Method of extracting lithium from lithium-containing solution

Abstract

The present invention relates to a method for producing lithium hydroxide using lithium carbonate. A method for producing lithium hydroxide using lithium carbonate according to the present invention comprises the steps of: extracting lithium carbonate from a lithium-containing solution; dissolving the lithium carbonate in an acid to obtain an aqueous lithium chloride solution; removing ionic impurities from the aqueous lithium chloride solution; and introducing the aqueous lithium chloride solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into an aqueous lithium hydroxide solution and obtaining byproducts, an aqueous acid solution and a salt solution.

Description

Technology Field

[0001] The present invention relates to a method for producing lithium hydroxide using lithium carbonate. More specifically, it relates to a method for extracting lithium comprising the step of dissolving lithium carbonate in hydrochloric acid. Background Technology

[0002] Globally, the number of electric vehicles reached 23 million in 2019 and is projected to continue increasing to approximately 210.9 million by 2030. Along with this, the performance of batteries used in electric vehicles is continuously improving through higher capacity and longer lifespans. Regarding cathode active materials for secondary batteries, the market share of high-energy-density High-Ni batteries is also predicted to rise to 76% by 2030. Consequently, the demand for lithium hydroxide, a lithium raw material for High-Ni cathode active materials, is also expected to increase.

[0003] Generally, lithium is produced by extracting it in the form of lithium carbonate from lithium-containing minerals or brine. Conventionally, lithium was manufactured from lithium carbonate into lithium hydroxide via the Lime process. Specifically, lithium carbonate is extracted from a salt lake, and a lithium hydroxide solution is obtained by reacting the extracted lithium carbonate with lime. Lithium hydroxide is then manufactured by crystallizing the obtained lithium hydroxide. However, this Lime process generates limestone as a byproduct; since large amounts of carbon dioxide are produced during kiln operation to recycle this limestone, the process is not environmentally friendly.

[0004] Therefore, the development of technology capable of manufacturing lithium hydroxide in an eco-friendly manner is required. The problem to be solved

[0005] The present invention aims to provide a method for manufacturing lithium hydroxide using lithium carbonate. More specifically, the invention aims to provide a method for manufacturing lithium hydroxide comprising the step of dissolving lithium carbonate in an acid. means of solving the problem

[0006] A method for producing lithium hydroxide using lithium carbonate according to one embodiment of the present invention comprises: a step of extracting lithium carbonate from a lithium-containing solution; a step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution; a step of removing ionic impurities from the lithium aqueous solution; and a step of introducing the lithium aqueous solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining an acid aqueous solution and a salt solution as byproducts.

[0007] In the step of dissolving lithium carbonate in acid to obtain a lithium aqueous solution, the concentration of the acid may be 7 to 18%.

[0008] The step of dissolving lithium carbonate in an acid to obtain an aqueous lithium solution may involve dissolving 1.5 to 3 moles of the acid per 1 mole of lithium carbonate.

[0009] In the step of dissolving lithium carbonate in acid to obtain a lithium aqueous solution, the lithium aqueous solution may not contain phosphorus (P).

[0010] In the step of extracting lithium carbonate from a lithium-containing solution, the lithium-containing solution may be one or more of a solution from which lithium dissolved in the ocean has been extracted, a solution generated from a process of recycling spent lithium batteries, a solution from which lithium ore has been leached, brine, lithium-containing hot spring water, lithium-containing groundwater, and lithium-containing brine.

[0011] In the step of dissolving lithium carbonate in acid to obtain an aqueous lithium solution, the purity of the lithium carbonate can be 90% or higher.

[0012] In the step of dissolving lithium carbonate in an acid to obtain an aqueous lithium solution, the acid may include at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0013] In the step of removing ionic impurities from a lithium aqueous solution, the ionic impurities may include at least one of Ca ions, Mg ions, B ions, heavy metals such as Al, Fe, and Mn, Sr, and Si.

[0014] The step of removing ionic impurities from a lithium aqueous solution may be performed using an ion exchange resin.

[0015] The step of removing ionic impurities from the lithium aqueous solution may be performed by adjusting the pH of the lithium aqueous solution to 4 or higher.

[0016] pH adjustment may be performed by adding lithium hydroxide.

[0017] The step of removing ionic impurities from the lithium aqueous solution may further include the step of adjusting the pH of the lithium aqueous solution to 10 or higher.

[0018] In the step of introducing a lithium aqueous solution from which ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts such as an acid aqueous solution and a salt solution, the bipolar electrodialysis device may have a structure in which a first bipolar membrane, an anion dialysis membrane, a cation dialysis membrane, and a second bipolar membrane are sequentially arranged.

[0019] In the step of introducing a lithium aqueous solution from which ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining by-products of an acid aqueous solution and a salt solution, the lithium concentration of the lithium aqueous solution from which ion impurities have been removed may be 10 to 20 g / L. The acid aqueous solution and the salt solution obtained in the step of introducing the lithium aqueous solution from which ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining by-products of an acid aqueous solution and a salt solution may be used in the step of dissolving the lithium carbonate in acid to obtain a lithium aqueous solution.

[0020] In the step of introducing a lithium aqueous solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts such as an acid aqueous solution and a salt solution, the concentration of acid in the acid aqueous solution obtained may be 7 to 18%.

[0021] The concentration of the acid in the step of dissolving lithium carbonate in acid to obtain a lithium aqueous solution and the concentration of the acid obtained in the step of introducing the lithium aqueous solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts of an acid aqueous solution and a salt solution may be the same.

[0022] The lithium concentration in the salt solution added in the step of dissolving lithium carbonate in acid to obtain a lithium aqueous solution may be 1 to 4 g / L.

[0023] After the step of introducing a lithium aqueous solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts such as an acid aqueous solution and a salt solution, the method may further include the step of concentrating and crystallizing the lithium hydroxide aqueous solution, and the step of drying the crystallized lithium hydroxide to obtain lithium hydroxide in powder form. Effects of the invention

[0024] A method for producing lithium hydroxide according to one embodiment of the present invention dissolves lithium carbonate in an acid containing anions with good mobility, so that during bipolar electrodialysis, the passage through the anion dialysis membrane is fast and the lithium concentration rate is fast, and accordingly, the concentration of the base proceeds rapidly, resulting in good productivity.

[0025] The method for producing lithium hydroxide according to one embodiment of the present invention has good productivity because no phosphorus precipitates are generated on the bipolar electrodialysis membrane.

[0026] The method for manufacturing lithium hydroxide according to one embodiment of the present invention allows for the recycling of the acid generated as a byproduct because the concentration of the acid is similar to the concentration of the acid used to dissolve lithium carbonate, resulting in significantly lower generation of byproducts in the overall process. Therefore, it is environmentally friendly.

[0027] The method for manufacturing lithium hydroxide according to one embodiment of the present invention is economical because it allows for the recycling of the salt solution generated as a byproduct, resulting in minimal loss of lithium. Brief explanation of the drawing

[0028] FIG. 1 shows a method for producing lithium hydroxide using lithium carbonate according to one embodiment of the present invention. Figure 2 is a graph of the change in current according to the lithium concentration time of Example 1 and Comparative Example 1 of the present invention. Figure 3 is a graph of base conductivity according to lithium concentration time of Example 1 and Comparative Example 1 of the present invention. Figure 4 is a graph of acid conductivity according to lithium concentration time of Example 1 and Comparative Example 1 of the present invention. Figure 5 is a photograph of the anion dialysis membrane and the cation dialysis membrane on the salt chamber side after bipolar electrodialysis according to Comparative Example 1 of the present invention. Specific details for implementing the invention

[0029] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0030] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0031] When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other part is interposed in between.

[0032] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0034] FIG. 1 schematically illustrates a method for producing lithium hydroxide using lithium carbonate according to one embodiment of the present invention.

[0035] Referring to FIG. 1, a method for producing lithium hydroxide using lithium carbonate according to one embodiment of the present invention comprises the steps of: extracting lithium carbonate from a lithium-containing solution (S100); dissolving lithium carbonate in an acid to obtain a lithium aqueous solution (S200); removing ionic impurities from the lithium aqueous solution (S300); and introducing the lithium aqueous solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts, an acid aqueous solution and a salt solution (S400).

[0036] In the following, a method for manufacturing lithium hydroxide using lithium carbonate according to one embodiment of the present invention is described step by step.

[0037] First, lithium carbonate is extracted from a lithium-containing solution (S100).

[0038] In this case, the lithium-containing solution includes all solutions containing lithium. Specifically, the lithium-containing solution may be one or more of the following: a solution obtained by extracting lithium dissolved in the ocean, a solution generated from the process of recycling spent lithium batteries, a solution obtained by leaching lithium ore, brine, lithium-containing hot spring water, lithium-containing groundwater, and lithium-containing brine. More specifically, it may be brine. The above description is merely an example of a lithium-containing solution, and the lithium-containing solution is not limited by the above description.

[0039] The lithium carbonate extracted at this stage can be used as a raw material for the manufacture of lithium hydroxide.

[0040] Next, lithium carbonate (Li2CO3) is dissolved in acid to obtain an aqueous lithium solution in which the acid is dissolved (S200).

[0041] At this time, the acid may include at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0042] In this embodiment, the acid may be hydrochloric acid (HCl), and more specifically, lithium carbonate (Li2CO3) is dissolved in hydrochloric acid to obtain an aqueous lithium chloride solution.

[0043] At this time, hydrochloric acid (HCl) is an aqueous hydrochloric acid solution, and the hydrochloric acid may be 7 to 18 weight percent relative to 100 weight percent of the aqueous hydrochloric acid solution. If the concentration of hydrochloric acid is too low, there is a disadvantage that evaporative concentration is required, and if the concentration of hydrochloric acid is too high, there is a disadvantage that the efficiency of Li production decreases. More specifically, the concentration of hydrochloric acid may be 7 to 17 percent. Even more specifically, the concentration of hydrochloric acid may be 7 to 10 percent.

[0044] In this step, 1.5 to 3 moles of hydrochloric acid may be dissolved per mole of lithium carbonate. If too little hydrochloric acid is dissolved, the Cl content of the stock solution entering the BPED is low, which has the disadvantage of low conductivity; if too much hydrochloric acid is dissolved, the conductivity is too high, leading to excessive acid concentration and a disadvantage of reduced Li production efficiency. More specifically, the number of moles of hydrochloric acid may be 1.5 to 2.5 moles. Even more specifically, the number of moles of hydrochloric acid may be 2 to 2.4 moles.

[0045] In addition, it is more desirable to dissolve lithium carbonate in hydrochloric acid at this stage. If lithium carbonate is dissolved in sulfuric acid instead of hydrochloric acid, the mobility of sulfate ions is inferior to that of chloride ions, which may result in slow passage through the anion dialysis membrane, a slower subsequent lithium concentration rate, and consequently, slower concentration of the base. Specifically, since the mobility of chloride ions (approx. 1.0388) is about twice as fast as the mobility of sulfate ions (approx. 0.544), it is preferable to dissolve it in hydrochloric acid rather than sulfuric acid.

[0046] Conversely, when lithium carbonate is dissolved in hydrochloric acid instead of sulfuric acid, the mobility of chloride ions is much better than that of sulfate ions, so it can pass through the anion dialysis membrane quickly, and subsequently, the concentration rate of lithium can be faster, and accordingly, the concentration of base can also be faster.

[0047] In addition, phosphorus (P) may not be present in the lithium aqueous solution at this stage. Phosphoric acid may also not be present. If phosphorus is present in the lithium aqueous solution, since phosphorus possesses both cationic and anionic properties, it can act as an impurity in both the anion membrane and the cation membrane during subsequent bipolar electrodialysis. After bipolar electrodialysis, phosphorus may precipitate as lithium phosphate (LP) on the cation and anion membranes in the salt chamber, thereby reducing the lithium extraction rate and hindering productivity.

[0048] At this stage, the purity of lithium carbonate can be 90% or higher. If a solution with too low a purity of lithium carbonate is introduced, it forms precipitates on the membrane, which has the disadvantage of poor current flow. Additionally, as various impurities migrate from the salt chamber to the base or acid and encounter the precipitation pH, they precipitate within the membrane, which can degrade the quality of the production solution. Specifically, the purity of lithium carbonate can be 95% or higher.

[0049] Next, ionic impurities are removed from the lithium aqueous solution (S300).

[0050] The ionic impurities at this stage may include at least one of Ca ions, Mg ions, B ions, heavy metals such as Al, Fe, and Mn, Sr, and Si. The content of these ionic impurities is controlled to 3 ppm or less.

[0051] The removal of ion impurities at this stage may be performed using an ion exchange resin.

[0052] Specifically, Ca 2+ , Mg 2+ The removal of divalent ion impurities such as the above may be performed by adjusting the pH of the lithium aqueous solution to 3 or higher. More specifically, it may be performed by adjusting the pH to 4 or higher.

[0053] At this time, pH adjustment may be performed by adding lithium hydroxide (LiOH). That is, lithium hydroxide is added to the lithium aqueous solution to adjust the pH to 4 or higher, and the solution can be passed through a divalent ion exchange membrane to remove ionic impurities.

[0054] Additionally, ionic impurities can be removed by further adjusting the pH of the lithium aqueous solution to 10 or higher. Ca 2+ , Mg 2+ If divalent ions such as are present at a concentration of approximately 100 ppm or higher, an additional Mg ion removal process may be added. The Mg ion removal process can be carried out by raising the pH of the lithium aqueous solution to 10 or higher using lithium hydroxide. In the lithium aqueous solution with a pH raised to 10 or higher, Mg ions can be removed as Mg(OH)2. At this time, the pH can be adjusted to 10.5 or higher.

[0055] Additionally, a process of passing through a boron (B) ion exchange membrane may be further included. In the case of lithium carbonate derived from brine, it may contain boron, and the boron (B) can be removed by passing the lithium aqueous solution through a boron ion exchange membrane.

[0056] Next, the lithium aqueous solution from which ionic impurities have been removed is fed into a bipolar electrodialysis device to be converted into a lithium hydroxide aqueous solution, and the byproducts, an aqueous hydrochloric acid solution and a salt solution, are obtained (S400).

[0057] At this stage, the lithium concentration in the lithium aqueous solution from which ionic impurities have been removed may be 10 to 20 g / L. If the lithium concentration in the lithium aqueous solution is too low, the Li content of the stock solution entering the BPED is low, resulting in low conductivity and poor current flow; if it is too high, too much Li escapes into the demineralization solution, resulting in a low recovery rate. More specifically, the lithium concentration may be 10 to 15 g / L. Even more specifically, the lithium concentration may be 10 to 12 g / L.

[0058] The bipolar electrodialysis device at this stage may have a structure in which an anode cell containing an anode, a first bipolar membrane, an anion dialysis membrane, a cation dialysis membrane, a second bipolar membrane, and a cathode cell containing a cathode are sequentially arranged.

[0059] Bipolar electrodialysis can be prepared by introducing a lithium aqueous solution from which ionic impurities have been removed in the previous step between an anion dialysis membrane and a cation dialysis membrane, and by introducing water between the first bipolar membrane and the anion dialysis membrane, and between the second bipolar membrane and the cation dialysis membrane, respectively.

[0060] When electricity is applied to a bipolar electrodialysis device into which a lithium aqueous solution and water are introduced, water splitting occurs at each bipolar membrane, and cations and anions in the lithium aqueous solution can move toward the cathode and anode, respectively, due to the electrophoretic effect.

[0061] Specifically, Cl meets hydrogen produced by water splitting at the first bipolar membrane on the anode side to be obtained as hydrochloric acid (HCl), and lithium ions moving to the cathode through the cation dialysis membrane meet OH generated at the second bipolar membrane - It can be obtained as lithium hydroxide (LiOH) by reacting with.

[0062] That is, the overall reaction is as shown in Reaction Equation 1 below.

[0063] [Reaction Equation 1]

[0064] LiCl + H2O → LiOH + HCl

[0065] At this time, between the anion dialysis membrane and the cation dialysis membrane, lithium and chloride ions may escape from the lithium aqueous solution, which is the raw material introduced into the bipolar electrodialysis device, and a salt solution in which some remains may be formed.

[0066] That is, the hydrochloric acid aqueous solution can be recovered between the first bipolar membrane and the anion dialysis membrane of the anode cell, the salt solution can be recovered between the anion dialysis membrane and the cation dialysis membrane, and the lithium hydroxide aqueous solution can be recovered between the cation dialysis membrane and the second bipolar membrane of the cathode cell.

[0067] The hydrochloric acid solution (Acid) and salt solution (Salt) obtained at this stage can be used by introducing them into the step (S200) of dissolving the aforementioned lithium carbonate in hydrochloric acid to obtain a lithium aqueous solution (S500).

[0068] The concentration of hydrochloric acid in the aqueous hydrochloric acid solution obtained at this stage may be 7 to 18%. More specifically, it may be 7 to 17%, and even more specifically, it may be 7 to 10%.

[0069] Since the concentration of hydrochloric acid obtained at this stage is similar to or identical to the concentration of hydrochloric acid required in the step (S200) of dissolving the aforementioned lithium carbonate in hydrochloric acid to obtain a lithium aqueous solution, it can be recycled in the S200 step. Because the hydrochloric acid aqueous solution obtained as a byproduct can be recycled in this process, the generation of byproducts is very low on an overall process basis, making it environmentally friendly.

[0070] More specifically, the concentration of hydrochloric acid in the step of dissolving lithium carbonate in hydrochloric acid to obtain an aqueous lithium solution can be the same as the concentration of hydrochloric acid obtained in the step of feeding the aqueous lithium solution, from which ionic impurities have been removed, into a bipolar electrodialysis device to convert it into an aqueous lithium hydroxide solution and obtaining the byproducts, an aqueous hydrochloric acid solution and a salt solution. If the concentrations of hydrochloric acid in the two steps are the same, hydrochloric acid recycling can be more economical.

[0071] The lithium concentration in the salt solution obtained at this stage may be 1 to 4 g / L. More specifically, it may be 2 to 3 g / L. Even more specifically, it may be 2.5 to 3 g / L.

[0072] The salt solution obtained at this stage can also be recycled in the step (S200) of dissolving the aforementioned lithium carbonate in hydrochloric acid to obtain an aqueous lithium solution, just like the aqueous hydrochloric acid solution. Thus, although 1 to 4 g / L of lithium is obtained in the salt solution, it can be recycled again to prevent the loss of lithium in the entire process. That is, the lithium extraction method according to the present invention can be economical because there is little lithium loss.

[0073] Next, the method may further include a step of concentrating and crystallizing an aqueous lithium hydroxide solution (S600), and a step of drying the crystallized lithium hydroxide to obtain lithium hydroxide in powder form.

[0075] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0077] Example 1 - Dissolution in 7.8% hydrochloric acid

[0078] (1) Lithium carbonate dissolution

[0079] Lithium carbonate (Li2CO3) was used as a raw material for lithium hydroxide. Lithium carbonate with a purity of 90% or higher was used. Specifically, lithium carbonate with a purity of 96.7% was used. Table 1 below shows the purity of the lithium carbonate used in Example 1.

[0081] Category (wt.%) Li S Ca Mg B K Na LC Purity (%) Li2CO3 18.16 0.15 0.034 0.021 0.026 0.25 0.64 96.7

[0082] Hydrochloric acid (HCl) with a concentration of 7.8% was prepared. Lithium carbonate was dissolved in hydrochloric acid by adding 2.2 moles of 7.8% hydrochloric acid per 1 mole of lithium carbonate. The composition, concentration, and pH of the aqueous lithium chloride solution (LiCl solution) dissolved in 7.8% hydrochloric acid were as shown in Table 2 below.

[0084] Classification (g / L) Li S Ca Mg B K Na pH LiCl solution 20.14 0.137 0.042 0.022 0.023 0.111 0.270 0.14

[0085] (2) Removal of impurities

[0086] The above LiCl solution was adjusted to pH 4 with an aqueous lithium hydroxide (LiOH) solution and removed using a divalent cation exchange membrane. The divalent cations removed at this time include Ca ions, Mg ions, etc.

[0087] After that, the LiCl solution was passed through a boron ion exchange membrane to remove boron (B) ions.

[0088] The solution composition before impurity removal, after passing through a divalent cation exchange membrane, and after passing through a boron ion exchange membrane was as shown in Table 3 below.

[0090] Solution composition (g / L) S Ca Mg B K Na Si Others Before removing impurities 0.141 0.045 0.021 0.022 0.103 0.227 - - After passing through the divalent ion exchange membrane 0.105 0.008 <0.003 0.014 0.077 0.150 <0.003 <0.003 B After passing through the ion exchange membrane 0.084 <0.003 <0.003 <0.003 0.063 0.127 <0.003 <0.003

[0091] (3) Converted to lithium hydroxide

[0092] The lithium concentration of the above-mentioned lithium chloride aqueous solution from which ionic impurities had been removed was adjusted to 11 g / L and introduced into a bipolar membrane to convert it into a lithium hydroxide solution. The conversion results were as shown in Table 4 below.

[0094] Solution composition (mg / L) Li K Ca S Na Si Cl Others Hydrochloric acid solution (Acid) 652 <3 4 107 42 <3 7.65(%) <3 Salt solution 2666 <3 <3 46 17 13 1.01(%) <3 undiluted 11450 30 <3 35 62 7 6.01(%) <3 Base 23840 91 <3 113 318 5 0.82(%) <3

[0095] (4) Current behavior according to concentration time

[0096] The current, base conductivity, and acid conductivity were measured according to the time of concentration with lithium hydroxide.

[0097] The measurement results of the current according to the time of concentration with lithium hydroxide are as shown in Figure 2.

[0098] The results of measuring base conductivity according to the time of concentration with lithium hydroxide are as shown in Figure 3.

[0099] The results of measuring acid conductivity according to the time of concentration with lithium hydroxide are as shown in Figure 4.

[0100] Looking at FIGS. 2 to 4, it can be seen that the lithium chloride aqueous solution prepared by dissolving lithium carbonate in hydrochloric acid without adding phosphorus (P) maintains its current without dropping even when lithium is concentrated into lithium hydroxide. In other words, it can be seen that the production rate of lithium hydroxide and hydrochloric acid is maintained without dropping.

[0103] Comparative Example 1 - Case where P is included

[0104] The experiment was conducted in the same manner as in Example 1, except that a mixture of 7.8% hydrochloric acid and phosphoric acid was prepared by adding phosphoric acid to add 250 ppm of phosphorus (P). Lithium hydroxide was prepared by electrodialysis using a bipolar membrane with an aqueous lithium chloride solution to which phosphoric acid was added.

[0105] As in Example 1, the current, base conductivity, and acid conductivity were measured according to the time of concentration with lithium hydroxide.

[0106] The measurement results of the current according to the time of concentration with lithium hydroxide are as shown in Figure 2.

[0107] The results of measuring base conductivity according to the time of concentration with lithium hydroxide are as shown in Figure 3.

[0108] The results of measuring acid conductivity according to the time of concentration with lithium hydroxide are as shown in Figure 4.

[0109] When compared with the results of Example 1 in Figures 2 to 4, it was confirmed that when phosphorus (P) was added, the production rate of lithium hydroxide and hydrochloric acid decreased as the current dropped sharply.

[0110] In addition, the anion and cation membranes on the salt chamber side were examined after the bipolar electrodialysis test. Photographs of the anion and cation membranes are shown in Fig. 5. Looking at Fig. 5, it was observed that lithium phosphate was precipitated on the anion and cation membranes when the aqueous lithium chloride solution containing P was electrodialyzed. It was inferred that the production rate of lithium hydroxide dropped sharply due to the precipitated lithium phosphate.

[0112] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

Claim 1 A method for producing lithium hydroxide using lithium carbonate, comprising: a step of extracting lithium carbonate from a lithium-containing solution; a step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution that does not contain phosphorus (P); a step of removing ionic impurities from the lithium aqueous solution; and a step of introducing the lithium aqueous solution from which ionic impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts, an aqueous hydrochloric acid solution and a salt solution. Claim 2 A method for producing lithium hydroxide using lithium carbonate according to claim 1, wherein, in the step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution, the concentration of the acid is 7 to 18% in percentage concentration. Claim 3 A method for producing lithium hydroxide using lithium carbonate, wherein, in paragraph 2, the step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution is to dissolve 1.5 to 3 moles of the acid per 1 mole of the lithium carbonate. Claim 4 delete Claim 5 A method for producing lithium hydroxide using lithium carbonate, wherein, in the step of extracting lithium carbonate from the lithium-containing solution, the lithium-containing solution is one or more of a solution obtained by extracting lithium dissolved in the ocean, a solution generated in a process of recycling spent lithium batteries, a solution obtained by leaching lithium ore, brine, lithium-containing hot spring water, lithium-containing groundwater, and lithium-containing brine. Claim 6 A method for producing lithium hydroxide using lithium carbonate according to claim 1, wherein, in the step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution, the purity of the lithium carbonate is 90% or higher. Claim 7 A method for producing lithium hydroxide using lithium carbonate according to claim 1, wherein, in the step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution, the acid comprises at least one of hydrochloric acid, sulfuric acid, and nitric acid. Claim 8 A method for producing lithium hydroxide using lithium carbonate, wherein, in the step of removing ionic impurities from the lithium aqueous solution, the ionic impurities include at least one of Ca ions, Mg ions, B ions, heavy metals such as Al, Fe and Mn, Sr, and Si. Claim 9 A method for producing lithium hydroxide using lithium carbonate, wherein, in claim 1, the step of removing ionic impurities from the lithium aqueous solution is performed using an ion exchange resin. Claim 10 A method for producing lithium hydroxide using lithium carbonate, wherein, in claim 1, the step of removing ionic impurities from the lithium aqueous solution is performed by adjusting the pH of the lithium aqueous solution to 4 or higher. Claim 11 A method for producing lithium hydroxide using lithium carbonate, wherein, in item 10, the pH adjustment is performed by adding lithium hydroxide. Claim 12 A method for producing lithium hydroxide using lithium carbonate, wherein the step of removing ionic impurities from the lithium aqueous solution according to claim 10 further includes the step of adjusting the pH of the lithium aqueous solution to 10 or higher. Claim 13 A method for producing lithium hydroxide using lithium carbonate, wherein, in the step of introducing the lithium aqueous solution from which the ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts such as an acid aqueous solution and a salt solution, the bipolar electrodialysis device has a structure in which a first bipolar membrane, an anion dialysis membrane, a cation dialysis membrane, and a second bipolar membrane are sequentially arranged. Claim 14 A method for producing lithium hydroxide using lithium carbonate, wherein, in the step of introducing the lithium aqueous solution from which ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts such as an acid aqueous solution and a salt solution, the lithium concentration of the lithium chloride aqueous solution from which ion impurities have been removed is 10 to 20 g / L. Claim 15 A method for producing lithium hydroxide using lithium carbonate, wherein, in the first step of introducing the lithium aqueous solution from which the ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining by-products, the acid aqueous solution and salt solution obtained therefrom are introduced into the step of dissolving the lithium carbonate in acid to obtain a lithium aqueous solution and used therein. Claim 16 A method for producing lithium hydroxide using lithium carbonate, wherein, in the step of introducing the lithium aqueous solution from which the ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts such as an acid aqueous solution and a salt solution, the concentration of acid in the acid aqueous solution obtained is 7 to 18%. Claim 17 A method for producing lithium hydroxide using lithium carbonate, wherein, in claim 1, the concentration of the acid in the step of dissolving the lithium carbonate in an acid to obtain a lithium aqueous solution and the concentration of the acid obtained in the step of introducing the lithium aqueous solution from which ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts of an acid aqueous solution and a salt solution are the same. Claim 18 A method for producing lithium hydroxide using lithium carbonate, wherein, in the step of dissolving the lithium carbonate in acid to obtain a lithium aqueous solution, the lithium concentration in the salt solution is 1 to 4 g / L. Claim 19 A method for producing lithium hydroxide using lithium carbonate, further comprising: a step of introducing the lithium aqueous solution from which the ion impurities have been removed into a bipolar electrodialysis device to convert it into a lithium hydroxide aqueous solution and obtaining byproducts, an acid aqueous solution and a salt solution, after which the lithium hydroxide aqueous solution is concentrated and crystallized; and a step of drying the crystallized lithium hydroxide to obtain lithium hydroxide in powder form.

Images