KR20240135931A - A system for manufacturing lithium hydroxide and a method for manufacturing lithium hydroxide using the same - Google Patents

Abstract

One aspect of the present invention provides a lithium hydroxide production system including an electrolysis unit including an anode chamber and a cathode chamber partitioned by a diaphragm; and a crystallization unit cooling a portion of the cathode product produced in the cathode chamber to produce solid lithium hydroxide; and a method for producing lithium hydroxide using the same.

Description

{A SYSTEM FOR MANUFACTURING LITHIUM HYDROXIDE AND A METHOD FOR MANUFACTURING LITHIUM HYDROXIDE USING THE SAME}

The present invention relates to a system for manufacturing lithium hydroxide and a method for manufacturing lithium hydroxide using the same, and more particularly, to a system for manufacturing lithium hydroxide capable of substantially omitting a process for processing raw materials and/or intermediates, thereby increasing productivity and stably obtaining high-purity lithium hydroxide, and a method for manufacturing lithium hydroxide using the same.

Lithium is used in various industries such as secondary batteries, glass, ceramics, alloys, lubricants, and pharmaceuticals. In particular, lithium secondary batteries have recently attracted attention as the main power source for hybrid and electric vehicles, and the lithium secondary batteries for electric vehicles are expected to grow into a huge market that is more than 100 times larger than the existing small battery market for mobile phones, laptops, etc. In addition, due to the strengthening of environmental regulations worldwide, the application fields are expanding to electronics, chemicals, energy, etc. in addition to the electric vehicle industry.

Currently, the main source of lithium is brine produced from natural salt lakes, and this brine contains various salts such as lithium, magnesium, calcium, sodium, and potassium. In order to recover high-purity lithium from the brine, first, salts other than lithium must be removed as impurities, and at the same time, since the concentration of lithium in the brine is very low, it is difficult to separate solid and liquid, so the recovery rate of lithium is low.

Conventionally, brine has been pumped from a salt lake, stored in evaporation ponds, and then evaporated from the brine over a long period of time to concentrate lithium, precipitate impurities, and separate solids and liquids, or adsorb impurities using an ion exchange resin and then recover lithium compounds.

However, in this case, since a lot of energy and time are required for evaporation and concentration of the brine, productivity is reduced, and lithium is not only precipitated together with other impurities during the evaporation and concentration of the brine, but also lithium is coprecipitated together during the solid-liquid separation of the impurities, resulting in loss of lithium and a decrease in the recovery rate of lithium. In addition, since impurities are precipitated together when recovering the lithium compound, it is difficult to increase the purity of the lithium compound.

Various processes for producing lithium hydroxide from brine are known. These processes are mainly carried out in an electrolysis tank in which an anode chamber and a cathode chamber are partitioned by a predetermined ion exchange membrane. Here, brine and water are supplied to the anode chamber and the cathode chamber, respectively, and lithium ions produced in the anode chamber pass through the ion exchange membrane to move to the cathode chamber and react with hydroxide ions produced in the cathode chamber, thereby producing lithium hydroxide.

As a means of increasing the purity of lithium hydroxide, a method of providing a raw material (lithium salt solution) containing almost no impurities by treating brine, a method of treating a substance generated in a cathode chamber (containing lithium hydroxide) to control the amount of impurities within a predetermined range, and then crystallizing the same have been proposed. However, the economy, productivity, and maintainability are reduced due to processes (concentration, adsorption, purification, filtration, washing, precipitation, etc.), reagents, and equipment for treating brine and/or other substances. In addition, since high-purity raw materials are also diluted to a predetermined concentration and applied, the current density and thus electrolysis efficiency are reduced. In addition, there is a problem that lithium is lost together with impurities as treatment processes such as washing are repeated.

The present invention is intended to solve the problems of the prior art as described above, and an object of the present invention is to provide a lithium hydroxide manufacturing system capable of substantially omitting the processing steps of raw materials and/or intermediates, thereby increasing productivity and stably obtaining high-purity lithium hydroxide, and a method for manufacturing lithium hydroxide using the same.

One aspect of the present invention provides a system for producing lithium hydroxide, including: an electrolysis unit including an anode chamber and a cathode chamber partitioned by a diaphragm; and a crystallization unit for cooling a portion of a cathode product generated in the cathode chamber to generate solid lithium hydroxide.

In one embodiment, the temperature of the electrolysis unit may be 70 to 100°C.

In one embodiment, the temperature of the crystallization unit may be 60° C. or less.

In one embodiment, the cooling may be performed in stages.

In one embodiment, the lithium hydroxide manufacturing system may further include a first circulation unit for circulating the remainder of the cathode product from the crystallization unit to the cathode chamber.

In one embodiment, the lithium hydroxide production system may further include a supply unit that receives a lithium salt aqueous solution from the outside and provides a lithium-enriched stream to the anode chamber; and a second circulation unit that circulates at least a portion of the anode product produced in the anode chamber to the supply unit.

In one embodiment, the second circulation unit may further include a regeneration unit that adds acid to the circulated positive electrode product.

In one embodiment, the concentration of the acid may be 3 mol/L or more based on ClO ₃ ^- 1 mol/L.

In one embodiment, the lithium hydroxide manufacturing system may further include a third circulation unit that circulates some of the lithium hydroxide to at least one of the supply unit and the lithium salt aqueous solution.

In one embodiment, the crystallization unit may include a buffer tank that accommodates the cathode product, and a crystallization tank that cools a portion of the cathode product overflowing from the buffer tank to produce solid lithium hydroxide.

Another aspect of the present invention provides a method for producing lithium hydroxide using the lithium hydroxide production system, the method comprising the steps of: (a) supplying a lithium-rich stream to the anode chamber and supplying at least one of water and a lithium hydroxide-reduced stream to the cathode chamber; (b) applying current to the electrolysis unit to obtain a lithium-reduced stream from the anode chamber and a lithium hydroxide-enriched stream from the cathode chamber; (c) transferring the lithium hydroxide-rich stream to the crystallization unit; and (d) cooling the crystallization unit to crystallize a portion of the lithium hydroxide-rich stream to produce solid lithium hydroxide.

A lithium hydroxide manufacturing system according to one aspect of the present invention comprises: an electrolysis unit including an anode chamber and a cathode chamber partitioned by a membrane; and a crystallization unit cooling a portion of the cathode product generated in the cathode chamber to generate solid lithium hydroxide; thereby substantially omitting a process for processing raw materials and/or intermediates, thereby increasing productivity and stably obtaining high-purity lithium hydroxide.

It should be understood that the effects of the present invention are not limited to the effects described above, but include all effects that can be inferred from the composition of the invention described in the detailed description or claims of the present invention.

Figure 1 shows a system for manufacturing lithium hydroxide according to one embodiment of the present invention.
Figure 2 is a graph showing the solubility of lithium hydroxide according to temperature.
Figure 3 shows a system for manufacturing lithium hydroxide according to another embodiment of the present invention.
Figure 4 shows a system for manufacturing lithium hydroxide according to another embodiment of the present invention.
Figure 5 shows a system for manufacturing lithium hydroxide according to another embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention can be implemented in various different forms, and therefore is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are assigned similar drawing reference numerals throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another part in between. Also, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it can have other components, unless otherwise specifically stated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

Figure 1 shows a lithium hydroxide manufacturing system according to one embodiment of the present invention. Referring to Figure 1, a lithium hydroxide manufacturing system according to one embodiment of the present invention may include an electrolysis unit (10) including an anode chamber (12) and a cathode chamber (13) partitioned by a membrane (11); and a crystallization unit (20) that cools a portion of the cathode product generated in the cathode chamber (13) to generate solid lithium hydroxide.

The above electrolysis unit (10) may include an anode chamber (12) and a cathode chamber (13) partitioned by a diaphragm (11). The diaphragm (11) may be an ion exchange membrane, and preferably, may be a cation exchange membrane that selectively allows lithium ions (Li ⁺ ) to pass through. A commercially available one may be used as the cation exchange membrane, and its type is not particularly limited.

At the time when the operation of the electrolysis unit (10) is initiated, a lithium-enriched stream (LE), for example, a lithium salt aqueous solution such as lithium chloride (LiCl), lithium sulfate (Li ₂ SO ₄ ), or lithium carbonate (Li ₂ CO ₃ ) can be supplied to the anode chamber (12), and water (H ₂ O) as a raw material can be supplied to the cathode chamber (13).

When a predetermined current is applied to the electrolysis unit (10), a reaction as shown in Table 1 below may occur in the anode chamber (12) and the cathode chamber (13) depending on the type of lithium salt.

division anode cathode chamber lithium chloride LiCl → Li ⁺ + Cl ^- 2Cl ^- → Cl ₂ (g) + 2e ^- 2H ₂ O + 2e ^- → H ₂ (g) + 2OH ^-
2Li ⁺ + 2OH ^- →2LiOH(aq) lithium sulfate 2Li ₂ SO ₄ + 2H ₂ O → 2H ₂ SO ₄ + 4Li ⁺ + O ₂ (g) + 2e ^- 2H ₂ O + 2e ^- → H ₂ (g) + 2OH ^- 2Li ⁺ + 2OH ^- →2LiOH(aq) lithium carbonate 2Li ₂ CO ₃ → 4Li ⁺ + 2CO ₂ (g) + O ₂ (g) + 2e ^- 2H ₂ O + 2e ^- → H ₂ (g) + 2OH ^- 2Li ⁺ + 2OH ^- →2LiOH(aq)

The cathode product generated in the anode chamber (12) may include lithium ions, unreacted lithium salt, chlorine gas (or oxygen gas), and water. The lithium ions pass through the diaphragm (11) and move to the cathode chamber (13), and the unreacted lithium salt, together with water, may form a lithium-reduced stream (LR) to be described later and may be discharged to the outside of the anode chamber (12) or circulated to the supply unit (30) to be described later, and the chlorine gas (or oxygen gas) may also be discharged to the outside of the anode chamber (12) as a by-product gas.

The cathode product generated in the cathode chamber (13) may include lithium hydroxide, hydrogen gas, and water. Among the cathode products, the lithium hydroxide may be transported to the crystallization unit (20) together with water to form a lithium hydroxide-enriched stream (LHE) to be described later, and the hydrogen gas may be discharged to the outside of the cathode chamber (13) as a by-product gas.

The temperature of the electrolysis unit (10) for inducing this reaction may be 70 to 100°C, preferably 75 to 90°C, and more preferably 80 to 90°C. If the temperature of the electrolysis unit (10) is less than 70°C, the reaction efficiency may be reduced, and if it is more than 100°C, the reaction may be unstable or the energy efficiency may be reduced.

At least a portion of the above cathode product, preferably the lithium hydroxide-rich stream (LHE), can be transported to the crystallization unit (20), and the crystallization unit (20) can cool the lithium hydroxide-rich stream (LHE) to produce solid lithium hydroxide.

FIG. 2 is a graph showing the solubility of lithium hydroxide according to temperature in a lithium hydroxide aqueous solution. Referring to FIG. 2, the solubility of lithium hydroxide is about 14 g/100 g at the temperature of the electrolysis unit (10), for example, about 80°C, and decreases as the temperature is lowered, and may be about 12.3 g/100 g at about 60°C. Here, the solubility of lithium hydroxide does not decrease linearly in proportion to the temperature, and shows a tendency for the change in solubility to be somewhat slowed down at about 60°C or lower, preferably, at 20 to 60°C.

In the electrolysis unit (10), the temperature of the cathode product may be substantially the same as the temperature of the electrolysis unit (10), and most of the lithium hydroxide among the cathode products may exist in a dissolved state in an aqueous solution.

The above crystallization unit (20) can cool some of the above cathode products, specifically, the lithium hydroxide-rich stream (LHE), to a temperature of 60°C or lower, preferably, 20 to 60°C, more preferably, 20 to 30°C, to produce solid lithium hydroxide according to the solubility difference. If the temperature of the above crystallization unit (20) exceeds 60°C, the yield and purity of the solid lithium hydroxide may decrease.

Solid lithium hydroxide may be precipitated at the bottom of the crystallization unit (20), and a lithium hydroxide-reduced stream (LHR) and hydrogen gas, which is a by-product gas, may remain at the top of the crystallization unit (20) as an aqueous solution. When necessary, the lithium hydroxide-reduced stream (LHR) may be transported and circulated to the cathode chamber (13), and the hydrogen gas may be discharged to the outside of the crystallization unit (20) by an appropriate means.

The temperature of the lithium hydroxide-rich stream (LHE) introduced into the crystallization unit (20) may be substantially the same as the temperature of the electrolysis unit (10). If the lithium hydroxide-rich stream (LHE) is introduced into the crystallization unit (20) while the crystallization unit (20) is preheated to a temperature of 60° C. or lower, the temperature of the system may change rapidly, which may cause a chemical shock to the crystallization of lithium hydroxide, and in particular, the crystallization may become unstable, such as due to the mixing of a large amount of impurities into the crystallized lithium hydroxide. In response to this, the cooling of the crystallization unit (20) for the crystallization of lithium hydroxide may be performed in steps. For example, the cooling of the crystallization unit (20) may be performed by continuously and/or discontinuously controlling the temperature of the lithium hydroxide-rich stream (LHE) heated by the electrolysis unit (10) to 60° C. or lower.

The temperature of the electrolysis unit (10) and/or the crystallization unit (20) can be controlled and maintained by a predetermined heat exchange unit, and the heat exchange unit can be driven in various ways such as air cooling, water cooling, and electric cooling.

The above lithium hydroxide manufacturing system may further include a first circulation unit (R1) for circulating a lithium hydroxide-deficient stream (LHR) excluding the remainder of the cathode product, specifically, crystallized solid-phase lithium hydroxide among the cathode product, from the crystallization unit (20) to the cathode chamber (13). The lithium hydroxide-deficient stream (LHR) may include unreacted lithium ions, a trace amount of lithium hydroxide, impurities, and water. The first circulation unit (R1) circulates the lithium hydroxide-deficient stream (LHR) to the cathode chamber (13), and the lithium hydroxide included in the circulated lithium hydroxide-deficient stream (LHR) may participate in a reaction in the cathode chamber (13) again to contribute to increasing the concentration of lithium hydroxide in the lithium hydroxide-rich stream (LHE).

The above lithium hydroxide manufacturing system may further include a supply unit (30) that receives a lithium salt aqueous solution from outside the lithium hydroxide manufacturing system and provides a lithium-enriched stream (LE) to the anode chamber (12); and a second circulation unit (R2) that circulates at least a portion of the anode product produced in the anode chamber (12) to the supply unit (30).

The supply unit (30) can provide the lithium-rich stream (LE) to the anode chamber (12), and the lithium-rich stream (LE) can include a lithium salt aqueous solution provided from the outside to the supply unit (30). The second circulation unit (R2) can connect the anode chamber (12) and the supply unit (30) to circulate at least a portion of the anode product generated in the anode chamber (12), specifically, a lithium-deficient stream (LR), to the supply unit (30), and when the supply unit (30) and the second circulation unit (R2) are provided together, the lithium-rich stream (LE) can include a lithium salt aqueous solution provided from the outside to the supply unit (30) and the lithium-deficient stream (LR) circulated from the anode chamber (12).

The lithium-deficient stream (LR) may include unreacted lithium ions, chlorine ions (or sulfate ions), chlorine gas (or oxygen gas), and water that do not participate in the reaction in the anode chamber (12) and remain. The second circulation unit (R2) circulates the lithium-deficient stream (LR) to the anode chamber (12), and the unreacted lithium ions included in the circulated lithium-deficient stream (LR) participate in the reaction in the cathode chamber (13) again to provide a larger amount of lithium ions to the cathode chamber (13), thereby contributing to increasing the concentration of lithium hydroxide in the lithium hydroxide-rich stream (LHE).

FIG. 3 shows a manufacturing system of lithium hydroxide according to another embodiment of the present invention. Referring to FIG. 3, the second circulation unit (R2) may further include a regeneration unit (40) that adds acid to the circulated positive electrode product. The regeneration unit (40) may chemically treat the lithium-deficient stream (LR) discharged from the negative electrode chamber (13) and convert it into a lithium-regeneration stream (LR'). The lithium-regeneration stream (LR') means that the lithium-deficient stream (LR) is chemically treated by the regeneration unit (40) into a form suitable for circulation and reuse.

When the lithium salt included in the lithium-rich stream (LE) provided by the supply unit (30) is lithium chloride, the lithium-deficient stream (LR) may include chlorine compounds such as OCl ^- , HOCl, and ClO ₃ ^- , which are reaction by-products in the anode chamber (12), and in particular, since the ClO ₃ ^- component is not easily removed and accumulates, if this component circulates and joins the lithium-rich stream (LE), the reaction in the anode chamber (12) may be inhibited.

The above regeneration unit (40) can appropriately lower the concentration of the ClO 3 - component included in the lithium-deficient stream (LR) by adding an acid, preferably an aqueous acid solution containing the same anion as the lithium salt, more preferably an aqueous hydrochloric acid, sulfuric acid, and/or nitric acid solution, to _a portion of the circulated positive ^electrode product in the second circulation unit (R2).

The concentration of the above acid solution may be 3 mol/L or more, preferably 3 to 6 mol/L, based on ClO ₃ ^- 1 mol/L. If the concentration of the above acid solution is less than 3 mol/L based on ClO ₃ ^- 1 mol/L, it is difficult to lower the concentration of the ClO ₃ ^- component to a required range, for example, 50% or less of the initial concentration, preferably 75% or less, and if it exceeds 6 mol/L, the concentration of the ClO ₃ ^- component substantially converges to about 0 ppm, which may lower the economy and efficiency. When the regeneration unit (40) adds the hydrochloric acid solution to the lithium-deficient stream (LR), the content (concentration) of the ClO ₃ ^- component in the lithium-regeneration stream (LR') according to the concentration of the hydrochloric acid solution is as shown in Table 2 below. Referring to Table 2, the content (concentration) of the ClO ₃ ^- component in the lithium-regeneration stream (LR') may be 5,000 ppm or less, preferably 1,000 ppm or less, more preferably 10 ppm or less.

HCl concentration
(M, mol/L) ClO ₃ ^-
(ppm) Available chlorine
(ppm) pH note 0 12,659 2,500 4.8 - 1 10,019 78 2.1 - 3 3,429 41 0.4 ClO ₃ ^- 75% reduction 6 0 8 -2 ClO ₃ ^- 100% reduction

Figure 4 shows a lithium hydroxide manufacturing system according to another embodiment of the present invention. Referring to Figure 4, the lithium hydroxide manufacturing system may further include a third circulation unit (R3) for circulating some of the lithium hydroxide to the supply unit (30). The lithium hydroxide circulated to the supply unit (30) by the third circulation unit (R3) may be some of the solid lithium hydroxide produced in the crystallization unit (20) and/or may be derived from some of the supernatant remaining in the upper portion of the crystallization unit (20).

In the above supply unit (30), the lithium-rich stream (LE) containing the lithium salt solution provided from the outside can be stored, and in some cases, the lithium-deficient stream (LR) circulated from the anode chamber (12) can be stored mixed therein.

The lithium-rich stream (LE) and the lithium-deficient stream (LR) residing in the supply unit (30) contain various salts such as lithium, magnesium (Mg), calcium (Ca), sodium (Na), and potassium (K) as impurities. Since these impurities can inhibit the reaction in the electrolysis unit (10), it is necessary to lower the concentration and substantially remove them in the supply unit (30). In general, lithium hydroxide can act as a coagulant that coagulates and removes the impurities among the substances remaining in the supply unit (30), but if such a coagulant is separately obtained and applied from outside the lithium hydroxide manufacturing system, it may be disadvantageous in terms of economic efficiency. Therefore, the third circulation unit (R3) circulates some of the lithium hydroxide into the lithium salt aqueous solution provided from the supply unit (30) and/or the outside to the supply unit (30) to appropriately coagulate the impurities remaining in the supply unit (30), and, if necessary, provides a means for filtering and removing the coagulated impurities, thereby ensuring economic efficiency and at the same time increasing the purity of the lithium-rich stream (LE) provided to the anode chamber (12) and the reaction efficiency in the electrolysis unit (10) accordingly.

Figure 5 shows a system for manufacturing lithium hydroxide according to another embodiment of the present invention. Referring to Figure 5, the crystallization unit (20) may include a buffer tank (21) that accommodates the cathode product, and a crystallization tank (22) that cools a portion of the cathode product overflowing from the buffer tank (21) to produce solid lithium hydroxide.

The lithium hydroxide-rich stream (LHE) discharged from the cathode chamber (13) is transferred to the buffer tank (21), and the lithium hydroxide-rich stream (LHE) overflowing from the buffer tank (21) can be transferred to the crystallization tank (22). The lithium hydroxide-deficient stream (LHR), excluding the solid lithium hydroxide crystallized in the crystallization tank (22), can be circulated to the cathode chamber (13) through the first circulation section (R1) via the buffer tank (21), and/or can be circulated directly to the cathode chamber (13) without passing through the buffer tank (21).

The temperature of the buffer tank (21) may be controlled to be equal to or lower than the temperature of the electrolysis unit (10), preferably, within a range equal to or lower than the temperature of the electrolysis unit (10) and higher than the temperature of the crystallization tank (22). For example, when the temperature of the electrolysis unit (10) is 80°C and the temperature of the crystallization tank (22) is 60°C, the temperature of the buffer tank (21) may be controlled to be 60 to 80°C, preferably, 70 to 80°C, and more preferably, 80°C, which is the same as the temperature of the electrolysis unit (10), to prevent lithium hydroxide from being randomly crystallized in the buffer tank (21). The control of the crystallization tank (22), the resulting operational effects, etc., are the same as those described above with respect to the crystallization unit (20). If necessary, the buffer tank (21) and the crystallization tank (22) may each include two or more unit vessels connected in series and/or in parallel.

Meanwhile, the lithium hydroxide-deficient stream (LHR) excluding the solid lithium hydroxide crystallized in the crystallization tank (22) is circulated to the cathode chamber (13) through the buffer tank (21) and the first circulation unit (R1), and since the temperatures of the crystallization tank (22) and the electrolysis unit (10) are, for example, 60°C and 80°C, respectively, it is necessary to appropriately increase the temperature of the lithium hydroxide-deficient stream (LHR) circulated to the cathode chamber (13) through the buffer tank (21) from the crystallization tank (22) and the first circulation unit (R1) to the temperature of the electrolysis unit in order to buffer the chemical shock. In this regard, the lithium hydroxide manufacturing system may further include a heat exchanger (not shown), preferably a water-cooled heat exchanger, for increasing the temperature of the lithium hydroxide-deficient stream (LHR) circulated to the cathode chamber (13) through the first circulation unit (R1) using at least one of the lithium-deficient stream (LR) and the lithium hydroxide-rich stream (LHE) in the anode chamber (12) and the cathode chamber (13) of the electrolysis unit (10). Since the heat exchanger can increase the temperature of the lithium hydroxide-deficient stream (LHR) using a predetermined stream generated along a part of the lithium hydroxide manufacturing system without using a separate heat source, energy, etc., it can contribute to improving energy efficiency and economic feasibility.

Another aspect of the present invention is a method for manufacturing lithium hydroxide using the lithium hydroxide manufacturing system, comprising: (a) a step of supplying a lithium-rich stream (LE) to the anode chamber (12) and supplying at least one of water and a lithium hydroxide-reduced stream to the cathode chamber (13); (b) a step of applying current to the electrolysis unit (10) to obtain a lithium-reduced stream (LR) from the anode chamber (12) and a lithium hydroxide-enriched stream (LHE) from the cathode chamber (13); (c) a step of transporting the lithium hydroxide-enriched stream (LHE) to the crystallization unit (20); and (d) a step of cooling the crystallization unit (20) to crystallize a portion of the lithium hydroxide-rich stream (LHE) to produce solid lithium hydroxide.

In the step (a), a lithium-rich stream (LE) may be supplied to the anode chamber (12), and at least one of water and a lithium hydroxide-reduced stream may be supplied to the cathode chamber (13). The lithium-rich stream (LE) may include a lithium salt aqueous solution, and the lithium salt may include, but is not limited to, lithium chloride, lithium sulfate, lithium carbonate, etc.

In the step (b) above, by applying current to the electrolysis unit (10), a lithium-reduced stream (LR) can be obtained from the anode chamber (12), and a lithium hydroxide-enriched stream (LHE) can be obtained from the cathode chamber (13). When current is applied to the electrolysis unit (10), a reaction as shown in Table 1 above can occur in the anode chamber (12) and the cathode chamber (13).

The lithium-deficient stream (LR) above is a material stream remaining after electrolysis of the lithium-rich stream (LE), specifically, a material stream excluding lithium ions generated in the anode chamber (12) that have passed through the membrane (11) and moved to the cathode chamber (13), and may include unreacted lithium ions, chlorine gas (or oxygen gas), chlorine ions (or sulfate ions), and water.

The lithium hydroxide-rich stream (LHE) generated in the cathode chamber (13) may include lithium hydroxide generated by the reaction of lithium ions and hydroxide ions moving from the anode chamber (12), and the lithium hydroxide may exist in a dissolved state in the lithium hydroxide-rich stream (LHE).

The temperature of the electrolysis unit (10) may be 70 to 100°C, preferably 75 to 90°C, and more preferably 80 to 90°C. If the temperature of the electrolysis unit (10) is less than 70°C, the reaction efficiency may be reduced, and if it is more than 100°C, the reaction may be unstable or the energy efficiency may be reduced.

In the step (c) above, the lithium hydroxide-rich stream (LHE) is transferred to the crystallization unit (20), and in the step (d) above, the crystallization unit (20) is cooled to crystallize a portion of the lithium hydroxide-rich stream (LHE) to produce solid lithium hydroxide having an impurity concentration of 0.1 g/L or less. The transfer, circulation, and cooling of the crystallization unit (20) of the lithium-deficient stream (LR) are as described above, and the results of analyzing the components of the solid lithium hydroxide obtained by controlling the temperatures of the electrolysis unit (10) and the crystallization unit (20) to 80°C and 60°C, respectively, are shown in Table 3 below.

division Lithium (Li) Sodium (Na) Potassium (K) Concentration (g/L) 25.46 - 0.07

In addition, since the above method for manufacturing lithium hydroxide is characterized by using the above lithium hydroxide manufacturing system, the transport, circulation, reaction, and control of each variable of the materials constituting the above lithium hydroxide manufacturing method are the same as those described above with respect to the lithium hydroxide manufacturing system.

The above description of the present invention is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential characteristics of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single component may be implemented in a distributed manner, and likewise, components described as distributed may be implemented in a combined manner.

The scope of the present invention is indicated by the claims set forth below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

10: Electrolysis section 11: Diaphragm
12: Anode chamber 13: Cathode chamber
20: Crystallization section 21: Buffer section
22: Crystallization tank 30: Supply section
40: Regeneration section R1: 1st circulation section
R2: Second circulation R3: Third circulation
LE: Lithium-rich stream LR: Lithium-deficient stream
LR': Lithium-regeneration stream LHE: Lithium hydroxide-rich stream
LHR: Lithium hydroxide-deficient stream

Claims (11)

An electrolysis unit including an anode chamber and a cathode chamber separated by a diaphragm; and
A lithium hydroxide manufacturing system including a crystallization unit that cools a portion of the cathode product generated in the cathode chamber to generate solid lithium hydroxide. In the first paragraph,
A lithium hydroxide manufacturing system in which the temperature of the above electrolysis unit is 70 to 100°C. In the first paragraph,
A lithium hydroxide manufacturing system wherein the temperature of the crystallization section is 60°C or less. In the first paragraph,
A lithium hydroxide manufacturing system in which the above cooling is performed in stages. In the first paragraph,
A lithium hydroxide manufacturing system further comprising a first circulation section for circulating the remainder of the cathode product from the crystallization section to the cathode chamber. In the first paragraph,
A supply unit that receives a lithium salt solution from the outside and provides a lithium-enriched stream to the anode chamber; and
A lithium hydroxide manufacturing system further comprising a second circulation unit for circulating at least a portion of the anode product generated in the anode chamber to the supply unit. In Article 6,
A lithium hydroxide manufacturing system, wherein the second circulation section further includes a regeneration section that adds acid to the circulated positive electrode product. In Article 7,
A lithium hydroxide manufacturing system having a concentration of the above acid of 3 mol/L or more based on ClO ₃ ^- 1 mol/L. In Article 6,
A system for producing lithium hydroxide further comprising a third circulation section for circulating some of the lithium hydroxide to at least one of the supply section and the lithium salt aqueous solution. In the first paragraph,
The above crystallization unit,
A lithium hydroxide manufacturing system comprising a buffer tank for accommodating the above cathode product, and a crystallization tank for cooling a portion of the above cathode product overflowing from the buffer tank to produce solid lithium hydroxide. In a method for manufacturing lithium hydroxide using a lithium hydroxide manufacturing system according to any one of claims 1 to 10,
(a) supplying a lithium-rich stream to the anode chamber and supplying at least one of water and a lithium hydroxide-reduced stream to the cathode chamber;
(b) a step of applying current to the electrolysis unit to obtain a lithium-reduced stream from the anode chamber and a lithium hydroxide-enriched stream from the cathode chamber;
(c) transporting the lithium hydroxide-rich stream to the crystallization unit; and
(d) a step of cooling the crystallization unit to crystallize a portion of the lithium hydroxide-rich stream to produce solid lithium hydroxide; A method for producing lithium hydroxide, comprising: