Process for producing lithium hydroxide monohydrate
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-08-06
- Publication Date
- 2026-08-14
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Figure 2026527660000001_ABST
Abstract
Description
Technical Field
[0001] The present invention is directed to a process for producing lithium hydroxide monohydrate from lithium chloride, particularly a process for producing battery-grade lithium hydroxide monohydrate.
Background Art
[0002] The commercial production of lithium hydroxide monohydrate from lithium chloride typically involves the electrolysis of lithium chloride or the conversion of lithium chloride to lithium carbonate by reaction with sodium carbonate. These processes are expensive and inefficient. For example, the production of lithium hydroxide monohydrate from the electrolysis of lithium chloride uses a very large amount of electricity (which is very inefficient compared to chlor-alkali electrolysis), while the production of lithium carbonate requires expensive reagents and produces a relatively impure lithium hydroxide monohydrate product. <(
[0003] Therefore, there is a need for a less expensive and more efficient process for preparing lithium hydroxide monohydrate from lithium chloride.
[0004] For this purpose, several publications have been issued regarding the production of lithium hydroxide monohydrate by reacting lithium chloride with a hydroxide source.
[0005] WO2022 / 147632A1 describes, for example, the direct production of lithium hydroxide monohydrate from lithium chloride using sodium hydroxide. The process involves adding a first sodium hydroxide-containing solution to a lithium chloride-containing brine at a temperature of 80°C to 120°C to form a mixture containing lithium hydroxide and sodium chloride. This mixture is cooled to a temperature of 20°C to 60°C (typically 35°C), and the lithium hydroxide monohydrate is said to be selectively separated by a fractional cooling crystallization step at a NaOH concentration of 0.1 to 10.5 wt%. The mother liquor is then mixed with a second sodium hydroxide-containing solution before undergoing preparative evaporation crystallization at a temperature of 80°C to 120°C (typically 100°C) to selectively separate the sodium chloride ready for disposal.
[0006] Similarly, WO2023 / 012512A1 discloses reacting a lithium chloride solution with a potassium hydroxide solution to form a reciprocal salt system containing potassium hydroxide, lithium chloride, potassium chloride, lithium hydroxide, and water, and then precipitating potassium chloride and lithium hydroxide from the reciprocal salt system to form lithium hydroxide crystals and potassium chloride crystals. In Example 1, the reciprocal salt system is cooled to selectively precipitate potassium chloride (temperatures down to -10°C are exemplified), heated (temperatures up to 96°C), and the water is evaporated to selectively precipitate lithium hydroxide.
[0007] However, the manufacturing methods described in WO2022 / 147632A1 and WO2023 / 012512A1 are not optimized with respect to process efficiency and lithium hydroxide monohydrate purity. For example, WO2022 / 147632A1 requires periodic purging of the mother liquor to reduce impurity accumulation and remove sodium chloride. Furthermore, the highest purity lithium hydroxide monohydrate obtained after washing is 95.5%. Similarly, WO2023 / 012512A1 describes large temperature fluctuations between heating and cooling to adequately precipitate potassium chloride and lithium hydroxide, suggesting that a large amount of energy is required. Working at low temperatures of -10°C is also very costly.
[0008] Therefore, there is a need for a process to address these issues. [Overview of the project]
[0009] This disclosure relates to a process for producing lithium hydroxide monohydrate from lithium chloride, and this process is a) Adding a sodium hydroxide-containing aqueous solution to a first lithium chloride-containing aqueous solution to obtain a mixture containing lithium hydroxide, sodium chloride, and water, b) The mixture obtained in a) is cooled to selectively precipitate lithium hydroxide monohydrate, thereby obtaining a lithium hydroxide monohydrate precipitate and a first mother liquor solution. c) Separating the lithium hydroxide monohydrate precipitate from the first mother liquor solution, d) Adding a second lithium chloride-containing aqueous solution to the separated first mother liquor solution to obtain a first mother liquor solution concentrated with lithium chloride, e) The method comprises removing water, preferably by evaporation, from the lithium chloride concentrated first mother liquor solution to selectively precipitate sodium chloride, thereby obtaining a sodium chloride precipitate and a second mother liquor solution.
[0010] Advantageously, it has been found that by adding sodium hydroxide to the process before lithium hydroxide monohydrate precipitation, and by adding lithium chloride to the process before sodium chloride precipitation, the process of the present invention has the effect of selectively precipitating lithium hydroxide monohydrate and sodium chloride with high purity at different points in the process. Temperature changes are also used to further optimize the selectivity of precipitation. This finding is surprising considering WO2022 / 147632A1, which states that the presence of excess sodium hydroxide affects the solubility of lithium hydroxide monohydrate and sodium chloride, and as a result they can be selectively precipitated.
[0011] By optimizing the difference in solubility between sodium chloride and lithium hydroxide monohydrate, the process of the present invention can also achieve a high (substantially complete) conversion of lithium chloride to lithium hydroxide monohydrate. This improves both process efficiency and water balance.
[0012] Therefore, as shown in the following examples, the process of the present disclosure has the following key advantages over WO2022 / 147632A1. • Increase in the amount of lithium hydroxide monohydrate formed on the total mass, • Energy costs are reduced because less water needs to be removed (e.g., evaporated) to produce the same amount of lithium hydroxide monohydrate. • Fewer flows, and therefore smaller containers, can enable similar production capacity, which means reduced operating costs and reduced capital investment, and • Purification of lithium hydroxide monohydrate obtained after washing. [Brief explanation of the drawing]
[0013] [Figure 1] Figure 1 is a flowchart illustrating a preferred embodiment of the present disclosure. [Modes for carrying out the invention]
[0014] Various aspects of the present invention will be further explained below.
[0015] As described above, in the first aspect, the present invention provides a process for producing lithium hydroxide monohydrate from lithium chloride, the process is a) Adding a sodium hydroxide-containing aqueous solution to a first lithium chloride-containing aqueous solution to obtain a mixture containing lithium hydroxide, sodium chloride, and water, b) The mixture obtained in a) is cooled to selectively precipitate lithium hydroxide monohydrate, thereby obtaining a lithium hydroxide monohydrate precipitate and a first mother liquor solution. c) Separating the lithium hydroxide monohydrate precipitate from the first mother liquor solution, d) Adding a second lithium chloride-containing aqueous solution to the separated first mother liquor solution to obtain a first mother liquor solution concentrated with lithium chloride, e) The method comprises removing water, preferably by evaporation, from the lithium chloride concentrated first mother liquor solution to selectively precipitate sodium chloride, thereby obtaining a sodium chloride precipitate and a second mother liquor solution.
[0016] As used in this disclosure, the term "high purity" refers to a level exceeding 98%, for example, exceeding 99%.
[0017] a) In this step, sodium hydroxide is added to lithium chloride to form lithium hydroxide and sodium chloride. The addition is preferably carried out at a temperature in the range of 10°C to 100°C, preferably 20°C to 95°C, and most preferably 25°C to 90°C. The first aqueous solution containing lithium chloride is preferably at or above this temperature range before the aqueous solution containing sodium hydroxide is added. The molar ratio of sodium hydroxide to lithium chloride added as an aqueous solution to the lithium chloride-containing solution is preferably in the range of 0.1:1 to 1.5:1, more preferably 0.3:1 to 0.9:1.
[0018] The sodium hydroxide-containing aqueous solution typically has a sodium hydroxide concentration of 10-50% by weight, preferably 15-40% by weight, and more preferably 20-35% by weight, based on the total weight of the sodium hydroxide-containing aqueous solution. In a preferred embodiment, at least a portion, and preferably all, or substantially all, of the sodium hydroxide-containing aqueous solution is obtained by electrolysis of the sodium chloride precipitate of e).
[0019] The first aqueous lithium chloride solution typically has a lithium concentration of 1.0 to 9.0% by weight, preferably 2.0 to 8.0% by weight, more preferably 2.5 to 7.5% by weight, based on the total weight of the first aqueous lithium chloride solution. In a preferred embodiment, at least a portion, and preferably all or substantially all, of the first aqueous lithium chloride solution is provided by a separated second mother liquor solution (see consideration (f) below). When the first aqueous lithium chloride solution is provided by a separated second mother liquor solution, the first aqueous lithium chloride solution preferably has a lithium concentration of 2.5 to 6.0% by weight, preferably 2.5 to 4.0% by weight, more preferably 2.8 to 3.4% by weight, based on the total weight of the first aqueous lithium chloride solution.
[0020] The mixture obtained in a) preferably has a molar ratio of lithium ions (Li + ) to hydroxyl ions (OH - ) of 0.7:1 to 2.0:1, preferably 0.9:1 to 1.7:1, preferably 0.95:1 to 1.5:1, more preferably 1 or 1.05:1 to 1.4:1.
[0021] In b), the mixture obtained in a) is cooled to a temperature of 5 to 50 °C, preferably 10 to 45 °C, more preferably 20 to 45 °C, to selectively precipitate lithium hydroxide monohydrate. The cooling can be achieved by any cooling method known in the art, such as using a coolant (e.g., water) within the double wall of a jacketed reactor or passing the contents of the reactor through a heat exchanger.
[0022] Adding in a) and precipitating in b) can be carried out sequentially or simultaneously. Similarly, adding in a) and precipitating in b) can be carried out in a single device, such as a crystallization reactor, or in separate devices, such as a reactor and a crystallizer. Preferably, an aqueous sodium hydroxide solution and the first aqueous lithium chloride solution are added to a reactor controlled at a specific temperature, then the reactor contents are maintained at that temperature for a specific mixing time, and the precipitated solid is separated.
[0023] The lithium hydroxide monohydrate precipitate obtained in b) can be separated from the first mother liquor solution in c) by typical solid-liquid separation techniques such as filtration, sedimentation, and / or centrifugation. Preferably, the separated lithium hydroxide monohydrate precipitate has a purity of at least 96%, preferably at least 97%, more preferably at least 98%, and most preferably at least 99% after washing. The washing step may consist of washing the precipitate with water saturated with lithium hydroxide on any solid / liquid separation device such as a filter or centrifuge. Alternatively, any other liquid having a higher solubility in sodium chloride than lithium hydroxide monohydrate can be used.
[0024] After the aforementioned washing step (which may be performed multiple times), a subsequent recrystallization step can be used, as is known in the art. In this step, lithium hydroxide can be redissolved in water, recrystallized, for example by evaporation of water, and then cooled. This may further increase the purity of the final lithium hydroxide.
[0025] d) A second lithium chloride-containing aqueous solution is added to the separated first mother liquor solution. The second lithium chloride-containing aqueous solution can be obtained from naturally occurring saline solutions such as warm brine, or from minerals containing rocks such as spodumene.
[0026] The second lithium chloride-containing aqueous solution typically has a lithium chloride concentration of 10-55% by weight, preferably 20-50% by weight, and more preferably 30-45% by weight, based on the total weight of the second lithium chloride-containing aqueous solution.
[0027] It is preferable to add equimolar amounts of lithium chloride and sodium hydroxide to the process using a second aqueous solution containing lithium chloride and sodium hydroxide, respectively. This is particularly advantageous when the process is continuous (or circular), as will be discussed below.
[0028] Preferably, the lithium chloride concentrated first mother liquor solution obtained in d) contains lithium ions (Li) in a ratio of 0.9:1 to 3.5:1, more preferably 0.95:1 to 2.5:1, and most preferably 1.0:1 to 2.0:1. + ) vs. hydroxyl ion (OH - It has the molar ratio of ).
[0029] e) Water is removed from the lithium chloride-concentrated first mother liquor solution, preferably by evaporation, to selectively precipitate sodium chloride. If water is removed by evaporation, evaporation may be caused by heating the first mother liquor solution and / or the lithium chloride-concentrated first mother liquor solution to a temperature of 50-120°C, preferably 60-95°C, more preferably 75-90°C. If necessary, evaporation may be carried out under vacuum to lower the evaporation temperature. The vacuum pressure is controlled by the cooling water temperature and is preferably 40-500 mbar.
[0030] The addition in d) and the removal in e) (e.g., evaporation) may be carried out sequentially or simultaneously. Similarly, the addition in d) and the removal in e) (e.g., evaporation) may be carried out in a single device, e.g., a crystallization reactor, or in separate devices, e.g., a reactor and a crystallizer. A multi-effect evaporator (MEE) or a mechanical vapor recompression (MVR) crystallizer is preferably used for evaporation and crystallization.
[0031] Preferably, the process of the present invention is f) Further comprising separating the sodium chloride precipitate from the second mother liquor solution to obtain the first lithium chloride-containing aqueous solution.
[0032] In step f), the sodium chloride precipitate obtained in step e) may be separated from the second mother liquor solution in particulate form or in solution. This is typically done using solid-liquid separation techniques such as filtration, sedimentation, and / or centrifugation. Preferably, the filtered solid is sent to an electrolyzer as a sodium-rich slurry. Preferably, the separated sodium chloride precipitate has a purity of at least 80%, more preferably at least 90%, and most preferably at least 95% after washing. The washing step may include washing with water saturated with sodium chloride.
[0033] The second mother liquor solution, once separated, can provide at least a portion, preferably all, or substantially all, of the first lithium chloride-containing aqueous solution to a). Thus, the inclusion of f) makes the process of the present invention a closed loop, and therefore eliminates the need to purge or discard a particular product stream.
[0034] Preferably, the process of the present invention is g) Further comprising electrolyzing the sodium chloride precipitate to obtain the sodium hydroxide-containing aqueous solution.
[0035] The electrolysis in g) offers the advantage of recycling the sodium chloride precipitate into the process as a sodium hydroxide-containing aqueous solution. This eliminates the need to discard the sodium chloride. The inclusion of the electrolysis loop also reduces the amount of water that needs to be removed (e.g., by evaporation) in e), thus improving the water balance of the process. The chlorine and hydrogen produced in the electrolysis process can then react to form hydrochloric acid.
[0036] The electrolysis in g) also means that a higher concentration of lithium in the sodium chloride precipitate is acceptable. This is because all the precipitate is recycled back into the process in the sodium hydroxide-containing aqueous solution. That is, the co-precipitated lithium is not lost, for example, by the disposal of the sodium chloride precipitate. This also provides the possibility of controlling the process so that a reduced amount of separation energy is required compared to when the sodium chloride needs to be of high purity, such as when it is to be disposed of or sold as a product. Thus, the sodium chloride slurry electrolyzed in g) may have a total concentration of lithium hydroxide and lithium chloride of 0 to 20% by weight, preferably 0 to 15% by weight, more preferably 0 to 10% by weight, and most preferably 0 to 6% by weight, based on the total weight of the sodium chloride precipitate.
[0037] The electrolysis in g) is preferably carried out using optimized membrane-based chlor-alkali electrolysis. Chloro-alkali electrolysis is well known in the art and is described, for example, in T. F O'Brien et al, The Handbook of Chlor-Alkali Technology, DOI https: / / doi.org / 10.1007 / b113786, eBook ISBN 978-0-306-48624-1, Published: December 31, 2008. The process involves supplying a solution of sodium chloride to an electrolyzer, in which case the sodium chloride is converted to sodium hydroxide, chlorine, and hydrogen. The advantage of using such standard chlor-alkali processes is that the current efficiency of these processes is higher than that of electrolysis of lithium-containing solutions, making it a more efficient process step.
[0038] Therefore, as described above and as shown in Figure 1, the process for producing lithium hydroxide monohydrate from lithium chloride according to the present invention is a) Adding a sodium hydroxide-containing aqueous solution to a first lithium chloride-containing aqueous solution to obtain a mixture containing lithium hydroxide, sodium chloride, and water, b) The mixture obtained in a) is cooled to selectively precipitate lithium hydroxide monohydrate, thereby obtaining a lithium hydroxide monohydrate precipitate and a first mother liquor solution. c) Separating the lithium hydroxide monohydrate precipitate from the first mother liquor solution, d) Adding a second lithium chloride-containing aqueous solution to the separated first mother liquor solution to obtain a first mother liquor solution concentrated with lithium chloride, e) Remove water from the lithium chloride concentrated first mother liquor solution, preferably by evaporation, to selectively precipitate sodium chloride, thereby obtaining a sodium chloride precipitate and a second mother liquor solution. f) Separating the sodium chloride precipitate from the second mother liquor solution to obtain the first lithium chloride-containing aqueous solution, g) The sodium chloride precipitate may be electrolyzed to obtain the sodium hydroxide-containing aqueous solution.
[0039] A preferred embodiment of this process is schematically illustrated in Figure 1. Note: LiCl (aqueous solution) 1 This is the first lithium chloride-containing aqueous solution, LiCl(aqueous solution) 2is a second aqueous solution containing lithium chloride, H2O(g) is evaporated water, NaCl(s) is sodium chloride precipitate, LHM is lithium hydroxide monohydrate precipitate, NaOH(aqueous solution) is an aqueous solution containing sodium hydroxide, A and B are crystallization reactors, and C is a chlorine-alkali electrolytic cell. In the process, the aqueous solution containing sodium hydroxide is added to the first aqueous solution containing lithium chloride via 2, and the mixture is supplied to crystallization reactor A via 1. Here, the mixture is cooled to selectively precipitate lithium hydroxide monohydrate, which is separated via 3. The separated first mother liquor solution remains in crystallization reactor A via 4. The second aqueous solution containing lithium chloride is added to the separated first mother liquor solution via 5, and the lithium chloride-concentrated first mother liquor solution is supplied to crystallization reactor B. In crystallization reactor B, the lithium chloride-concentrated first mother liquor solution is heated, and water is evaporated via 6 to selectively precipitate sodium chloride. The sodium chloride precipitate is separated from crystallization reactor B via 7.
[0040] Furthermore, optional recycling steps in the process are indicated by dashed lines 8, 9, and 10. Here, line 8 represents the return of at least a portion, preferably all, or substantially all of the second mother liquor solution obtained from crystallization reactor B, and the first lithium chloride-containing aqueous solution LiCl(aqueous solution) 1 This is to provide the following. Line 9 is the recycling of at least a portion, preferably all, or substantially all of the sodium chloride precipitate obtained from crystallization reactor B to alkali chloride electrolyzer C. Line 10 is the return of at least a portion of the electrolyzed sodium chloride precipitate, which is to provide an aqueous sodium hydroxide solution NaOH (aqueous solution). Thus, the circular process, via 3 and 12, produces only lithium hydroxide monohydrate, chlorine, and hydrogen as products.
[0041] The process of the present invention can be carried out sequentially or in batches.
[0042] The lithium hydroxide monohydrate produced by this process can be used in lithium-ion batteries. It can also be converted to lithium carbonate by means known in the art, such as reaction with carbon dioxide.
[0043] It should be noted that the various elements of the present invention include, but are not limited to, a preferred range of various parameters, and can be combined as long as they are not mutually exclusive.
[0044] The present invention is not limited to, or may be illustrated by, the following embodiments. [Examples]
[0045] In the following experiment, - To simulate the circular process shown in Figure 1, the concentrations of recycled LiCl, LiOH, NaOH, and NaCl in the first and second mother liquors were estimated, and the corresponding solutions were prepared as the starting mixtures for each experiment. - Chloride analysis (and recalculation to %NaCl) was performed using a Metrohm Titrino plus instrument by silver titration with 0.1 M AgNO3. - Sodium analysis was performed by inductively coupled plasma (ICP) spectroscopy. - Drying was performed in an infrared moisture analyzer (Sartorius MA35) at 105-110°C. - The obtained lithium hydroxide monohydrate sample was washed in batches three times on a glass filter with a saturated solution of lithium hydroxide in desalinated water. - The XRD procedure was as follows: The sample was placed in a standard sample holder, and the diffraction pattern was recorded using a BrukerAXS D8 reflectance diffractometer with Cu-Kα emission. The generator settings were 40kV, 40mA. A Soller slit with fixed sample irradiation of 2.5° and 15mm was used. A scattering prevention knife was employed. Measurement range: 2θ = 5~70.0°, measurement time with Lynxeye_XE_T (1D mode) detector was 0.25 seconds / step.
[0046] Example 1 (Comparison): Efficiency of the process described in WO2022 / 147632A1
[0047] WO2022 / 147632A1 describes adding a lithium chloride solution to the return mother liquor (ML-2), then cooling the mixture to 35°C to yield a lithium hydroxide monohydrate (LHM) precipitate. Subsequently, the filtrate (mother liquor 1, ML-1) is mixed with a sodium hydroxide (NaOH) solution, and then the water is evaporated at 100°C to yield a sodium chloride (NaCl) precipitate. The filtrate is returned as ML-2 and mixed again with lithium chloride.
[0048] WO2022 / 147632A1 does not specify the amount of LHM to precipitate or the amount of water that must evaporate to produce NaCl. Therefore, to determine the efficiency of this process, these parameters were determined by defining the mass balance equation of the process using the reported composition, and then calculating the necessary parameters until the calculated composition matched the measured composition.
[0049] The amounts of LHM and NaCl precipitates were calculated based on the following rules. 1) Lithium added as lithium chloride reacts with LHM via a reaction. LiCl + NaOH → LiOH + NaCl LiOH + H2O → LHM 2) The composition and mass flow after the entire cycle must match the starting point to ensure a closed, steady-state process. 3) The molar amount of added LiCl is equal to the molar amount of added NaOH, because otherwise either LiCl or NaOH would begin to accumulate. [Note that this assumption can be relaxed by substantial purging.]
[0050] Based on these rules, a set of formulas describing the mass balance of the process was defined, including the number of variables calculated from the results and the number of variables remaining as "fit" parameters. These fit parameters were varied using a computational global optimization routine until the compositions of various flows precisely matched the reported compositions. It was found that only one unique solution described the experimental data. The calculated compositions of ML-1 and ML-2 were matched with the measured compositions from sample-4 (described in WO2022 / 147632A1, and expected to be the most stable as they had progressed the most over time), and the results shown in Table 1 were obtained.
[0051] [Table 1]
[0052] Based on the calculated amount of precipitated LHM and the amount of evaporated water, the following efficiencies were determined for the WO2022 / 147632A1 process. 1) The LHM precipitate is approximately 1.75% by weight of the total mass that enters the LHM crystallizer. 2) Approximately 152 g of LHM was generated per 1 kg of evaporated water.
[0053] Example 2: Production of lithium hydroxide monohydrate using this process
[0054] This experiment was conducted in a jacketed reactor (Radleys Reactor-Ready, 1 liter) that included an internal filter, allowing for filtration at reactor temperature.
[0055] To mimic the first mother liquor solution separated in this process, a mixture containing lithium hydroxide, sodium chloride, and water was prepared by dissolving 49.8 g of LiOH and 144.9 g of NaCl in 610.2 g of H2O to obtain a clear solution. To this solution, 196.7 g of a 40 wt% LiCl solution in H2O was added at 80°C to obtain a concentrated lithium chloride mixture. This represents flows 4 and 5 entering B, as shown in Figure 1.
[0056] Upon mixing the two solutions, immediate precipitation of the solid material was visually detected. The mixture was stirred at 80°C for 3 hours, and after evaporating the water by applying a vacuum of approximately 450 millibars, the mixture was filtered. A total of 45 g of wet solid and 815.8 g of clear filtrate solution were obtained, while 138 g of water was removed from the mixture by evaporation. Determination of chloride by AgNO3 titration (and taking into account the presence of chloride as LiCl in the adsorbent solution) showed that the unwashed wet filtrate cake contained 90.0% NaCl. After infrared drying, this was measured again via titration and determined to be 97.5%.
[0057] Of the filtrate, 770.3 grams were added to a cleaned jacketed reactor and maintained at 40°C. To this, 251.1 g of a 24% NaOH solution (prepared and maintained at room temperature) was added while stirring. This corresponds to flows 8, 1, and 2 entering A, as shown in Figure 1.
[0058] The mixture was mixed at 40°C for 1 hour, and then the solution was filtered. 39 g of a wet solid was obtained. The water content, determined by infrared drying at 105°C, was found to be 48.5% (including crystal water present in the LHM), and the NaCl content, determined by AgNO3 titration, was found to be 4.6%. From this, the mass of LHM in the solid was calculated to be 32.04 g. Subsequently, the sample was washed three times with water saturated with LiOH, and then infrared dried at 105°C to remove all water, including crystal water. The NaCl content was measured and calculated to be 0.25% relative to the LHM, resulting in an LHM purity of 99.75%.
[0059] This indicates that this process has the following efficiencies. 1) The amount of LHM precipitate is approximately 3.1% by weight of the total mass at the start of LHM crystallization (32g LHM in a total mass of 1022g). 2) Approximately 232g of LHM was generated per 1kg of evaporated water (32g of LHM per 138g of evaporated water).
[0060] Examples 3A and 3B: Selective precipitation of sodium chloride and lithium hydroxide
[0061] Example 3A: Selective precipitation of sodium chloride
[0062] To mimic the first mother liquor solution separated in this process, a mixture containing lithium hydroxide, sodium chloride, and water was prepared by mixing 31.0 g of LiOH, 53.9 g of NaCl, and 303.1 g of H2O in a beaker glass using a magnetic stirrer at 80°C. To this mixture, a lithium chloride-containing aqueous solution (at room temperature) containing 56.15 g of LiCl and 56.2 g of H2O was rapidly added (i.e., within 5 seconds) to obtain a concentrated lithium chloride mixture. This represents flows 4 and 5 entering B, as shown in Figure 1.
[0063] After stirring at 80°C for 1 hour without forcibly evaporating the water, the lithium chloride concentrate was passed through a Buchner funnel at 80°C. This corresponds to flow 7 in Figure 1.
[0064] The resulting filtered cake, as determined by X-ray diffraction (XRD), contained 0.9 g of H2O, 6.8 g of NaCl, and 1.3 g of LHM. This suggests that approximately 12.6% of the original NaCl and approximately 2.4% of the original LiOH precipitated, indicating that sodium chloride was the primary precipitation component in this process.
[0065] Example 3B: Selective precipitation of lithium hydroxide
[0066] 423.9 g of the filtrate from Example 3A was mixed with 83.8 g of a 28.0% NaOH solution (prepared and maintained at room temperature). This represents flows 8, 1, and 2 entering A, as shown in Figure 1. The mixture was held at 40°C for 1 hour and then filtered on a glass filter.
[0067] The wet, unwashed filtration cake weighed 43.41 g and contained 27 g of LHM. After washing with saturated LiOH solution, the wet solid contained 84.4% w / w LHM and 15.4% H2O. In the final LHM produced, 0.89 g / kg of Na was detected by ICP analysis, which corresponds to 0.23 wt% NaCl. It is estimated that approximately 28% of the total amount of LiOH in the mixture precipitated as LHM. This indicates that the procedure used can produce a considerable amount of high-purity LHM.
[0068] Since 27g of LHM was produced from a total mass of 507.7g entering the crystallization process, the process has an LHM efficiency of approximately 5.3% (=27 / 507.7) for (unwashed) LHM.
[0069] Example 4: Production of lithium hydroxide monohydrate using this process with recycling
[0070] This experiment was carried out using the jacketed reactor of Example 2.
[0071] a) To mimic the separated second mother liquor solution of this process, a first lithium chloride-containing aqueous solution was prepared by dissolving 68 g of LiOH, 135 g of NaCl, and 75 g of LiCl in 720 g of H2O and heating to 85°C. To this solution, 203 g of 27 wt% NaOH solution (prepared by diluting a 50 wt% NaOH stock solution with water) was added to obtain a mixture containing lithium hydroxide, sodium chloride, and water. This represents flows 1 and 2 entering A, as shown in Figure 1.
[0072] b) Next, the mixture obtained in a) was cooled to 35°C and mixed for 1 hour.
[0073] The solution obtained in c):b) was filtered. 70.5 g of a wet solid was obtained. The water content, determined by infrared drying at 105°C, was found to be 49.7% (including crystal water present in the LHM), and the NaCl content, determined by AgNO3 titration, was found to be 4.7%. From this, the mass of LHM in the solid was calculated to be 56.4 g. Subsequently, the sample was washed three times with water saturated with LiOH, and then infrared dried at 105°C to remove all water, including crystal water. The NaCl content was measured and calculated to be 0.2% relative to the LHM, resulting in an LHM purity of 99.8%.
[0074] d):1093g of the filtrate obtained in c) was added to a washed jacketed reactor and heated to 85°C. To this, 140g of a 40% LiCl H2O solution (at a temperature of 40-55°C) was added to obtain a concentrated lithium chloride mixture. This corresponds to flows 4 and 5 entering B, as shown in Figure 1.
[0075] The lithium chloride concentrate mixture obtained in e):d) was stirred at 85°C for 2 hours under an applied vacuum of approximately 600 mbar to evaporate the water, and then stirred at 85°C for 1 hour under atmospheric pressure before filtration. A total of 94 g of wet solid and 914 g of clear filtrate solution were obtained, while 221 g of water was removed from the mixture by evaporation. Determination of chloride by AgNO3 titration (and considering the presence of chloride as LiCl in the adhering liquid) showed that the unwashed wet filtrate cake contained 76.7% NaCl.
[0076] This indicates that after one cycle (i.e., a) to e)), the process has the following efficiencies. 1) The LHM precipitate is approximately 4.7% by weight of the total mass at the start of LHM crystallization (56.4g of LHM in a total mass of 1201g). 2) Approximately 257g of LHM was generated per 1kg of evaporated water (56.4g of LHM per 221g of evaporated water).
[0077] To illustrate an optional recycling step of this process, 870 g of the filtrate obtained in e) was added to a jacketed reactor washed at 85°C. To this solution, 177 g of 27 wt% NaOH solution was added to obtain a mixture containing lithium hydroxide monohydrate, sodium chloride, and water. This represents flows 8, 1, and 2 entering A, as shown in Figure 1.
[0078] Next, the mixture was cooled to 35°C and mixed for 1 hour, after which the solution was filtered. 59.7 g of a wet solid was obtained. The water content, determined by infrared drying at 105°C, was found to be 45.4% (including crystal water present in the LHM), and the NaCl content, determined by AgNO3 titration, was found to be 7.8%. From this, the mass of LHM in the solid was calculated to be 48.9 g. Subsequently, the sample was washed three times with water saturated with LiOH, and then infrared dried at 105°C to remove all water, including crystal water. The NaCl content was measured and calculated to be 0.1% relative to the LHM, resulting in an LHM purity of 99.9%.
[0079] Of this filtrate, 932 g was added to a washed jacketed reactor and heated to 85°C. To this, 119 g of a 40% LiCl H2O solution (at a temperature of 40-55°C) was added to obtain a concentrated lithium chloride mixture. This corresponds to flows 4 and 5 entering B, as shown in Figure 1.
[0080] The lithium chloride concentrate mixture was stirred at 85°C for 2 hours under an applied vacuum of approximately 600 millibars to evaporate the water, and then stirred at 85°C for 1 hour under atmospheric pressure before filtration. A total of 69 g of wet solid and 801 g of clear filtrate solution were obtained, while 176 g of water was removed from the mixture by evaporation. Determination of chloride by AgNO3 titration (and taking into account the presence of chloride as LiCl in the adsorbent solution) showed that the unwashed wet filtrate cake contained 78.7% NaCl.
[0081] Therefore, it can be seen that the second cycle of this process has the following efficiencies. 1) The LHM precipitate is approximately 4.7% by weight of the total mass at the start of LHM crystallization (48.9g of LHM in a total mass of 1047g). 2) Approximately 277g of LHM was generated per 1kg of evaporated water (48.9g of LHM per 176g of evaporated water).
[0082] Although the present invention has been described with reference to exemplary embodiments, it will be understood that various modifications are possible within the scope of the invention.
[0083] In this specification, unless expressly suggested otherwise, the term “or” is used to mean an operator that returns true when either or both of the stated conditions are met, as opposed to “exclusive or,” which is an operator that requires only one of the conditions to be met. The word “comprising” is used to mean “including,” and not “consisting of.” All prior teachings mentioned above are incorporated herein by reference. No reference in this specification to any previously published document should be construed as an acknowledgment or representation that such teaching was common knowledge in Europe or elsewhere as of the date of this specification.
Claims
1. A process for producing lithium hydroxide monohydrate from lithium chloride, a) Adding a sodium hydroxide-containing aqueous solution to a first lithium chloride-containing aqueous solution to obtain a mixture containing lithium hydroxide, sodium chloride, and water, b) Cooling the mixture obtained in a) to selectively precipitate lithium hydroxide monohydrate, thereby obtaining a lithium hydroxide monohydrate precipitate and a first mother liquor solution. c) Separating the lithium hydroxide monohydrate precipitate from the first mother liquor solution, d) Adding a second lithium chloride-containing aqueous solution to the separated first mother liquor solution to obtain a first mother liquor solution concentrated with lithium chloride, e) A process comprising removing, preferably by evaporation, water from the lithium chloride concentrated first mother liquor solution to selectively precipitate sodium chloride, thereby obtaining a sodium chloride precipitate and a second mother liquor solution.
2. a) The mixture obtained in the above is 0.7:1 to 2.0:1, preferably 0.9:1 to 1.7:1, preferably 0.95:1 to 1.5:1, more preferably 1 or 1.05:1 to 1.4:1 lithium ions (Li ＋ ) vs. hydroxyl ion (OH － The process according to claim 1, having the molar ratio of ).
3. The process according to claim 1 or 2, wherein the mixture obtained in a) is cooled in b) to a temperature of 5 to 50°C, preferably 10 to 45°C, more preferably 20 to 45°C.
4. The lithium chloride concentrated first mother liquor solution contains lithium ions (Li) in a ratio of 0.9:1 to 3.5:1, preferably 0.95:1 to 2.5:1, and more preferably 1.0:1 to 2.0:
1. ＋ ) vs. hydroxyl ion (OH － The process according to any one of claims 1 to 3, having the molar ratio of ).
5. The process according to any one of claims 1 to 4, wherein the first mother liquor solution and / or the lithium chloride-concentrated first mother liquor solution are heated to a temperature of 50 to 120°C, preferably 60 to 95°C, more preferably 75 to 90°C to result in removal by evaporation in e).
6. The process according to any one of claims 1 to 5, wherein the aqueous solution containing sodium hydroxide has a sodium hydroxide concentration of 10 to 50% by weight, preferably 15 to 40% by weight, and more preferably 20 to 35% by weight, based on the total weight of the aqueous solution containing sodium hydroxide.
7. The process according to any one of claims 1 to 6, wherein the second aqueous solution containing lithium chloride has a lithium chloride concentration of 10 to 55% by weight, preferably 20 to 50% by weight, and more preferably 30 to 45% by weight, based on the total weight of the second aqueous solution containing lithium chloride.
8. The process according to any one of claims 1 to 7, wherein equimolar amounts of lithium chloride and sodium hydroxide are added to the process by the second aqueous solution containing lithium chloride and the aqueous solution containing sodium hydroxide, respectively.
9. f) Separating the sodium chloride precipitate from the second mother liquor solution to obtain the first lithium chloride-containing aqueous solution, The process further includes the process according to any one of claims 1 to 8.
10. g) To obtain the sodium hydroxide-containing aqueous solution by electrolyzing the sodium chloride precipitate, The process described in claim 9 is further included.
11. The process according to claim 10, wherein the sodium chloride precipitate has a total concentration of lithium chloride and lithium hydroxide of 0 to 15% by weight, preferably 0 to 10% by weight, and more preferably 0 to 6% by weight, based on the total weight of the sodium chloride precipitate.
12. The process according to claim 10 or 11, wherein the electrolysis is carried out using membrane-based chlor-alkali electrolysis.