Method for producing lithium-containing solution

Abstract

To provide a method for producing lithium containing-solution which is capable of suppressing a production cost for producing lithium by suppressing the amount of solution after an adsorption step, increasing the lithium content in lithium containing-solution, and suppressing the amount of solution used in a step after a manganese oxidizing step.SOLUTION: In a method for producing lithium containing-solution, an adsorption step, an elution step and a manganese oxidizing step are executed in this order. Then, in the adsorption step, anion exchange resin is used together with lithium adsorbent. According to this embodiment, adsorption reaction can be promoted because anion exchange resin adsorbs hydrogen ions created in the adsorption step. Thus, the amount of solution after the adsorption step can be suppressed, the lithium content in lithium containing-solution is increased, and the amount of solution used in a step after the manganese oxidizing process is suppressed. This makes it possible to suppress a production cost for producing lithium.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a lithium-containing solution. More specifically, the present invention relates to a method for producing a lithium-containing solution that can increase the lithium content in a solution after an elution step by increasing the adsorption efficiency in an adsorption step, and can reduce the production cost for lithium production by reducing the amount of the solution used in a step after the elution step. [Background technology]

[0002] Lithium manganese oxide (LiMn2O4, Li 1.33 Mn 1.67 O4, Li 1.6 Mn 1.6 λ-MnO2 (HMn2O4, HO4, etc.) is obtained by contacting mineral acids such as hydrochloric acid with 1.33 Mn 1.67 O4, H 1.6 Mn 1.6 It is known that λ-MnO2, which is an adsorbent, selectively adsorbs lithium, is one of the adsorbents that has attracted attention in the DLE (Direct Lithium Extraction) technology. When λ-MnO2 is used to recover lithium, it has the advantage that the amount of neutralizing agent used in lithium recovery can be significantly reduced because λ-MnO2 does not adsorb impurities. For this reason, commercial use of this method is expected. A method for producing a lithium-containing solution using λ-MnO2 is disclosed in Patent Document 1.

[0003] The method for producing a lithium-containing solution in Patent Document 1 comprises an adsorption step, an elution step, and a manganese oxidation step, and the amount of the elution solution used in the steps after the elution step is reduced by adding an acid to the total amount of the elution solution obtained in the elution step to adjust the hydrogen ion concentration of the acid-containing solution used in the elution step. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 210847 Summary of the Invention [Problem to be solved by the invention]

[0005] Lithium adsorbents derived from lithium manganate (e.g., H 1.6 Mn 1.6 The reaction between lithium ions (O4) and lithium chloride is shown in Equation 1. This reaction is reversible, and when the pH is high the reaction proceeds to the right, and when the pH is low the reaction proceeds to the left. In other words, when a lithium adsorbent made from lithium manganate is brought into contact with salt lake brine or the like containing lithium ions at a high pH level, the lithium adsorbent adsorbs lithium and becomes lithium manganate (adsorption process), and when it is brought into contact with acid again, the lithium ions are eluted into the aqueous solution, returning it to the lithium adsorbent (elution process). Equation 1 shows the reaction with lithium chloride, but similar chemical reactions occur with other types of lithium salts, such as lithium sulfate.

[0006] [Number 1] 1.6LiCl+H 1.6 Mn 1.6 O4⇔1.6HCl+Li 1.6 Mn 1.6 O4

[0007] However, when lithium is adsorbed using a lithium adsorbent made from lithium manganate, an acid corresponding to the lithium is generated at the same time as the lithium is adsorbed, and the pH of the solution in the adsorption process drops. When the pH of the chemical reaction of lithium adsorption drops, the reaction of equation 1 becomes less likely to proceed to the right, and when the pH drops to a certain value, the adsorption reaction no longer occurs, which is a problem.

[0008] To solve the above problem, if a method of adding a liquid alkali neutralizer such as an aqueous sodium hydroxide solution is adopted during lithium adsorption, the amount of liquid increases after the adsorption process. In addition, the lithium adsorbent may be used as a particulate material with a binder, for example. There is a problem that the binder may be deteriorated by a strong alkali such as sodium hydroxide, and the binding ability may decrease, causing the particulate material to collapse.

[0009] In view of the above circumstances, the present invention has an object to provide a method for producing a lithium-containing solution that can reduce the production cost for lithium production by reducing the amount of solution after the adsorption step, increasing the lithium content in the lithium-containing solution obtained through the adsorption step, elution step, and manganese oxidation step, and reducing the amount of solution used in the steps after the manganese oxidation step. [Means for solving the problem]

[0010] The method for producing a lithium-containing solution of the first invention includes the steps of: an adsorption step of bringing a low-concentration lithium-containing solution into contact with a lithium adsorbent obtained from lithium manganate to obtain an adsorbed lithium manganate; an elution step of bringing the adsorbed lithium manganate into contact with an acid-containing solution to obtain an elution solution; and a manganese oxidation step of adding an oxidizing agent and a pH adjuster to the elution solution to oxidize manganese and obtain a lithium-containing solution with a reduced manganese concentration. The adsorption step is characterized in that an anion exchange resin is used together with the lithium adsorbent to remove hydrogen ions from the solution of the adsorption step. No. 2 The method for producing a lithium-containing solution of the present invention comprises the steps of: The anion exchange resin is used in the adsorption step in a state that allows it to be separated when sieved in the elution step. No. 3 The method for producing a lithium-containing solution of the present invention is characterized in that, in the adsorption step, the anion exchange resin removes hydrogen ions from the solution in the adsorption step through a reaction represented by any one of the following chemical reaction formulas (1) to (4). Chemical reaction equation: R-NH2 + HCl → R-NH2 HCl (1) Chemical reaction formula: R2-NH+HCl→R2-NH·HCl···(2) Chemical reaction: R3-N + HCl → R3-N HCl (3) Chemical reaction: R4-NOH+HCl → R4-NCl+H2O (4) (In the chemical reaction formula, R is a primary amino group, R2 is a secondary amino group, R3 is a tertiary amino group, and R4 is a quaternary ammonium group.) No. 4 The method for producing a lithium-containing solution of the present invention is characterized in that, in the first aspect, the weight ratio of the anion exchange resin to the lithium adsorbent is 0.5 or more and 2.5 or less. No. 5 The method for producing a lithium-containing solution of the present invention is characterized in that, in the first aspect, the lithium adsorbent forms a particulate material, and the particulate material contains a binder. No. 6 The method for producing a lithium-containing solution of the invention is characterized in that, in the first invention, a regeneration step is provided after the elution step to return the functional group of the anion exchange resin to a hydroxyl group form, and the anion exchange resin that has been subjected to the regeneration step is used in the adsorption step. Effect of the Invention

[0011] According to the first invention, in the adsorption step, an anion exchange resin is used together with the lithium adsorbent, and the anion exchange resin adsorbs the hydrogen ions generated in the adsorption step, so that the pH in the adsorption step can be kept high without using an additional alkaline neutralizer, and the adsorption reaction can be promoted. Therefore, the amount of solution after the adsorption step can be reduced, so that the lithium content in the lithium-containing solution obtained through the adsorption step, elution step, and manganese oxidation step can be increased, and the amount of solution used in the steps after the manganese oxidation step can be reduced. This reduces the manufacturing cost for lithium production. No. 4 According to the 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 high while the amount of the anion exchange resin is suppressed. No. 5 According to the invention, even if the lithium adsorbent forms a particulate material and the particulate material contains a binder, an anion exchange resin is used together with the lithium adsorbent in the adsorption process, so that deterioration of the binder can be suppressed and the life of the particulate material can be extended. No. 6 According to the invention, after the elution process, a regeneration process is provided in which the functional groups of the anion exchange resin are converted back to a hydroxyl group form. The anion exchange resin that has undergone the regeneration process is used in the adsorption process, thereby suppressing the increase in costs due to the use of the anion exchange resin. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a flow diagram of a method for producing a lithium-containing solution according to a first embodiment of the present invention. [Diagram 2] FIG. 5 is a flow diagram of a method for producing a lithium-containing solution according to a second embodiment of the present invention. [Diagram 3] 1 is a graph showing the relationship between mixing stirring time and pH. [Figure 4] 1 is a graph showing the relationship between mixing and stirring time and the amount of lithium adsorption. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below is merely an example of a method for producing a lithium-containing solution to embody 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.

[0014] The method for producing a lithium-containing solution according to the present invention includes an adsorption step in which a low-concentration lithium-containing solution is brought into contact with a lithium adsorbent obtained from lithium manganate to obtain lithium manganate after adsorption, 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 oxidizing agent and a pH adjuster are added to the elution solution to oxidize manganese, thereby obtaining a lithium-containing solution in which the manganese concentration is suppressed. In the adsorption step, an anion exchange resin is used together with the lithium adsorbent.

[0015] In the adsorption step, the anion exchange resin is used together with the lithium adsorbent, and the hydrogen ions generated in the adsorption step are adsorbed by the anion exchange resin, so that the pH in the adsorption step can be maintained high without using an additional alkaline neutralizer, and the adsorption reaction can be promoted. Therefore, the amount of solution after the adsorption step can be reduced, so that the lithium content in the lithium-containing solution obtained through the adsorption step, elution step, and manganese oxidation step can be increased, and the amount of solution used in the steps after the manganese oxidation step can be reduced. This reduces the manufacturing cost for lithium production.

[0016] In addition, the weight ratio of the anion exchange resin to the lithium adsorbent is preferably 0.5 to 2.5. This embodiment makes it possible to maintain a high pH in the adsorption step while suppressing the amount of the anion exchange resin.

[0017] In addition, it is preferable that the lithium adsorbent is in the form of a particulate material, and the particulate material contains a binder. Even when the lithium adsorbent is in the form of a particulate material and the particulate material contains a binder, since an anion exchange resin is used together with the lithium adsorbent in the adsorption step, deterioration of the binder can be suppressed, and the life of the particulate material can be extended.

[0018] In addition, it is preferable that a regeneration step is provided after the elution step in which the functional groups of the anion exchange resin are returned to the hydroxyl group form, and the anion exchange resin that has been subjected to the regeneration step is used in the adsorption step. This embodiment makes it possible to suppress an increase in cost due to the use of the anion exchange resin.

[0019] (First embodiment) (Pre-adsorption process) In the adsorption step, a low-concentration lithium-containing solution is brought into contact with a lithium adsorbent to obtain lithium manganate after adsorption. A method for obtaining a lithium adsorbent used in this adsorption step will be described. Note that FIG. 1 shows a flow diagram of a method for producing a lithium-containing solution according to a first embodiment of the present invention, and the explanation of the "pre-adsorption step" is given in the H 1.6 Mn 1.6 This is the stage where O4 is obtained.

[0020] Lithium manganate becomes a lithium adsorbent by acid treatment as shown in formula 2. In formula 2, lithium manganate is Li 1.6 Mn 1.6 Although it is expressed as O4, lithium manganese oxide is not limited to this. For example, Li 1.33 Mn 1.67 O4 can also be used, i.e. lithium manganate is Li 1.6 Mn 1.6 If O4, the lithium adsorbent is H 1.6 Mn 1.6 O4, but lithium manganese oxide, for example, Li 1.33 Mn 1.67 If O4, the lithium adsorbent is H 1.33 Mn 1.67 O4. Although the acid used in the acid treatment is HCl, it is not limited to this. For example, sulfuric acid, nitric acid, etc. can also be used.

[0021] The shape of lithium manganate is determined by considering the adsorption of lithium in the adsorption process. For example, lithium manganate can be in various shapes such as powder, granulated powder, or sprayed onto the fibers of a column. When the acid treatment is performed, for example, H 1.6 Mn 1.6 O4 is obtained. The shape of the lithium adsorbent is the same as that of the lithium manganese oxide before the acid treatment.

[0022] [Number 2] Li 1.6 Mn 1.6 O4+1.6HCl→H 1.6 Mn 1.6 O4+1.6LiCl

[0023] (Adsorption process) 1 shows a flow diagram of a method for producing a lithium-containing solution according to a first embodiment of the present invention. In the adsorption step, a low-concentration lithium-containing solution is brought into contact with a lithium adsorbent to obtain adsorbed lithium manganate by an ion exchange reaction between H and Li shown in Equation 3. In this specification, the lithium manganate obtained in the adsorption step is sometimes referred to as adsorbed lithium manganate.

[0024] [Number 3] H 1.6 Mn 1.6 O4+1.6LiCl→Li 1.6 Mn 1.6 O4+1.6HCl

[0025] The low-concentration lithium-containing solution is, for example, seawater or salt lake brine. For example, seawater contains an average of 0.17 ppm 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 producing a lithium-containing solution of the present invention, it is possible to selectively recover lithium from the low-concentration lithium-containing solution in which these elements are dissolved. Note that the low-concentration lithium-containing solution means that the amount of lithium per unit volume is smaller than that of the Li-containing solution described below.

[0026] In the adsorption process, the contact method between the low-concentration lithium-containing solution and the adsorbent differs depending on the shape of the adsorbent. For example, when the adsorbent is powder, a predetermined amount of the adsorbent is put into the low-concentration lithium-containing solution and stirred for a predetermined time, so that the low-concentration lithium-containing solution comes into contact with the adsorbent, and lithium is adsorbed to the adsorbent. When the adsorbent is particulate, a particulate adsorbent is sealed in a liquid passage container, and the low-concentration lithium-containing solution is passed through the liquid passage container, so that the low-concentration lithium-containing solution comes into contact with the adsorbent, and lithium is adsorbed to the adsorbent. When the adsorbent is sprayed onto the fibers of the column, the low-concentration lithium-containing solution passes through the column, so that the low-concentration lithium-containing solution comes into contact with the adsorbent, and lithium is adsorbed to the adsorbent. When the low-concentration lithium-containing solution is passed through the column, the low-concentration lithium-containing solution may be passed through repeatedly to ensure the number of times it comes into contact with the adsorbent.

[0027] In the adsorption step of this embodiment, an anion exchange resin is used together with the lithium adsorbent. An anion exchange resin is a type of synthetic resin that has a structure that ionizes as an ion exchange group in a part of its molecular structure, and the ion exchange group has an anion property. Anion exchange resins are classified into weakly basic anion exchange resins having primary to tertiary amino groups as functional groups and strongly basic anion exchange resins having quaternary ammonium groups as functional groups, but any anion exchange resin may be used. In the case of a weakly basic anion exchange resin, that is, a primary amino group, hydrogen ions are adsorbed from the solution in the adsorption step according to a reaction formula represented by the formula 4, in the case of a secondary amino group, and in the case of a tertiary amino group, by a reaction formula represented by the formula 6. In addition, in the case of a strongly basic anion exchange resin, that is, an anion exchange resin having a quaternary ammonium group, hydrogen ions are adsorbed from the solution in the adsorption step according to a reaction formula represented by the formula 7. Note that, although hydrochloric acid is described as an acid in each reaction formula, this is not limited to this. For example, other acids such as sulfuric acid undergo similar reactions. In addition, R in each reaction formula represents a carbon skeleton formed by carbon bonds to which hydrogen, nitrogen, oxygen, etc. are bonded.

[0028] [Number 4] R-NH2+HCl → R-NH2 HCl

[0029] [Number 5] R2-NH+HCl → R2-NH HCl

[0030] [Number 6] R3-N+HCl → R3-N HCl

[0031] [Number 7] R4-NOH+HCl → R4-NCl+H2O

[0032] In the adsorption step, the anion exchange resin is used together with the lithium adsorbent, and the hydrogen ions generated in the adsorption step are adsorbed by the anion exchange resin, so that the pH in the adsorption step can be maintained high without using an additional alkaline neutralizer, and the adsorption reaction can be promoted. Therefore, the amount of solution after the adsorption step can be reduced, so that the lithium content in the lithium-containing solution obtained through the adsorption step, elution step, and manganese oxidation step can be increased, and the amount of solution used in the steps after the manganese oxidation step can be reduced. This reduces the manufacturing cost for lithium production.

[0033] The way in which the anion exchange resin is used may vary depending on the shape of the lithium adsorbent or the method of contacting with the low-concentration lithium-containing solution. For example, when the lithium adsorbent is in the form of a powder, a predetermined amount of the adsorbent and a predetermined amount of the anion exchange resin are put into a beaker or the like in which the low-concentration lithium-containing solution is stored, and the mixture is stirred for a predetermined time, whereby the low-concentration lithium-containing solution comes into contact with the lithium adsorbent, and lithium is adsorbed onto the lithium adsorbent.

[0034] When the lithium adsorbent has a particulate shape, the particulate material containing the lithium adsorbent and an anion exchange resin are enclosed in a liquid passage container, and a low-concentration lithium-containing solution is passed through the liquid passage container, whereby the low-concentration lithium-containing solution comes into contact with the lithium adsorbent, and lithium is adsorbed onto the lithium adsorbent.

[0035] When the lithium adsorbent is sprayed onto the fibers of the column, an anion exchange resin is enclosed within the column, and the low-concentration lithium-containing solution passes through the column, whereby the low-concentration lithium-containing solution comes into contact with the lithium adsorbent, and lithium is adsorbed onto the lithium adsorbent.

[0036] Although the above describes the contact method that is likely to be adopted depending on 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 introducing a particulate material containing a lithium adsorbent into a low-concentration lithium-containing solution and stirring the mixture may be adopted.

[0037] In addition, regardless of the shape of the lithium adsorbent or the contact method, the weight ratio of the anion exchange resin to the lithium adsorbent is preferably 0.5 to 2.5. In other words, the value obtained by dividing the "weight of the anion exchange resin" by the "weight of the lithium adsorbent" is preferably 0.5 to 2.5.

[0038] By setting the weight ratio of the anion exchange resin to the lithium adsorbent to 0.5 or more and 2.5 or less, the pH in the adsorption step can be maintained high while the amount of the anion exchange resin is suppressed.

[0039] After the adsorption process, the adsorbent becomes lithium manganese oxide after adsorption. The low-concentration lithium-containing solution becomes a post-adsorption liquid after lithium is adsorbed by the adsorbent. This post-adsorption liquid is discharged into the sea or lake from which the low-concentration lithium-containing solution was collected. At that time, the post-adsorption liquid is discharged after being treated, such as neutralized, to make it suitable for discharge.

[0040] (Elution step) In the elution step, the lithium manganate after adsorption is contacted with an acid-containing solution to obtain an elution solution by the reaction shown in Equation 8. At this time, the lithium manganate after adsorption is Li + and H +Through this exchange reaction between cations, the lithium adsorbent is regenerated as a lithium adsorbent, and this lithium adsorbent is reused in the adsorption step.

[0041] [Number 8] Li 1.6 Mn 1.6 O4+1.6HCl→H 1.6 Mn 1.6 O4+1.6LiCl

[0042] In this embodiment, the acid-containing solution includes a solution of an acid alone, such as hydrochloric acid, and an elution solution obtained by adding an acid to the elution solution obtained by one elution step. For example, in this embodiment, the elution step is divided into multiple steps, and in the first step, the acid-containing solution is a solution of an acid alone, and in the second step and after, the elution solution obtained in the previous step is used, and the elution step in the second step and after is performed using the elution solution to which an acid has been added, but is not limited to this. For example, there is a case where only a solution of an acid alone is used as the acid-containing solution.

[0043] In the elution step of this embodiment, the hydrogen ion concentration of the acid-containing solution to be contacted with the lithium manganate after adsorption is preferably 0.1 mol / L or more and 4.0 mol / L or less, and more preferably 0.5 mol / L or more and 2.0 mol / L or less.

[0044] When the hydrogen ion concentration of the acid-containing solution is less than 0.1 mol / L, the exchange reaction between cations cannot be sufficiently carried out, and the efficiency of this exchange reaction decreases. When the acid-containing solution is more than 4.0 mol / L, the lithium manganate dissolves in its entirety in the acid solution, and the lithium manganate cannot be used again as a lithium adsorbent after adsorption. The acid used in the acid-containing solution is preferably hydrochloric acid, but is not limited thereto. For example, sulfuric acid or acetic acid may be used.

[0045] Depending on the shape of the lithium manganate, the form of contact between the adsorbed lithium manganate and the acid solution in the elution step varies. For example, if the lithium manganate is in powder form, one method is to put the powder of the adsorbed lithium manganate into the acid solution and stir it to contact the adsorbed lithium manganate with the acid solution. If the lithium manganate is in particulate form or is sprayed onto the fibers of a column, one method is to pass the acid solution through the liquid passage container while the particulate lithium manganate and the column are stored in the liquid passage container, and the adsorbed lithium manganate is contacted with the acid solution.

[0046] In addition, when the lithium manganate after adsorption is in the form of a powder or particulate, in this embodiment, it is preferable to separate the lithium manganate after adsorption from the anion exchange resin in the elution step. This is because the lithium adsorbent after the elution step can be reused in the adsorption step. This separation is performed, for example, by sieving.

[0047] (Manganese oxidation process) In the manganese oxidation process, an oxidizing agent and a pH adjuster are added to the elution solution obtained in the elution process to oxidize divalent manganese to tetravalent manganese, resulting in a lithium-containing solution with a reduced manganese concentration. Tetravalent manganese is poorly soluble, so it precipitates in the solution. This makes it possible to reduce the concentration of manganese in the elution solution. Furthermore, the precipitated manganese can be reused as a raw material for lithium adsorbents.

[0048] In order to oxidize divalent manganese to tetravalent manganese, an oxidizing agent and a pH adjuster are added to the elution solution. When the oxidizing agent and the pH adjuster are added, it is preferable to adjust the pH to a range of 3 to 7 and the redox potential to 600 mV to 1100 mV using a silver-silver chloride electrode. That is, the pH and the redox potential are measured simultaneously, and the oxidizing agent and the pH adjuster are added simultaneously or alternately so that they are within the above range. As the oxidizing agent, for example, sodium hypochlorite, sodium chlorite, ozone, permanganate, etc. can be used. However, the oxidizing agent is not limited to these, and there is no problem as long as the redox potential can be adjusted. As the pH adjuster, for example, an alkaline neutralizing agent such as sodium hydroxide or slaked lime can be used. However, the oxidizing agent is not limited to these, and there is no problem as long as the pH can be adjusted.

[0049] (Post-manganese oxidation process) In the lithium-containing solution obtained in the manganese oxidation step, lithium exists in the form of lithium chloride (LiCl) in this embodiment, so that lithium can be obtained in the form of, for example, lithium carbonate by adding an alkali to this solution or by concentrating it by superheating.

[0050] After the adsorption, the lithium manganate is converted into a lithium adsorbent by the acid solution, and this lithium adsorbent is reused in the adsorption step.

[0051] Second embodiment 2 shows a flow diagram of a method for producing a lithium-containing solution according to a second embodiment of the present invention. The difference between the first embodiment and the second embodiment is that a regeneration process is provided for returning the functional group of the anion exchange resin to a hydroxyl group form for the anion exchange resin separated from the lithium manganate after adsorption after the elution process, and the other points are the same as those of the first embodiment. Therefore, only the differences will be described below, and other descriptions will be omitted.

[0052] (Regeneration process) Most of the anion exchange resins used in the regeneration process are in a state of absorbing hydrogen ions because they have been in contact with acid in the adsorption process and the elution process. In this embodiment, a regeneration process is carried out on the anion exchange resin separated from the lithium manganate after adsorption in the elution process, in which the functional groups of the anion exchange resin are returned to the hydroxyl group form, and the anion exchange resin obtained through the regeneration process is used in the adsorption process.

[0053] A method for returning the functional groups of the anion exchange resin to the hydroxyl group form is preferably carried out by passing the anion exchange resin separated in the elution step through an alkaline aqueous solution such as an aqueous sodium hydroxide solution, an aqueous ammonia solution, or an aqueous sodium carbonate solution. Equations 9 to 12 show chemical reaction formulas when an aqueous sodium hydroxide solution is used in the regeneration step.

[0054] [Number 9] R-NH2+HCl+NaOH→R-NH2+NaCl+H2O

[0055] [Number 10] R2-NH+HCl+NaOH→R2-NH+NaCl+H2O

[0056] [Number 11] R3-N+HCl+NaOH → R3-N+NaCl+H2O

[0057] [Number 12] R4-NCl+NaOH → R4-NOH+NaCl

[0058] After the elution process, a regeneration process is provided in which the functional groups of the anion exchange resin are converted back to a hydroxyl group form. The anion exchange resin that has undergone the regeneration process is used in the adsorption process, thereby suppressing the increase in costs due to the use of the anion exchange resin.

[0059] In addition, the regeneration step may be performed in a state where the anion exchange resin and the lithium adsorbent are mixed. That is, since the lithium adsorbent does not have the ability to adsorb metal elements other than lithium, when the above-mentioned alkaline aqueous solution does not contain lithium, in the regeneration step, the lithium adsorbent does not adsorb any metal elements and maintains its adsorption ability, while the anion exchange resin is regenerated, and the lithium adsorbent can be used as it is in the next adsorption step. Similarly, even if the alkaline aqueous solution contains some lithium and the adsorption ability of the lithium adsorbent decreases, it can be used in the next adsorption step as long as the adsorption ability remains in the lithium adsorbent. In addition, when the alkaline aqueous solution contains a considerable amount of lithium (when saturation of the lithium adsorbent is a concern), the anion exchange resin and the lithium adsorbent need to be separated in the elution step. As a separation method, sieving or the like can be used. EXAMPLES

[0060] Hereinafter, specific examples of the method for producing a lithium-containing solution according to the present invention will be described, but the present invention is not limited to these examples.

[0061] <Example 1> (Adsorption process) Powdered lithium adsorbent H 1.6 Mn 1.6 10g of O4 was mixed with 20g of a weakly basic anion exchange resin (A830W: manufactured by Purolite Co., Ltd.). In this case, the weight ratio of the anion exchange resin to the lithium adsorbent was 2. This mixture was added to a 1L beaker containing 400mL of salt lake brine adjusted to pH 8.5, and the mixture was stirred and mixed for 60 minutes to carry out the adsorption process. Table 1 shows the analytical values ​​of the salt lake brine used in this adsorption process. In addition, the pH was measured every 10 minutes from the start of stirring and mixing until 60 minutes. The results are shown in Table 2 and Figure 3. In addition, a specified amount of solution was taken from the beaker every 10 minutes.

[0062] (Elution step) The lithium manganate after adsorption present in the solution whose pH was measured was contacted with an acid-containing solution. The acid-containing solution was only hydrochloric acid with a hydrogen ion concentration of 0.5 mol / L. The pH of the acid-containing solution in this case was 0.4. All the solutions flowing out of the column were mixed to make a homogeneous solution.

[0063] (Manganese oxidation process) The manganese oxidation process was carried out using the second eluent. An oxidizing agent and a pH adjuster were used to obtain a lithium-containing solution. The amount of lithium contained in this lithium-containing solution is shown in Table 3 and Figure 4.

[0064] <Example 2> The difference between Example 1 and Example 2 is that the anion exchange resin in the adsorption step is 10 g of a strong 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 for 60 minutes from the start of stirring and mixing. The results are shown in Table 2 and FIG. 3. The amount of lithium contained in the lithium-containing solution obtained through the manganese oxidation step is shown in Table 3 and FIG. 4.

[0065] <Example 3> The difference between Example 1 and Example 3 is that the anion exchange resin in the adsorption step is 20 g of a strong 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 for 60 minutes from the start of stirring and mixing. The results are shown in Table 2 and FIG. 3. The amount of lithium contained in the lithium-containing solution obtained through the manganese oxidation step is shown in Table 3 and FIG. 4.

[0066] <Comparative Example 1> The difference between Example 1 and Comparative Example 1 is that no anion exchange resin was used in the adsorption step. The other parameters were the same as those of Example 1. The pH was measured every 10 minutes for 60 minutes from the start of stirring and mixing. The results are shown in Table 2 and FIG. 3. The amount of lithium contained in the lithium-containing solution obtained through the manganese oxidation step is shown in Table 3 and FIG. 4.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

[0070] As shown in Fig. 3, there is almost no difference in pH between the beginning and end of stirring and mixing in Example 1 and Example 3. In addition, even after 60 minutes of stirring and mixing, the pH of Example 2 remains at 8.0 or higher, and it was found that the decrease in pH is smaller than that of the comparative example. In addition, as shown in Fig. 4, after 60 minutes of stirring and mixing, 1.0 mmol / g (manganese-based adsorbent) or more of lithium can be adsorbed in each of the examples, whereas in the comparative example, adsorption in the adsorption step was not sufficient, and only 0.8 mmol / g (manganese-based adsorbent) of lithium was obtained.

Claims

1. an adsorption step of contacting a low-concentration lithium-containing solution with a lithium adsorbent obtained from lithium manganate to obtain lithium manganate after adsorption; an elution step of contacting the lithium manganate after the adsorption with an acid-containing solution to obtain an elution solution; a manganese oxidation step of adding an oxidizing agent and a pH adjuster to the elution solution to oxidize manganese and obtain a lithium-containing solution having a reduced manganese concentration; Execute in this order, In the adsorption step, an anion exchange resin is used together with the lithium adsorbent to remove hydrogen ions from the solution of the adsorption step.

2. The method for producing a lithium-containing solution comprising the steps of:

2. In the adsorption step, the anion exchange resin is used in a state in which it can be separated when sieved in the elution step. The method for producing a lithium-containing solution according to claim 1 .

3. In the adsorption step, The anion exchange resin removes hydrogen ions from the solution in the adsorption step through a reaction represented by any one of the following chemical reaction formulas (1) to (4): The method for producing a lithium-containing solution according to claim 1 . Chemical reaction formula:R-NH ２ +HCl→R-NH ２ ・HCl・・・(1) Chemical reaction formula: R ２ -NH+HCl→R ２ -NH・HCl・・・(2) Chemical reaction formula: R ３ −N+HCl→R ３ -N・HCl...(3) Chemical reaction formula: R ４ -NOH+HCl→R ４ -NCl+H ２ O...(4) (In the chemical reaction formula, R is a primary amino group, R ２ is a secondary amino group, R ３ is a tertiary amino group, R ４ is a quaternary ammonium group.)

4. The weight ratio of the anion exchange resin to the lithium adsorbent is 0.5 or more and 2.5 or less. The method for producing a lithium-containing solution according to claim 1 .

5. The lithium adsorbent is in the form of particles, The particulate matter includes a binder. The method for producing a lithium-containing solution according to claim 1 .

6. After the elution step, a regeneration step is provided for converting the functional groups of the anion exchange resin back to a hydroxyl group form; The anion exchange resin that has been subjected to the regeneration step is used in the adsorption step. The method for producing a lithium-containing solution according to claim 1 .

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