Method for producing lithium-containing solution

Abstract

Provided is a method for producing a lithium-containing solution with which it is possible to suppress the amount of a solution after an adsorption step, increase the lithium content in the lithium-containing solution, and suppress the amount of a solution used in a step after a manganese oxidation step, thereby making it possible to suppress the production cost for producing lithium. The method for producing a lithium-containing solution sequentially executes an adsorption step, an elution step, and a manganese oxidation step. Moreover, in the adsorption step, an anion exchange resin can be used together with the lithium adsorbent. In this manner, since the anion exchange resin adsorbs hydrogen ions generated in the adsorption step, the adsorption reaction can be promoted. Therefore, the amount of the solution after the adsorption step can be suppressed, the lithium content in the lithium-containing solution can be increased, and the amount of the solution used in the step after the manganese oxidation step can be suppressed. This makes it possible to suppress the manufacturing cost for manufacturing lithium.

Description

Technical Field

[0001] The present invention relates to a method for producing a lithium-containing solution. More specifically, the method for producing a lithium-containing solution according to the present invention improves the adsorption efficiency in the adsorption process, thereby increasing the lithium content in the solution after the elution process, and suppresses the amount of solution used in the process after the elution process, thereby suppressing the manufacturing cost for producing lithium. Background Art

[0002] It is known that by using lithium manganese oxide (LiMn 2 O 4 , Li 1.33 Mn 1.67 O 4 , Li 1.6 Mn 1.6 O 4 λ-MnO having a spinel structure obtained by contacting with inorganic acids such as hydrochloric acid 2 (HMn 2 O 4 , H 1.33 Mn 1.67 O 4 , H 1.6 Mn 1.6 O 4 etc.) selectively adsorb lithium. 2 It is one of the adsorbents that has attracted much attention in DLE (Direct Lithium Extraction) technology. 2 In the case of lithium recovery, due to the 2 Since it does not adsorb impurities, it has the advantage of being able to significantly reduce the amount of neutralizer used in lithium recovery. Therefore, the commercial use of this method is expected. 2 A method for producing a lithium-containing solution is disclosed in Patent Document 1.

[0003] The method for manufacturing a lithium-containing solution of Patent Document 1 is composed of an adsorption step, an elution step, and a manganese oxidation step. As an acid-containing solution used in the elution step, acid is added to the total amount of the elution solution obtained in the elution step to adjust the hydrogen ion concentration of the acid-containing solution, thereby suppressing the amount of elution solution used in the step after the elution step.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent document 1: International Publication No. 2022 / 210847. Summary of the invention

[0007] Problems to be solved by the invention

[0008] The lithium adsorbent (e.g. H 1.6 Mn 1.6 O 4 ) and lithium chloride is shown in Mathematical Formula 1. This reaction is a reversible reaction. If the pH is high, the reaction proceeds to the right, and if the pH is low, the reaction proceeds to the left. That is, when a salt lake brine containing lithium ions is brought into contact with a lithium adsorbent obtained from lithium manganate under a high pH state, the lithium adsorbent adsorbs lithium to become lithium manganate (adsorption process). If it is brought into contact with an acid again, the lithium ions are eluted in an aqueous solution and the lithium adsorbent is restored (elution process). Although Mathematical Formula 1 shows a reaction with lithium chloride, the same chemical reaction also occurs with other types of lithium salts such as lithium sulfate.

[0009] [Mathematical formula 1]

[0010]

[0011] However, when lithium is adsorbed using a lithium adsorbent obtained from lithium manganate, an acid corresponding to the amount of adsorbed lithium is generated simultaneously with the adsorption of lithium, so the pH of the solution in the adsorption process decreases. There is a problem that in the chemical reaction of lithium adsorption, if the pH decreases, the reaction of mathematical formula 1 is difficult to proceed to the right, and if the pH drops to a certain value, the adsorption reaction will not occur.

[0012] Regarding the above problem, if a method of adding a liquid alkaline neutralizer such as sodium hydroxide aqueous solution during lithium adsorption is adopted, there is a problem of increased liquid volume after the adsorption process. In addition, the lithium adsorbent is sometimes used as a particle body using, for example, a binder. Sometimes, there is a problem that the binder is degraded by a strong base such as sodium hydroxide, its binding ability decreases, and the particle body disintegrates.

[0013] In view of the above situation, the present invention aims to provide a method for manufacturing a lithium-containing solution, which can suppress the manufacturing cost for manufacturing lithium by suppressing the amount of solution after the adsorption process, increasing the lithium content in the lithium-containing solution obtained after the adsorption process, the elution process, and the manganese oxidation process, and suppressing the amount of solution used in the process after the manganese oxidation process.

[0014] Means for solving problems

[0015] The first invention is a method for producing a lithium-containing solution, characterized in that the following steps are performed in sequence: an adsorption step, in which a lithium adsorbent obtained from lithium manganate is brought into contact with a low-concentration lithium-containing solution to obtain adsorbed lithium manganate; an elution step, in which the adsorbed lithium manganate is brought into contact with an acid-containing solution to obtain an elution solution; and a manganese oxidation step, in which manganese is oxidized by adding an oxidant and a pH adjuster to the elution solution to obtain a lithium-containing solution with suppressed manganese concentration, wherein an anion exchange resin is used together with the lithium adsorbent in the adsorption step.

[0016] The method for producing a lithium-containing solution according to a second invention is characterized in that, in the first invention, a weight ratio of the anion exchange resin to the lithium adsorbent is 0.5 or more and 2.5 or less.

[0017] A method for producing a lithium-containing solution according to a third invention is characterized in that, in the first invention or the second invention, the lithium adsorbent is in a particulate form, and the particulate form contains a binder.

[0018] The method for producing a lithium-containing solution of the fourth invention is characterized in that, in any one of the first to third inventions, a regeneration process is provided after the elution process, the regeneration process restores the functional groups of the anion exchange resin to a hydroxyl form, and the anion exchange resin that has undergone the regeneration process is used in the adsorption process.

[0019] Effects of the Invention

[0020] According to the first invention, in the adsorption process, an anion exchange resin is used together with a lithium adsorbent, and the anion exchange resin adsorbs hydrogen ions generated in the adsorption process. Therefore, without using an additional alkali neutralizer, the pH in the adsorption process can be maintained at a high state, thereby promoting the adsorption reaction. Therefore, since the amount of solution after the adsorption process can be suppressed, the lithium content in the lithium-containing solution obtained through the adsorption process, the elution process, and the manganese oxidation process is increased, and the amount of solution used in the process after the manganese oxidation process is suppressed. As a result, the manufacturing cost for manufacturing lithium can be suppressed.

[0021] According to the second invention, the weight ratio of the anion exchange resin to the lithium adsorbent is 0.5 or more and 2.5 or less, so that the pH in the adsorption step can be maintained at a high state while suppressing the amount of the anion exchange resin.

[0022] According to the third invention, even when the lithium adsorbent constitutes a particulate body and the particulate body contains a binder, since the anion exchange resin is used together with the lithium adsorbent in the adsorption step, deterioration of the binder can be suppressed, thereby extending the life of the particulate body.

[0023] According to the fourth invention, a regeneration step is provided after the elution step to restore the functional groups of the anion exchange resin to hydroxyl form, and the anion exchange resin that has undergone the regeneration step is used in the adsorption step, thereby suppressing an increase in cost due to the use of the anion exchange resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the method for producing a lithium-containing solution according to the first embodiment of the present invention.

[0025] Figure 2 This is a flow chart of a method for producing a lithium-containing solution according to a second embodiment of the present invention.

[0026] Figure 3 This is a graph showing the relationship between mixing time and pH.

[0027] Figure 4 This is a graph showing the relationship between the mixing and stirring time and the amount of lithium adsorption. DETAILED DESCRIPTION

[0028] Next, embodiments of the present invention will be described based on the drawings. However, the embodiments described below are examples of methods for producing a lithium-containing solution for embodying the technical concept of the present invention, and the present invention does not limit the method for producing a lithium-containing solution to the following method.

[0029] The method for manufacturing a lithium-containing solution of the present invention sequentially performs: an adsorption step, in which a lithium adsorbent obtained from lithium manganate is brought into contact with a low-concentration lithium-containing solution to obtain adsorbed lithium manganate; an elution step, in which the adsorbed lithium manganate is brought into contact with an acid-containing solution to obtain an elution solution; and a manganese oxidation step, in which an oxidant and a pH adjuster are added to the elution solution to oxidize manganese to obtain a lithium-containing solution with suppressed manganese concentration. In the adsorption step, an anion exchange resin is used together with the lithium adsorbent.

[0030] In the adsorption process, by using an anion exchange resin together with a lithium adsorbent, since the anion exchange resin adsorbs hydrogen ions generated in the adsorption process, the pH in the adsorption process can be maintained at a high state without using an additional alkali neutralizer, thereby promoting the adsorption reaction. Therefore, since the amount of solution after the adsorption process can be suppressed, the lithium content in the lithium-containing solution obtained through the adsorption process, the elution process, and the manganese oxidation process is increased, and the amount of solution used in the process after the manganese oxidation process is suppressed. As a result, the manufacturing cost for manufacturing lithium can be suppressed.

[0031] In addition, the weight ratio of the anion exchange resin to the lithium adsorbent is preferably 0.5 or more and 2.5 or less. In this way, the pH in the adsorption process can be maintained at a high state while suppressing the amount of the anion exchange resin.

[0032] In addition, the lithium adsorbent preferably comprises a granular body and the granular body contains a binder. Even if the lithium adsorbent comprises a granular body and the granular body contains a binder, in the adsorption process, since the anion exchange resin is used together with the lithium adsorbent, the binder can be suppressed from deteriorating, thereby extending the life of the granular body.

[0033] In addition, it is preferred that a regeneration step is provided after the elution step, in which the functional groups of the anion exchange resin are restored to the hydroxyl form, and the anion exchange resin that has undergone the regeneration step is used in the adsorption step. In this way, the cost increase due to the use of the anion exchange resin can be suppressed.

[0034] (First Embodiment)

[0035] (Preliminary stage of adsorption process)

[0036] In the adsorption process, the lithium adsorbent is brought into contact with a low-concentration lithium-containing solution to obtain adsorbed lithium manganate. A method for obtaining the lithium adsorbent used in the adsorption process is described. Figure 1 In the flowchart of the method for producing a lithium-containing solution according to the first embodiment of the present invention, the description of the "pre-adsorption process" is located in Figure 1 The top section gets H 1.6 Mn 1.6 O 4 stage.

[0037] As shown in Mathematical Formula 2, lithium manganate is treated with acid to become a lithium adsorbent. 1.6 Mn 1.6 O 4 , but lithium manganate is not limited thereto. For example, Li 1.33 Mn 1.67 O 4 That is, when lithium manganate is Li 1.6 Mn 1.6 O 4 In the case of 1.6 Mn 1.6 O 4 , for example, lithium manganate is Li 1.33 Mn 1.67 O 4 In the case of lithium adsorbent being H 1.33 Mn 1.67 O 4 In addition, although the acid used for the acid treatment is HCl, it is not limited to this. For example, sulfuric acid, nitric acid, etc. can also be used.

[0038] The shape of lithium manganate is a form that takes into account the lithium adsorption in the adsorption process. For example, the shape of lithium manganate can be various shapes such as powder, granular particles obtained by granulating the powder, and columnar shapes blown to the fibers of the column. When acid treatment is performed, for example, H is obtained as a lithium adsorbent. 1.6 Mn 1.6 O 4 The shape of the lithium adsorbent is the same as the shape of the lithium manganese oxide before the acid treatment.

[0039] [Mathematical formula 2]

[0040] Li 1.6 Mn 1.6 O 4 +1.6HCl→H 1.6 Mn 1.6 O 4 +1.6LiCl

[0041] (Adsorption process)

[0042] Figure 1 A flow chart showing a method for producing a lithium-containing solution according to a first embodiment of the present invention is shown. In the adsorption step, a lithium adsorbent is brought into contact with a low-concentration lithium-containing solution, and adsorbed lithium manganate is obtained by an ion exchange reaction of H and Li as shown in Mathematical Formula 3. In this specification, the lithium manganate obtained in the adsorption step is sometimes referred to as adsorbed lithium manganate.

[0043] [Mathematical formula 3]

[0044] H 1.6 Mn 1.6 O 4 +1.6LiCl→Li 1.6 Mn 1.6 O 4 +1.6HCl

[0045] The low-concentration lithium-containing solution is, for example, equivalent to salt water in seawater or a salt lake. For example, seawater contains an average of 0.17 ppm of lithium. However, in addition to lithium, elements such as sodium, magnesium or calcium are dissolved in these low-concentration lithium-containing solutions. According to the method for manufacturing a lithium-containing solution of the present invention, lithium can be selectively recovered from a low-concentration lithium-containing solution in which these elements are dissolved. It should be noted that the low-concentration lithium-containing solution means that the amount of lithium per unit volume is less than that of the lithium-containing solution described later.

[0046] In the adsorption process, the contact method between the low-concentration lithium-containing solution and the adsorbent is different depending on the shape of the adsorbent. For example, in the case where the adsorbent is in powder form, as a method, a method can be cited in which a predetermined amount of adsorbent is added to the low-concentration lithium-containing solution, and the mixture is stirred and mixed for a predetermined time, so that the low-concentration lithium-containing solution is brought into contact with the adsorbent, and lithium is adsorbed on the adsorbent. In the case where the adsorbent is in a particulate form, as a method, a method can be cited in which a particulate adsorbent is sealed in a liquid-passing container, and a low-concentration lithium-containing solution is passed through, so that the low-concentration lithium-containing solution and the adsorbent are brought into contact, and lithium is adsorbed on the adsorbent. In the case where the adsorbent is blown to the fibers of the column, as a method, a method can be cited in which a low-concentration lithium-containing solution is passed through the column, so that the low-concentration lithium-containing solution and the adsorbent are brought into contact, and lithium is adsorbed on the adsorbent. It should be noted that when the low-concentration lithium-containing solution is passed through, in order to ensure the number of contacts with the adsorbent, there is a situation where repeated liquid passing is performed.

[0047] In the adsorption process of the present embodiment, an anion exchange resin is used together with a lithium adsorbent. Anion exchange resin is a type of synthetic resin, and a part of the molecular structure has a structure that is ionized as an ion exchange group, and the ion exchange group refers to a substance with anionic properties. Anion exchange resins are divided into weakly basic anion exchange resins having 1st to 3rd amino groups as functional groups and strongly basic anion exchange resins having 4th-level ammonium groups as functional groups, but no matter which anion exchange resin is used, there is no problem. In the case of a weakly basic anion exchange resin, that is, in the case of a 1st-level amino group, a reaction formula represented by mathematical formula 4 is used, in the case of a 2nd-level amino group, a reaction formula represented by mathematical formula 5 is used, and in the case of a 3rd-level amino group, a reaction formula represented by mathematical formula 6 is used to adsorb hydrogen ions from the solution in the adsorption process. In addition, in the case of a strongly basic anion exchange resin, that is, an anion exchange resin having a 4th-level ammonium group, hydrogen ions are adsorbed from the solution in the adsorption process by a reaction formula represented by mathematical formula 7. It should be noted that although hydrochloric acid is recorded as an acid in each reaction formula, it is not limited to this. For example, other acids such as sulfuric acid also become the same reaction. In addition, R represented in each reaction formula is a group in which hydrogen, nitrogen, oxygen, etc. are bonded to a carbon skeleton formed by bonding carbon atoms to each other.

[0048] [Formula 4]

[0049] R-NH 2 +HCl→R-NH 2 HCl

[0050] [Formula 5]

[0051] R 2 -NH+HCl→R 2 -NH·HCl

[0052] [Mathematical formula 6]

[0053] R 3 -N+HCl→R 3 -N·HCl

[0054] [Mathematical formula 7]

[0055] R 4 -NOH+HCl→R 4 -NCl+H 2 O

[0056] In the adsorption process, an anion exchange resin is used together with a lithium adsorbent. Since the anion exchange resin adsorbs hydrogen ions generated in the adsorption process, the pH in the adsorption process can be maintained at a high state without using an additional alkali neutralizer, thereby promoting the adsorption reaction. Therefore, since the amount of solution after the adsorption process can be suppressed, the lithium content in the lithium-containing solution obtained through the adsorption process, the elution process, and the manganese oxidation process is increased, and the amount of solution used in the process after the manganese oxidation process is suppressed. As a result, the manufacturing cost for manufacturing lithium can be suppressed.

[0057] The method of using the anion exchange resin may differ depending on the shape of the lithium adsorbent or the method of contacting the lithium-containing solution with the low concentration. For example, when the lithium adsorbent is in powder form, a predetermined amount of the adsorbent and a predetermined amount of the anion exchange resin are added to a beaker or the like storing the lithium-containing solution at a low concentration, and stirred for a predetermined time, so that the lithium-containing solution at a low concentration contacts the lithium adsorbent, and lithium is adsorbed on the lithium adsorbent.

[0058] When the lithium adsorbent is in the form of particles, the particles containing the lithium adsorbent and an anion exchange resin are sealed in a liquid flow container, and a low-concentration lithium-containing solution is passed through the container, so that the low-concentration lithium-containing solution contacts the lithium adsorbent and lithium is adsorbed on the lithium adsorbent.

[0059] When the lithium adsorbent is blown onto the fibers of the column, the column is enclosed with an anion exchange resin, and the low-concentration lithium-containing solution is passed through the column, so that the low-concentration lithium-containing solution contacts the lithium adsorbent, and lithium is adsorbed on the lithium adsorbent.

[0060] Although the above description describes the contact method that is more likely to be used according to the shape of the lithium adsorbent, the combination of the shape of the lithium adsorbent and the contact method is not limited to the above combination. For example, a method of putting a particle containing a lithium adsorbent into a low-concentration lithium-containing solution and stirring it may also be used.

[0061] In any shape or contact method of the lithium adsorbent, the weight ratio of the anion exchange resin to the lithium adsorbent is preferably 0.5 or more and 2.5 or less. That is, the value obtained by dividing the weight of the anion exchange resin by the weight of the lithium adsorbent is preferably 0.5 or more and 2.5 or less.

[0062] When the weight ratio of the anion exchange resin to the lithium adsorbent is 0.5 or more and 2.5 or less, the amount of the anion exchange resin can be suppressed and the pH in the adsorption step can be maintained at a high state.

[0063] After the adsorption process, the adsorbent becomes adsorbed lithium manganate. In addition, the low-concentration lithium-containing solution becomes adsorbed liquid after lithium is adsorbed by the adsorbent. The adsorbed liquid is discharged to the ocean or lake where the low-concentration lithium-containing solution is collected. At this time, the adsorbed liquid is discharged after being treated to a state suitable for discharge by neutralization treatment or the like.

[0064] (Elution process)

[0065] In the elution process, the adsorbed lithium manganese oxide is brought into contact with an acid-containing solution, and an elution solution is obtained through the reaction shown in Mathematical Formula 8. At this time, the adsorbed lithium manganese oxide is regenerated as a lithium adsorbent through an exchange reaction between Li+ and H+ cations, and the lithium adsorbent is used again in the adsorption process.

[0066] [Mathematical formula 8]

[0067] Li 1.6 Mn 1.6 O 4 +1.6HCl→H 1.6 Mn 1.6 O 4 +1.6LiCl

[0068] In this embodiment, the acid-containing solution includes a solution of an acid monomer such as hydrochloric acid and a solution in which an acid is added to an elution solution obtained through a single elution process. For example, in this embodiment, the elution process is divided into a plurality of stages, and in the first stage, the acid-containing solution is a solution of an acid monomer, and in the second stage and after, the elution solution obtained in the previous stage is used, and the elution process after the second stage is performed by adding an acid solution to the elution solution, but it is not limited thereto. For example, as the acid-containing solution, sometimes only a solution of an acid monomer is used.

[0069] The hydrogen ion concentration of the acid-containing solution that contacts the adsorbed lithium manganate in the elution step of the present embodiment is preferably 0.1 mol / L to 4.0 mol / L, and preferably 0.5 mol / L to 2.0 mol / L.

[0070] When the hydrogen ion concentration of the acid solution is more dilute than 0.1 mol / L, the exchange reaction between the cations cannot be fully carried out, and the efficiency of the exchange reaction is reduced. In addition, when the acid solution is more concentrated than 4.0 mol / L, since the lithium manganate is dissolved in the acid solution as a whole, the lithium manganate cannot be used as a lithium adsorbent again after adsorption. It should be noted that the acid used in the acid solution is preferably hydrochloric acid, but is not limited thereto. For example, sulfuric acid or acetic acid are sometimes used.

[0071] Depending on the shape of the lithium manganate, the form of contact between the adsorbed lithium manganate and the acid solution in the elution process is different. For example, if the lithium manganate is in powder form, one method may include adding the powder of the adsorbed lithium manganate into the acid solution and stirring the adsorbed lithium manganate to contact the acid solution. In the case where the lithium manganate is a particulate body, or is blown to the fibers of the column, one method may include passing the acid solution into the liquid-passing container while the particulate lithium manganate and the column are contained in the liquid-passing container to contact the adsorbed lithium manganate and the acid solution.

[0072] In addition, when the shape of the adsorbed lithium manganate is a powder or a particulate body, in the present embodiment, in the elution step, the adsorbed lithium manganate and the anion exchange resin are preferably separated. This is because the lithium adsorbent after the elution step can be used again in the adsorption step. The separation is performed, for example, by sieving.

[0073] (Manganese oxidation process)

[0074] In the manganese oxidation step, an oxidant and a pH adjuster are added to the elution solution obtained in the elution step, thereby oxidizing divalent manganese to tetravalent manganese, thereby obtaining a lithium-containing solution with a suppressed manganese concentration. Since tetravalent manganese is poorly soluble, it precipitates in the solution. Thus, the concentration of manganese contained in the elution solution can be suppressed. Furthermore, the precipitated manganese can be reused as a raw material for a lithium adsorbent.

[0075] In order to oxidize divalent manganese to tetravalent manganese, an oxidant and a pH regulator are added to the elution solution. When adding the oxidant and the pH regulator, it is preferred that the pH be in the range of more than 3 and less than 7, and the redox potential be adjusted to more than 600mV and less than 1100mV using a silver-silver chloride electrode. That is, the pH and the redox potential are measured simultaneously, and the oxidant and the pH regulator are added simultaneously or alternately so that they fall within the above range. As an oxidant, for example, sodium hypochlorite, sodium chlorite, ozone, permanganate, etc. can be used. But it is not limited to these, as long as it is an oxidant that can adjust the redox potential, there is no problem. As a pH regulator, for example, an alkali neutralizer such as sodium hydroxide and slaked lime can be used. But it is not limited to this, as long as the pH can be adjusted, there is no problem.

[0076] (Last stage of manganese oxidation process)

[0077] In the present embodiment, since lithium exists in the form of lithium chloride (LiCl) in the lithium-containing solution obtained in the manganese oxidation step, alkali is added to the solution or the solution is superheated and concentrated to obtain lithium in the form of, for example, lithium carbonate.

[0078] In addition, the lithium manganese oxide after adsorption becomes a lithium adsorbent by passing through an acid solution, and thus the lithium adsorbent can be used again in the adsorption process.

[0079] (Second Embodiment)

[0080] Figure 2 The flowchart of the method for producing a lithium-containing solution according to the second embodiment of the present invention is shown. The difference between the first embodiment and the second embodiment is that a regeneration process is provided after the elution process, and in the regeneration process, the functional groups of the anion exchange resin separated from the adsorbed lithium manganate are restored to the hydroxyl form, and other aspects are the same as the first embodiment. Therefore, only the differences are described below and other descriptions are omitted.

[0081] (Regeneration process)

[0082] Since most of the anion exchange resins used in the regeneration process are in contact with the acid in the adsorption process and the elution process, they are in a state of absorbing hydrogen ions. In this embodiment, a regeneration process is performed to restore the functional groups of the anion exchange resin to the hydroxyl form for the anion exchange resin separated from the adsorbed lithium manganate in the elution process, and the anion exchange resin obtained through the regeneration process is used in the adsorption process.

[0083] As a method for restoring the functional groups of the anion exchange resin to the hydroxyl form, it is preferable to pass the anion exchange resin separated in the elution step through an alkaline aqueous solution such as sodium hydroxide aqueous solution, ammonia aqueous solution, sodium carbonate aqueous solution, etc. In mathematical formulas 9 to 12, chemical reaction formulas are shown when sodium hydroxide aqueous solution is used in the regeneration step.

[0084] [Mathematical formula 9]

[0085] R-NH 2 +HCl+NaOH→R-NH 2 +NaCl+H 2 O

[0086] [Formula 10]

[0087] R 2 -NH+HCl+NaOH→R 2 -NH+NaCl+H 2 O

[0088] [Mathematical formula 11]

[0089] R 3 -N+HCl+NaOH→R 3 -N+NaCl+H 2 O

[0090] [Mathematical formula 12]

[0091] R 4 -NCl+NaOH→R 4 -NOH+NaCl

[0092] By providing a regeneration step for returning the functional groups of the anion exchange resin to the hydroxyl form after the elution step and using the anion exchange resin after the regeneration step in the adsorption step, it is possible to suppress an increase in cost due to the use of the anion exchange resin.

[0093] It should be noted that the regeneration process can sometimes be carried out in a state where the anion exchange resin and the lithium adsorbent are mixed. That is, since the lithium adsorbent has no ability to adsorb metal elements other than lithium, when the above-mentioned alkaline aqueous solution does not contain lithium, in the regeneration process, the lithium adsorbent does not adsorb any metal elements and maintains the adsorption capacity. On the other hand, the anion exchange resin is regenerated and the lithium adsorbent can be used as it is in the next adsorption process. Similarly, even if the alkaline aqueous solution contains some lithium and the adsorption capacity of the lithium adsorbent decreases, as long as its adsorption capacity remains in the lithium adsorbent, it can be used in the next adsorption process. It should be noted that in the case where the alkaline aqueous solution contains a considerable amount of lithium (when there is a concern about saturation of the lithium adsorbent), the anion exchange resin and the lithium adsorbent need to be separated in the elution process. As a separation method, screening, etc. can be used.

[0094] Example

[0095] Hereinafter, specific examples of the method for producing a lithium-containing solution of the present invention will be described, but the present invention is not limited to these examples.

[0096] <Example 1>

[0097] (Adsorption process)

[0098] 10 g of powdered lithium adsorbent H 1.6 Mn 1.6 O 4The mixture was mixed with 20 g of a weakly basic anion exchange resin (A830W: manufactured by Purolite Co., Ltd.). The weight ratio of the anion exchange resin to the lithium adsorbent in this case was 2. The mixture was added to a 1 L beaker containing 400 mL of salt lake brine adjusted to pH 8.5 and stirred for 60 minutes to perform an adsorption process. The analytical values ​​of the salt lake brine used in the adsorption process are shown in Table 1. In addition, the pH was measured every 10 minutes from the start of stirring and mixing to 60 minutes. The results are shown in Tables 2 and Figure 3 In addition, a predetermined amount of the solution was collected from the beaker every 10 minutes.

[0099] (Elution process)

[0100] The adsorbed lithium manganate present in the solution whose pH is measured is brought into contact with the acid-containing solution. The acid-containing solution is set to be only hydrochloric acid with a hydrogen ion concentration of 0.5 mol / L. The pH of the acid-containing solution at this time is 0.4. All the solutions flowing out of the column are mixed to form a uniform solution.

[0101] (Manganese oxidation process)

[0102] The manganese oxidation step was carried out using the second elution solution. At this time, an oxidant and a pH adjuster were used to obtain a lithium-containing solution. The amount of lithium contained in the lithium-containing solution is shown in Tables 3 and Figure 4 .

[0103] <Example 2>

[0104] The difference between Example 1 and Example 2 is that the anion exchange resin in the adsorption step is 10 g of a strongly basic anion exchange resin (DIAION SA10A: manufactured by Mitsubishi Chemical Corporation). The other parameters are the same as those in Example 1. The pH was measured every 10 minutes from the start of stirring and mixing until 60 minutes. The results are shown in Tables 2 and Figure 3 In addition, the amount of lithium contained in the lithium-containing solution obtained through the manganese oxidation step is shown in Tables 3 and Figure 4 .

[0105] <Example 3>

[0106] The difference between Example 1 and Example 3 is that the anion exchange resin in the adsorption step is 20 g of a strongly basic anion exchange resin (DIAION SA10A: manufactured by Mitsubishi Chemical Corporation). The other parameters are the same as those in Example 1. The pH was measured every 10 minutes from the start of stirring and mixing until 60 minutes. The results are shown in Tables 2 and 3. Figure 3 In addition, the amount of lithium contained in the lithium-containing solution obtained through the manganese oxidation step is shown in Tables 3 and Figure 4 .

[0107] <Comparative Example 1>

[0108] The difference between Example 1 and Comparative Example 1 is that no anion exchange resin is used in the adsorption step. The other parameters are the same as those of Example 1. The pH was measured every 10 minutes from the start of stirring and mixing to 60 minutes. The results are shown in Tables 2 and Figure 3 In addition, the amount of lithium contained in the lithium-containing solution obtained through the manganese oxidation step is shown in Tables 3 and Figure 4 .

[0109] [Table 1]

[0110] Element Name Li K Mg Na Ca Content [g / L] 0.86 9.3 7.8 96 11

[0111] [Table 2]

[0112] Mixing time 0 10 20 30 40 50 60 Example 1 8.69 8.49 8.53 8.55 8.57 8.59 8.58 Example 2 8.82 8.72 8.65 8.49 8.31 8.19 8.08 Example 3 8.82 8.81 8.80 8.79 8.78 8.76 8.74 Comparative Example 1 8.39 8.13 7.96 7.82 7.73 7.65 7.58

[0113] [Table 3]

[0114] Mixing time 0 10 20 30 40 50 60 Example 1 0.00 0.86 0.94 1.08 1.15 1.40 1.34 Example 2 0.00 0.52 0.71 0.85 0.93 1.06 1.12 Example 3 0.00 0.58 0.77 0.91 0.98 1.12 1.17 Comparative Example 1 0.00 0.29 0.36 0.48 0.55 0.68 0.73

[0115] according to Figure 3 In Examples 1 and 3, there was almost no pH difference between the start and end of the stirring and mixing. In addition, in Example 2, the pH was maintained above 8.0 even after the 60-minute stirring and mixing was completed, and the pH decrease was less compared with the comparative example. Figure 4 It was found that after 60 minutes of stirring and mixing, all examples were able to adsorb more than 1.0 mmol / g (manganese-based adsorbent) of lithium. In contrast, in the comparative example, adsorption in the adsorption step was not fully carried out, and only 0.8 mmol / g (manganese-based adsorbent) of lithium was obtained.

Claims

1. A method for producing a lithium-containing solution, characterized in that: The method for manufacturing the lithium-containing solution is performed in sequence: An adsorption step, in which a lithium adsorbent obtained from lithium manganate is brought into contact with a low-concentration lithium-containing solution to obtain adsorbed lithium manganate; an elution step, in which the adsorbed lithium manganese oxide is brought into contact with an acid-containing solution to obtain an elution solution; as well as a manganese oxidation step, in which an oxidizing agent and a pH adjusting agent are added to the elution solution to oxidize manganese, thereby obtaining a lithium-containing solution with a suppressed manganese concentration; In the adsorption process, an anion exchange resin is used together with the lithium adsorbent.

2. The method for producing a lithium-containing solution according to claim 1, characterized in that: The weight ratio of the anion exchange resin to the lithium adsorbent is 0.5 to 2.

5.

3. The method for producing a lithium-containing solution according to claim 1 or 2, characterized in that: The lithium adsorbent is in the form of particles. The particulate material contains a binder.

4. The method for producing a lithium-containing solution according to any one of claims 1 to 3, characterized in that: A regeneration step is provided after the elution step, wherein the functional groups of the anion exchange resin are restored to a hydroxyl form. The anion exchange resin that has undergone the regeneration step is used in the adsorption step.

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