Method for recovering lithium

Abstract

A method for recovering lithium according to one embodiment of the present invention comprises: a step of preparing a solution containing lithium; a precipitation step of forming a precipitate by adding an impurity remover to the solution containing lithium; and a solid-liquid separation step of mixing a solid-liquid separation aid into a slurry, and separating and thereby obtaining a filtrate, wherein the solid-liquid separation aid may include an ore residue.

Description

How to recover lithium

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

[0002]

[0003] 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.

[0004] 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.

[0005] In addition, it is known that a total of 2.5×1011 tons of lithium are dissolved in seawater, and the technology that mainly extracts lithium by selectively adsorbing lithium by inserting a recovery device containing an adsorbent into seawater and then treating it with acid is used, but since the concentration of lithium 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.

[0006] 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.

[0007] 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 then trapped in evaporation ponds, 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.

[0008] One of the biggest challenges in the process of manufacturing lithium compounds from brine is the extremely slow filtration rate during the process of removing Mg and Ca, which are impurities contained in the concentrated brine. This is likely due to the nature of the precipitates, including Mg(OH)2, generated during the impurity removal process. Considering the entire process, there is a need to improve the speed of the solid-liquid separation liming process and the Mg / Ca removal process. Common methods for improving solid-liquid separation speed include using coagulants or filter aids. However, both existing coagulants and filter aids are expensive, and cellulose, which is widely used as a filter aid, tends to decompose over time.

[0009] The lithium compound manufacturing industry is continuously demanding solutions to problems arising in the process of removing impurities from lithium-containing brine. To this end, it is essential to develop technologies that can improve the separation speed of precipitates formed in the process of removing Mg and Ca, thereby improving overall productivity, and to enhance the lithium recovery rate.

[0010]

[0011] One object of the present invention relates to a method for recovering lithium from a lithium-containing solution such as brine.

[0012] Another object of the present invention is to provide a method for quickly and efficiently separating a slurry by using residue generated during an ore lithium process in a process for removing impurities in a lithium-containing solution.

[0013]

[0014] A method for recovering lithium from brine according to one embodiment of the present invention comprises: a step of preparing a solution containing lithium; a precipitation step of adding an impurity removing agent to the solution containing lithium to form a precipitate; and a solid-liquid separation step of mixing a solid-liquid separation aid with the slurry obtained in the precipitation step and adding the mixture to a filter to filter the filtrate; wherein the solid-liquid separation aid may include ore residue.

[0015] According to another embodiment of the present invention, a method for recovering lithium from brine includes the steps of: preparing a solution containing lithium; a precipitation step of adding an impurity removing agent to the solution containing lithium to form a precipitate; and a solid-liquid separation step of adding a slurry obtained in the precipitation step to a filter and filtering the filtrate; wherein, before adding the slurry to the filter, distilled water having a solid-liquid separation aid dispersed therein may be added to the filter to form a uniform solid-liquid separation aid coating layer on the surface of the filter.

[0016] The above ore is lithium ore residue.

[0017] The particle size D(90) of the above solid-liquid separation aid is 300㎛ or less, and the specific surface area BET of the above solid-liquid separation aid is 200 m 2 / g is more than that.

[0018] In the step of preparing the above lithium-containing solution, the lithium (Li) concentration in the lithium-containing solution is 0.1 to 1.0 g / L.

[0019] In the step of preparing the above lithium-containing solution, the concentration ratio of magnesium (Mg) to lithium (Li) in the lithium-containing solution (Mg / Li) is 1500 or more.

[0020] In the step of preparing the above lithium-containing solution, the concentration ratio of calcium (Ca) to lithium (Li) in the lithium-containing solution (Ca / Li) is 100 to 200.

[0021] The amount of the above solid-liquid separation aid is 40 to 60 wt% of the total weight of the solid separated in the above solid-liquid separation step.

[0022] In the precipitation step of forming a precipitate by adding an impurity removing agent to the above lithium-containing solution, the impurity removing agent includes at least one selected from calcium carbonate (CaCO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), sodium sulfate (Na2SO4), and potassium hydroxide (KOH).

[0023] The above impurity remover is added in an amount of 0.8 to 1.3 equivalents (eq / mol) based on the total equivalents of magnesium and calcium included in the solution containing the lithium.

[0024] In the above solid-liquid separation step, the filtration speed of the filtrate exceeds 0.1 cm / min.

[0025] The thickness of the above high-liquid separation auxiliary material coating layer is 0.8 to 1.2 cm.

[0026]

[0027] According to one embodiment of the present invention, by using the residue generated during the ore lithium process as a solid-liquid separation aid, there are environmentally friendly and economical advantages.

[0028] According to one embodiment of the present invention, by adding a solid-liquid separation aid to the slurry formed in the process of removing magnesium and calcium in brine, the cycle time is reduced due to an increase in the solid-liquid separation speed, and the filter cloth replacement cycle is extended, thereby improving the productivity of the unit process.

[0029]

[0030] Figure 1 shows the results of a slurry sedimentation test.

[0031] Figure 2 shows the results of a high-liquid separation experiment.

[0032]

[0033] In this specification, the terms first, second, and third, etc. are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0035] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0036] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0037] 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.

[0038] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0039]

[0040] One embodiment of the present invention relates to a method for recovering lithium.

[0041] A method for recovering lithium according to one embodiment of the present invention may include: a step of preparing a solution containing lithium; a precipitation step of adding an impurity removing agent to the solution containing lithium to form a precipitate; and a solid-liquid separation step of mixing a solid-liquid separation aid into the slurry obtained in the precipitation step and performing solid-liquid separation to obtain a filtrate.

[0042] Meanwhile, the high-liquid separation aid may include lithium ore residue.

[0043]

[0044] First, a step of preparing a solution containing lithium is performed.

[0045] In the present invention, the lithium-containing solution is an aqueous solution containing lithium, a lithium-containing liquid that is extracted from underground through a pump or introduced into a process in a form that is dissolved on its own, exists in the form of groundwater within the earth's crust, or is introduced underground due to industrial needs (e.g., introduced underground in an oil extraction process or introduced underground for geothermal power generation), and is not limited to brine in a salt lake region, geothermal brine, oil field brine (oil well brine), etc.

[0046] Specifically, the lithium-containing solution may be a saline solution. More specifically, the lithium-containing solution may be a concentrated saline solution.

[0047] The method for obtaining the above-mentioned concentrated brine is not limited in the present invention.

[0048] The concentration of the lithium component in the above lithium-containing solution may be 0.01 to 0.1 g / L, and specifically 0.04 to 0.06 g / L.

[0049] The concentration ratio of magnesium (Mg) and lithium (Li) in the above lithium-containing solution (Mg / Li) may be 1500 or more, and the concentration ratio of calcium (Ca) and lithium (Li) (Ca / Li) may be 100 to 200.

[0050] The concentration of sulfur (S) in the above lithium-containing solution may be 1.0 to 30.0 g / L, and specifically, 1.0 to 20.0 g / L, 5.0 to 20.0 g / L, or 5.0 to 15.0 g / L.

[0051] The concentration ratio (S / Mg) of sulfur (S) components and magnesium (Mg) components in the above lithium-containing solution may be 1.10 to 1.30, and specifically, 1.15 to 1.25.

[0052]

[0053] Next, a precipitation step can be performed to form a precipitate by adding an impurity removing agent to the solution containing the lithium.

[0054] The step of forming a precipitate by adding an impurity removing agent to the above lithium-containing solution is specifically a step of forming a precipitate and slurry containing magnesium and calcium by adding an impurity removing agent for precipitating magnesium and calcium.

[0055] In the present invention, the removing agent for removing magnesium may include at least one selected from calcium carbonate (CaCO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), sodium sulfate (Na2SO4), and potassium hydroxide (KOH).

[0056] In the present invention, the solution containing lithium may have a pH of 10 or higher, and specifically, 10.5 or higher. When the pH is 10.5 or higher, the solubility of Mg(OH)2 or CaCO3 is low, so it is easily precipitated, and solid-liquid separation is facilitated, which is preferable.

[0057] Specifically, when the pH is 10.5 or higher, OH - Mg contained in the above solution 2+ Mg(OH)2 is generated and precipitated by reacting with ions. At this time, as alkaline substances such as calcium hydroxide are supplied, SO4 contained in the solution containing lithium 2- Ion Ca 2+CaSO4 hydrate is also produced by reacting with it. Since brine generally contains more S than Mg, when a removing agent such as calcium hydroxide is added in the Mg removal process, the Mg cake produced contains more CaSO4 hydrate than Mg(OH)2. The reaction that occurs when calcium hydroxide is added to concentrated brine can be expressed by the reaction equation shown below.

[0058] Ca(OH)2(s)+ Mg 2+ (aq) + SO4 2- (aq) + 2H2O(l) → Mg(OH)2(s) + CaSO4·2H2O(s)

[0059] When alkaline substances such as calcium hydroxide are added, precipitation of CaSO4 mainly occurs in the low pH range at the beginning of the addition, and as the pH value increases, the amount of precipitation of Mg(OH)2 precipitate increases. Typically, to completely remove Mg, an impurity contained in concentrated brine, the amount of alkaline substance added and the reaction time must be controlled so that the pH value is 11 or higher.

[0060] Meanwhile, CaSO4 particles generated in a relatively low pH region have a coarse needle-like, plate-like, or square shape, and the pH value of the reaction slurry gradually increases as the amount of alkaline substance input increases. At pH values ​​higher than 9.5, the cross-reaction between the CaSO4-Ca(OH)2-Mg(OH)2 phases progresses, causing the coarse CaSO4 particles generated in the low pH region to become finer, and the generation of fine Ca(OH)2 and Mg(OH)2 particle phases actively progresses. If the pH value increases further into the alkaline region, this particle refinement trend can accelerate, and the increase in such fine sediments can cause clogging by attaching to the pores of the filter cloth in the filter device for sediment separation, which becomes a factor that hinders the input of subsequent washing water. As a result, it not only reduces the filtration speed in the solid-liquid separation process after the Mg removal reaction and shortens the life of the filter cloth, but also becomes the main cause of reducing the productivity of the entire process.

[0061] In order to solve the above problem, the present invention aims to improve the filtration speed and efficiency by adding a high-liquid separation aid.

[0062] In the present invention, in the step of forming a precipitate by adding a removing agent to the lithium-containing solution, the pH of the reactant is controlled to a desired level by adjusting the equivalence ratio of the removing agent to perform a Mg removal process in which the size of the generated particles is increased.

[0063] In one embodiment of the present invention, the step of forming a precipitate by adding a removing agent to a solution containing lithium may specifically include adding 0.5 to 2.0 equivalents of the removing agent based on the equivalent weight of magnesium and calcium ions in the solution containing lithium, and specifically, adding 0.8 to 1.3 equivalents.

[0064] In one embodiment of the present invention, the first precipitation step and the second precipitation step are steps performed while stirring using a stirrer, and can be stirred at a stirring speed of 100 rpm to 400 rpm. This is preferable because stirring at the stirring speed allows the lithium-containing solution and the impurity remover to effectively contact each other, thereby effectively precipitating magnesium and calcium.

[0065]

[0066] Next, a solid-liquid separation aid may be mixed into the slurry obtained in the above-mentioned precipitation step, and a solid-liquid separation step may be performed.

[0067] The above solid-liquid separation aid may include lithium ore residue, and the metal component content of the lithium ore residue is obtained through XRF analysis, and the C content is calculated by measuring the amount of carbon dioxide in the gas generated by burning the lithium ore residue. The analysis results are shown in Table 1 below.

[0068] Composition Na2OMgOAl2O3SiO2CaOTiO2Fe2O3MnOCOtherWt%0.130.1622.3055.205.190.181.490.230.7014.42

[0069] The above lithium ore residue is a residue discharged from the ore process and can be produced as a by-product through processes such as calcination, roasting, precipitation, purification, and solid-liquid separation of lithium-containing ores such as spodumene.

[0070] In the present invention, by using lithium ore residue as a solid-liquid separation aid as described above, there is an environmentally friendly and economical advantage in utilizing waste resources.

[0071]

[0072] The particle size (D90) of the above high-liquid separation aid may be 300㎛ or less, and (D50) may be 60 to 80㎛ or 65 to 75㎛.

[0073] In the present invention, the particle size can be measured using PSA (Particle size analysis), which is a general method for measuring powder particle size and a detailed description thereof is omitted herein.

[0074] The BET specific surface area of ​​the above high-liquid separation aid is 200 m 2 / g or more, specifically 200 to 350 m 2 / g, 250 to 300 m 2 / g could be.

[0075] In the present invention, the “specific surface area” was measured using the Brunauer-Emmett-Teller Analysis method according to the nitrogen adsorption method, and a method of measuring the specific surface area of ​​a material was adopted by measuring the adsorption amount according to partial pressure by adsorbing and desorbing nitrogen gas on the surface of a solid sample using the BET (Brunauer Emmett Teller) formula.

[0076] When the particle size and specific surface area of ​​the above-mentioned solid-liquid separation aid satisfy the above-mentioned range, it is preferable that the solid substance in the slurry obtained in the precipitation step of forming a precipitate by adding an impurity removing agent to the solution containing lithium can be quickly separated from the liquid substance.

[0077]

[0078] The above solid-liquid separation aid can be added in an amount of 20 to 100 wt% based on the total weight of magnesium and calcium solid precipitates per unit volume of the solution containing the lithium.

[0079] Meanwhile, the amount of the solid-liquid separation aid may be 40 to 60 wt% of the total weight of the solid separated in the solid-liquid separation step, specifically 45 to 55%, and more specifically 50%.

[0080] When a high-liquid separation aid is added within the above range, it is preferable to improve the separation speed of magnesium and calcium precipitates and liquid substances in a lithium-containing solution by an impurity removal agent and to improve the separation efficiency.

[0081] After mixing a solid-liquid separation aid into the slurry obtained in the above precipitation step, the solid content may be 5 to 50 wt% based on the total weight.

[0082] When the above range is satisfied, it is desirable to improve the solid-liquid separation speed and solid-liquid separation efficiency in the solid-liquid separation step.

[0083] Meanwhile, after mixing a solid-liquid separation aid into the slurry obtained in the sedimentation step, the sedimentation rate of the solid content in the slurry may be 1.5 ml / min or more, specifically 2.0 ml / min or more, and more specifically 2.78 ml / min or more.

[0084] The slurry formed in the above-described sedimentation step can be separated into solid and liquid substances using a pressurized solid-liquid separation device. Here, the volume of the liquid substance filtered and the solid-liquid separation time when performing solid-liquid separation of the same volume of slurry were measured, and then the value was converted by dividing it by the filter cloth area to calculate the respective filtration rates.

[0085] In the above solid-liquid separation step, the filtration speed of the filtrate in the step may be greater than 0.1 cm / min, specifically 0.13 cm / min or more, and more specifically 0.13 to 0.25 cm / min, 0.15 to 0.20 cm / min.

[0086]

[0087] In one embodiment of the present invention, after the solid-liquid separation step, the method may further include a step of obtaining a washing liquid by injecting washing water into a separator containing the solid material.

[0088] The above-mentioned washing solution may contain lithium contained in the above-mentioned solid material and may be mixed with the filtrate separated in the above-mentioned solid-liquid separation step. Including such a step is preferable because it can improve the lithium recovery rate in the overall lithium recovery process.

[0089]

[0090] Another embodiment of the present invention provides a method for recovering lithium, comprising the steps of: preparing a solution containing lithium; a precipitation step of adding an impurity removing agent to the solution containing lithium to form a precipitate; and a step of introducing the slurry obtained in the precipitation step into a filter to separate solids and liquids. In this case, the filter may be a filter in which a solid-liquid separation aid is applied to the entire filter surface by passing an aqueous solution containing a solid-liquid separation aid through the filter before introducing the slurry.

[0091] The thickness of the high-liquid separation aid coating layer applied to the filter surface of the above filter may be 0.5 to 2 cm, specifically 0.8 to 1.2 cm, and more specifically 1 cm.

[0092] When a high-liquid separation aid coating layer is formed with the above thickness, it is preferable because the high-liquid separation speed and separation efficiency for the slurry can be improved.

[0093] Since the high-liquid separation aid has been explained in detail above, it is omitted here.

[0094]

[0095] Hereinafter, embodiments of the present invention will be described in more detail through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0096]

[0097] (Preparation of lithium-containing aqueous solution)

[0098] A lithium-containing aqueous solution having the composition shown in Table 2 below was prepared.

[0099] The unit of each composition concentration is g / L.

[0100] LiSCaMgBNaKpH concentration ratio (S / Mg) 102.5 1.5 11.5 8 0 5 0 6.6 2.5

[0101]

[0102] (Preparation of high-value separation aid)

[0103] The residue, a by-product from the lithium ore process, was classified by particle size and used in the experiment.

[0104] The particle size and specific surface area of ​​the residue before particle separation were analyzed and shown in Table 3 below.

[0105] Particle size D10 (㎛) Particle size D50 (㎛) Particle size D910 (㎛) Specific surface area (m 2 / g)13.171.12232.5

[0106] The above residue was classified into particle sizes of ① 100 μm or less (solid-liquid separation aid 1), ② 100-150 μm (solid-liquid separation aid 2), and ③ 150-300 μm (solid-liquid separation aid 3).

[0107]

[0108] (Experiment on precipitation of Mg and Ca in lithium-containing aqueous solution)

[0109] Na2CO3 was used as a remover for removing Mg and Ca from lithium-containing aqueous solutions.

[0110] After the Mg removal reaction in the lithium-containing aqueous solution, Na2CO3 was added in an amount of approximately 1 equivalent based on the total Mg and Ca components to completely remove the Mg concentration in the filtrate to a level of 0.003 g / L or less. In both the comparative example and the example, the total reaction time was maintained at 2 hours so that the pH value was 11 or higher.

[0111] After adding Na2CO3, maintain the temperature at 60℃ for 2 hours.

[0112] The reaction was carried out while stirring at a stirring speed of 300 rpm, and after adding secondary Ca(OH)2, the reaction was terminated after stirring at a stirring speed of 300 rpm for 1 hour to form a slurry.

[0113]

[0114] (Slurry Settling Test)

[0115] In the above sedimentation experiment, 1 L of the slurry formed was added with the prepared solid-liquid separation aid at 50 wt% of the final formed sediment weight, and the sedimentation rate of the solid content was analyzed.

[0116] Figure 1 is a graph measuring the change in height of the solid material (or slurry) layer located at the bottom, which is distinct from the upper transparent water layer, according to the settling time according to the particle size of the high-liquid separation aid.

[0117] Referring to Figure 1, the slurry sedimentation rate was found to be somewhat faster in the beginning as the particle size of the solid-liquid separation aid was smaller, and showed almost similar results after about 180 minutes. In other words, when the solid-liquid separation aid is mixed, it can be confirmed that it acts as a sedimentation aid that helps the slurry settle at a similar speed regardless of the particle size up to the level of 300 μm. On the other hand, when the solid-liquid separation aid is mixed, it can be confirmed that the sedimentation rate is significantly faster compared to the slurry without the solid-liquid separation aid mixed.

[0118] Therefore, it can be confirmed that when the solid-liquid separation aid according to the present invention is mixed, the separation rate between solid substances and water in the slurry can be improved. In addition, when performing solid-liquid separation using a sedimentation tank, it can be confirmed that the use of the solid-liquid separation aid according to the present invention facilitates the formation of a solid-liquid separation layer.

[0119]

[0120] (High-liquid separation experiment)

[0121] In the above sedimentation experiment, 1 L of the slurry formed was added with the prepared solid-liquid separation aid at 50 wt% of the final formed sediment weight, stirred uniformly, and then a solid-liquid separation experiment was performed using a filter.

[0122]

[0123] After mixing the above slurry and the solid-liquid separation aid, the solid concentration was measured to be about 1.5 to 10 wt%.

[0124] At this time, the filter area of ​​the filter is 100cm 2 am.

[0125] The volume of the separated filtrate according to the filtration time was measured and shown in Figure 2.

[0126] Referring to Figure 2, when no solid-liquid separation aid was mixed, it took about 50 minutes to complete the solid-liquid separation of 1 L of slurry, when solid-liquid separation aid 3 (particle size 150-300 μm) was used, it took about 45 minutes, when solid-liquid separation aid 2 (particle size 100-150 μm) was used, it took about 37 minutes, and when solid-liquid separation aid 1 (particle size 100 μm or less) was used, it took about 30 minutes.

[0127] It was confirmed that when using the high-liquid separation aid 1 (particle size of 100 μm or less), the high-liquid separation time can be shortened by up to 40% compared to when the high-liquid separation aid is not mixed.

[0128] By using the solid-liquid separation aid according to the present invention, the cycle time of the solid-liquid separation process in the process of removing Mg and Ca contained in brine can be shortened, and the filter cloth replacement cycle can be extended, so there is an advantage of being able to dramatically improve productivity.

[0129] In particular, by using the solid-liquid separation aid of the present invention, which utilizes waste by-products discharged from the ore process instead of expensive conventional filter aids, there is an effect that can significantly improve the economic feasibility of the entire process for producing lithium compound products.

[0130]

[0131] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

[0132] Accordingly, the actual scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Step of preparing a solution containing lithium; A precipitation step of forming a precipitate by adding an impurity removing agent to the solution containing the lithium; and A solid-liquid separation step of mixing a solid-liquid separation aid into the slurry obtained in the above precipitation step and putting it into a filter to filter the filtrate; The above high-liquid separation aid comprises ore residue, Method of recovering lithium.

2. Step of preparing a solution containing lithium; A precipitation step of forming a precipitate by adding an impurity removing agent to the solution containing the lithium; and A solid-liquid separation step of putting the slurry obtained in the above precipitation step into a filter and filtering the filtrate; Before putting the slurry into the filter, distilled water in which the high-liquid separation aid is dispersed is put into the filter to form a uniform high-liquid separation aid coating layer on the surface of the filter. Method of recovering lithium.

3. In paragraph 1 or 2, The above ore residue is lithium ore residue. How to recover lithium:

4. In paragraph 1 or 2, The particle size D(90) of the above high-liquid separation aid is 300㎛ or less. Method of recovering lithium.

5. In paragraph 1 or 2, The BET surface area of ​​the above high-liquid separation aid is 200 m 2 / g or more, Method of recovering lithium.

6. In paragraph 1 or 2, In the step of preparing the above lithium-containing solution, The lithium (Li) concentration in the solution containing the lithium is 0.1 to 1.0 g / L. Method of recovering lithium.

7. In paragraph 1 or 2, In the step of preparing the above lithium-containing solution, The concentration ratio of magnesium (Mg) to lithium (Li) in the solution containing the lithium (Mg / Li) is 1500 or more. Method of recovering lithium.

8. In paragraph 1 or 2, In the step of preparing the above lithium-containing solution, The concentration ratio of calcium (Ca) to lithium (Li) in the solution containing the lithium (Ca / Li) is 100 to 200. Method of recovering lithium.

9. In paragraph 1, The amount of the above solid-liquid separation aid is 40 to 60 wt% of the total weight of the solid separated in the above solid-liquid separation step. Method of recovering lithium.

10. In paragraph 1, In the precipitation step of forming a precipitate by adding an impurity remover to the solution containing the lithium, The above impurity remover comprises at least one selected from calcium carbonate (CaCO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), sodium sulfate (Na2SO4), and potassium hydroxide (KOH). Method of recovering lithium.

11. In paragraph 1, The above impurity remover is added in an amount of 0.8 to 1.3 equivalents (eq / mol) based on the total equivalents of magnesium and calcium included in the solution containing lithium. Method of recovering lithium.

12. In paragraph 1 or 2, In the above high-liquid separation step, the filtration speed of the filtrate exceeds 0.1 cm / min. Method of recovering lithium.

13. In paragraph 2, The thickness of the high-liquid separation auxiliary material coating layer is 0.8 to 1.2 cm. Method of recovering lithium.

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