solid electrolyte is brought into contact with one side of the partition wall, a stock solution containing a Li component and an impurity component, and the other side of the partition wall is brought into contact with a recovered solution; and in this state, an electric field is applied to the partition wall so that the stock solution side is positive and the recovered solution side is negative, thereby selectively passing the Li component on the stock solution side through the partition wall in the form of Li ions and extracting them into the recovered solution side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-81953 [Patent Document 2] Japanese Patent Application Publication No. 10-102270 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the techniques described in Patent Documents 1 and 2, lithium ions are efficiently recovered from a source solution containing lithium ions using a lithium ion conductor. However, there is a need to further reduce the cost of recovering lithium ions, and there is a demand for further improvement in the efficiency of lithium recovery.

[0006] An object of the present invention is to provide a lithium recovery device and a lithium recovery method that can recover lithium ions with high efficiency from a lithium ion extract extracted from a processing member of a lithium secondary battery. [Means for solving the problem]

[0007] The present invention provides the following methods. [1] A lithium recovery device that recovers lithium in a recovery solution by transferring lithium ions from a lithium ion extract extracted from a processing component of a lithium secondary battery to a recovery solution that is an aqueous solution, a lithium permselective membrane installed in a treatment tank so as to separate the lithium ion extract from the recovered liquid, with the lithium ion extract on one main surface side and the recovered liquid on the other main surface side; a mesh-shaped first electrode fixed to the one main surface side of the lithium permselective membrane; a mesh-shaped second electrode fixed to the other main surface of the lithium permselective membrane; a storage tank for the lithium ion extract; an extractant pipe provided between the storage tank and the treatment tank; a temperature control means selected from at least a temperature control means A for controlling the temperature of the lithium ion extract and a temperature control means B for controlling the temperature of the lithium permselective membrane; A lithium recovery device comprising: [2] The lithium recovery device according to the above [1], wherein the temperature adjusting means A adjusts the temperature in a space accommodating at least the storage tank, the extracting liquid pipe, and the treatment tank. [3] The lithium recovery device according to the above [1] or [2], further comprising a recovery liquid tank for storing the recovery liquid, and a recovery liquid pipe provided between the treatment tank and the recovery liquid tank, wherein the temperature adjustment means A adjusts the temperature in at least the recovery liquid tank and a space accommodating the recovery liquid pipe. [4] The lithium recovery device according to any one of the above [1] to [3], wherein the temperature adjusting means A is provided in contact with at least one of the storage tank and the extraction liquid pipe. [5] The lithium recovery device according to the above [3] or [4], wherein the temperature control means A is provided in contact with at least one of the recovery liquid tank and the recovery liquid piping. [6] The lithium recovery device according to the above [4] or [5], wherein the temperature adjustment means A is a heat exchanger. [7] The lithium recovery device according to any one of the above [3] to [6], wherein the storage tank comprises a first storage tank and a second storage tank, and the recovery liquid tank comprises a first recovery liquid tank and a second recovery liquid tank. [8] The lithium recovery device according to [7] above, wherein a lithium ion extract is continuously or intermittently supplied to the first storage tank or the second storage tank, and pure water is continuously or intermittently supplied to the first recovery liquid tank or the second recovery liquid tank. [9] The lithium recovery device according to any one of the above [1] to [8], further comprising a circulation means for circulating the lithium ion extract between the storage tank and the treatment tank.

[10] The lithium recovery device according to any one of the above [1] to [9], further comprising a concentration means for increasing the lithium ion concentration of the lithium ion extract.

[11] The lithium recovery device according to any one of the above [1] to

[10] , wherein the lithium permselective membrane has been subjected to a surface lithium adsorption treatment.

[12] The lithium recovery device according to any one of the above [1] to

[11] , comprising a pH adjusting means for adjusting the pH of the lithium ion extract.

[13] A method for recovering lithium from a lithium ion extract extracted from a processing component of a lithium secondary battery, using a lithium permselective membrane, and adjusting at least one of the temperature of the lithium ion extract and the temperature of the lithium permselective membrane to 30°C or higher and 100°C or lower, to transfer lithium ions to a recovery solution that is an aqueous solution, thereby recovering lithium in the recovery solution.

[14] The method for recovering lithium according to the above

[13] , which comprises adjusting the temperature of the recovery solution to 30°C or higher and 100°C or lower. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a lithium recovery device and a lithium recovery method that can recover lithium ions with high efficiency from a lithium ion extract extracted from a processing member of a lithium secondary battery. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of a lithium recovery device according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing the configuration of a lithium recovery device according to an embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing the configuration of a lithium recovery device according to an embodiment of the present invention. [Figure 4] 1 is a schematic diagram showing the configuration of a lithium recovery device according to an embodiment of the present invention. [Figure 5] 1 is a graph showing the change in current value over time in Examples 1 and 2 and Comparative Example 1. [Figure 6] 1 is a graph showing the change over time in the amount of recovered lithium in Examples 1 and 2 and Comparative Example 1. [Figure 7] 10 is a graph showing the change over time in current value and lithium recovery rate in Example 5. [Figure 8] 1 is a graph showing the change over time in current value and lithium recovery rate in Examples 6 and 7. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a lithium recovery device according to one embodiment of the present invention (hereinafter referred to as "this embodiment") will be described. Note that this lithium recovery device according to one embodiment of the present invention is merely one embodiment of the lithium recovery device of the present invention, and the present invention is not limited to this lithium recovery device according to one embodiment of the present invention. Furthermore, in this specification, lithium means both lithium and lithium ions, and should be interpreted appropriately unless technical contradictions arise.

[0011] [Lithium recovery device] The lithium recovery device of this embodiment is a lithium recovery device that recovers lithium by transferring lithium ions from a lithium ion extract solution extracted from a processing component of a lithium secondary battery to a recovery solution, which is an aqueous solution, and includes: a lithium permselective membrane installed in a treatment tank so as to separate the lithium ion extract solution from the recovery solution, with the lithium ion extract solution on one main surface side and the recovery solution on the other main surface side; a first mesh electrode fixed to one main surface side of the lithium permselective membrane; a second mesh electrode fixed to the other main surface side of the lithium permselective membrane; a storage tank for the lithium ion extract solution; an extract solution pipe installed between the storage tank and the treatment tank; and temperature control means selected from temperature control means A for controlling the temperature of at least the lithium ion extract solution and temperature control means B for controlling the temperature of the lithium permselective membrane. The first and second electrodes may be fixed to the main surfaces of the lithium permselective membrane, and there are no particular limitations on the form thereof. However, from the viewpoint of improving the lithium ion pass rate, it is preferable that at least one of these electrodes be in close contact with the main surface side of the lithium permselective membrane. From the viewpoint of versatility in operation of the device, the lithium recovery device of the present embodiment preferably further comprises a recovery liquid tank for storing the recovery liquid, and a recovery liquid piping provided between the treatment tank and the recovery liquid tank, and preferably comprises a recovery liquid temperature adjustment means for adjusting the temperature of the recovery liquid.

[0012] (Lithium ion extract) The lithium ion extract used in the lithium recovery device of this embodiment is a lithium ion extract extracted from a processing member of a lithium secondary battery, and is not particularly limited as long as it is extracted from the processing member. For example, it may be extracted from a processing member of a lithium secondary battery containing a sulfide-based solid electrolyte, i.e., a lithium ion extract containing a sulfide-based solid electrolyte. In this embodiment, the sulfide-based solid electrolyte refers to a solid electrolyte containing at least lithium and sulfur elements, and representative examples include those containing lithium, sulfur, and phosphorus, such as Li2S-P2S5, and further containing halogen elements, such as Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-LiI-LiBr, Li2S-P2S5-Li2O-LiI, and Li2S-SiS2-P2S5-LiI. The lithium ion extract used in this embodiment can obtain the effect of the present invention, that is, to efficiently recover lithium ions, as long as it is an extract containing lithium ions, and therefore, for example, concentrated water obtained by concentrating seawater, salt lake brine, mining wastewater, geothermal water, or a combination of any of these by means of evaporation or the like may be used. Furthermore, any one of these may be used alone, or a combination of two or more of them may be used.

[0013] The processing components of a lithium secondary battery containing a sulfide-based solid electrolyte contain lithium and sulfur, derived from, for example, raw materials (unreacted raw materials) used in the manufacturing process of the sulfide-based solid electrolyte, reaction by-products, etc. The lithium recovery device of this embodiment is intended to efficiently recover lithium from the processing components containing lithium and sulfur. A representative example of the lithium ion extract extracted from the processing components of a lithium secondary battery containing a sulfide-based solid electrolyte is an aqueous solution of sulfide-based solid electrolyte obtained by dissolving the sulfide-based solid electrolyte used in the lithium secondary battery in an alkaline aqueous solution.

[0014] Preferred examples of the alkaline component of the alkaline aqueous solution for dissolving the sulfide-based solid electrolyte include sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, calcium hydroxide, barium hydroxide, europium(II) hydroxide, thallium(I) hydroxide, and guanidine. These alkaline components may be used alone or in combination of two or more. From the viewpoint of ease of dissolving the sulfide-based solid electrolyte, sodium hydroxide, potassium hydroxide, and calcium hydroxide are more preferred as the alkaline component.

[0015] The recovery liquid used in the lithium recovery device of this embodiment is not particularly limited as long as it is an aqueous solution that can dissolve lithium ions, and can be appropriately selected depending on the form of lithium to be finally obtained. For example, a preferred recovery liquid is water such as pure water or ion-exchanged water.

[0016] (Temperature control means) The temperature control means used in the lithium recovery device of this embodiment is a temperature control means selected from at least a temperature control means A that controls the temperature of the lithium ion extract and a temperature control means B that controls the temperature of the lithium permselective membrane. The lithium recovery device of this embodiment may have temperature control means A alone, temperature control means B alone, or both temperature control means A and B, but it is preferable to have temperature control means B, and it is more preferable to have both temperature control means A and B. First, the temperature adjusting means A will be described.

[0017] (Temperature control means A) The temperature adjusting means A is not particularly limited as long as it can adjust at least the temperature of the lithium ion extract. Furthermore, it is preferable that the temperature adjusting means A can adjust the temperature of the recovered solution as well as the temperature of the lithium ion extract. By adjusting the temperature of the recovered solution as well as the temperature of the lithium ion extract, the temperature of the lithium ion extract can be adjusted with higher precision, thereby increasing the amount of lithium ions flowing through the lithium permselective membrane and enabling more efficient recovery of lithium ions from the lithium ion extract.

[0018] In this embodiment, from the viewpoint of recovering lithium ions with higher efficiency, the temperature adjustment means A preferably has a function of adjusting the temperature of the lithium ion extract to within a range of 30°C or higher and 100°C or lower, more preferably 40°C or higher and 95°C or lower, and even more preferably 50°C or higher and 90°C or lower. In this specification, the upper and lower limits of the numerical range for the temperature of the lithium ion extract include a range of less than ±2.0° C. The same applies to the temperature of the recovery solution and the temperature of the lithium permselective membrane, which will be described later.

[0019] Adjusting the temperature of the lithium ion extract within the above range increases the amount of lithium ions flowing through the lithium permselective membrane, allowing for efficient recovery of lithium ions from the lithium ion extract. This is presumably due to the following reasons, although it is not intended to limit the present invention. If the temperature of the lithium ion extract is not adjusted, the frequency of collisions of lithium ions with the surface of the lithium permselective membrane remains low, the amount of lithium ions flowing through the lithium permselective membrane does not increase, and the recovery rate of lithium from the lithium ion extract may decrease. On the other hand, adjusting the temperature of the lithium ion extract solution increases the frequency of lithium ion collisions with the surface of the lithium permselective membrane in contact with the lithium ion extract solution. This also facilitates dissociation of hydrated lithium ions in the lithium extract solution, potentially increasing the lithium ion concentration at the surface of the lithium permselective membrane. This results in a large lithium ion concentration gradient near the surface of the lithium permselective membrane. This increases the lithium ion concentration in the crystals of the lithium permselective membrane as well as in the grain boundaries. The synergistic effect of this increase in the lithium ion concentration in the crystals of the lithium permselective membrane and the increase in the lithium ion concentration in the grain boundaries is thought to result in the diffusion of lithium ions with higher conductivity. As a result, it is thought that the amount of lithium ions flowing through the lithium permselective membrane can be significantly increased compared to when the temperature of the lithium permselective membrane is adjusted instead of the lithium ion extract solution.

[0020] The temperature adjusting means A is preferably capable of adjusting the temperature within the space accommodating at least the storage tank, the extracting liquid pipe, and the treatment tank. That is, it is preferable that at least the storage tank, the extracting liquid pipe, and the treatment tank are arranged in the same closed space. By using the air in the space, the temperatures of at least the storage tank, the extracting liquid pipe, and the treatment tank can be adjusted simultaneously and stably. Furthermore, the temperature of the lithium ion extract can be adjusted through at least the storage tank, the extracting liquid pipe, and the treatment tank. Therefore, the temperature of the lithium ion extract can be adjusted more efficiently, stably, and reliably.

[0021] As described above, the lithium recovery apparatus of this embodiment preferably further includes a recovery liquid tank for storing the recovery liquid and a recovery liquid piping provided between the treatment tank and the recovery liquid tank. The temperature control means A preferably can also adjust the temperature of the recovery liquid, and preferably can adjust the temperature within at least the space accommodating the recovery liquid tank and the recovery liquid piping. That is, at least the recovery liquid tank and the recovery liquid piping are preferably arranged in the same closed space. By using air in the space, the temperatures of at least the recovery liquid tank and the recovery liquid piping can be simultaneously and stably adjusted. Furthermore, since the temperature of the recovery liquid can be adjusted through at least the recovery liquid tank and the recovery liquid piping, the temperature of the recovery liquid can be adjusted more efficiently, stably, and reliably. As a result, by adjusting the temperatures of the lithium ion extract and the recovery liquid, the temperature of the lithium permselective membrane can also be adjusted. This allows for more efficient recovery of lithium ions from the lithium ion extract. From the same viewpoint, it is also preferable that the temperature adjusting means A can adjust the temperature in the space accommodating the storage tank, the extraction liquid piping, the treatment tank, and further the recovery liquid tank and recovery liquid piping. In the portion where temperature control is not performed, it is preferable to take measures to keep the temperature warm to prevent a drop in temperature.

[0022] When the temperature in the space is adjusted, the temperature adjustment means A is preferably an air conditioner. The use of an air conditioner makes it possible to maintain a uniform temperature in the space, easily adjust the temperature of the lithium ion extract, increase the amount of lithium ions flowing through the lithium permselective membrane, and enable highly efficient recovery of lithium ions from the lithium ion extract.

[0023] The temperature control means A can be provided in contact with at least one of the storage tank and the extract piping. This allows the temperature of at least one of the storage tank and the extract piping to be directly controlled, thereby enabling the temperature of the lithium ion extract to be controlled with higher precision. For example, when the temperature control means A is a heat exchanger, the temperature control means A can be provided in contact with at least one of the storage tank and the extract piping by closely contacting the heat exchanger with at least one of the storage tank and the extract piping. There are no particular limitations on the type of heat exchanger, and it may be selected appropriately depending on the usage mode. For example, a jacket-type or heater-type heat exchanger using electricity or a heat medium may be used. For example, it is preferable to use a jacket-type heat exchanger for the extract piping and a heater-type heat exchanger for the storage tank.

[0024] The temperature control means A can be provided in contact with at least one of the recovery liquid tank and the recovery liquid piping. This allows the temperature of the recovery liquid to be controlled with even higher precision. Furthermore, since the temperature of the lithium permselective membrane can be controlled with high precision by both the recovery liquid and the lithium ion extract, lithium ions can be recovered more efficiently from the lithium ion extract. For example, when the temperature control means A is a heat exchanger, the temperature control means A can be provided in contact with at least one of the recovery liquid tank and the recovery liquid piping by closely contacting the heat exchanger with at least one of the recovery liquid tank and the recovery liquid piping. As the heat exchanger provided in the recovery liquid tank and the recovery liquid piping, the heat exchangers described above as being capable of being provided in the extraction liquid tank and the extraction liquid piping can be used.

[0025] When the temperature adjustment means A is provided in contact with at least one of the storage tank and the extract piping, or when the temperature adjustment means A is provided in contact with at least one of the recovery tank and the recovery piping, it is preferable that the temperature adjustment means A is a heat exchanger. This makes it possible to directly adjust the temperature of at least one of the storage tank and the extract piping, and at least one of the recovery tank and the recovery piping, using various heat media, and to adjust the temperatures of the lithium ion extract and the recovery liquid with higher accuracy. For example, the temperature of the lithium ion extract may be adjusted via a heat exchanger using hot water heated by utilizing waste heat from a boiler or other plant.

[0026] The temperature adjustment means A can be provided in contact with at least one of the storage tank and the extraction liquid piping, and can also be provided in contact with at least one of the recovery liquid tank and the recovery liquid piping, in order to more directly adjust the lithium ion extraction liquid and recovery liquid and recover lithium ions more efficiently. Furthermore, from the viewpoint of recovering lithium ions more efficiently, the temperature control means A is preferably provided in contact with at least one of the storage tank and the extractant piping, and at least one of the recovery liquid phase and the recovery liquid piping, which can more directly control the temperature. For the extractant piping, it is preferably provided at least on the piping from the storage tank to the treatment tank. For the recovery liquid piping, it is preferably provided at least on the piping from the treatment tank to the recovery liquid tank. It is also preferably provided on the storage tank and the extractant piping, and preferably on the recovery liquid phase and the recovery liquid piping. From the same viewpoint, a device that controls the temperature in the space accommodating the storage tank, the extractant piping, the treatment tank, etc., can be used in combination with a device that is provided in contact with at least one of the storage tank and the extractant piping. For example, the temperature in the space accommodating the storage tank, the extractant piping, the treatment tank, and the recovery liquid tank and the recovery liquid piping can be adjusted by an air conditioning device, and a heat exchanger can be provided in contact with at least one of the storage tank and the extractant piping, and at least one of the recovery liquid tank and the recovery liquid piping to adjust the temperature of the lithium ion extract and the recovery liquid.

[0027] (Temperature adjustment means B) The lithium recovery device of this embodiment has, as temperature control means, a temperature control means selected from the above-mentioned temperature control means A and temperature control means B that controls the temperature of the lithium permselective membrane. Among these, the temperature control means preferably has temperature control means B that controls the temperature of the lithium permselective membrane. This is because directly controlling the temperature of the lithium permselective membrane makes it easier for lithium ions to flow through the lithium permselective membrane, thereby enabling more efficient recovery of lithium ions.

[0028] In this embodiment, from the viewpoint of recovering lithium ions with higher efficiency, the temperature adjusting means B preferably has a function of adjusting the temperature of the lithium permselective membrane within a range of 30° C. to 100° C., more preferably 40° C. to 95° C., and even more preferably 50° C. to 90° C. In other words, this is the same as the preferred range of the temperature of the lithium ion extract adjusted by the temperature adjusting means A.

[0029] The temperature control means B is not particularly limited as long as it is a means capable of controlling the temperature of the lithium permselective membrane, and may be appropriately selected from the heat exchangers described above as possible means for use as the temperature control means A. Among these, considering ease of installation on the lithium permselective membrane, heat exchangers such as electric jacket types and heater types are preferred, and they should be installed so as to be in contact with the lithium permselective membrane. There are also no particular limitations on the shape of the heat exchanger, and it may be appropriately selected depending on the shape of the lithium permselective membrane; for example, a rod-shaped or plate-shaped one may be used.

[0030] By employing the temperature control means B, the temperature of not only the lithium permselective membrane but also the lithium ion extract and recovery solution in contact with the lithium permselective membrane increases. On the other hand, by employing the temperature control means A, the temperature of not only the lithium ion extract but also the lithium permselective membrane increases. Therefore, by employing either the temperature control means A or B, the temperature of an object that is not originally the target of temperature control can be adjusted, thereby achieving an excellent and efficient lithium ion recovery effect. In particular, from the viewpoint of efficient lithium ion recovery, it is preferable to employ the temperature control means A and B in combination.

[0031] (Storage tanks and treatment tanks) The storage tank may include a first storage tank and a second storage tank. This allows lithium ions to be efficiently recovered from a larger amount of lithium ion extract. Since the amount of recovered liquid may also be large, the recovery tank may include a first recovery tank and a second recovery tank. An embodiment having multiple storage tanks and recovery tanks, such as a first storage tank, a second storage tank, a first recovery tank, and a second recovery tank, will be described in detail in the description of FIG. 3 below. The mode may be appropriately selected depending on the amount of lithium ion extract to be treated, and three or more storage tanks or recovery tanks may be provided depending on the amount to be treated.

[0032] The lithium recovery device of this embodiment may include, as the extractant piping provided between the storage tank and the treatment tank, at least an extractant piping capable of supplying a lithium ion extract from the storage tank to the treatment tank, but may also include a circulation means for circulating the lithium ion extract between the storage tank and the treatment tank. This can further improve the recovery rate of lithium ions from the lithium ion extract. That is, the extractant piping provided between the storage tank and the treatment tank may include a piping for supplying the lithium ion extract from the storage tank to the treatment tank and a piping for returning the lithium ion extract from the treatment tank to the storage tank. In addition, in order to smoothly circulate the lithium ion extract, a pump can be provided in the extract piping as necessary.

[0033] Furthermore, when the recovery liquid piping is provided between the recovery liquid tank and the treatment tank, it is sufficient that the recovery liquid piping includes at least a recovery liquid piping that can recover the recovery liquid from the treatment tank to the recovery liquid tank, but from the viewpoint of versatility in the operation of the lithium recovery device, a circulation means that circulates the recovery liquid between the recovery liquid tank and the treatment tank may be further provided. That is, the recovery liquid piping provided between the recovery liquid tank and the treatment tank may include a piping for recovering the recovery liquid from the treatment tank to the recovery liquid tank and a piping for returning the recovery liquid from the recovery liquid tank to the treatment tank. In addition, in order to smoothly circulate the recovered liquid, a pump can be provided in the recovered liquid piping as necessary.

[0034] The lithium recovery device of this embodiment can further include a concentration means for increasing the lithium ion concentration of the lithium ion extract. This allows lithium ions to be recovered more efficiently from the lithium ion extract. For example, the lithium ion concentration of the lithium ion extract can be increased by evaporating water from the extract.

[0035] (pH control means) The lithium recovery device of this embodiment may be equipped with a pH control means. The pH control means used in the lithium recovery device of this embodiment for adjusting the pH of the lithium ion extract is not particularly limited as long as it is capable of adjusting the pH of the lithium ion extract. The pH control means for the lithium ion extract preferably has the function of adjusting the pH to a range of 12 to 14, and more preferably has the function of adding an alkaline aqueous solution to the lithium ion extract. This allows for efficient recovery of lithium ions even from a solution extracted from a processing component of a lithium secondary battery containing sulfur, for example, a sulfide-based solid electrolyte. Furthermore, by combining this with the above-mentioned temperature control means, lithium ions can be even more efficiently recovered from the lithium ion extract. In this specification, pH refers to a value measured using a pH meter capable of measuring the hydrogen ion exponent of an aqueous solution, and a pH meter may be used as the pH control means. Furthermore, in this specification, when referring to a pH of 12 or higher and 14 or lower, a pH of 12 includes a value of 11.5 or higher but lower than 12.5, and a pH of 14 includes a value of 13.5 or higher but lower than 14.5, and essentially means a range of 11.5 or higher but lower than 14.5.

[0036] The reason why lithium ions can be efficiently recovered even from a solution extracted from a processing component of a lithium secondary battery containing sulfur, for example, a sulfide-based solid electrolyte, is presumed to be due to the following reasons, although this does not limit the scope of the present invention: When the pH of the lithium ion extract is not adjusted, OH groups that contribute to the alkalinity of the adjusted solution gradually increase with the migration of lithium ions. - (hydroxide ions) decreases, and the efficiency of lithium recovery also decreases. - Due to the lack of hydroxide ions, the lithium ion conducting sites on the surface of the lithium permselective membrane are + This is thought to be because they are replaced with OH (protons) and prevent the permeation of lithium ions. -The reaction with PSO4 is also thought to be a cause of the decrease in lithium recovery. 3- The phosphorus-sulfur complex oxide ions shown in the figure are generated, and these phosphorus-sulfur complex oxide ions are gradually hydrolyzed to finally decompose into phosphate ions and sulfate ions. These sulfate ions are generated via sulfite ions, thiosulfate ions, etc. Therefore, a large amount of thiosulfate ions is present in the lithium ion extract, and during lithium exchange on the surface of the lithium permselective membrane, the thiosulfate ions are decomposed to generate fine colloidal sulfur particles. The presence of this sulfur on the surface of the lithium permselective membrane may be responsible for the reduced lithium recovery rate. On the other hand, by adjusting the pH of the lithium ion extract, OH - This eliminates the shortage of hydroxide ions and also suppresses the generation of colloidal sulfur particles, which is thought to enable efficient recovery of lithium ions.

[0037] Preferred examples of alkaline components of the alkaline aqueous solution used to adjust the pH of the lithium ion extract include sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, calcium hydroxide, barium hydroxide, europium(II) hydroxide, thallium(I) hydroxide, and guanidine. These alkaline components may be used alone or in combination of two or more. Among these, sodium hydroxide is more preferred from the viewpoint of being able to quickly adjust the pH of the lithium ion extract.

[0038] The pH of the lithium ion extract may be adjusted by the pH control means before or during the recovery of lithium, and may be adjusted at any stage of the recovery of lithium as long as it does not interfere with the achievement of the object of the present invention. From the viewpoint of maintaining the performance of the lithium permselective membrane, it is preferable to adjust the pH of the lithium ion extract during the recovery of lithium, and it is preferable to adjust the pH of the lithium ion extract so that it is at least temporarily within the above-mentioned range, i.e., the range of 12 to 14, during the recovery of lithium, and it is particularly preferable to adjust the pH so that it is within the above-mentioned range from the start to the end of the recovery of lithium. If the pH of the lithium ion extract before adjusting the pH is, for example, within the aforementioned range of pH 12 or more and pH 14 or less, it is not necessary to adjust the pH of the lithium ion extract, and if the pH of the lithium ion extract before adjusting the pH is, for example, close to the aforementioned range of pH 12 or more and pH 14 or less, the pH of the lithium ion extract may be adjusted by diluting the lithium ion extract with water or the like. Furthermore, if the sulfide-based solid electrolyte is dissolved using a strong alkaline aqueous solution, it is not necessary to adjust the pH by adding a strong alkaline aqueous solution to the lithium ion extract.

[0039] The pH control means can be used to control lithium ion extracts extracted from a wide range of liquids, such as environmental water such as seawater and treatment materials for lithium secondary batteries containing a sulfide-based solid electrolyte, and the pH can be adjusted as desired. From the viewpoint of efficiently recovering lithium ions, the pH range of the lithium ion extract adjusted by the pH control means is preferably within the above-mentioned range, i.e., a range of 12 to 14.

[0040] From the viewpoint of more efficiently recovering lithium from the lithium ion extract, the lithium ion extract may be oxidized with an oxidizing agent. Preferred examples of the oxidizing agent include hydrogen peroxide, permanganic acid, hypochlorous acid, dichromate, fluorine, hydroxy radical, ozone, and chlorine. From the viewpoint of more efficiently recovering lithium from the lithium ion extract, the preferred oxidizing agent is hydrogen peroxide.

[0041] (About Figures 1 to 4) Next, the lithium recovery device according to this embodiment will be described with reference to FIGS. 1 to 4 are diagrams illustrating a preferred embodiment of the specific configuration of the lithium recovery device 1 according to this embodiment. The lithium recovery device 1 uses a lithium permselective membrane 10 that selectively allows lithium to pass through. A mesh-like first electrode 11 and a mesh-like second electrode 12 are formed on both main surfaces of the flat lithium permselective membrane 10. This structure is provided in a treatment tank 8, and lithium ions (Li + The lithium ion extract 100, which is an aqueous solution containing lithium ions 50, and the recovery solution 200, which is an aqueous solution from which lithium is recovered, are separated by this lithium permselective membrane 10 in the treatment tank 8. The lithium ion extract 100 contains monovalent cations other than the lithium ions 50 (here, sodium ions (Na + ) 51) is also included along with lithium ion 50.

[0042] 1 and 2 show an embodiment in which the lithium recovery apparatus 1 includes a storage tank 71 for a lithium ion extract, extract pipes 74 and 75 provided between the storage tank 71 and the treatment tank 8, and a temperature adjustment means 85 for adjusting the temperature of the lithium ion extract 100. The temperature adjustment means 85 is a means for adjusting the temperature of the lithium ion extract, and corresponds to the temperature adjustment means A. 1 shows an embodiment in which the temperature adjusting means 85 is an air conditioner 85 that adjusts the temperature in the space that houses the storage tank 71, the extraction liquid pipes 74 and 75, the treatment tank 8, the recovery liquid tank 72, and the recovery liquid pipes 76 and 77. The air conditioner 85 may include an indoor unit 85A, an outdoor unit 85B, and a heat medium 85C circulating between the indoor unit 85A and the outdoor unit 85B. The indoor unit 85A includes a heat exchanger 851A used to adjust the temperature in the lithium recovery apparatus. Meanwhile, the outdoor unit 85B includes a heat exchanger 851B that exchanges heat between the heat medium 85C and outside air, and a compressor 852B that compresses the heat medium.

[0043] In Figure 1, the air conditioning device 85 is shown as being capable of adjusting the temperature within the space housing the storage tank 71, the extraction liquid pipes 74 and 75, the treatment tank 8, the recovery liquid tank 72, and the recovery liquid pipes 76 and 77, but as already mentioned, it may also be capable of adjusting the temperature within the space housing at least the storage tank 71, the extraction liquid pipes 74 and 75, and the treatment tank 8, or it may be capable of adjusting the temperature within the space housing at least the recovery liquid tank 72, and the recovery liquid pipes 76 and 77.

[0044] 2 also shows that the temperature control means 85 is a heat exchanger, and that the heat exchanger is provided in contact with the storage tank 71, the extractant pipe 75, the recovery liquid tank 72, and the recovery liquid pipe 76. In FIG. 2, heat exchangers 855, 853, 856, and 854 are provided in contact with the storage tank 71, the extractant pipe 75, the recovery liquid tank 72, and the recovery liquid pipe 77, respectively. However, in this embodiment, the heat exchangers may be provided in contact with either the storage tank 71 or the extractant pipe 75, or with either the recovery liquid tank 72 or the recovery liquid pipe 77, or with either the extractant pipe 74 or 75, the extractant pipes 74 and 64, or the recovery liquid pipes 76 or 77, or with the recovery liquid pipes 76 and 77. From the viewpoint of more efficient temperature control, it is preferable that the heat exchangers be provided in the pipes supplying the treatment tank 8, i.e., the extractant pipe 75 and the recovery liquid pipe 77. Other preferred embodiments are as described above.

[0045] 1 and 2 show an embodiment in which the lithium recovery apparatus 1 includes a circulation means between the treatment tank 8 and the storage tank 71, and a circulation means between the treatment tank 73 and the recovery liquid tank 72. That is, the lithium ion extract 100 is circulated using the extract pipes 74 and 75 and the pumps 81 and 82, and the recovery liquid 200 is circulated using the recovery liquid pipes 76 and 77 and the pumps 83 and 84. This makes it possible to treat a large amount of the lithium ion extract 100 without increasing the size of the treatment tank 73, the lithium permselective membrane 10, etc. The storage tank 71, the extract pipes 74 and 75, the recovery liquid tank 72, and the recovery liquid pipes 76 and 77 can be provided in any configuration.

[0046] 3 shows an embodiment having two storage tanks 7 and a recovery liquid tank 8 in FIG. 1, specifically, storage tank 71 for the lithium ion extract has a first storage tank 71A and a second storage tank 71B corresponding to extraction liquid pipes 74 and 75, respectively, and recovery liquid tank 72 has a first recovery liquid tank 72A and a second recovery liquid tank 72B corresponding to recovery liquid pipes 76 and 77, respectively. By adopting such an embodiment, the lithium ion extract supplied from storage tank 71 to treatment tank 8 and the lithium ion extract returned from treatment tank 8 to storage tank 71 are not mixed, and the recovery liquid returned from treatment tank 8 to recovery liquid tank 72 and the recovery liquid supplied from recovery liquid tank 72 to treatment tank 8 are not mixed. Therefore, the concentration gradient between the lithium ion extract 100 and the recovery liquid 200 in the treatment tank 8 can be made larger, making it possible to recover lithium ions more efficiently and accommodate larger lithium permselective membranes 10, etc., while also making it possible to treat large amounts of lithium extract 100 without increasing the size.

[0047] Furthermore, for example, by adopting the embodiment shown in FIG. 3 and continuously or intermittently supplying the lithium ion extract 100 to the treatment tank 8 via the second storage tank 71B and continuously or intermittently supplying pure water to the treatment tank 8 via the second recovery liquid tank 72B, the concentration gradient can be made even larger, and it is therefore possible to recover lithium ions in a single pass like a circulation system without circulating the lithium ion extract and recovery liquid.

[0048] When the lithium ion extract 100 is circulated using pumps 81 and 82 during the lithium ion recovery process, a large volume of the lithium ion extract 100 can be processed without the need to increase the size of the treatment tank 8 (lithium permselective membrane 10, etc.). In this case, the total volume of the recovery liquid 200 from which the lithium ions are recovered must be increased, and a large-capacity recovery liquid tank 72 is preferably used. For this reason, the recovery liquid 200 is also preferably circulated between the recovery liquid tank 72 and the treatment tank 8 using pumps 83 and 84. A smaller total volume of the recovery liquid 200 can increase the lithium concentration, while a larger total volume can increase the total amount of recovered lithium ions. For example, the total volume of the recovery liquid 200 can be approximately half the total volume of the lithium ion extract 100.

[0049] 3, in addition to an air conditioner 85 (indoor unit 85A, outdoor unit 85B, and heat medium 85C) which is temperature adjustment means A, a heater 86 is provided as temperature adjustment means B. In this way, the lithium recovery device may be provided with temperature adjustment means B in addition to temperature adjustment means A. Temperature adjustment means B may be provided adjacent to or in contact with the lithium permselective membrane. A temperature adjustment device using a planar or rod-shaped heat medium may also be used so as to face the lithium permselective membrane in a position that does not obstruct the flow of the electrodes or liquid. When heater 86 is provided, it is preferable to provide it so as to be in contact with the side surface of the lithium permselective membrane, as shown in Fig. 3. In Fig. 3, rod-shaped heater 86 is shown to be provided so as to be in contact with the front side surface of the plate-shaped lithium permselective membrane, and although it is not visible that it is provided on the back side surface, it is preferable that heater 86 be provided so as to be in contact with the back side surface as well.

[0050] In the lithium recovery device shown in FIG. 4, the storage tank 71, the recovery liquid tank 72, and the treatment tank 8 are each housed in a storage chamber, which prevents outside air from entering and makes it easier to adjust the temperature inside each tank. Heat exchangers 857 to 859 can be provided in the storage chambers that house the storage tank 71, the recovery liquid tank 72, and the treatment tank 8, respectively, and these heat exchangers make it possible to more accurately adjust the temperature in each tank. Note that the heat exchanger may be provided in each tank, as shown in FIG. 2.

[0051] In Fig. 4, each of the storage tank 71, the recovery liquid tank 72, and the treatment tank 8 is sealed with a sealing lid for sealing the tank. By sealing the tank with a sealing lid in this way, it becomes easier to more accurately adjust the temperature inside each tank. By more accurately adjusting the temperature inside each tank, the recovery rate of lithium ions is improved.

[0052] When each tank is sealed with a sealing lid, a mechanism for venting gases that may fill the tank (pressure regulation valves 781 to 784 in FIG. 4 ) may be provided. In particular, in treatment tank 8, chlorine gas, hydrogen gas, and the like may be generated on the electrodes. Therefore, providing a venting mechanism is effective from the viewpoint of recovery efficiency in preventing the generated gases from adhering to the electrode surface, and pressure control is effective from the viewpoint of safety. The type of gas venting mechanism is not particularly limited as long as it can vent the gases generated in each tank. It may be a type such as an exhaust port, or a pressure regulation valve as shown in FIG. 4 may be used. The use of a pressure regulation valve is preferable from the viewpoint of more accurately adjusting the temperature in each tank by ensuring the sealing of each tank, preventing the generated gases from adhering to the electrode surface, and improving the recovery rate of lithium battery material ions. When a pressure regulating valve is employed, the internal pressure of each tank may be adjusted to be kept below a certain pressure simply in consideration of the pressure resistance of each tank, or may be adjusted to be kept within a certain range in order to prevent the generated gas from adhering to the electrode surface. From the viewpoint of improving the recovery rate of lithium ions, it is preferable to adjust the internal pressure of each tank to be kept within a certain range. The type of pressure regulating valve is not particularly limited, and a check valve type, for example, may be used. Furthermore, although Fig. 4 shows that the exhaust from the pressure regulating valve is performed inside the storage chamber, the exhaust from the pressure regulating valve may be performed outside the storage chamber, or a separate exhaust mechanism (pressure regulating valve, exhaust port, etc.) may be provided in the storage chamber. Furthermore, although the storage tank 71, the recovery liquid tank 72, and the processing tank 8 are stored in a space in Figs. 1 and 3, a mechanism for exhausting gas from the space may be provided.

[0053] (First electrode and second electrode) The structure and materials of the first electrode 11 and the second electrode 12 are the same as those described in WO2015 / 020121. In the structure of FIG. 1, as described in WO2015 / 020121, a current collector made of a carbon felt sheet or the like may be interposed between the mesh-like first electrode 11, second electrode 12 and the lithium permselective membrane 10. Similarly, the area of ​​the lithium permselective membrane 10 can be increased by using an adhesive layer.

[0054] In this case, the lithium recovery device 1 can be used as a battery that extracts power from the first electrode 11 and the second electrode 12 without applying an external voltage to them (battery mode). In this case, the lithium ions 50 can be moved from the lithium ion extract 100 to the recovery solution 200 (the lithium ions 50 flow as an ion current), and at the same time, a voltage is generated such that the first electrode 11 is negative and the second electrode 12 is positive. On the other hand, by applying a voltage to the first electrode 11 and the second electrode 12 from the outside, the ion current of the lithium ions 50 can be made larger than in the above case (electrodialysis mode). In this case, although power is required, the recovery efficiency of lithium (lithium ions 50) into the recovery solution 200 can be increased.

[0055] (Lithium permselective membrane) The lithium permselective membrane 10 preferably comprises a lithium permselective membrane body 10A made of a superlithium ion conductor (ion conductor) having particularly high ionic conductivity, and a lithium adsorption layer 10B formed as a thin layer on the lithium ion extract 100 side (first electrode 11 side).

[0056] When a super lithium ion conductor is used as the lithium permselective membrane body 10A, the ionic current of lithium ions flowing between the electrodes is increased, thereby improving the lithium recovery efficiency. Here, the lithium ions contained in the aqueous solution exist as lithium hydrate ions with water molecules coordinated around them. Therefore, in order to further increase the ionic current, it is effective to create a situation where water molecules can be easily removed from the surface of the lithium permselective membrane (the interface between the lithium permselective membrane and the lithium ion extract). For this reason, it is preferable that a lithium adsorption layer that adsorbs lithium ions (excluding hydrates) in the lithium ion extract is formed on the surface of the lithium permselective membrane. That is, it is preferable that the lithium permselective membrane is one that has been subjected to a surface lithium adsorption treatment. As the lithium adsorption layer, as will be described later, one formed by modifying the surface of the material that constitutes the lithium permselective membrane is preferred.

[0057] The material constituting the lithium permselective membrane body 10A is specifically lithium lanthanum titanate (Li x ,La y )TiO z (where x=3a-2b, y=2 / 3-a, z=3-b, 0<a≦1 / 6、0≦b≦0.06、x> 0) (hereinafter referred to as LLTO) can be used, and more specifically, Li 0.29 La 0.57 TiO3 (a ≈ 0.1, b ≈ 0) can be used. These materials can be obtained as a sintered body by mixing particles made of this material with a sintering aid or the like and sintering the mixture at high temperatures (1000°C or higher). In this case, the surface of the lithium permselective membrane 10 can be configured as a porous body in which fine particles made of LLTO are bonded (sintered), thereby increasing the effective surface area of ​​the lithium permselective membrane body 10A.

[0058] In addition to the above-mentioned lithium lanthanum titanate, the super lithium ion conductor that can be used as a material for constituting the lithium permselective membrane body 10A includes, for example, Li substituted NASICON (Na Super Ionic Conductor) type crystal. 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12 (where 0≦x≦0.6, 0≦y≦0.6) and the like are also possible.

[0059] The super lithium ion conductor contains lithium as one of its constituent elements, and exhibits ionic conductivity by the movement of lithium ions outside the crystal between lithium sites in the crystal. Lithium ions 50 flow within the lithium permselective membrane body 10A, but sodium ions 51 cannot flow within the lithium permselective membrane body 10A. At this time, it is the lithium ions (Li + ) 50, and lithium hydrate ions present in the lithium ion extract 100 together with the lithium ions 50 cannot enter the lithium sites and therefore do not conduct through the crystal. In this respect, it is the same as the lithium permselective membrane described in WO2015 / 020121.

[0060] Here, if only a large amount of lithium ions 50 are adsorbed onto the surface of the lithium permselective membrane body 10A by the lithium adsorption layer 10B, the water molecules of the lithium hydrated ions are removed during the adsorption, leaving only lithium ions, and therefore the conduction efficiency of the lithium ions 50 (the ionic current flowing through the lithium permselective membrane body 10A) from the lithium ion extract 100 side (one main surface side) of the lithium permselective membrane body 10A to the recovery liquid 200 side (the other main surface side) can be increased.

[0061] The positive electrode and negative electrode are bonded to the right surface (one of the main surfaces) and left surface (the other main surface) of the lithium permselective membrane in FIG. 1, respectively. With this configuration, the right and left surfaces of the lithium permselective membrane are maintained at a constant positive and negative potential, respectively. Metal materials that do not undergo electrochemical reactions in the lithium ion extract or recovery solution can be used as the materials for the positive electrode and negative electrode. Examples of such metal materials that can be used include SUS, Ti, and Ti-Ir alloys.

[0062] Although the materials used as the lithium permselective membrane are solid, they are known to exhibit electrical conductivity due to the flow of lithium ions in a form similar to free electrons within the crystal. Therefore, in the configuration shown in Figure 1, when the positive electrode is at a positive potential and the negative electrode is at a negative potential, lithium ions (positive ions) in the lithium ion extract on the positive electrode side that reach the right surface of the lithium permselective membrane flow from the right surface to the left surface of the lithium permselective membrane by ionic conduction. Lithium ions that reach the left surface of the lithium permselective membrane are collected in the recovery solution. Therefore, after a certain time has passed, the lithium ion concentration in the lithium ion extract decreases, while the lithium ion concentration in the recovery solution increases.

[0063] The lithium adsorption layer 10B is formed as a thin layer on the surface of the lithium permselective membrane body 10A by chemically treating the lithium permselective membrane body 10A. Specifically, it is formed by acid treating one main surface of the lithium permselective membrane body 10A (LLTO), for example by exposing this surface to hydrochloric acid or nitric acid for five days. This treatment causes lithium, which is particularly susceptible to oxidation among the constituent elements of LLTO, to be replaced with hydrogen in the acid, forming H 0.29 La 0.57 It is presumed that a material layer (HLTO) with a composition similar to TiO3 is formed. The formation of the thin surface layer (HLTO) is supported by the X-ray diffraction results in WO2017 / 131051, which show that the lithium permselective membrane body 10A (LLTO) has a peak different from that of the lithium permselective membrane body 10A.

[0064] The H sites in HLTO are originally sites for lithium to enter, so H is particularly likely to be replaced by lithium ions, but is difficult to be replaced by other ions (such as sodium ions 51). Therefore, HLTO functions as the lithium adsorption layer 10B. Furthermore, because HLTO is produced by a reaction with acid, it is formed only on the outermost surface of the lithium permselective membrane body 10A.

[0065] The lithium permselective membrane used in the lithium recovery device of this embodiment preferably has a sintered density of 90% or more and 105% or less. By improving the thermal conductivity of the lithium permselective membrane, the temperature uniformity is improved, and lithium ions can flow more easily across the entire surface of the lithium permselective membrane. As a result, the lithium recovery efficiency is improved. For the same reason, the sintered density is more preferably 91% or more, and even more preferably 93% or more, with the upper limit being more preferably 100% or less, even more preferably 98% or less, and even more preferably 95% or less.

[0066] In this specification, the sintered density of the lithium permselective membrane is the ratio of the bulk density to the theoretical density calculated by the following method, that is, calculated by the following formula. Sintered density (%) = bulk density / theoretical density x 100

[0067] Here, the bulk density is a value (g / cm) calculated from the volume and weight of the lithium permselective membrane after measuring its weight and dimensions. 3 ) The theoretical density is a density that can be determined depending on the material that constitutes the lithium permselective membrane. Specifically, the number of molecules per unit lattice of the material that constitutes the lithium permselective membrane is Z, the assumed molecular weight is M (g / mol), and the volume of the unit lattice is V (Å 3 ) is calculated using the following formula: Theoretical density (g / cm 3 )=1.66×m×z / v

[0068] For example, the lithium permselective membrane may be made of the above-mentioned lithium lanthanum titanate (Li x ,La y )TiO z (where x=3a-2b, y=2 / 3-a, z=3-b, 0<a≦1 / 6、0≦b≦0.06、x> 0) (hereafter referred to as LLTO) is used, the number of molecules per unit cell of LLTO, z, is 2, the assumed molecular weight, M, is 177 g / mol, and the volume of the unit cell of the crystal, v, measured by powder X-ray diffraction (XRD), is 116 Å. 3 ), the theoretical density of LLT is 5.07 (g / cm3 ) is calculated as follows.

[0069] (Preparation of lithium ion extract) In this embodiment, the lithium ion extract can be prepared using a commonly known electrodialysis device. + ), sodium ions (Na + ) and other monovalent cations pass through the cation exchange membrane and move to the negative electrode (treatment liquid) side, while other polyvalent cations have difficulty passing through the cation exchange membrane, and negative ions do not pass through the cation exchange membrane. For this reason, the lithium ions (Li + ) moves from the raw material liquid to the treatment liquid. At the negative electrode, OH is generated by the electrolysis of water. - Therefore, by using an electrodialysis device, lithium ions in the raw material solution can be transferred to the treatment solution, and at the same time, the treatment solution can be made alkaline. However, in this electrodialysis treatment, sodium ions (Na ions), which are monovalent positive ions, are also generated along with the lithium ions. + ) and other (non-lithium monovalent cations) also migrate into the treated solution. Therefore, by using the treated solution after electrodialysis as the lithium ion extraction solution in Figure 1, lithium ions can be selectively recovered in the recovered solution.

[0070] That is, when the lithium ion extract is non-alkaline, an alkaline aqueous solution (treatment solution) containing lithium ions can be produced using a commonly known, general electrodialysis device, and this can be used as the lithium ion extract in the lithium recovery device 1, thereby enabling lithium (lithium ions) to be obtained in the recovery solution with high efficiency.

[0071] (Extraction of lithium from recovered solution) A method for extracting lithium from a recovery solution 200 containing a high concentration of lithium ions 50 will be described. As described in WO2015 / 020121, considering the intended use of lithium (such as lithium ion batteries), it is preferable to extract lithium as lithium carbonate (Li2CO3) powder. For this reason, WO2015 / 020121 describes a method of adding hydrochloric acid (HCl) to the recovery solution 200 to recover lithium, and then adding an aqueous solution of sodium carbonate (Na2CO3) to extract lithium as lithium carbonate (Li2CO3). In this embodiment, lithium carbonate (Li2CO3) can be extracted using this method. However, from the perspective of extracting lithium carbonate (Li2CO3) more inexpensively, it is preferable to extract it using, for example, the following method.

[0072] The lithium recovery apparatus 1 described above can particularly increase the concentration of lithium ions 50 in the recovery solution 200. Therefore, the recovery solution 200 can be initially pure water. After lithium recovery, a gas containing carbon dioxide (CO2) is passed through the recovery solution 200 (e.g., by bubbling). This causes the CO2 to bond with the lithium ions 50 in the recovery solution 200, producing lithium carbonate (Li2CO3), which can then be extracted. This process makes the recovery solution 200 cloudy, allowing lithium carbonate (Li2CO3) to be extracted as a precipitate. This method is particularly effective when using the lithium recovery apparatus 1 described above, which can particularly increase the concentration of lithium ions 50 in the recovery solution 200. Because CO2 can be obtained inexpensively or free of charge from various facilities (such as thermal power plants) that secondarily generate CO2, lithium carbonate (Li2CO3) can be obtained inexpensively. Furthermore, because pure water without the addition of hydrochloric acid or the like can be used as the recovery solution 200, lithium carbonate can be obtained inexpensively and safely.

[0073] [Method for recovering lithium] Next, the lithium recovery method of this embodiment will be described. Note that this lithium recovery method of this embodiment is merely one embodiment of the lithium recovery method of the present invention, and the present invention is not limited to this lithium recovery method of this embodiment.

[0074] The method for recovering lithium according to the present embodiment includes using a lithium permselective membrane to transfer lithium ions from a lithium ion extract extracted from a processing component of a lithium secondary battery to a recovery solution that is an aqueous solution, and recovering lithium in the recovery solution by adjusting at least one of the temperature of the lithium ion extract and the temperature of the lithium permselective membrane to a range of 30°C to 100°C.

[0075] Here, it is necessary to adjust at least one of the temperatures of the lithium ion extract and the lithium permselective membrane to be 30° C. or higher and 100° C. or lower, and it is sufficient to adjust at least one of these temperatures to be within the range of 30° C. or higher and 100° C. or lower at least temporarily. From the viewpoint of more efficient lithium recovery, it is preferable to adjust at least one of these temperatures to be within the range of 30° C. or higher and 100° C. or lower from the start to the end of lithium recovery. Furthermore, from the viewpoint of more efficient lithium recovery, it is preferable to adjust the temperature of the lithium permselective membrane, and it is more preferable to adjust the temperatures of both the lithium ion extract and the lithium permselective membrane.

[0076] Furthermore, the temperature of the lithium ion extract and the temperature of the lithium permselective membrane are preferably adjusted to be 40°C or higher and 95°C or lower, more preferably 50°C or higher and 90°C or lower, even more preferably 60°C or higher and 85°C or lower, and even more preferably 75°C or higher and 85°C or lower.

[0077] In the lithium recovery method of this embodiment, the temperature of the recovery solution may be adjusted to 30°C or higher and 100°C or lower. Here, the temperature of the recovery solution is adjusted to 30°C or higher and 100°C or lower, and the temperature of the recovery solution may be adjusted to be within the range of 30°C or higher and 100°C or lower at least temporarily. From the viewpoint of more efficient lithium recovery, it is preferable that the temperature of the recovery solution is adjusted to be within the range of 30°C or higher and 100°C or lower from the start to the end of lithium recovery. The adjustment of the temperature of the recovery solution is the same as that described for the adjustment of the temperature of the lithium ion extract by the temperature adjustment means (temperature adjustment means A). The temperature of the recovery liquid is more preferably adjusted to 40°C or higher and 95°C or lower, and even more preferably adjusted to 50°C or higher and 90°C or lower.

[0078] The method of adjusting the pH in the lithium recovery method is the same as that described for adjusting the pH of the lithium ion extract in the pH control means, including the fact that the pH may be adjusted before or during lithium recovery. The lithium recovery method of this embodiment can be carried out using, for example, the lithium recovery device of this embodiment described above.

[0079] In another embodiment of the lithium recovery method, lithium is recovered into a recovery solution from a lithium ion extract extracted from a processing component of a lithium secondary battery using the lithium recovery device of the present embodiment. The lithium recovery method of the present embodiment can be easily carried out by using the lithium recovery device of the present embodiment.

[0080] The lithium ion extract, lithium permselective membrane, recovery solution, etc. extracted from the treatment components of the lithium secondary battery in the lithium recovery methods of these embodiments have been described in the lithium recovery apparatus of the present embodiment above, and therefore description of these will be omitted. Note that, as the lithium ion extract used in the present embodiment, any extract containing lithium ions can provide the effect of the present invention of efficiently recovering lithium ions, so for example, concentrated water obtained by concentrating seawater, salt lake brine, mining wastewater, geothermal water, or a combination of these by means of evaporation or the like may be used, and it is also possible to use one or a combination of two or more of these, as described in the lithium recovery apparatus of the present embodiment above.

[0081] From the viewpoint of recovering lithium from the lithium ion extract more efficiently, the lithium ion extract may be oxidized with an oxidizing agent. That is, the lithium recovery method of this embodiment preferably includes, before recovering lithium, adding an oxidizing agent to the lithium ion extract to perform an oxidation treatment for oxidizing the lithium ion extract. Note that the oxidizing agent used in the oxidation treatment has been described in the lithium recovery device of this embodiment above, and therefore a description of the oxidizing agent will be omitted. [Example]

[0082] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples in any way.

[0083] (1) Production of lithium sulfide (Li2S) A 10-liter autoclave equipped with a stirring blade was charged with 336.4 g (33.6 mol) of N-methyl-2-pyrrolidone (NMP) and 287.4 g (12 mol) of lithium hydroxide. The temperature was raised to 130 °C while the stirring blade was rotating at 300 rpm. After the temperature was raised, hydrogen sulfide was bubbled into the liquid at a feed rate of 3 L / min for 2 hours. The reaction liquid was then heated under a nitrogen stream (200 cc / min) to dehydrosulfide a portion of the reacted hydrogen sulfide. As the temperature increased, water produced as a by-product from the reaction between hydrogen sulfide and lithium hydroxide began to evaporate. This water was condensed and removed from the system. The temperature of the reaction liquid rose as the water was distilled out of the system, but the temperature increase was stopped when it reached 180 °C and maintained constant. The dehydrosulfidation reaction was terminated (approximately 80 minutes) and lithium sulfide (LiS) was obtained.

[0084] (2) Purification of lithium sulfide After decanting the NMP from 500 mL of the slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1) above, 100 mL of dehydrated NMP was added and stirred at 105°C for approximately 1 hour. The NMP was decanted while maintaining that temperature. Another 100 mL of NMP was added, and the mixture was stirred at 105°C for approximately 1 hour. The NMP was decanted while maintaining that temperature. This procedure was repeated a total of four times. After decantation, the lithium sulfide was dried under normal pressure at 230°C (a temperature above the boiling point of NMP) in a nitrogen stream for 3 hours to purify the lithium sulfide.

[0085] (3) Manufacturing of solid electrolytes The lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5, manufactured by Aldrich) obtained in (2) above were used as starting materials. Approximately 1 g of a mixture prepared in a molar ratio of 75:25 was placed in a 45 mL alumina container along with 10 alumina balls with a particle size of 10 mm. Mechanical milling was performed in a planetary ball mill (model "P-7", manufactured by Fritsch) in nitrogen at room temperature (25°C) at a rotation speed of 370 rpm for 20 hours to obtain an amorphous sulfide-based solid electrolyte in the form of a whitish-yellow powder. This powder (amorphous sulfide-based solid electrolyte) was subjected to a firing treatment in a nitrogen atmosphere at a temperature range of room temperature (25°C) to 550°C to produce a crystalline sulfide-based solid electrolyte. Differential thermal analysis was also performed simultaneously with the firing treatment. The temperature increase and decrease rates were 10° C. / min, and after the temperature was increased to 550° C., the mixture was cooled to room temperature to produce a crystalline sulfide-based solid electrolyte.

[0086] (4) Manufacturing of lithium permselective membranes The constituent material is lithium lanthanum titanate (Li 0.29 La 0.57 A lithium permselective membrane body was fabricated using TiO3), and one main surface of the body was exposed to hydrochloric acid at 60°C for 5 days to obtain a lithium permselective membrane in which a lithium adsorption layer (HLTO) was formed on one main surface of the lithium permselective membrane body (LLTO). The obtained lithium permselective membrane was used in the lithium recovery device used in the following examples. The bulk density of the obtained lithium permselective membrane measured by the above method was 4.76 g / cm 3 and the theoretical density is 5.07 g / cm 3 (This is the theoretical density of LLTO calculated by the above method.) Therefore, the sintered density was 94%.

[0087] [Reference example 1] 100 grams of the crystalline sulfide-based solid electrolyte produced in the above Production Example was dissolved in 1.0 mol / L sodium hydroxide solution, and the total volume was adjusted to 2 L to obtain a lithium ion extract. As a result of ICP emission spectrometry, the element concentrations of the lithium ion extract 100 were 0.57 mass% lithium, 2.2 mass% sodium, 0.86 mass% phosphorus, and 3.8 mass% sulfur. 10 mL of hydrogen peroxide (30% aqueous solution) was added to 25 mL of the lithium ion extract to convert all sulfur to sulfate ions, and then the total volume was adjusted to 250 mL with 0.22 mol / L sodium hydroxide solution to dilute the lithium ion extract 10-fold. 200 mL of the diluted solution was used as the donor solution to the lithium recovery device. The pH of the donor solution was 13.5. The OH concentration, which contributes to the alkalinity, was 0.1 mol / L. The donor solution and the pure water recovery solution were placed in the lithium recovery device of Figure 1, and the current flowing between the first electrode and the second electrode was measured when a voltage of 5 V was applied. The air conditioner 85 was not used, and the temperature of the donor solution was 23°C.

[0088] The current value became 0 240 hours after the voltage was applied, and the lithium recovery rate at that time was 60 mass%. This demonstrated that lithium ions could be recovered from the lithium ion extract using this device. The lithium recovery rate refers to the ratio of the amount of lithium element in the recovered solution after lithium recovery to the amount of lithium element in the donor solution before lithium recovery.

[0089] The relationship between the temperature of the donor solution (extraction solution), recovery efficiency (ion current), and amount of recovered lithium was evaluated as follows using a lithium hydroxide standard solution.

[0090] Example 1 200 mL of a 3.0 M aqueous solution of lithium hydroxide (pH 14.6) was used as the extraction solution. As in Reference Example 1, the donor solution and pure water as the recovery solution were placed in the recovery device shown in FIG. 1 , the internal temperature of which was adjusted to 30°C using air conditioning unit 85. After the temperature of the donor solution reached 30°C, a voltage of 5 V was applied, and the current flowing between the first and second electrodes was measured to determine the amount of lithium recovered. The maximum current was 0.132 A.

[0091] Example 2 The current flowing between the first and second electrodes was measured and the amount of recovered lithium was measured in the same manner as in Example 1, except that the internal temperature was adjusted to 40° C. using air conditioner 85 and a voltage of 5 V was applied after the temperature of the donor solution reached 40° C. The maximum current was 0.238 A.

[0092] Example 3 The current flowing between the first and second electrodes was measured and the amount of recovered lithium was measured in the same manner as in Example 1, except that the internal temperature was adjusted to 50° C. using air conditioner 85 and a voltage of 5 V was applied after the temperature of the donor solution reached 50° C. The maximum current was 0.343 A.

[0093] Example 4 The current flowing between the first and second electrodes was measured and the amount of recovered lithium was measured in the same manner as in Example 1, except that the internal temperature was adjusted to 60° C. using air conditioner 85 and a voltage of 5 V was applied after the temperature of the donor solution reached 60° C. The maximum current was 0.624 A.

[0094] Example 5 200 mL of 1.0 M lithium hydroxide aqueous solution (pH 14.0) was used as the extraction solution. In the recovery apparatus shown in FIG. 4, pure water was placed in each tank as in Reference Example 1, and the internal temperature was adjusted to 65°C using heat exchangers 857-859. A voltage of 5 V was applied, and the current flowing between the first and second electrodes was measured. The amount of lithium recovered was measured, and the lithium recovery rate was calculated. Since an increase in the liquid temperature causes an increase in internal pressure, the internal pressure was controlled by pressure regulating valves (check valve type) 781-784 of the treatment tank, recovery tank, and storage tank to prevent the internal pressure from rising too much. The concentration of lithium carbonate in the recovered solution was 0.1% by mass or less.

[0095] Example 6 The current value flowing between the first electrode and the second electrode was measured, the amount of recovered lithium was measured, and the lithium recovery rate was calculated in the same manner as in Example 5, except that the internal temperature was adjusted to 80° C. using heat exchangers 857 to 859. The concentration of lithium carbonate in the recovered solution was 0.1% by mass or less.

[0096] Example 7 The current value flowing between the first and second electrodes was measured, and the amount of recovered lithium was measured to calculate the lithium recovery rate in the same manner as in Example 6, except that the pressure was adjusted using a check valve-type pressure regulating valve to a level that prevented the generated gas from adhering to the electrodes. The concentration of lithium carbonate in the recovered solution was 0.1 mass% or less.

[0097] Comparative Example 1 The current value flowing between the first electrode and the second electrode was measured, the amount of recovered lithium was measured, and the lithium recovery rate was calculated in the same manner as in Example 1, except that the internal temperature was adjusted to 23° C. using air conditioner 85 and a voltage of 5 V was applied after the temperature of the donor solution reached 23° C. The maximum current value was 0.083 A.

[0098] FIG. 5 is a graph showing the change in current value over time in Examples 1 and 2 and Comparative Example 1. As shown in FIG. 5, in Examples 1 (T = 30°C) and 2 (T = 40°C), the initial slope of the current value was larger than in Comparative Example 1 (T = 23°C), and the maximum current values ​​of Examples 1 and 2 were approximately 1.5 times and approximately 3 times larger, respectively. Furthermore, the time required to reach the maximum current value was reduced to less than half and less than one-third, respectively, of the comparative example. Note that the lithium ion conductivity of a solid electrolyte typically does not increase by more than 1.5 times or 3 times even when the temperature is increased from 23°C to 30°C or 40°C. Considering this, the increase in current value in Examples 1 and 2 compared to Comparative Example 1 was a surprising result.

[0099] FIG. 6 is a graph showing the change over time in the amount of recovered lithium in Examples 1 and 2 and Comparative Example 1. As shown in Figure 6, it was confirmed that the recovery rate was faster in Examples 1 (T = 30°C) and 2 (T = 40°C) than in Comparative Example 1 (T = 23°C). The lithium recovery rate when the temperature was raised from 23°C to 40°C was expected to be approximately 1.44 times the theoretical value (calculated with reference to the tables under "LLTO Molded Body" and "Lithium Ion Conductivity" on the Toho Titanium Co., Ltd. website (https: / / www.toho-titanium.co.jp / products / llto.html)), but it was dramatically improved by approximately 3 times, confirming a significant improvement that exceeded the theoretical value.

[0100] In Example 3 (T = 50°C), the theoretical lithium recovery rate was expected to be about 3.1 times higher, but the measured value was 4.3 times higher. In Example 4 (T = 60°C), the theoretical lithium recovery rate was expected to be about 4.7 times higher, but the measured value was 7.7 times higher. In both cases, a significant improvement exceeding the theoretical value was confirmed.

[0101] FIG. 7 is a graph showing the change in lithium recovery rate and current over time in Example 5 (T=65° C.), and FIG. 8 is a graph showing the change in lithium recovery rate and current over time in Examples 6 and 7 (T=80° C.). Examples 5 to 7 were performed using the apparatus shown in FIG. 4, with the temperature increased to 65°C and 80°C. In Examples 6 and 7, the lithium recovery rate reached nearly 100% within one day, whereas in Comparative Example 1, it took approximately 10 days for the lithium recovery rate to reach approximately 90%, demonstrating extremely efficient lithium recovery. Furthermore, in Example 7, the positive pressure in the tank was maintained by the gas generated at the electrodes in FIG. 4, but the pressure was adjusted using a pressure control valve to a level sufficient to prevent the generated gas from adhering to the electrodes. As shown in FIG. 8, the lithium recovery rate reached nearly 100% in approximately 0.5 days, indicating that almost all lithium was recovered in approximately half the time compared to Example 6, which was adjusted to the same temperature. This demonstrates that precise adjustment of the pressure in each tank (each solution) can improve lithium recovery efficiency.

[0102] Example 8 1 used in Example 1, a rod-shaped electric heater was further provided as temperature control means B so as to be in contact with the plate-shaped lithium permselective membrane. The temperature of the lithium permselective membrane was measured with a thermocouple provided so as to be in contact with the lithium permselective membrane. Using the recovery device provided with temperature control means B and the thermocouple, the temperature of the lithium permselective membrane was set to 30°C, and lithium was recovered in the same manner as in Example 1. The maximum current value was 0.132 A, which was the same result as in Example 1 in which the temperature of the lithium ion extract was set to 30°C, the same temperature as the temperature of the lithium permselective membrane in Example 8. Other results (the results of the example shown in Figures 5 and 6) were also similar to those in Example 1.

[0103] Examples 9 to 14 In Example 8, lithium was recovered in the same manner as in Examples 2 to 7, except that the temperature of the lithium permselective membrane was adjusted to the same temperatures as those of the lithium ion extract in Examples 2 to 7 (40°C, 50°C, 60°C, 65°C, 80°C, and 80°C) using temperature adjustment means b. The results of Examples 9 to 14 were equivalent to the results of Examples 2 to 7, respectively. [Explanation of symbols]

[0104] 1. Lithium recovery equipment 8. Treatment tank 10. Lithium permselective membrane 10A. Lithium selective permeable membrane body 10B. Lithium adsorption layer 11.First electrode 12.Second electrode 50. Lithium-ion 51. Sodium ion 71. Reservoir 72. Recovery liquid tank 74, 75. Extraction liquid piping 76, 77. Recovery liquid piping 781~784. Pressure Regulating Valve 81-84. Pump 85.Temperature control means A (air conditioner) 85A.Indoor unit 85B.Outdoor unit 85C.Heating medium 86. Temperature control means B (heater) 100. Lithium ion extract 200.Recovered liquid 851A,851B.Heat exchanger 852B. Compressor 853~859.Heat exchanger

Claims

1. A lithium recovery device that recovers lithium into a recovery solution that is an aqueous solution by transferring lithium ions from a lithium ion extract extracted from a treatment component of a lithium secondary battery, the lithium ions being extracted into the recovery solution, a lithium permselective membrane installed in a treatment tank so as to separate the lithium ion extract from the recovered liquid, with the lithium ion extract on one main surface side and the recovered liquid on the other main surface side; a mesh-shaped first electrode fixed to the one main surface side of the lithium permselective membrane; a mesh-shaped second electrode fixed to the other main surface of the lithium permselective membrane; a storage tank for the lithium ion extract; an extractant pipe provided between the storage tank and the treatment tank; A temperature adjusting means A for adjusting the temperature of the lithium ion extract; Equipped with the temperature adjusting means A adjusts the temperature in a space accommodating at least the storage tank, the extract liquid piping, and the treatment tank; The lithium recovery device further includes a recovery liquid tank that stores the recovery liquid, and a recovery liquid piping that is provided between the treatment tank and the recovery liquid tank, and the temperature adjustment means A adjusts the temperature in a space that accommodates at least the recovery liquid tank and the recovery liquid piping.

2. A lithium recovery device as described in claim 1, further comprising a temperature control means B for adjusting the temperature of the lithium selective permeable membrane in addition to a temperature control means A for adjusting the temperature of the lithium ion extract.

3. 3. The lithium recovery apparatus according to claim 1, wherein the temperature adjusting means A is provided in contact with at least one of the storage tank and the extraction liquid pipe.

4. 4. The lithium recovery device according to claim 1, wherein the temperature adjusting means A is provided in contact with at least one of the recovery liquid tank and the recovery liquid pipe.

5. 5. The lithium recovery apparatus according to claim 3, wherein the temperature adjusting means A is a heat exchanger.

6. 6. The lithium recovery device according to claim 1, wherein the storage tank comprises a first storage tank and a second storage tank, and the recovery liquid tank comprises a first recovery liquid tank and a second recovery liquid tank.

7. 7. The lithium recovery device according to claim 6, wherein a lithium ion extract is continuously or intermittently supplied to the first storage tank or the second storage tank, and pure water is continuously or intermittently supplied to the first recovery liquid tank or the second recovery liquid tank.

8. 8. The lithium recovery device according to claim 1, further comprising a circulation means for circulating the lithium ion extract between the storage tank and the treatment tank.

9. The lithium recovery device according to any one of claims 1 to 8, further comprising a concentrating means for increasing the lithium ion concentration of the lithium ion extract.

10. 10. The lithium recovery device according to claim 1, wherein the lithium permselective membrane is subjected to a surface lithium adsorption treatment.

11. 11. The lithium recovery device according to claim 1, further comprising a pH adjusting means for adjusting the pH of the lithium ion extract.

12. A method for recovering lithium using the lithium recovery device according to any one of claims 1 to 11, comprising: using a lithium permselective membrane to transfer lithium ions from a lithium ion extract containing lithium ions extracted from a treatment component of a lithium secondary battery to a recovery solution that is an aqueous solution, and recovering lithium in the recovery solution by adjusting at least one of the temperature of the lithium ion extract and the temperature of the lithium permselective membrane to 30°C or higher and 100°C or lower.

13. The method for recovering lithium according to claim 12, further comprising adjusting the temperature of the recovery solution to 30°C or higher and 100°C or lower.

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