Granular body for lithium adsorption and method for producing same

Abstract

Provided are: a granular body for lithium adsorption, which has durability and is capable of effectively exhibiting the ability of a lithium adsorbent; and a method for producing the granular body for lithium adsorption. Granules for lithium adsorption include a precursor of a lithium adsorbent and an aqueous polymer surrounding the precursor. In addition, the water-containing polymer can form a gel-like granular body. Due to this configuration, the granular body is in the form of a gel when the water-containing polymer has a predetermined moisture content, so that a part of the granular body does not fall off, and the durability of the granular body is improved. Furthermore, since the aqueous polymer is permeable to a liquid such as seawater, the lithium adsorbent can be brought into contact with the liquid as a whole, and the ability of the lithium adsorbent can be effectively exhibited.

Description

Technical Field

[0001] The present invention relates to lithium adsorbing granules and a method for producing the same. More specifically, the present invention relates to lithium adsorbing granules including a precursor of a lithium adsorbent and a method for producing the same. Background Art

[0002] A system for recovering lithium from brine water is disclosed in Non-Patent Document 1. The document discloses using a lithium adsorbent to adsorb lithium from brine water and desorbing the adsorbed lithium until high-purity Li2CO3 is generated. In addition, in the document, lithium adsorption is performed by granulating lithium manganate powder with PVC into a size of 0.5 to 1 mm in diameter.

[0003] Patent Document 1 discloses a porous structure for ion exchange, comprising: a) a structural support, and b) a substance such as coated ion exchange particles. Lithium is selectively extracted from seawater or the like through the porous structure.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent document 1: Japanese Patent Application Publication No. 2019-535503.

[0007] Non-patent literature

[0008] Non-patent document 1: Tang Weiping, "Development of a system for recovering lithium from brine", [online], June 11, 2022, Kagawa Industrial Support Foundation, [November 22, 2022], Internet (https: / / www.kagawa-isf.jp / wp-content / uploads / 2022 / 02 / 21tang.pd f). Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in the granules or porous bodies described in these documents, the adsorbent for adsorbing lithium, i.e., powder such as lithium manganate, is actually made into a predetermined size using other substances such as a binding material, so a portion of it falls off each time the lithium-containing solution passes through, resulting in a problem of a short lifespan for repeated use.

[0011] Furthermore, since there is a bond with a substance that does not participate in the adsorption of lithium, lithium cannot be adsorbed at the bonded portion, and there is a problem that part of the capacity of the lithium adsorbent cannot be used.

[0012] In view of the above circumstances, an object of the present invention is to provide a lithium adsorbing granular body having durability and capable of effectively exerting the ability of a lithium adsorbent, and a method for producing the same.

[0013] Means for solving problems

[0014] The lithium adsorbing granules of the first invention are characterized by comprising a precursor of a lithium adsorbent and an aqueous polymer surrounding the precursor, wherein the aqueous polymer is capable of forming a gel-like granule.

[0015] The lithium adsorbing granules according to the second invention are characterized in that, in the first invention, the lithium adsorbing granules are gel-like granules.

[0016] The lithium adsorbing granules according to a third invention are characterized in that, in the first invention or the second invention, the water-containing polymer has an amide group.

[0017] The lithium adsorbing granules according to a fourth invention are characterized in that, in the third invention, the aqueous polymer having the amide group is polyacrylamide.

[0018] The lithium adsorbing granular material according to a fifth invention is characterized in that, in any one of the first to fourth inventions, the precursor of the lithium adsorbent is lithium manganate.

[0019] The method for producing lithium adsorbing granules of the sixth invention is characterized in that it includes a suspension polymerization step, in which an aqueous solution for suspension polymerization obtained by mixing a raw material of an aqueous polymer, a precursor of a lithium adsorbent and a polymerization initiator is suspended in a dispersion medium to obtain lithium adsorbing granules.

[0020] The method for producing lithium adsorbing granules of the seventh invention is characterized in that, in the sixth invention, a mixing step of mixing the raw material of the aqueous polymer and the precursor of the lithium adsorbent to obtain a mixed aqueous solution is provided before the suspension polymerization step, and after the mixing step, an aqueous solution for suspension polymerization obtained by mixing a polymerization initiator in the mixed aqueous solution is used in the suspension polymerization step.

[0021] The method for producing lithium adsorbing granules according to an eighth invention is characterized in that, in the seventh invention, in the mixing step, a predetermined amount of ethanol is added before mixing.

[0022] The method for producing lithium adsorbing granules according to the ninth invention is characterized in that, in any one of the sixth to eighth inventions, the aqueous polymer is polyacrylamide, and the raw materials of the polyacrylamide are acrylamide and N,N'-methylenebisacrylamide.

[0023] The method for producing lithium adsorbing granules according to a tenth invention is characterized in that, in any one of the sixth to ninth inventions, the suspension polymerization step is performed under a nitrogen atmosphere in which a nitrogen ratio is within a predetermined range.

[0024] Effects of the Invention

[0025] According to the first invention, the lithium adsorbing granules include a precursor of a lithium adsorbent and an aqueous polymer. Since the granules are in a gel state when the aqueous polymer has a predetermined amount of water, a part of the granules does not fall off, thereby improving the durability of the granules. In addition, since the aqueous polymer can permeate liquids such as seawater, the lithium adsorbent can be brought into contact with the liquid as a whole, thereby effectively exerting the ability of the lithium adsorbent.

[0026] According to the second invention, since the lithium adsorbing granules are gel-like granules, they can be stored in a capsule that allows liquid such as seawater to pass through and used as they are.

[0027] According to the third invention, since the water content of the water-containing polymer increases due to the amide group in the water-containing polymer, the entire lithium adsorbent is more likely to come into contact with the liquid, and the ability of the lithium adsorbent can be more effectively exerted.

[0028] According to the fourth invention, since the aqueous polymer having an amide group is polyacrylamide, it is possible to achieve both the durability of the granules and the efficiency of the lithium adsorbent at a higher level.

[0029] According to the fifth invention, since the precursor of the lithium adsorbent is lithium manganate, the lithium adsorption capacity is increased.

[0030] According to the sixth invention, the method for producing lithium adsorbing granules includes a suspension polymerization step, thereby obtaining an aqueous polymer of a gel-like granule containing a precursor of a lithium adsorbent. In the suspension polymerization step, an aqueous suspension polymerization solution obtained by mixing a raw material of an aqueous polymer, a precursor of a lithium adsorbent, and a polymerization initiator is suspended in a dispersion medium, thereby obtaining lithium adsorbing granules.

[0031] According to the seventh invention, a mixing step of mixing a raw material of an aqueous polymer and a precursor of a lithium adsorbent to obtain a mixed aqueous solution is provided before the suspension polymerization step. After the mixing step, an aqueous solution for suspension polymerization obtained by mixing a polymerization initiator in the mixed aqueous solution is used in the suspension polymerization step. By this aspect, the raw material of the aqueous polymer and the precursor of the lithium adsorbent can be mixed before the start of polymerization, thereby reducing their deviation and reducing the unevenness of the composition.

[0032] According to the eighth aspect of the present invention, by adding a predetermined amount of ethanol in the mixing step, it is possible to more easily obtain a hydrous polymer in the form of a gel-like granular body containing a precursor of a lithium adsorbent.

[0033] According to the ninth invention, since the raw materials of polyacrylamide are acrylamide and N,N'-methylenebisacrylamide, polyacrylamide can be easily obtained.

[0034] According to the tenth invention, the suspension polymerization step is performed under a predetermined nitrogen atmosphere, so that the polymerization reaction proceeds efficiently, thereby reducing the amount of unreacted raw materials and increasing the strength of the gel constituting the lithium adsorbing granular material. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of lithium adsorbing granular material according to an embodiment of the present invention.

[0036] Figure 2 This is a flow chart of the method for producing lithium adsorbing granules according to the first embodiment of the present invention.

[0037] Figure 3 This is a flow chart of a method for producing lithium adsorbing granules according to a second embodiment of the present invention.

[0038] Figure 4 This is a flow chart of a method for producing lithium adsorbing granules according to a third embodiment of the present invention.

[0039] Figure 5 This is a flow chart of a method for producing lithium adsorbing granules according to a fourth embodiment of the present invention.

[0040] Figure 6 This is a flow chart of a method for producing lithium adsorbing granules according to a fifth embodiment of the present invention.

[0041] Figure 7 This is a flow chart of a method for producing lithium adsorbing granules according to a sixth embodiment of the present invention.

[0042] Figure 8 This is a flow chart of a method for producing lithium adsorbing granules according to the seventh embodiment of the present invention.

[0043] Fig. 9 (a) is a SEM photograph of the lithium adsorbing granular body before use in Example 1 of the present invention. (b) is a SEM photograph of the lithium adsorbing granular body after use in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The following describes the embodiments of the present invention based on the accompanying drawings. However, the embodiments shown below are examples of lithium adsorbing granules and methods for producing the same for embodying the technical concept of the present invention, and the present invention does not specify the lithium adsorbing granules and methods for producing the same to the following contents. It should be noted that the components shown in the claims are not specified to the components of the embodiments.

[0045] <Lithium adsorption granules>

[0046] The lithium adsorbing granules disclosed in the present specification include a precursor of a lithium adsorbent and an aqueous polymer surrounding the precursor, and the aqueous polymer is capable of forming a gel-like granule.

[0047] With this structure, since the granules are in a gel state when the aqueous polymer has a predetermined amount of water, a part of the granules will not fall off, thereby improving the durability of the granules. In addition, since the aqueous polymer can permeate liquids such as seawater, the lithium adsorbent can be brought into contact with the liquid as a whole, thereby effectively exerting the ability of the lithium adsorbent.

[0048] The lithium adsorbing granules are preferably gel-like granules. With this configuration, the granules can be used by being contained in a capsule that passes through a liquid such as seawater.

[0049] In the lithium adsorbing granules, the water-containing polymer preferably has an amide group. With this configuration, the water content of the water-containing polymer increases, so that the entire lithium adsorbent is more easily in contact with the liquid, and the ability of the lithium adsorbent can be more effectively exerted.

[0050] In the lithium adsorbing granules, the aqueous polymer having an amide group is preferably polyacrylamide. With this configuration, both the durability of the granules and the efficiency of the lithium adsorbent can be achieved at a higher level.

[0051] In the lithium adsorbing granules, it is preferable that the precursor of the lithium adsorbent is lithium manganate. With this configuration, the lithium adsorption capacity becomes high.

[0052] Figure 1 A schematic diagram of lithium adsorbing granules according to one embodiment of the present invention is shown in FIG. This schematic diagram schematically shows that the aqueous polymer constituting the lithium adsorbing granules includes water, and the lithium adsorbing granules are in a gel-like state. The lithium adsorbing granules according to this embodiment are composed of a precursor of a lithium adsorbent included in the aqueous polymer capable of forming a gel-like granule. Figure 1 In the patent document "A", polyacrylamide is described as an example of the aqueous polymer, and lithium manganate is described as an example of the precursor of the lithium adsorbent.

[0053] (Precursor of lithium adsorbent)

[0054] The precursor of the lithium adsorbent can be a compound such as lithium manganate, lithium titanate, etc. For example, Li 1.6 Mn 1.6 O4、Li 1.33 Mn 1.67 O4、Li4Mn5O 12 、Li4Ti5O 12, Li2TiO3, Li2MnO3, Li2SnO3, LiMn2O4, LiAlO2, LiCuO2, LiTiO2, Li4TiO4, Li7Ti 11 O 24 , Li3VO4, Li2Si3O7, LiFePO4, LiMnPO4, and Li2CuP2O7.

[0055] The precursor of the lithium adsorbent is treated with an acid before adsorbing lithium to become a lithium adsorbent. 1.6 Mn 1.6 In the case of O4, it becomes the following lithium adsorbent by acid treatment with hydrochloric acid.

[0056] Li 1.6 Mn 1.6 O4+1.6HCl→H 1.6 Mn 1.6 O4+1.6LiCl

[0057] (Aqueous polymer)

[0058] The aqueous polymer is a polymer that can contain water. By containing water, a liquid containing lithium, such as seawater, can be impregnated into the aqueous polymer. When a lithium adsorbent is present in the aqueous polymer, the lithium adsorbent can come into contact with seawater, etc., thereby being able to adsorb lithium contained in the seawater, etc.

[0059] In addition, the aqueous polymer constituting the lithium adsorbent granules of the present embodiment can form gel-like granules. Furthermore, the aqueous polymer constituting the lithium adsorbent granules of the present embodiment needs to have stability against chemicals such as acids. Examples of the aqueous polymer include polymethacrylate-2-hydroxyethyl ester, polyacrylic acid, polyvinyl alcohol, and aqueous polymers having an amide group. In addition, polyacrylamide is more preferred among the aqueous polymers having an amide group. The chemical formula of the polyacrylamide is shown below. In the chemical formula, the part marked with "..." indicates that the same structure is repeatedly connected. By using polyacrylamide as the aqueous polymer having an amide group, both the durability of the granules and the high efficiency of the lithium adsorbent can be achieved at a higher level. As monomers for forming polyacrylamide, for example, 2-acrylamide, N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine, N-(hydroxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N,N-dimethylacrylamide, N-(1,1-dimethyl-3-oxobutyl)acrylamide, etc. can be used.

[0060] [Chemical formula 1]

[0061]

[0062] It should be noted that "gel" refers to a substance in which particles with a size of about 1nm to 1000nm float or suspend in a gas, liquid or solid, that is, a solid substance in a substance called a dispersion system. In addition, "gel-like" means that the substance is "gel" or "gel-like substance".

[0063] The lithium adsorbing granules of the present embodiment may be in a state of low water content. If the lithium adsorbing granules are in a state of low water content, the density of the lithium adsorbing granules can be reduced, thereby reducing the transportation cost.

[0064] <Method for producing lithium adsorbing granules>

[0065] The method for producing lithium adsorbing granules disclosed in the present specification includes a suspension polymerization step, in which an aqueous suspension polymerization aqueous solution obtained by mixing a raw material of an aqueous polymer, a precursor of a lithium adsorbent, and a polymerization initiator is suspended in a dispersion medium to obtain lithium adsorbing granules. In this way, an aqueous polymer containing a gel-like granule of a precursor of a lithium adsorbent can be obtained.

[0066] In the method for producing lithium adsorbing granules, it is preferred that a mixing step is provided before the suspension polymerization step, in which a raw material of an aqueous polymer and a precursor of a lithium adsorbent are mixed to obtain a mixed aqueous solution, and after the mixing step, an aqueous solution for suspension polymerization obtained by mixing a polymerization initiator in the mixed aqueous solution is used in the suspension polymerization step. According to this aspect, the raw material of an aqueous polymer and a precursor of a lithium adsorbent can be mixed before the start of polymerization, so that the deviation of these substances can be reduced and the non-uniformity of the composition can be reduced.

[0067] In the method for producing lithium adsorbing granules, it is preferable that the aqueous polymer is polyacrylamide and the raw materials of the polyacrylamide are acrylamide and N,N'-methylenebisacrylamide. In this aspect, polyacrylamide can be easily obtained.

[0068] The method for producing lithium adsorbing granules preferably includes performing the suspension polymerization step under a nitrogen atmosphere. This can prevent the aqueous polymer from being degraded by oxidation.

[0069] The method for producing lithium adsorbing granules preferably comprises a solid-liquid separation step after the suspension polymerization step, in which the lithium adsorbing granules are subjected to reduced pressure filtration to obtain filtered lithium adsorbing granules. This aspect can improve the removal efficiency of the dispersion medium attached to the lithium adsorbing granules.

[0070] The method for producing lithium adsorbing granules preferably comprises a washing step after the solid-liquid separation step, in which the filtered lithium adsorbing granules are washed to obtain washed lithium adsorbing granules. This aspect can further improve the removal efficiency of the dispersion medium.

[0071] (First Embodiment)

[0072] The flowchart of the method for producing lithium adsorbing granules according to the first embodiment is shown in FIG. Figure 2 The following steps are explained based on this figure.

[0073] (Suspension polymerization process)

[0074] The method for producing lithium adsorbing granules of the present embodiment performs a suspension polymerization step in which an aqueous suspension polymerization aqueous solution obtained by mixing an aqueous polymer raw material, a lithium adsorbent precursor, and a polymerization initiator is suspended in a dispersion medium to obtain lithium adsorbing granules.

[0075] In the suspension polymerization process, the raw material of the aqueous polymer is first dissolved in water to a predetermined concentration, a precursor of a lithium adsorbent is added to the aqueous solution to a predetermined ratio, and a predetermined amount of a polymerization initiator is further added to obtain an aqueous solution for suspension polymerization. It should be noted that in the suspension polymerization preparation process, the mixing of the raw material of the aqueous polymer, the precursor of the lithium adsorbent and the polymerization initiator is not limited to the above order. It also includes the case where all are dissolved in water at once, and the case where the raw material of the aqueous polymer and the polymerization initiator are first dissolved in water. However, since the case where the polymerization initiator is added first delays the progress of polymerization, it is preferred to pre-cool the raw material of the aqueous polymer.

[0076] The aqueous polymer can form a gel-like granular body. Furthermore, the aqueous polymer constituting the lithium adsorbing granular body of the present embodiment needs to have stability against chemicals such as acid. The aqueous polymer having an amide group may be polyacrylamide.

[0077] When the aqueous polymer is polyacrylamide, the raw materials of the aqueous polymer are preferably acrylamide and N,N'-methylenebisacrylamide. In this aspect, polyacrylamide can be easily obtained.

[0078] The precursor of the lithium adsorbent can be a compound such as lithium manganate, lithium titanate, etc. For example, Li 1.6 Mn 1.6 O4、Li 1.33 Mn 1.67 O4、Li4Mn5O 12 、Li4Ti5O 12, Li2TiO3, Li2MnO3, Li2SnO3, LiMn2O4, LiAlO2, LiCuO2, LiTiO2, Li4TiO4, Li7Ti 11 O 24 , Li3VO4, Li2Si3O7, LiFePO4, LiMnPO4 and Li2CuP2O7.

[0079] The polymerization initiator has no problem as long as it is a substance that polymerizes the raw materials of the aqueous polymer. For example, when the aqueous polymer is polyacrylamide, and its raw materials are acrylamide and N,N'-methylenebisacrylamide, the polymerization initiator can be a combination of ammonium persulfate (APS) and tetramethylethylenediamine (TEMED).

[0080] In the suspension polymerization process, for example, a liquid dispersion medium is placed in a container of a predetermined size, and while stirring it with a stirrer, a predetermined amount of suspension polymerization aqueous solution is placed per unit time. Here, as a liquid dispersion medium, for example, silicone oil is preferred. However, it is not limited to this, and there is no particular problem as long as it is a hydrophobic solvent. In addition, as a dispersion medium, gas, i.e., gas, can also be used. In this case, an atomizer is preferably used.

[0081] The suspension polymerization step is preferably performed in a nitrogen atmosphere having a nitrogen ratio within a predetermined range. In this case, the nitrogen ratio in the gas composition of the nitrogen atmosphere is more preferably 99% or more.

[0082] The lithium adsorbing granules obtained in the suspension polymerization step are contained in a mixture with a dispersion medium and the like, and are delivered to a user of the lithium adsorbing granules in this state, or are used for lithium adsorption through a solid-liquid separation step disclosed in the third embodiment described later.

[0083] (Second Embodiment)

[0084] The flowchart of the method for producing lithium adsorbing granules according to the second embodiment is shown in FIG. Figure 3 The difference between the first embodiment and the second embodiment is that a mixing step is provided before the suspension polymerization step, in which a raw material of an aqueous polymer and a precursor of a lithium adsorbent are mixed to obtain a mixed aqueous solution, and after the mixing step, an aqueous solution for suspension polymerization obtained by mixing a polymerization initiator in the mixed aqueous solution is used in the suspension polymerization step. Since the other parts are the same as those of the first embodiment, the description of the parts that are the same as those of the first embodiment is omitted.

[0085] (Mixing process)

[0086] In the method for producing lithium adsorbing granules according to the present embodiment, a mixing step is performed before the suspension polymerization step. In the mixing step, a raw material of an aqueous polymer and a precursor of a lithium adsorbent are mixed to obtain a mixed aqueous solution.

[0087] In the mixing step, the raw material of the aqueous polymer is first dissolved in water to a predetermined concentration, the precursor of the lithium adsorbent is added to the aqueous solution to a predetermined ratio, and the raw material of the aqueous polymer and the precursor of the lithium adsorbent are mixed by stirring. The mixed liquid is a mixed aqueous solution.

[0088] (Suspension polymerization process)

[0089] In the suspension polymerization step of the present embodiment, an aqueous solution for suspension polymerization obtained by mixing a polymerization initiator with the mixed aqueous solution obtained in the mixing step is used, and the aqueous solution for suspension polymerization is suspended in a dispersion medium to obtain lithium adsorbing granules.

[0090] (Third Embodiment)

[0091] The flowchart of the method for producing lithium adsorbing granules according to the third embodiment is shown in FIG. Figure 4 . The difference between the second embodiment and the third embodiment is that, in the mixing process, in addition to the raw material of the aqueous polymer and the precursor of the lithium adsorbent, a predetermined amount of ethanol is added. Since the other parts are the same as the second embodiment, the description of the parts that are the same as the second embodiment is omitted. It should be noted that although the third embodiment is an aspect in which a predetermined amount of ethanol is added in the mixing process of the second embodiment, the aspect in which a predetermined amount of ethanol is added in the method for producing lithium adsorbent granules of the first embodiment is also included in the method for producing lithium adsorbent granules of the present application.

[0092] The amount of ethanol added is determined according to the weight of the powder (precursor of the lithium adsorbent) mixed in the mixing step. It should be noted that the ethanol added is preferably volatilized during the stirring process of the suspension polymerization step.

[0093] (Fourth Embodiment)

[0094] A flowchart of a method for producing lithium adsorbing granules according to a fourth embodiment is shown in FIG. Figure 5. The difference between the second embodiment and the fourth embodiment is that a solid-liquid separation process is provided after the suspension polymerization process. Since the other parts are the same as the second embodiment, the description of the parts that are the same as the second embodiment is omitted. It should be noted that although the fourth embodiment adds a solid-liquid separation process after the method for producing lithium adsorbing granules in the second embodiment, the aspect of adding a solid-liquid separation process after the method for producing lithium adsorbing granules in the first embodiment is also included in the method for producing lithium adsorbing granules in the present application.

[0095] (Solid-Liquid Separation Process)

[0096] The solid-liquid separation process is a process of filtering the lithium adsorption granules obtained in the suspension polymerization process under reduced pressure to obtain filtered lithium adsorption granules. In the suspension polymerization process, since the lithium adsorption granules are immersed in the liquid, the gel-like lithium adsorption granules and the liquid are separated in the solid-liquid separation process. At this time, it is preferred that the lithium adsorption granules are filtered under reduced pressure at a predetermined pressure. In the reduced pressure filtration, it is preferred to use a vacuum pump that reaches a vacuum degree of 10 hPa, for example. It should be noted that the filtered lithium adsorption granules obtained in the solid-liquid separation process are one aspect of the lithium adsorption granules.

[0097] By providing a solid-liquid separation step of filtering the lithium adsorbing granular bodies under reduced pressure to obtain filtered lithium adsorbing granular bodies after the suspension polymerization step, it is possible to improve the removal efficiency of the dispersion medium adhering to the lithium adsorbing granular bodies.

[0098] (Fifth Embodiment)

[0099] A flowchart of a method for producing lithium adsorbing granules according to a fifth embodiment is shown in FIG. Figure 6 . The difference between the fourth embodiment and the fifth embodiment is that, in the mixing process, in addition to the raw material of the aqueous polymer and the precursor of the lithium adsorbent, a predetermined amount of ethanol is added. Since the other parts are the same as the fourth embodiment, the description of the same parts as the fourth embodiment is omitted. It should be noted that although the fifth embodiment is an aspect of adding a predetermined amount of ethanol in the mixing process of the fourth embodiment, the aspect of adding a predetermined amount of ethanol in the method for producing lithium adsorbent granules in the first embodiment is also included in the method for producing lithium adsorbent granules of the present application.

[0100] The amount of ethanol to be added is determined according to the weight of the powder (precursor of the lithium adsorbent) mixed in the mixing step. It should be noted that the ethanol to be added is preferably volatilized during the stirring process of the suspension polymerization step.

[0101] (Sixth Embodiment)

[0102] A flowchart of a method for producing lithium adsorbing granules according to the sixth embodiment is shown in FIG. Figure 7 . The difference between the fourth embodiment and the sixth embodiment is that a washing step is provided after the solid-liquid separation step. Since the other parts are the same as the fourth embodiment, the description of the parts that are the same as the fourth embodiment is omitted. It should be noted that although the sixth embodiment is an aspect in which a washing step is added after the method for producing lithium adsorbing granules in the fourth embodiment, the aspect in which a solid-liquid separation step is added after the method for producing lithium adsorbing granules in the first embodiment and a washing step is added thereafter is also included in the method for producing lithium adsorbing granules of the present application.

[0103] (Cleaning process)

[0104] The washing step is a step of washing the filtered lithium adsorption granules obtained in the solid-liquid separation step to obtain washed lithium adsorption granules. The filtered lithium adsorption granules after the solid-liquid separation step are in a state of being coated with a hydrophobic liquid remaining on the outside of the filtered lithium adsorption granules, so the washing step is used to remove the coating. The reason is that in the state of the residual hydrophobic liquid coating, the contact between the lithium-containing liquid and the lithium adsorption granules is hindered by the coating. It should be noted that the washed lithium adsorption granules obtained in the washing step are one aspect of the lithium adsorption granules. In the washing step, liquids such as pure water, methanol or ethanol of a predetermined purity are appropriately used.

[0105] By providing a washing step after the solid-liquid separation step, the removal efficiency of the dispersion medium can be further improved.

[0106] (Seventh Embodiment)

[0107] A flowchart of a method for producing lithium adsorbing granules according to the seventh embodiment is shown in FIG. Figure 8 . The difference between the sixth embodiment and the seventh embodiment is that, in the mixing process, in addition to the raw material of the aqueous polymer and the precursor of the lithium adsorbent, a predetermined amount of ethanol is added. Since the other parts are the same as the sixth embodiment, the description of the same parts as the sixth embodiment is omitted. It should be noted that although the seventh embodiment is an aspect of adding a predetermined amount of ethanol in the mixing process of the sixth embodiment, the aspect of adding a predetermined amount of ethanol in the method for producing lithium adsorbent granules in the first embodiment is also included in the method for producing lithium adsorbent granules of the present application.

[0108] The amount of ethanol to be added is determined according to the weight of the powder (precursor of the lithium adsorbent) mixed in the mixing step. It should be noted that the ethanol to be added is preferably volatilized during the stirring process of the suspension polymerization step.

[0109] Example

[0110] Hereinafter, specific examples of the lithium adsorbing granular material and the method for producing the same of the present invention will be described, but the present invention is not limited to these examples.

[0111] (Example 1)

[0112] <Preparation of Lithium Adsorption Granular Body>

[0113] This embodiment is implemented according to the second embodiment described above. First, a mixing process is implemented. As raw materials for aqueous polymers, powdered acrylamide and powdered N,N'-methylenebisacrylamide are prepared. The ratio of acrylamide to N,N'-methylenebisacrylamide is 100:3. These raw materials are dissolved in industrial pure water to prepare an aqueous solution having a concentration of 50 wt %. 8 g of the aqueous solution is mixed with 3.2 g of lithium manganate, a precursor of a lithium adsorbent, to obtain a mixed aqueous solution.

[0114] Next, as the first half of the suspension polymerization step, an adding step was performed. In the adding step, 40 μL of ammonium persulfate and 8 μL of tetramethylethylenediamine were added as polymerization initiators to the above-mentioned mixed aqueous solution to obtain an aqueous solution for suspension polymerization.

[0115] Next, the second half of the suspension polymerization process was implemented. In the second half of the suspension polymerization process, the aqueous solution for suspension polymerization was suspended in the dispersion medium, i.e., silicone oil. 72 mL of silicone oil was prepared in a container, and a stirring blade was set in the silicone oil. The silicone oil was stirred by rotating the stirring blade at 300 rpm. The stirring was carried out in a nitrogen environment with a nitrogen concentration of more than 99% and a constant temperature of 30°C. In this state, the aqueous solution for suspension polymerization was added dropwise, and after 3 hours of polymerization, a gel-like granular body for lithium adsorption was obtained.

[0116] Next, a solid-liquid separation step and a washing step were performed. After the solid-liquid separation step and the washing step, the washed lithium adsorption granules can be obtained. After the washing step, the SEM photograph of the lithium adsorption granules before use after lithium adsorption is shown in FIG. Fig. 9 (a) The circular shape in the figure shows a lithium adsorbing granular body. The part located at the outer periphery of the circle and shown in a lighter color is a gel-like aqueous polymer, and the part located inside and shown in a darker color is a precursor of a lithium adsorbent.

[0117] The washed lithium adsorbing granules were used to perform 15 times of the elution step of converting the precursor of the lithium adsorbing agent into the lithium adsorbing agent and the adsorption step of bringing the lithium adsorbing agent into contact with the lithium-containing solution so that lithium is adsorbed on the lithium adsorbing agent. The lithium adsorbing granules after 15 times of the elution step are shown in FIG. Fig. 9 (b) With Fig. 9(a) is the same, it can be seen that there is a gel-like aqueous polymer on the outer periphery of the lithium adsorption granules, and there is a precursor of the lithium adsorbent inside. From this figure, it can be seen that the lithium adsorbent does not flow out of the lithium adsorption granules, and the durability is improved. In addition, before and after the washing process, that is, when the weight of the lithium adsorption granules after filtration and the lithium adsorption granules after washing are measured, the weight change is less than 1% of the lithium adsorption granules after filtration. In the lithium adsorption granules made using alumina binders, etc., the weight is usually reduced by more than 10% by weight before and after the washing process. It is believed that this is due to the initial collapse in the granules, so it can be seen that compared with the case of the granules, the weight change in the lithium adsorption granules is very small, and in this respect, the collapse is reduced and the durability is improved.

Claims

1. A granular body for lithium adsorption, characterized in that: include: Precursors of lithium adsorbents; as well as an aqueous polymer surrounding the precursor, The aqueous polymer can form gel-like granules.

2. The lithium adsorbing granular body according to claim 1, characterized in that: The lithium adsorbing granules are gel-like granules.

3. The lithium adsorbing granular body according to claim 1 or 2, characterized in that: The aqueous polymer has an amide group.

4. The lithium adsorbing granular body according to claim 3, characterized in that: The aqueous polymer having the amide group is polyacrylamide.

5. The lithium adsorbing granular body according to any one of claims 1 to 4, characterized in that: The precursor of the lithium adsorbent is lithium manganate.

6. A method for producing a granular body for lithium adsorption, characterized in that: include: In the suspension polymerization step, an aqueous suspension polymerization solution obtained by mixing a raw material of an aqueous polymer, a precursor of a lithium adsorbent, and a polymerization initiator is suspended in a dispersion medium to obtain lithium adsorbing granules.

7. The method for producing lithium adsorbing granules according to claim 6, characterized in that: A mixing step is provided before the suspension polymerization step, in which a raw material of the aqueous polymer and a precursor of the lithium adsorbent are mixed to obtain a mixed aqueous solution, After the mixing step, an aqueous solution for suspension polymerization obtained by mixing a polymerization initiator with the mixed aqueous solution is used in the suspension polymerization step.

8. The method for producing lithium adsorbing granules according to claim 7, wherein: In the mixing step, a predetermined amount of ethanol is added and then mixed.

9. The method for producing lithium adsorbing granules according to any one of claims 6 to 8, characterized in that: The aqueous polymer is polyacrylamide, The raw materials of the polyacrylamide are acrylamide and N,N'-methylenebisacrylamide.

10. The method for producing lithium adsorbing granules according to any one of claims 6 to 9, characterized in that: The suspension polymerization step is performed under a nitrogen atmosphere in which the ratio of nitrogen is within a predetermined range.

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