Method for producing lithium-containing solution

Abstract

Provided is a method for producing a lithium-containing solution, the method being capable of suppressing the production cost for producing lithium by increasing the lithium content of a solution after an elution step and suppressing the amount of the solution in a step after the elution step. The method for producing a lithium-containing solution comprises the following steps in this order: an adsorption step; an elution step for obtaining an eluted solution by bringing the adsorbed lithium manganate into contact with an acid-containing solution; and a manganese oxidation step. The elution step includes a first elution step in which the hydrogen ion concentration of the acid-containing solution is high, and a second elution step in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution step. The second elution step is performed after the first elution step. With this configuration, elution is efficiently performed in the first elution step, and since the hydrogen ion concentration of the acid-containing solution does not need to be increased in the second elution step, the amount of acid added to the acid-containing solution can be suppressed, and the amount of an elution solution used in the manganese oxidation step can be suppressed.

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, which can reduce the production cost for producing lithium by increasing the lithium content in the solution after the elution process and reducing the amount of the solution used in the process after the elution process. Background Art

[0002] It is known that by reacting an inorganic acid such as hydrochloric acid with lithium manganate (LiMn2O4, Li 1.33 Mn 1.67 O4、Li 1.6 Mn 1.6 O4, etc.) to obtain a spinel-type structure of λ-MnO2 (HMn2O4, H 1.33 Mn 1.67 O4、H 1.6 Mn 1.6 O4, etc.) selectively adsorbs lithium. When using the λ-MnO2 to recover lithium, the λ-MnO2 does not adsorb impurities, and therefore 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. Patent document 1 discloses a method for producing a lithium-containing solution using the λ-MnO2.

[0003] In the method for producing a lithium-containing solution of Patent Document 1, an acid-containing solution used in the elution step 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 the elution solution used in the steps 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] However, the acid-containing solution needs to be supplemented with acid so that the hydrogen ion concentration becomes a predetermined value. If the amount of acid added is large, there is a problem that the effect of suppressing the amount of solution used in the steps after the elution step is limited.

[0009] In view of the above situation, the present invention aims to provide a method for producing a lithium-containing solution, which can reduce the manufacturing cost for producing lithium by increasing the lithium content in the solution after the elution process and reducing the amount of solution used in the process after the elution process.

[0010] Means for solving problems

[0011] The first invention is a method for producing a lithium-containing solution, characterized in that the method for producing a lithium-containing solution sequentially performs: 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 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 the elution step is composed of a first elution step and a second elution step in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution step, and the second elution step is performed after the first elution step.

[0012] The method for producing a lithium-containing solution of the second invention is characterized in that, in the first invention, the hydrogen ion concentration of the acid-containing solution in the first elution step is greater than 1.0 mol / L and less than 4.0 mol / L, and the hydrogen ion concentration of the acid-containing solution in the second elution step is greater than 0.1 mol / L and less than 0.5 mol / L.

[0013] The method for producing a lithium-containing solution according to the third invention is characterized in that, in the first invention or the second invention, in the elution step, the elution solution is separated into a high-concentration lithium elution solution containing lithium at a high concentration and a low-concentration lithium elution solution having a lithium concentration lower than that of the high-concentration lithium elution solution, the acid-containing solution used in the elution step contains a solution in which acid is added to the low-concentration lithium elution solution, and the elution solution used in the manganese oxidation step contains the high-concentration lithium elution solution.

[0014] The fourth invention is a method for producing a lithium-containing solution, characterized in that, in the third invention, the high-concentration lithium elution solution is obtained by extracting a volume of the elution solution predetermined based on the initial acquisition of the elution solution from the elution solution obtained through the elution step.

[0015] The method for producing a lithium-containing solution according to the fifth invention is characterized in that, in the third invention, the high-concentration lithium eluting solution is the eluting solution obtained between a start time and an end time that are predetermined from the start of the elution step.

[0016] The method for producing a lithium-containing solution of the sixth invention is characterized in that, in any one of the first to fifth inventions, a water washing step for washing the eluted lithium adsorbent obtained after the elution step is arranged after the elution step, and the water-washed liquid obtained in the water washing step is added to the acid-containing solution.

[0017] Effects of the Invention

[0018] According to the first invention, the elution process includes a first elution process and a second elution process in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution process. The second elution process is performed after the first elution process, so that elution is efficiently performed in the first elution process. In addition, since the hydrogen ion concentration of the acid-containing solution does not need to be increased in the second elution process, the amount of acid added to the acid-containing solution can be reduced, and the amount of elution solution used in the manganese oxidation process can be reduced. As a result, the manufacturing cost for manufacturing lithium can be reduced.

[0019] According to the second invention, by setting the hydrogen ion concentration of the acid-containing solution in the first elution step and the hydrogen ion concentration of the acid-containing solution in the second elution step to predetermined values, dissolution of manganese from the lithium adsorbent can be suppressed and the elution efficiency can be improved.

[0020] According to the third invention, the elution solution used in the manganese oxidation step contains a high-concentration lithium elution solution, thereby increasing the lithium content of the elution solution used in the manganese oxidation step. In addition, since only the low-concentration lithium elution solution is added to the acid-containing solution, the hydrogen ion concentration in the acid-containing solution can be increased by adding only a small amount of acid, and as a result, the amount of the acid-containing solution can be further reduced, and the amount of the elution solution used in the manganese oxidation step can be reduced.

[0021] According to the fourth invention, the high-concentration lithium eluting solution is obtained by extracting the eluting solution by a predetermined volume based on the start of obtaining the eluting solution, thereby increasing the lithium content of the high-concentration lithium eluting solution.

[0022] According to the fifth invention, the high-concentration lithium eluting solution is an eluting solution obtained between the start time and the end time determined in advance from the start of the elution step, and thus the high-concentration lithium eluting solution can be easily obtained.

[0023] According to the sixth invention, the water-washed liquid obtained in the water-washing step is added to the acid-containing solution, thereby recovering lithium that has to be discarded in the water-washing step. 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 flow chart of a method for producing a lithium-containing solution according to a third embodiment of the present invention.

[0027] Figure 4 This is a flow chart of a method for producing a lithium-containing solution according to a fourth embodiment of the present invention.

[0028] Figure 5 It is shown in Figure 2 A diagram showing the lithium concentration of each volume amount predetermined based on the start of obtaining an elution solution in a method for producing a lithium-containing solution.

[0029] Figure 6 It is shown in Figure 3 A diagram showing the lithium concentration of each volume amount predetermined based on the start of obtaining a water-washed solution in a method for producing a lithium-containing solution. DETAILED DESCRIPTION

[0030] Next, embodiments of the present invention will be described based on the drawings. However, the embodiments described below illustrate a method for producing a lithium-containing solution for embodying the technical concept of the present invention, and the present invention does not specify the method for producing a lithium-containing solution as the following method.

[0031] The method for manufacturing a lithium-containing solution of the present invention sequentially performs: 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 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 the elution step is composed of a first elution step and a second elution step in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution step, and the second elution step is performed after the first elution step.

[0032] The elution process includes a first elution process and a second elution process in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution process. The second elution process is performed after the first elution process, so that elution is efficiently performed in the first elution process. In addition, since the hydrogen ion concentration of the acid-containing solution does not need to be increased in the second elution process, the amount of acid added to the acid-containing solution can be reduced, and the amount of elution solution used in the manganese oxidation process can be reduced. As a result, the manufacturing cost for manufacturing lithium can be reduced.

[0033] In addition, the hydrogen ion concentration of the acid-containing solution in the first elution step is 1.0 mol / L or more and 4.0 mol / L or less, and the hydrogen ion concentration of the acid-containing solution in the second elution step is preferably 0.1 mol / L or more and 0.5 mol / L or less. According to this embodiment, the dissolution of manganese from the lithium adsorbent can be suppressed, and the elution efficiency can be improved.

[0034] In addition, it is preferred that, in the elution step, the elution solution is separated into a high-concentration lithium elution solution containing lithium at a high concentration and a low-concentration lithium elution solution having a lithium concentration lower than that of the high-concentration lithium elution solution, the acid-containing solution used in the elution step contains a solution obtained by adding an acid to the low-concentration lithium elution solution, and the elution solution used in the manganese oxidation step contains the high-concentration lithium elution solution. According to this method, the lithium content of the elution solution used in the manganese oxidation step can be increased. In addition, since only the low-concentration lithium elution solution is added to the acid-containing solution, the hydrogen ion concentration in the acid-containing solution can be increased by adding only a small amount of acid, and as a result, the amount of the acid-containing solution can be further suppressed, and the amount of the elution solution used in the manganese oxidation step can be suppressed.

[0035] In addition, the high-concentration lithium elution solution is preferably obtained by extracting a predetermined volume of the elution solution from the elution solution obtained through the elution step based on the start of obtaining the elution solution. According to this embodiment, the lithium content of the high-concentration lithium elution solution can be increased.

[0036] In addition, the high-concentration lithium eluting solution is preferably the eluting solution obtained between a start time and an end time that are predetermined from the start of the elution step. According to this embodiment, a high-concentration lithium eluting solution can be easily obtained.

[0037] In addition, it is preferred that a water washing step for washing the eluted lithium adsorbent obtained after the elution step is provided after the elution step, and the water-washed liquid obtained in the water washing step is added to the acid-containing solution. According to this embodiment, lithium that has to be discarded in the water washing step can be recovered.

[0038] (First Embodiment)

[0039] (Preliminary stage of adsorption process)

[0040] In the adsorption process, the low-concentration lithium-containing solution is brought into contact with a lithium adsorbent to obtain adsorbed lithium manganate. A method for obtaining the lithium adsorbent used in the adsorption process is described below. 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 to obtain the Figure 1 The top H 1.6 Mn 1.6 O4 stage.

[0041] As shown in Mathematical Formula 1, lithium manganate is treated with an acid to become a lithium adsorbent. 1.6 Mn 1.6O4, but lithium manganate is not limited thereto. For example, Li 1.33 Mn 1.67 O4. That is, when lithium manganate is Li 1.6 Mn 1.6 When O4, the lithium adsorbent is H 1.6 Mn 1.6 O4, lithium manganate such as Li 1.33 Mn 1.67 When O4, the lithium adsorbent is H 1.33 Mn 1.67 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.

[0042] 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 form obtained by granulating the powder, and columnar form obtained by blowing fibers into a column. When acid treatment is performed, for example, H 1.6 Mn 1.6 O4. The shape of the lithium adsorbent is the same as the shape of lithium manganate before the acid treatment.

[0043] (Mathematical formula 1)

[0044] Li 1.6 Mn 1.6 O4+1.6HCl→H 1.6 Mn 1.6 O4+1.6LiCl

[0045] (Adsorption process)

[0046] exist Figure 1 , a flow chart of a method for producing a lithium-containing solution according to a first embodiment of the present invention is shown. In the adsorption step, a low-concentration lithium-containing solution is brought into contact with a lithium adsorbent, and adsorbed lithium manganate is obtained by an ion exchange reaction of H and Li as shown in Mathematical Formula 2. In this specification, the lithium manganate obtained in the adsorption step is sometimes referred to as adsorbed lithium manganate.

[0047] (Mathematical formula 2)

[0048] H 1.6 Mn 1.6 O4+1.6LiCl→Li 1.6 Mn 1.6 O4+1.6HCl

[0049] The low-concentration lithium-containing solution is, for example, salt water from seawater or salt lakes. 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, that is, the lithium concentration is low.

[0050] 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 in contact with the adsorbent, and lithium is adsorbed on the adsorbent. In the case where the adsorbent is granular, as a method, a method can be cited in which a granular 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 is in contact with the adsorbent, 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 is in contact with the adsorbent, 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 the liquid is passed repeatedly.

[0051] After the adsorption process, the adsorbent becomes adsorbed lithium manganate. In addition, after the adsorbent adsorbs lithium, the low-concentration lithium-containing solution becomes adsorbed liquid. 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 treated to a state suitable for discharge after neutralization treatment, etc., and then discharged.

[0052] (Elution process)

[0053] In the elution step, the acid solution is brought into contact with the adsorbed lithium manganese oxide, and an elution solution is obtained through the reaction shown in Mathematical Formula 3. At this time, the adsorbed lithium manganese oxide is reacted by Li + and H + Such an exchange reaction between cations regenerates the lithium adsorbent, and the lithium adsorbent is used again in the adsorption step.

[0054] (Mathematical formula 3)

[0055] Li 1.6 Mn 1.6 O4+1.6HCl→H 1.6 Mn 1.6 O4+1.6LiCl

[0056] In the present embodiment, the acid-containing solution includes a solution of an acid monomer such as hydrochloric acid and a solution obtained by adding an acid to an elution solution obtained through an elution process. For example, in the present embodiment, the elution process is divided into a plurality of stages such as a first elution process and a second elution process. The first elution process is an elution process in which the hydrogen ion concentration of the acid-containing solution is relatively high, and the second elution process is an elution process in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution process. For example, in the initial stage of the first elution process, the acid-containing solution can be set as an acid monomer solution, and then, an acid is added to the elution solution obtained in the previous stage to make it have a specified hydrogen ion concentration. In this case, in the second elution process, it becomes a solution formed by adding an acid to the elution solution obtained in the previous stage. In addition, it is also possible to set the acid-containing solution in the first elution process only as an acid monomer solution, and set the acid-containing solution in the second elution process as a solution formed by adding an acid to the elution solution obtained in the previous stage.

[0057] The smaller the pH value of the acid-containing solution used in the elution process, the better the reaction shown in Mathematical Formula 3 proceeds. However, if the reaction shown in Mathematical Formula 3 proceeds to a certain extent, the pH value of the acid-containing solution becomes larger, and therefore, the reaction shown in Mathematical Formula 3 no longer proceeds. In Patent Document 1, International Publication No. 2022 / 210847, in order not to reach this state, the elution process is carried out in multiple stages, and after the second stage of the multiple stages, a solution obtained by adding acid to the elution solution obtained in the previous stage is used as the acid-containing solution. At this time, the acid is supplied to make its pH the same as that of the acid-containing solution initially supplied, and therefore, the suppression of the amount of the elution solution is limited.

[0058] The elution process includes a first elution process and a second elution process in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution process. The second elution process is performed after the first elution process, so that elution is efficiently performed in the first elution process. In addition, since the hydrogen ion concentration of the acid-containing solution does not need to be increased in the second elution process, the amount of acid added to the acid-containing solution can be reduced, and the amount of elution solution used in the manganese oxidation process can be reduced. As a result, the manufacturing cost for manufacturing lithium can be reduced.

[0059] As described above, if the lithium content of the elution solution can be increased, the size of the equipment in the subsequent process can be suppressed, or the load of the process when lithium is obtained in solid form can be reduced. That is, if the lithium content is increased, the amount of the lithium-containing solution itself can be reduced, so there is no need to increase the size of the equipment in the subsequent process. In addition, in the case of obtaining lithium in solid form, the time for boiling the solution can be shortened, or the amount of the pH adjuster in the manganese oxidation process described later or the pH adjuster in the neutralization process set after the manganese oxidation process can be suppressed. For example, the neutralization process is set to remove magnesium. In addition, the solution containing lithium at a high concentration can also be shipped directly to the customer.

[0060] In addition, although the elution step is described as being divided into a plurality of stages, the elution step is not limited to this embodiment and may include, for example, a case where an acid is continuously added to the elution solution to form an acid-containing solution.

[0061] The hydrogen ion concentration of the acid-containing solution in contact with the adsorbed lithium manganate in the elution step, i.e., the first elution step and the second elution step of the present embodiment is preferably 0.1 mol / L or more and 4.0 mol / L or less. Further, the hydrogen ion concentration is preferably 0.25 mol / L or more and 2.0 mol / L or less. Further, the hydrogen ion concentration is preferably 0.5 mol / L or more and 1.0 mol / L or less.

[0062] In the elution step, the hydrogen ion concentration of the acid-containing solution is 0.1 mol / L or more and 4.0 mol / L or less, so that the Li + and H + The efficiency of the exchange reaction between such cations can be improved, and the dissolution of all lithium manganate can be suppressed. That is, the lithium adsorbent can be reused.

[0063] When the hydrogen ion concentration of the acid-containing solution is lower than 0.1 mol / L, the exchange reaction between the cations cannot be fully carried out, and the efficiency of the exchange reaction decreases. In addition, when the acid-containing solution is higher than 4.0 mol / L, all lithium manganate is dissolved in the acid-containing solution, and therefore, the lithium manganate after adsorption cannot be used again as a lithium adsorbent. It should be noted that the acid used in the acid-containing solution is preferably hydrochloric acid, but is not limited thereto. For example, sulfuric acid or acetic acid are sometimes used.

[0064] Furthermore, the hydrogen ion concentration of the acid-containing solution in the first elution step is 1.0 mol / L to 4.0 mol / L, and the hydrogen ion concentration of the acid-containing solution in the second elution step is preferably 0.1 mol / L to 0.5 mol / L.

[0065] When the hydrogen ion concentration of the acid-containing solution in the first elution step and the hydrogen ion concentration of the acid-containing solution in the second elution step are predetermined values, dissolution of manganese from the lithium adsorbent can be suppressed and the elution efficiency can be improved.

[0066] Depending on the shape of the lithium manganate, the manner of contacting the adsorbed lithium manganate with the acid-containing solution in the elution process is different. For example, if the lithium manganate is in powder form, as one method, a method of contacting the adsorbed lithium manganate with the acid-containing solution can be cited by adding the powder of the adsorbed lithium manganate into the acid-containing solution and stirring and mixing. In the case where the lithium manganate is granular or blown to the fiber of the column, as one method, a method of contacting the adsorbed lithium manganate with the acid-containing solution can be cited by passing the acid-containing solution into the liquid-passing container while the granular lithium manganate and the column are contained in the liquid-passing container.

[0067] (Manganese oxidation process)

[0068] 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.

[0069] 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 3 or more and 7 or less, and the redox potential be adjusted to 600 mV or more and 1100 mV or less with 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 the pH and the redox potential fall within the above range. For example, sodium hypochlorite, sodium chlorite, ozone, and permanganate can be used as oxidants. But it is not limited to these, as long as it is an oxidant that can adjust the redox potential, there is no problem. For example, an alkali neutralizer such as sodium hydroxide and slaked lime can be used as a pH regulator. But it is not limited to these, as long as the pH can be adjusted, there is no problem.

[0070] (Last stage of manganese oxidation process)

[0071] In the present embodiment, lithium exists in the form of lithium chloride (LiCl) in the lithium-containing solution obtained in the manganese oxidation step. Therefore, alkali is added to the solution or the solution is concentrated by superheating to obtain lithium in the form of lithium carbonate, for example.

[0072] In addition, since the adsorbed lithium manganese oxide is converted into a lithium adsorbent by using an acid-containing solution, the lithium adsorbent can be used again in the adsorption process.

[0073] (Second Embodiment)

[0074] Figure 2 , a flow chart of a method for producing a lithium-containing solution according to a second embodiment of the present invention is shown in FIG. The method for producing a lithium-containing solution according to the second embodiment differs from the method for producing a lithium-containing solution according to the first embodiment in that, in the elution step, the elution solution is separated into a high-concentration lithium elution solution containing lithium at a high concentration and a low-concentration lithium elution solution having a lithium concentration lower than that of the high-concentration lithium elution solution, the acid-containing solution includes a solution obtained by adding an acid to the low-concentration lithium elution solution, and the elution solution used in the manganese oxidation step includes a high-concentration lithium elution solution, and other aspects are the same as those of the first embodiment. Therefore, the above differences are described below.

[0075] (Elution Step in Second Embodiment)

[0076] In this embodiment, in the elution step, the elution solution is separated into a high-concentration lithium elution solution and a low-concentration lithium elution solution. The high-concentration lithium elution solution is an elution solution containing lithium at a high concentration, and the low-concentration lithium elution solution is an elution solution having a lithium concentration lower than that of the high-concentration lithium elution solution.

[0077] In the present embodiment, the acid-containing solution in the elution step includes a solution of an acid monomer such as hydrochloric acid and a solution obtained by adding an acid to a low-concentration lithium elution solution.

[0078] Since the high-concentration lithium elution solution is an elution solution containing lithium at a high concentration, it is used in a step performed after the elution step. For example, the step performed after the elution step is a manganese oxidation step.

[0079] By including a high-concentration lithium elution solution in the elution solution used in the manganese oxidation step, the lithium content of the elution solution used in the manganese oxidation step can be increased. In addition, since only a low-concentration lithium elution solution is added to the acid-containing solution, the hydrogen ion concentration in the acid-containing solution can be increased by adding only a small amount of acid, and as a result, the amount of the acid-containing solution can be suppressed, and the amount of the elution solution used in the manganese oxidation step can be suppressed. As a result, the manufacturing cost for manufacturing lithium can be suppressed.

[0080] For the separation of the high-concentration lithium elution solution and the low-concentration lithium elution solution, for example, when the elution process is performed by batch processing, the elution solution that has been extracted by a predetermined volume based on the elution solution obtained by adding the acid-containing solution can be used as the high-concentration lithium elution solution, and the other solution can be used as the low-concentration lithium elution solution. For example, for the type of low-concentration lithium-containing solution and the lithium adsorbent, when it is expected to what extent lithium will be eluted, the elution solution with a volume that is a predetermined multiple relative to the volume of the lithium adsorbent can be used as the high-concentration lithium elution solution, and the subsequent elution solution can be used as the low-concentration lithium elution solution.

[0081] In addition, Figure 5 The graph of lithium concentrations in each volume amount predetermined based on the initial elution solution in this embodiment is shown in FIG. The horizontal axis is BV (bed volume: a unit indicating the volume of the lithium adsorbent in the column in multiples), and the vertical axis indicates the lithium concentration contained in the elution solution obtained after the elution process. For example, in the case of Figure 5 In the case shown, BV2 and BV3 exceeding the second horizontal line from the top can be extracted as "a volume predetermined based on the start of obtaining the elution solution" and separated as a high-concentration lithium elution solution, and BV1 and BV4 to BV9 can be separated as a low-concentration lithium elution solution.

[0082] The high-concentration lithium eluting solution is obtained by extracting a predetermined volume of the eluting solution based on the initial volume of the eluting solution, thereby increasing the lithium content of the high-concentration lithium eluting solution.

[0083] It should be noted that in this embodiment, BV2 and BV3 are extracted as high-concentration lithium elution solutions, but this is not limited to this. For example, a predetermined volume of BV1 to BV4 can be extracted from the beginning of obtaining the elution solution as a high-concentration lithium elution solution. In addition, only BV3 can be used as a high-concentration lithium elution solution.

[0084] In addition, for example, when the elution process is carried out by batch processing and the flow rate of the acid-containing solution used in the elution process is a predetermined rate, for the separation of the high-concentration lithium elution solution and the low-concentration lithium elution solution, the elution solution obtained between the predetermined start time and the end time from the start of the elution process can be used as the high-concentration lithium elution solution, and the elution solution obtained thereafter can be used as the low-concentration lithium elution solution. The flow rate is usually expressed as SV (spatial velocity: the flow volume BV per unit time (1 hour)). When the SV is constant, the high-concentration lithium elution solution can be set to the elution solution obtained between the predetermined start time and the end time from the start of the elution process. In addition, the start of the elution process can be predetermined when the acid-containing solution is started to be injected or when the elution solution is started to be recovered.

[0085] The high-concentration lithium eluting solution is an eluting solution obtained within a predetermined time from the start of the eluting step, and thus the high-concentration lithium eluting solution can be easily obtained.

[0086] (Third Embodiment)

[0087] Figure 3 A flow chart of a method for producing a lithium-containing solution according to a third embodiment of the present invention is shown. The method for producing a lithium-containing solution according to the third embodiment differs from the method for producing a lithium-containing solution according to the first embodiment in that a water washing step for washing the eluted lithium adsorbent obtained through the elution step is provided after the elution step and the water-washed solution obtained in the water washing step is added to the acid-containing solution, and other aspects are the same as those of the first embodiment. Therefore, the above differences are described below.

[0088] (Water washing process)

[0089] In the elution step in the second embodiment, an eluted lithium adsorbent is obtained. The eluted lithium adsorbent is washed in a water washing step. In the water washing step, for example, pure water is used, or industrial water is used in consideration of cost. The eluted lithium adsorbent washed in the water washing step is regenerated as a lithium adsorbent, and the lithium adsorbent is used again in the adsorption step.

[0090] The washed liquid after washing and eluting the lithium adsorbent in the washing process sometimes contains lithium. For example, the lithium concentration of the washed liquid obtained just after washing is high. In the present embodiment, the washed liquid is added to the acid-containing solution. The washed liquid added to the acid-containing solution can be all of the washed liquid or a portion thereof. However, since the lithium concentration of the washed liquid obtained just after washing is high, it is preferred that the washed liquid of a predetermined amount after washing is added to the acid-containing solution.

[0091] Figure 6 The figure shows the lithium concentration of each volume amount predetermined based on the water-washed liquid obtained at the beginning of the present embodiment. The horizontal axis is the BV of the water-washed liquid, and the vertical axis represents the concentration of lithium contained in the water-washed liquid obtained after the water-washing process. For example, in the present embodiment, it is preferred that the water-washed liquid of BV1, that is, only the water-washed liquid of BV1 from the beginning of the water-washed liquid obtained at the beginning of the water-washing process, is added to the acid-containing solution.

[0092] By adding the water-washed liquid obtained in the water-washing step to the acid-containing solution, lithium that has to be discarded in the water-washing step can be recovered.

[0093] (Fourth Embodiment)

[0094] Figure 4A flow chart of the method for producing a lithium-containing solution according to the fourth embodiment of the present invention is shown in FIG. The method for producing a lithium-containing solution according to the fourth embodiment differs from the method for producing a lithium-containing solution according to the second embodiment in that a water washing step for washing the eluted lithium adsorbent obtained through the elution step is provided after the elution step and the water-washed liquid obtained in the water washing step is added to the acid-containing solution, and other aspects are the same as those of the second embodiment. In addition, a detailed description of the water washing step is included in the description of the third embodiment. Therefore, a detailed description of the water washing step is omitted.

[0095] Example

[0096] 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.

[0097] <Example 1>

[0098] (Adsorption process)

[0099] The powdered lithium adsorbent H 1.6 Mn 1.6 O4 is kept in a glass column with a diameter of 20 mm. Then, a low-concentration lithium-containing solution, i.e., a solution simulating salt lake water and containing lithium, is passed through the column to make the lithium adsorbent become lithium manganate, i.e., Li 1.6 Mn 1.6 O4. The lithium concentration of the low-concentration lithium-containing solution is 0.7 g / L. In the adsorption process, SV15 is used to pass the solution, and the low-concentration lithium-containing solution of BV30 is passed.

[0100] (Elution process)

[0101] The adsorbed lithium manganate in the glass column is contacted with an acid-containing solution. As the first elution process, for the acid-containing solution, an acid-containing solution consisting of only 1 mol / L hydrochloric acid is passed through BV2. In the following second elution process, the acid-containing solution is used to add hydrochloric acid to the elution solution after the first elution process to become a 0.5 mol / L solution. The flow rate at this time is BV10, and the flow rate is SV15. That is, from BV3 to BV12, it is the second elution process, and the hydrogen ion concentration of the acid-containing solution is 0.5 mol / L. The solution flowing out of the column is separated into a high-concentration lithium elution solution that is in the initial stage of the outflow and contains lithium at a high concentration and a low-concentration lithium elution solution that is in the stage after the initial stage and has a lithium concentration lower than the high-concentration lithium elution solution. In this embodiment, the concentration of the high-concentration lithium elution solution is 6.5 g / L. It should be noted that since the liquid is passed through BV12, the liquid volume of the elution solution is 120 mL. In addition, the manganese concentration of the elution solution at this time was 0.02 g / L.

[0102] (Manganese oxidation process)

[0103] The eluted solution obtained in the elution step was used to carry out a manganese oxidation step. An oxidant and a pH adjuster were used to obtain a lithium-containing solution. The manganese concentration at this time was 0.0 g / L.

[0104] <Comparative Example 1>

[0105] For Comparative Example 1, the parameters other than setting the hydrogen ion concentration of the acid-containing solution in the elution process to 0.5 mol / L (initially only hydrochloric acid is used, which is 0.5 mol / L, and then hydrochloric acid is added to the elution solution that has undergone one elution process to become 0.5 mol / L) are the same as those in Example 1. The concentration of the high-concentration lithium elution solution in Comparative Example 1 is 3.4 g / L. It should be noted that the liquid volume of the elution solution at this time is the same as that in Example 1, which is 120 mL. In addition, the manganese concentration of the elution solution at this time is 0.02 g / L.

[0106] <Comparative Example 2>

[0107] For Comparative Example 2, the parameters other than setting the hydrogen ion concentration of the acid-containing solution in the elution process to 1.0 mol / L (initially only hydrochloric acid is used, which is 1.0 mol / L, and then hydrochloric acid is added to the elution solution that has undergone one elution process to become 1.0 mol / L) are the same as those in Example 1. The concentration of the high-concentration lithium elution solution in Comparative Example 2 is 5.2 g / L. It should be noted that the liquid volume of the elution solution at this time is the same as that in Example 1, which is 120 mL. In addition, the manganese concentration of the elution solution at this time is 0.06 g / L.

[0108] (Summarize)

[0109] It can be seen that in Example 1, the high-concentration lithium elution solution is 6.5 g / L, which is 6.0 g / L or more, and a high lithium concentration is maintained. In contrast, in Comparative Example 1, the high-concentration lithium elution solution is 3.4 g / L, and in Comparative Example 2, the high-concentration lithium elution solution is 5.2 g / L, which is less than 6.0 g / L, and the lithium concentration of the high-concentration lithium elution solution is low. In this way, it can be seen that in Example 1, the lithium concentration of the high-concentration lithium elution solution is high, so when the final lithium amount obtained is a specified value, the total amount of the elution solution can be suppressed. In addition, it can be seen that in Example 1, compared with Comparative Example 2, the manganese concentration can also be suppressed at a low level, and the deterioration of the lithium adsorbent can be suppressed.

[0110] It should be noted that the term "based on the initial acquisition" includes "based on the physical quantity at the initial acquisition", and the physical quantity includes concentration, time, volume and the like.

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, wherein a low-concentration lithium-containing solution is brought into contact with a lithium adsorbent obtained from lithium manganate to obtain adsorbed lithium manganate; an elution step, contacting the adsorbed lithium manganese oxide with an acid solution to obtain an elution solution; as well as a manganese oxidation step, wherein an oxidizing agent and a pH adjusting agent are added to the elution solution to oxidize manganese, thereby obtaining a lithium-containing solution having a suppressed manganese concentration; The elution process includes a first elution process and a second elution process in which the hydrogen ion concentration of the acid-containing solution is lower than that of the first elution process. The second elution step is performed after the first elution step.

2. The method for producing a lithium-containing solution according to claim 1, wherein: The hydrogen ion concentration of the acid-containing solution in the first elution step is 1.0 mol / L or more and 4.0 mol / L or less, The hydrogen ion concentration of the acid-containing solution in the second elution step is 0.1 mol / L or more and 0.5 mol / L or less.

3. The method for producing a lithium-containing solution according to claim 1 or 2, wherein: In the elution step, the elution solution is separated into a high-concentration lithium elution solution containing lithium at a high concentration and a low-concentration lithium elution solution having a lower lithium concentration than the high-concentration lithium elution solution. The acid-containing solution used in the elution step includes a solution obtained by adding an acid to the low-concentration lithium elution solution. The elution solution used in the manganese oxidation step includes the high-concentration lithium elution solution.

4. The method for producing a lithium-containing solution according to claim 3, wherein: The high-concentration lithium elution solution is obtained by extracting a predetermined volume of the elution solution from the elution solution obtained through the elution step based on the start of obtaining the elution solution.

5. The method for producing a lithium-containing solution according to claim 3, wherein: The high-concentration lithium elution solution is the elution solution obtained between a predetermined start time and a predetermined end time from the start of the elution step.

6. The method for producing a lithium-containing solution according to any one of claims 1 to 5, characterized in that: The step of washing the eluted lithium adsorbent obtained after the elution step is arranged after the elution step. The water-washed liquid obtained in the water-washing step is added to the acid-containing solution.

Images