Recovering method of lithium

Abstract

A recovering method of lithium according to the present invention comprises the steps of: preparing a lithium-containing solution; adding a decalcifier to the lithium-containing solution to form a calcium-containing precipitate; and separating the formed precipitate to obtain a calcium-removed, lithium-containing solution, wherein the recovery rate of lithium satisfies equation 1.

Description

How to recover lithium

[0001] The present invention relates to a method for recovering lithium.

[0002] Lithium compounds are used for a variety of purposes across various industries, including secondary batteries, ceramics, glass, alloys, and pharmaceuticals. With the recent commercialization of electric vehicles and the increasing need for power storage, demand for lithium materials is expected to grow significantly in the future.

[0003] Raw materials for manufacturing lithium materials include minerals, brine, and seawater. Among these, ores, such as spodumene, petalite, and lepidolite, contain relatively high lithium contents of about 1 to 1.5%. However, extracting lithium from minerals requires many processes such as flotation, high-temperature calcination, crushing, acid mixing, extraction, purification, concentration, and precipitation, making the recovery process complex, costly due to high energy consumption, and severe environmental pollution due to the use of acid in the lithium extraction process.

[0004] Additionally, seawater contains a total of 2.5×10 11 It is known that lithium is dissolved in seawater, and the main technology is to selectively adsorb lithium by inserting a recovery device containing an adsorbent into seawater and then extract lithium by acid treatment. However, since the concentration of lithium contained in seawater is only 0.1 to 0.2 ppm, extracting lithium from seawater is very inefficient and has a problem of low economic feasibility.

[0005] Due to these problems, lithium is currently extracted primarily from brine, which comes from natural salt lakes, and more than 70% of the world's reserves are distributed in South America, including Argentina, Chile, and Bolivia.

[0006] Lithium contained in brine is mainly extracted in the form of lithium carbonate. In a commercialized process, to extract lithium carbonate from lithium-containing brine, a well is drilled in a natural salt lake at an altitude of 3,000 m or higher, the brine is pumped out, and the brine is placed in evaporation ponds. This is then naturally evaporated over a long period of several months to a year to concentrate the lithium several to several dozen times, and then impurities such as Mg, Ca, and B are precipitated and removed, and the lithium is recovered by causing an amount exceeding the solubility of lithium carbonate to precipitate.

[0007] These brine solutions contain a higher concentration of divalent cation impurities than lithium. These impurities precipitate together with the lithium when the lithium is extracted as a solid, so a purification process is required to remove them before lithium extraction. However, this purification process poses a problem: lithium precipitates as a salt along with other impurities, resulting in lithium loss.

[0008] Therefore, there is a need to develop a method for recovering lithium that minimizes lithium precipitation during the purification process and allows for easy removal of impurities.

[0009] The present invention aims to provide a method for recovering lithium by quantifying process technology for efficiency according to calcium concentration, thereby minimizing lithium loss and easily removing calcium.

[0010] The present invention provides a method for recovering lithium, comprising the steps of: preparing a solution containing lithium; adding a calcium removing agent to the solution containing lithium to precipitate a precipitate containing calcium; and separating the precipitated precipitate to obtain a solution containing lithium from which calcium has been removed; wherein the recovery rate of lithium satisfies the following equation 1.

[0011] [Formula 1]

[0012] Lithium recovery rate (%) = [A × [Temperature of the lithium-containing solution before calcium removal reaction (℃)] + B × [Lithium concentration of the lithium-containing solution before calcium removal reaction (g / L)] + C × [Calcium / lithium ratio of the lithium-containing solution before calcium removal reaction (w / w)] + D] × 100

[0013] In the above equation 1,

[0014] A is a rational number between -0.0008 and -0.0012,

[0015] B is a rational number between -0.008 and -0.012,

[0016] C is a rational number between -0.1 and -0.15,

[0017] D is a rational number between 1.05 and 1.20.

[0018] The method for recovering lithium according to the present invention has the advantage of easily predicting the lithium recovery rate by quantifying the process technology according to the concentration of lithium and calcium and the reaction temperature.

[0019] In addition, the lithium recovery method according to the present invention has the advantage of easily removing calcium while minimizing lithium loss.

[0020] Figure 1 is a diagram showing the solubility of Li2CO3 according to temperature.

[0021] Figure 2 is a graph showing the decrease in lithium concentration according to calcium content / lithium content.

[0022] Figure 3 is a graph showing the lithium recovery rate according to the lithium concentration of a lithium-containing solution.

[0023] Figure 4 is a graph showing the lithium recovery rate according to the manufacturing example and the predicted value calculated using Equation 1.

[0024] 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. The present invention is defined solely by the scope of the claims set forth below.

[0025] In the present invention, when it is said that a member is located “on” another member, this includes not only cases where a member is in direct contact with another member, but also cases where another member is interposed between the two members.

[0026] When a part of the present invention is said to "include" a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated.

[0027]

[0028] One aspect of the present invention relates to a method for recovering lithium, comprising the steps of: preparing a solution containing lithium; adding a calcium removing agent to the solution containing lithium to precipitate a precipitate containing calcium; and separating the precipitated precipitate to obtain a solution containing lithium from which calcium has been removed; wherein the recovery rate of lithium satisfies the following equation 1.

[0029] [Formula 1]

[0030] Lithium recovery rate (%) = [A × [Temperature of the lithium-containing solution before calcium removal reaction (℃)] + B × [Lithium concentration of the lithium-containing solution before calcium removal reaction (g / L)] + C × [Calcium / lithium ratio of the lithium-containing solution before calcium removal reaction (w / w)] + D] × 100

[0031] In the above equation 1,

[0032] A is a rational number between -0.0008 and -0.0012,

[0033] B is a rational number between -0.008 and -0.012,

[0034] C is a rational number between -0.1 and -0.15,

[0035] D is a rational number between 1.05 and 1.20.

[0036]

[0037] The method for recovering lithium according to the present invention has the advantage of being able to predict the recovery rate of lithium and recover lithium more effectively and efficiently by controlling the temperature of the lithium-containing solution, the concentration of lithium, and the content ratio of calcium / lithium in removing the calcium from the lithium-containing solution, that is, the step of precipitating a precipitate containing calcium.

[0038]

[0039] In the present invention, the “lithium-containing solution before calcium removal reaction” refers to a solution in a state before the calcium removal reaction begins, immediately after the “lithium-containing solution” and the “calcium removal agent in the form of powder or solution” are mixed.

[0040]

[0041] A method for recovering lithium according to the present invention comprises the step of preparing a solution containing lithium.

[0042] In the present invention, the solution containing lithium may be seawater, salt lake and / or brine containing lithium.

[0043] Specifically, the lithium-containing solution may be a saline solution. More specifically, the lithium-containing solution may be a concentrated saline solution.

[0044] The above concentrated brine contains lithium and may have a pH ranging from, but not limited to, 5.0 to 7.0.

[0045] The method for obtaining the above-mentioned concentrated brine is not limited in the present invention.

[0046] The concentration of lithium component in the above lithium-containing solution, specifically the concentrated brine, may be 0.5 to 20 g / L, preferably 3 to 15 g / L, and more preferably 4 to 12 g / L, but is not limited thereto.

[0047] The concentration of calcium (Ca) in the above lithium-containing solution, specifically the concentrated brine, may be in the range of 1 to 40 g / L, preferably 2 to 15 g / L, and more preferably 2 to 5 g / L, but is not limited thereto.

[0048]

[0049] A method for recovering lithium according to the present invention includes a step of adding a calcium removing agent to a solution containing the lithium to precipitate a precipitate containing calcium.

[0050] In one embodiment of the present invention, the calcium remover may include at least one selected from the group consisting of sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), sodium sulfate (Na2SO4), and potassium hydroxide (KOH).

[0051] In another embodiment of the present invention, the calcium remover may be sodium carbonate.

[0052] When the above sodium carbonate is mixed with water and added, it is preferable because it is not a saturated solution, has excellent calcium removal efficiency, and can suppress lithium Li2CO3 precipitation. In addition, when the lithium-containing solution contains magnesium, it is preferable because calcium and magnesium can be removed simultaneously.

[0053]

[0054] The above calcium remover may be included in an amount of 0.6 to 1.5 equivalents (eq / mol), specifically 1.1 to 1.3 equivalents, based on the equivalent of calcium ions in the solution containing lithium.

[0055] When the above calcium remover satisfies the above equivalent range, the calcium / lithium content ratio of Equation 1 can be controlled within an appropriate range, thereby increasing the lithium recovery rate, which is preferable.

[0056]

[0057] The method for recovering lithium according to the present invention may further include a step of precipitating a precipitate containing calcium from the lithium-containing solution; and a step of pretreating the lithium-containing solution beforehand.

[0058] In short, the method for recovering lithium according to the present invention may further include a step of precipitating a precipitate containing calcium from the lithium-containing solution; and a step of pretreating the lithium-containing solution to control the above formula 1.

[0059]

[0060] In another embodiment of the present invention, the step of pretreating the solution containing lithium may include a step of further adding an additional additive for precipitating impurities other than calcium.

[0061] For example, additional additives may be added to remove impurities such as magnesium, boron, sulfur, potassium, and sodium.

[0062] The above additional additive may be different from the calcium additive described above.

[0063]

[0064] In another embodiment of the present invention, the additional additive may be calcium hydroxide.

[0065] When the calcium hydroxide is used as the additional additive, magnesium can be removed in the form of Mg(OH)2 by introducing hydroxide ions, and in addition to providing pH conditions for removing metal impurities as carbonates, there are advantages in that the occurrence of lithium sulfate precipitation can be suppressed even when calcium ions meet with sulfate ions and are precipitated and further concentrated, and the B concentration can be lowered by forming a compound by meeting with borate ions.

[0066] In another embodiment of the present invention, in the step of further adding an additional additive for precipitating impurities other than calcium, the content of the additional additive can be controlled to control the above formula 1.

[0067] Specifically, by controlling the amount of the additional additive containing calcium, the recovery rate of lithium can be increased by reducing the calcium / lithium content ratio multiplied by C in Equation 1.

[0068]

[0069] The above additional additive may be added in an amount of 0.2 to 1.10 equivalents (eq / mol), specifically 0.8 to 1.10 equivalents, and more specifically 0.92 to 1.02 equivalents, based on the equivalents of impurities, specifically sulfate ions and borate ions.

[0070] When the above additional additive satisfies the above range, it is preferable because it is excellent in removing impurities, specifically sulfate ions and borate ions, while reducing the calcium / lithium content ratio multiplied by C in the above formula 1.

[0071]

[0072] In another embodiment of the present invention, the step of pretreating the solution containing lithium may include a step of adjusting the temperature of the solution containing lithium to 50°C or higher, specifically 50 to 95°C, and more specifically 50 to 70°C.

[0073] When the temperature of the solution containing the lithium is within the above range, there is an advantage in that the expected lithium recovery rate can be increased without changing the lithium concentration multiplied by B. In addition, it is preferable because the solubility of calcium precipitates, such as calcium carbonate, is lowered within the solubility of the lithium compound in the solution containing the lithium.

[0074]

[0075] In another embodiment of the present invention, the pretreatment step of the lithium-containing solution may include a step of adding a solution having a lower lithium concentration than the lithium-containing solution to the lithium-containing solution.

[0076] When a solution having a lower lithium concentration than the lithium-containing solution is added to the lithium-containing solution, the lithium recovery rate can be increased by lowering the lithium concentration in the lithium-containing solution multiplied by B in Equation 1, which is preferable.

[0077]

[0078] A solution having a lower lithium concentration than the above lithium-containing solution may be, but is not limited to, a calcium-free raw material solution, a liquid solution in a lithium-containing process having a low concentration, or fresh water.

[0079]

[0080] The solution containing the lithium to which the calcium remover has been added can be maintained at a pH of 9.3 or higher, specifically 10.0 or higher, and more specifically 10.0 to 11.3.

[0081] The above pH can be adjusted with one or more alkaline substances selected from the group consisting of NaOH and Ca(OH)2.

[0082] The above NaOH is preferable because it has a relatively high degree of dissociation compared to Ca(OH)2, and thus can be adjusted to the desired pH with a small amount of input.

[0083] The above Ca(OH)2 is preferable compared to the above NaOH because it can increase the filtration speed during solid-liquid separation in the step of obtaining a solution containing lithium from which calcium has been removed by separating the precipitated precipitate, which will be described later.

[0084] The content of the above alkaline substance can be added so as to satisfy the desired pH.

[0085] When the pH range satisfies the above range, not only is the calcium removal rate excellent, but the filtration speed during solid-liquid separation in the step of obtaining a solution containing lithium from which calcium has been removed by separating the precipitated precipitate, which will be described later, can be improved, which is preferable. In addition, since the resulting precipitate has an appropriate particle size, it is advantageous in that filtration is easy.

[0086]

[0087] The step of precipitating a calcium-containing precipitate from the lithium-containing solution may include a step of adding the calcium remover to the lithium-containing solution and then stirring the lithium-containing solution.

[0088] The step of stirring the above lithium-containing solution can be performed for 30 minutes to 3 hours, preferably 40 minutes to 3 hours, and more preferably 1 hour to 2 hours.

[0089] When the step of stirring the solution containing the lithium is performed within the above time range, it is preferable that the calcium is sufficiently precipitated while minimizing the precipitation time.

[0090]

[0091] The step of stirring the above lithium-containing solution can be performed at 50 to 400 RPM, preferably 100 to 300 RPM, and more preferably 200 to 300 RPM.

[0092] When the solution containing the lithium is stirred within the RPM range, the reaction rate between the calcium remover and calcium is accelerated, thereby improving the precipitation rate and thus reducing the overall process time, which is advantageous.

[0093]

[0094] The method for recovering lithium according to the present invention includes a step of separating the precipitated precipitate to obtain a solution containing lithium from which calcium has been removed.

[0095]

[0096] Separation of the above sediment can be performed using a filtration separation device, but is not limited thereto.

[0097] Specifically, in the step of obtaining a solution containing lithium from which calcium has been removed by separating the precipitate, a solution containing lithium from which calcium has been removed can be obtained by separating the precipitate using a filter cloth of a filtration separation device.

[0098] The above filtration separation device or the filter cloth may be a filtration separation device or filter cloth used in a conventional lithium recovery process or impurity removal process in brine, and the present invention is not limited thereto.

[0099]

[0100] The solution containing lithium from which the calcium has been removed may have a calcium concentration of 0.020 g / L or less, specifically 0.015 g / L or less, and more specifically 0.003 g / L or less.

[0101]

[0102] In another embodiment of the present invention, the step of lowering the temperature of a solution containing lithium into which the calcium remover has been added may be further included.

[0103] Figure 1 is a graph showing the solubility of lithium carbonate (Li2CO3) according to temperature. It can be seen that the solubility of lithium carbonate decreases as the temperature increases.

[0104] For example, by lowering the temperature of a lithium-containing solution containing the calcium remover to 45°C or lower, specifically 35°C or lower, and more specifically 5 to 15°C, the lithium recovery rate can be increased. In addition, there is an advantage in that the energy required for heating to remove calcium can be saved.

[0105]

[0106] In another embodiment of the present invention, the method may further include a step of adding a solution having a lower lithium concentration than the solution containing lithium from which calcium has been removed to the solution containing lithium from which calcium has been removed.

[0107] It is preferable to add a solution having a lower lithium concentration to the above solution, as this lowers the lithium concentration of the solution and lowers the saturation during the reaction, thereby increasing the lithium recovery rate.

[0108]

[0109] The solution having a lower lithium concentration than the solution containing the lithium from which calcium has been removed may be, but is not limited to, a calcium-removed raw material solution, a liquid solution in a lithium-containing process having a low concentration, or fresh water.

[0110] In short, a solution having a lower lithium concentration than the solution containing the lithium from which the calcium has been removed may be equally applied to a solution having a lower lithium concentration than the solution containing the lithium from which the calcium has been removed, provided that the solution has a lower lithium concentration than the solution containing the lithium from which the calcium has been removed.

[0111]

[0112] In the present invention, the recovery rate of lithium recovered through the solution containing lithium from which calcium has been removed is expressed by the following equation 1.

[0113]

[0114] [Formula 1]

[0115] Lithium recovery rate (%) = [A × [Temperature of the lithium-containing solution before calcium removal reaction (℃)] + B × [Lithium concentration of the lithium-containing solution before calcium removal reaction (g / L)] + C × [Calcium / lithium ratio of the lithium-containing solution before calcium removal reaction (w / w)] + D] × 100

[0116]

[0117] In the above equation 1,

[0118] A is a factor obtained from a graph of lithium recovery rate according to temperature. The above A may preferably be in the range of -0.0009 to -0.0010.

[0119] B is a factor obtained from a graph of lithium recovery rate according to concentration. The above B may preferably be in the range of -0.009 to -0.010.

[0120] C is a factor obtained from a graph of lithium recovery rate according to the ratio of Ca to Li. The C may preferably be in the range of -0.12 to -0.13.

[0121] D is a factor that converts the recovery rate in a saturated solution to 100% after the factors A, B, and C are determined. The above D may preferably be in the range of 1.08 to 1.15, more preferably 1.09 to 1.11.

[0122]

[0123] In the above formula 1, the temperature of the lithium-containing solution before the calcium removal reaction may be 45°C or lower, specifically 35°C or lower, and more specifically 5 to 15°C. The temperature of the lithium-containing solution before the calcium removal reaction may be applied as described above.

[0124] In the above formula 1, the lithium concentration of the lithium-containing solution before the calcium removal reaction may be 0.5 to 20 g / L, preferably 3 to 10 g / L, and more preferably 3 to 5 g / L.

[0125] In the above formula 1, the calcium content / lithium content of the lithium-containing solution before the calcium removal reaction may be 0.9 or less, preferably 0.88 or less.

[0126]

[0127] In another embodiment of the present invention, there is provided a step of separating the precipitated precipitate to obtain a solution containing lithium from which calcium has been removed; after this, the lithium loss rate may be 5% or less.

[0128] Specifically, when compared to the lithium-containing solution before the calcium remover is added, the lithium loss rate of the lithium-containing solution from which the calcium has been removed may be 5% or less, specifically 3% or less.

[0129]

[0130] The above lithium can be recovered by separating the solution containing lithium from which calcium has been removed into a solid phase and a liquid phase through a vacuum filtration method after the reaction in which the above precipitate is precipitated is completed, and recovering the lithium from the solution containing the lithium from which calcium has been removed.

[0131] For example, the solution containing lithium from which the calcium has been removed can be carbonated or phosphorized to recover lithium carbonate or lithium phosphate, but is not limited thereto.

[0132]

[0133] The method for recovering lithium according to the present invention has the advantage of facilitating the removal of calcium while minimizing lithium loss by quantifying the process technology for efficiency according to the calcium concentration before calcium removal as Equation 1.

[0134]

[0135] Hereinafter, preferred embodiments and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0136]

[0137] Manufacturing example

[0138] The composition of the lithium-containing solution before adding Na2CO3 as a calcium remover and the composition of the lithium-containing solution from which calcium has been removed after precipitating calcium using Na2CO3 are shown in Tables 1 to 4. At this time, the lithium-containing solution from which calcium has been removed was obtained by the following method.

[0139] To 200 ml of concentrated brine containing a lithium solution, 1.2 equivalents of Na2CO3 powder was added based on the calcium content. The concentrated brine was then adjusted to maintain the temperature according to Tables 1 and 3 below, and stirred at 200 RPM for 2 hours to precipitate a precipitate.

[0140] After the sediment was precipitated, calcium was removed by separating the solid phase and the liquid phase using a pressurized solid-liquid separation device, and the components of the solution containing lithium from which calcium was removed were analyzed, and the results are shown in Tables 1 to 4 below. In addition, whether Equation 1 was satisfied or not is shown in Tables 2 and 4 below.

[0141] Component analysis was performed using an ICP analyzer.

[0142]

[0143] Temperature (℃) Composition of solution containing lithium (g / L) LiSCaMgBKNaCa / Li Manufacturing example 1-54.2862.2762.6121.2451.22136.03483.8980.609 Manufacturing example 2-54.3171.7253.3480.1561.24336.12084.2130.776 Manufacturing example 3-54.2171.6253.7820.0001.47335.98683.0970.897 Manufacturing example 4-54.1751.5914.0440.0001.44135.88683.4560.969 Manufacturing example Manufacturing Example 5-54.2621.8752.7511.1941.32536.02083.7310.645 Manufacturing Example 6-54.2901.2244.4610.0001.49236.02783.7681.040 Manufacturing Example 753.9482.4342.4011.4911.06234.84081.8100.608 Manufacturing Example 853.9641.7503.1220.3791.01535.12082.4200.788 Manufacturing Example 953.9621.4653.8940.0001.37235.36082.8200.983 Manufacturing Example Manufacturing example 1053.8741.3713.9510.0001.38835.13082.2101.020 Manufacturing example 1153.9801.8152.8750.3401.28035.65785.0730.722 Manufacturing example 1253.9111.2154.2530.0001.28635.62385.2051.088 Manufacturing example 13154.2051.8312.1680.8760.86436.06683.4430.516 Manufacturing example Manufacturing example 14154.1931.3003.0430.0331.03835.81682.9260.726 Manufacturing example 15154.1531.2043.6300.0001.44535.95083.4110.874 Manufacturing example 16154.1291.2663.5620.0001.33836.05483.6260.863 Manufacturing example 17154.1771.6382.4850.1471.10535.58083.5960.595 Manufacturing example 18154.1801.1704.3500.0001.33835.63683.0031.041

[0144]

[0145] Composition of solution containing lithium from which calcium has been removed (g / L) Recovery rate Formula 1 Calculation result LiSCaMgBKNa Manufacturing example 14.0751.5260.4830.0000.85935.96987.92295.08%98.58% Manufacturing example 24.1802.3040.0980.6910.73435.66288.36296.83%96.48% Manufacturing example 34.1041.8080.0090.0590.77535.36188.64397.32%95.06% Manufacturing example 44.0071.4650.0730.0001.09335.59388.70995.98%94.21% Manufacturing Example 54.1572.0600.3290.9261.28836.01487.72297.54%98.15% Manufacturing Example 63.8841.5770.3130.0001.49136.01290.48190.54%93.21% Manufacturing Example 73.9452.3570.3741.0270.88034.46386.62499.92%97.99% Manufacturing Example 83.9171.7950.0990.2090.86334.35987.06798.80%95.74% Manufacturing example 93.6501.4100.0070.0001.34333.06784.37292.14%93.31% Manufacturing example 103.5861.3290.0050.0001.34232.92885.10492.58%92.93% Manufacturing example 113.8271.8150.2830.2621.14535.66488.60296.14%96.54% Manufacturing example 123.5021.2150.2490.0001.28635.62391.30889.55%92.05% Manufacturing Example 134.1481.9280.4170.6740.74335.98086.81098.64%97.99% Manufacturing Example 144.0711.2980.0140.0001.01935.98087.60097.09%95.38% Manufacturing Example 153.9031.1730.0080.0001.37535.42087.42093.98%93.57% Manufacturing Example 163.8111.2190.0130.0001.25634.78085.74092.30%93.74% Manufacturing Example 174.0421.6380.3220.1051.02935.58486.57896.77%97.03% Manufacturing Example 183.8191.1700.3150.0001.33835.63688.94291.36%91.47%.

[0146]

[0147] Referring to Tables 1 and 2 above, it can be seen that the recovery rate of lithium is 95% or higher when the calcium content / lithium content is less than 0.9 and the temperature of the solution containing lithium with added Na2CO3 is maintained at -5°C or 5°C, and it can be confirmed that this can be predicted using Equation 1.

[0148] Additionally, it can be seen that the recovery rate of lithium is somewhat reduced when the calcium content / lithium content is 0.9 or higher.

[0149] It can be seen that when the temperature of the solution containing lithium with added Na2CO3 is maintained at 15°C, the recovery rate of lithium is somewhat reduced even when the calcium content / lithium content is less than 0.9.

[0150]

[0151] Temperature (℃) Composition of solution containing lithium (g / L) LiSCaMgBKNaCa / Li Manufacturing example 19404.1341.1823.5400.0001.36635.77883.8720.856 Manufacturing example 20404.0921.1183.9830.0001.33235.79183.1790.973 Manufacturing example 21703.9381.6041.6600.0001.41335.73183.2230.421 Manufacturing example 22703.9120.8673.6010.0001.34635.76583.2050.921 Manufacturing example Manufacturing example 23705.9350.5725.2790.0001.34635.76583.0700.889 Manufacturing example 24709.0050.4308.2060.0001.34635.76582.9530.911 Manufacturing example 257013.6630.29812.7540.0001.34635.76582.8340.933

[0152]

[0153] Composition of solution containing lithium from which calcium has been removed (g / L) Recovery rate Formula 1 Calculation result LiSCaMgBKNa Manufacturing example 193.8641.1820.3790.0001.36635.77888.46493.47%91.52% Manufacturing example 203.7301.1180.3550.0001.33235.79288.61791.14%90.10% Manufacturing example 213.6281.6040.4220.0001.41335.73185.72092.14%94.37% Manufacturing example 223.4090.8670.3930.0001.34635.76588.60787.14%88.17% Manufacturing Example 235.2040.5720.9810.0001.34635.76590.44487.68%86.71% Manufacturing Example 247.5970.4302.5280.0001.34635.76594.14484.36%83.64% Manufacturing Example 2510.7320.2986.2970.0001.34635.76599.95578.55%79.11%

[0154]

[0155] Referring to Tables 3 and 4 above, it can be seen that the recovery rate of lithium decreases somewhat when the concentration of Li increases even when the temperature of the solution containing lithium with added Na2CO3 is maintained the same.

[0156] Figure 2 is a graph showing the lithium concentration reduction (100% - recovery rate) according to the calcium content / lithium content of Manufacturing Examples 1 to 18. In addition, Figure 3 is a graph showing the lithium recovery rate according to the lithium concentration of the lithium-containing solutions of Manufacturing Examples 22 to 25.

[0157] Referring to Figures 2 and 3, it can be seen that as the calcium / lithium content ratio increases, the amount of lithium concentration reduction decreases, and as the lithium concentration of the lithium-containing solution increases, the lithium recovery rate decreases. Furthermore, Figure 4 confirms that the predicted results of Equation 1 and the actual results show a similar trend.

[0158] In short, it can be seen that the recovery rate of lithium can be controlled by controlling the temperature of the lithium-containing solution before the calcium removal reaction according to the present invention, the lithium concentration of the lithium-containing solution before the calcium removal reaction, and the calcium / lithium ratio of the lithium-containing solution before the calcium removal reaction.

[0159]

[0160] The present invention is not limited to the above-described embodiments, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Step of preparing a solution containing lithium; A step of adding a calcium remover to the solution containing the lithium to precipitate a precipitate containing calcium; and A step of separating the precipitated precipitate to obtain a solution containing lithium from which calcium has been removed; The recovery rate of lithium satisfies the following equation 1: How to recover lithium: [Formula 1] Lithium recovery rate (%) = [A × [Temperature of lithium-containing solution before calcium removal reaction (℃)] + B × [Lithium concentration of lithium-containing solution before calcium removal reaction (g / L)] + C × [Calcium / lithium ratio of lithium-containing solution before calcium removal reaction (w / w)] + D] × 100 In the above equation 1, A is a rational number between -0.0008 and -0.0012, B is a rational number between -0.008 and -0.012, C is a rational number between -0.1 and -0.15, D is a rational number between 1.05 and 1.

20.

2. In paragraph 1, A method for recovering lithium, comprising: a step of precipitating a precipitate containing calcium from the solution containing lithium; and a step of precipitating the solution containing lithium beforehand.

3. In paragraph 2, A method for recovering lithium, comprising: a step of pretreating a solution containing lithium; a step of further adding an additional additive for precipitating impurities other than calcium; 4. In paragraph 2, A method for recovering lithium, comprising: a step of pretreating a solution containing lithium; a step of controlling the temperature of the solution containing lithium to 50° C. or higher.

5. In paragraph 3, A method for recovering lithium, wherein the content of the additional additive is controlled to control the above formula 1 in a step of further adding an additional additive for precipitating impurities other than the above calcium.

6. In paragraph 2, A method for recovering lithium, comprising: a pretreatment step of the lithium-containing solution; a step of introducing a solution having a lower lithium concentration than the lithium-containing solution into the lithium-containing solution; 7. In paragraph 1, A method for recovering lithium, wherein the calcium remover comprises at least one selected from the group consisting of sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), sodium sulfate (Na2SO4), and potassium hydroxide (KOH).

8. In paragraph 7, A method for recovering lithium, wherein the calcium remover is sodium carbonate (Na2CO3).

9. In paragraph 1, A method for recovering lithium, wherein the calcium remover is added in an amount of 0.2 to 1.0 equivalents (eq / mol) based on the equivalent weight of calcium ions.

10. In paragraph 3, A method for recovering lithium, wherein the additional additive is calcium hydroxide (Ca(OH)2).

11. In paragraph 1, A method for recovering lithium, further comprising the step of lowering the temperature of a solution containing lithium into which the calcium remover has been added.

12. In paragraph 1, A method for recovering lithium, further comprising the step of adding a solution having a lower lithium concentration than the solution containing lithium from which calcium has been removed to the solution containing lithium from which calcium has been removed.

13. In paragraph 1, A step of obtaining a solution containing lithium from which calcium has been removed by separating the precipitated precipitate; and a method for recovering lithium thereafter, wherein the lithium loss rate is 5% or less.

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