Method for directly extracting lithium contained in brine

Abstract

An embodiment of the present invention provides a method for directly extracting lithium contained in brine, the method comprising the steps of: preparing a lithium-containing brine; adjusting the pH of the lithium-containing brine to 1.0 to 6.0; adding an extraction agent to the lithium-containing brine and then primarily stirring to produce a lithium compound-containing brine, the extraction agent comprising a carbonate compound, a sulfuric acid compound, a phosphate compound, or a combination thereof and a coagulant mixture containing an anionic polymer and an alkaline coagulant; adjusting the pH of the lithium compound-containing brine to 8.5 to 14.0; subjecting the lithium compound-containing brine to secondary stirring to obtain a coagulated lithium compound; subjecting the coagulated lithium compound to solid-liquid separation to separate a lithium compound and treated brine; and dehydrating the separated lithium compound to obtain a first lithium compound and an effluent.

Description

Method for directly extracting lithium contained in brine

[0001] The present invention relates to a method for directly extracting lithium contained in brine.

[0002] Lithium compounds are used across industries, particularly as electrode materials and electrolytes for lithium secondary batteries. Lithium secondary batteries are used in a wide range of industries, including portable electronic devices, electric vehicles (EVs), and energy storage systems (ESS). As these industries rapidly grow, demand for lithium, a key material, is expected to continue to grow.

[0003] Lithium can be obtained by extracting it from mines or brine. First, extracting lithium from mines is a complex process that requires significant energy and costs. Furthermore, the excessive use of acid during the extraction process can lead to environmental pollution.

[0004] Another common method for extracting lithium from brine involves storing underground brine (with a lithium concentration of approximately 300 mg / L to 3,000 mg / L) in ponds and allowing it to evaporate naturally to produce high-concentration lithium compounds. However, the evaporation process requires excessive time, raises concerns about water resource depletion due to the large volume of brine evaporated, and entails environmental damage due to the need for large pond construction sites.

[0005] Accordingly, there is a need for an extraction method that can produce lithium in large quantities economically without causing environmental destruction.

[0006] The present disclosure provides a method for directly extracting lithium contained in brine, which can obtain high concentrations of lithium in an economical and environmentally friendly manner.

[0007] A method for directly extracting lithium contained in brine according to one embodiment comprises the steps of: preparing brine containing lithium; adjusting the pH of the brine containing lithium to be 1.0 to 6.0; adding an extractant comprising a carbonate compound, a sulfuric acid compound, a phosphoric acid compound, or a combination thereof, and a coagulant mixture comprising an anionic polymer and an alkaline coagulant to the brine containing lithium and then first stirring the mixture to produce brine containing a lithium compound; adjusting the pH of the brine containing the lithium compound to be 8.5 to 14.0; second stirring the brine containing the lithium compound to obtain a coagulated lithium compound; solid-liquid separating the coagulated lithium compound to separate the lithium compound and a treated brine; and dehydrating the separated lithium compound to obtain a first lithium compound and a leached solution.

[0008] The method for directly extracting lithium contained in the brine may further include a step of adjusting the pH of the separated treated brine to 7.5 to 11.5 to re-agglomerate the lithium compound; a step of solid-liquid separation of the re-agglomerated lithium compound to separate the re-agglomerated lithium compound and the re-treated brine; and a step of dehydrating the separated re-agglomerated lithium compound to obtain a second lithium compound and the leached liquid.

[0009] In the step of preparing the brine containing lithium, the solubility of lithium in the brine may be 300 mg / L to 3000 mg / L.

[0010] In the step of adjusting the pH of the brine containing lithium to 1.0 to 6.0, a first pH adjusting agent including polyaluminum chloride (PAC), aluminum sulfate, ferric sulfate, ferric chloride, or a combination thereof may be added.

[0011] The carbonate compound may include sodium carbonate, sodium percarbonate, calcium carbonate, potassium carbonate, manganese carbonate, iron carbonate, copper carbonate, zinc carbonate, magnesium carbonate, nickel carbonate, or a combination thereof.

[0012] The above sulfuric acid compound may include sodium sulfate, aluminum sulfate, calcium sulfate, magnesium sulfate, iron sulfate, potassium sulfate, or a combination thereof.

[0013] The above phosphoric acid compound may include sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, calcium phosphate, potassium phosphate, or a combination thereof.

[0014] The above carbonic acid compound may include the sodium carbonate and the sodium percarbonate in a weight ratio of 4:6 to 6:4.

[0015] The above carbonic acid compound is x:(5-x):5 (0) of the sodium carbonate, the sodium percarbonate, and the calcium carbonate. <x<5)의 중량비로 포함할 수 있다.

[0016] The above sulfuric acid compound may include the sodium sulfate and the calcium sulfate in a weight ratio of 4:6 to 6:4.

[0017] The above sulfuric acid compound is y:(5-y):5 (0) of the sodium sulfate, the calcium sulfate, and the potassium sulfate. <y<5)의 중량비로 포함할 수 있다.

[0018] The above phosphoric acid compound may include the sodium phosphate and the sodium hydrogen phosphate in a weight ratio of 4:6 to 6:4.

[0019] The above phosphoric acid compound is the sodium phosphate, the sodium hydrogen phosphate, and the calcium phosphate in the ratio y:(5-y):5 (0 <y<5)의 중량비로 포함할 수 있다.

[0020] The above extractant may contain the carbonic acid compound and the sulfuric acid compound in a weight ratio of 4:6 to 6:4.

[0021] The above extractant may contain the phosphoric acid compound and the sulfuric acid compound in a weight ratio of 4:6 to 6:4.

[0022] The above extractant may contain the phosphoric acid compound and the carbonic acid compound in a weight ratio of 4:6 to 6:4.

[0023] For the above extractant, the carbonic acid compound, sulfuric acid compound, phosphoric acid compound, or a combination thereof and the coagulant mixture may be included in a weight ratio of 4:6 to 6:4.

[0024] For the above coagulant mixture, the anionic polymer and the alkaline coagulant may be included in a weight ratio of 1:3 to 1:10.

[0025] In the above first stirring process, the stirring speed may be 240 rpm / min to 380 rpm / min, and the stirring time may be 1 to 5 minutes.

[0026] In the step of adjusting the pH of the brine to 8.5 to 14.0, a second pH adjusting agent including an alkaline compound may be added.

[0027] The alkaline compound may include sodium aluminate, sodium hydroxide, calcium hydroxide, sodium carbonate, potassium hydroxide, or a combination thereof.

[0028] The step of obtaining a coagulated lithium compound by secondarily stirring the brine in which the lithium compound is produced includes a first coagulation step and a second coagulation step, and the stirring speed of the first coagulation step may be faster than the stirring speed of the second coagulation step.

[0029] The stirring speed of the first coagulation step may be 120 rpm / min to 240 rpm / min, and the stirring speed of the second coagulation step may be 60 rpm / min to 180 rpm / min.

[0030] The step of separating the above-mentioned treated brine may include a solid-liquid separation step using a sieve screen, a belt thickener, a drum screen, or a vibrating screen.

[0031] The step of dehydrating the above lithium compound can use a screw press dehydrator, a belt press dehydrator, or a filter press dehydrator.

[0032] The above-mentioned liquid can be reintroduced into the step of obtaining the above-mentioned aggregated lithium compound.

[0033] By the method of directly extracting lithium contained in the above brine, the production amount of the extracted lithium compound can be 5.0 kg or more when processing 1 ton of brine, based on a lithium solubility of 1300 mg / L in the brine.

[0034] A method for directly extracting lithium contained in brine according to an embodiment of the present invention has the advantage of being able to obtain high concentrations of lithium in an economical and environmentally friendly manner.

[0035] Figures 1 to 3 are flowcharts schematically illustrating a method for directly extracting lithium contained in brine according to one embodiment.

[0036] Figures 4 to 7 show images of each extraction step according to Example 1.

[0037] Figure 8 is a graph showing the production amount of lithium compounds (kg, based on 1 ton of brine treatment) according to reaction time for Example 1 and Examples 10 to 12.

[0038] Below, specific implementation examples are described in detail so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various different forms and is not limited to the implementation examples described herein.

[0039] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0040] Here, “combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0041] It should be understood that the terms "include," "comprising," or "having" herein are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0042] Here, "or" is not interpreted in an exclusive sense, for example, "A or B" is interpreted to include A, B, A+B, etc.

[0043]

[0044] A method for directly extracting lithium contained in brine according to one embodiment includes the steps of: preparing brine containing lithium (S10); adjusting the pH of the brine containing lithium to 1.0 to 6.0 (S20); adding an extractant including a carbonate compound, a sulfuric acid compound, a phosphoric acid compound, or a combination thereof, and a coagulant mixture including an anionic polymer and an alkaline coagulant to the brine containing lithium and then first stirring the mixture to produce brine containing a lithium compound (S30); adjusting the pH of the brine containing the lithium compound to 8.5 to 14.0 (S40); second stirring the brine containing the lithium compound to obtain a coagulated lithium compound (S50); solid-liquid separating the coagulated lithium compound to separate the lithium compound and a treated brine (S60); and dehydrating the separated lithium compound to obtain a first lithium compound and a leached solution (S70).

[0045] For example, the method for directly extracting lithium contained in the brine may further include a step (S80) of adjusting the pH of the separated treated brine to 7.5 to 11.5 to re-agglomerate the lithium compound; a step (S90) of separating the re-agglomerated lithium compound from the re-treated brine by solid-liquid separation; and a step (S100) of dehydrating the separated re-agglomerated lithium compound to obtain a second lithium compound and the leached liquid.

[0046]

[0047] Hereinafter, a method for directly extracting lithium contained in brine according to an embodiment will be described in detail with reference to FIGS. 1 to 3.

[0048] The step (S10) of preparing brine containing the lithium is a step of preparing brine as a lithium source, and may be prepared using naturally existing brine or by dissolving a lithium salt in brine having a salinity of 3% to 5%.

[0049] Any type of lithium salt that can supply lithium to brine can be used without limitation, and lithium hydroxide can be used as a specific example.

[0050] For example, the solubility of lithium in the brine containing lithium may be 300 mg / L to 3000 mg / L.

[0051] For example, in a brine containing lithium salts, lithium is dissolved in Cl present in the brine. - It can exist as ionic and ionic bonded forms, LiCl.

[0052] The step (S20) of adjusting the pH of the brine containing lithium to be 1.0 to 6.0 is a step for increasing the ion exchange reactivity of lithium existing as LiCl before adding an extractant to the brine, and may be a step for adjusting the brine to exhibit acidity.

[0053] For example, by adding an acidic compound, which is a first pH adjuster, to the brine containing lithium, the brine containing lithium can be adjusted to exhibit acidity.

[0054] The first pH adjusting agent may include polyaluminum chloride (PAC), aluminum sulfate, ferric sulfate, ferric chloride, or a combination thereof.

[0055] The step (S30) of adding an extractant to the brine containing lithium and then stirring it for the first time to produce a brine containing a lithium compound may be a step of coagulating lithium into a lithium compound through an ion exchange reaction between lithium and the extractant to form colloid particles.

[0056] For example, the amount of the extractant added may be 1 g to 30 g per 1 L of the brine, for example, 5 g to 30 g, or 5 g to 26 g.

[0057] The extractant comprises a carbonic acid compound, a sulfuric acid compound, a phosphoric acid compound, or a combination thereof; and a coagulant mixture comprising an anionic polymer and an alkaline coagulant.

[0058] The above extractant can coagulate lithium contained in the brine in the form of a lithium compound by including a carbonic acid compound, a sulfuric acid compound, a phosphoric acid compound, or a combination thereof.

[0059]

[0060] For example, the extractant may include both the carbonic acid compound and the sulfuric acid compound, in which case the carbonic acid compound and the sulfuric acid compound may be included in a weight ratio of 4:6 to 6:4. For example, the carbonic acid compound and the sulfuric acid compound may be included in the extractant in a weight ratio of 4:6 to 5:5, or a weight ratio of 4:6 to 4.5:5.5.

[0061] For example, the extractant may include both the phosphoric acid compound and the sulfuric acid compound, in which case the phosphoric acid compound and the sulfuric acid compound may be included in a weight ratio of 4:6 to 6:4. For example, the phosphoric acid compound and the sulfuric acid compound may be included in the extractant in a weight ratio of 4:6 to 5:5, or in a weight ratio of 4:6 to 4.5:5.5.

[0062] For example, the extractant may include both the phosphoric acid compound and the carbonic acid compound, and in this case, the phosphoric acid compound and the carbonic acid compound may be included in a weight ratio of 4:6 to 6:4. For example, the extractant may include the phosphoric acid compound and the carbonic acid compound in a weight ratio of 4:6 to 5:5, or a weight ratio of 4:6 to 4.5:5.5.

[0063] The carbonate compound may be a carbonate or percarbonate containing an alkali metal, an alkaline earth metal, or a transition metal. For example, the carbonate compound may include sodium carbonate, sodium percarbonate, calcium carbonate, potassium carbonate, manganese carbonate, iron carbonate, copper carbonate, zinc carbonate, magnesium carbonate, nickel carbonate, or a combination thereof. As a specific example, the carbonate compound may include sodium carbonate, sodium percarbonate, calcium carbonate, or a combination thereof.

[0064] For example, when the sodium carbonate and the sodium percarbonate are used together as the carbonic acid compound, the weight ratio of the sodium carbonate and the sodium percarbonate may be 4:6 to 6:4, for example, 4:6 to 5:5, or 4:6 to 4.5:5.5.

[0065] For example, when using the sodium carbonate, the sodium percarbonate, and the calcium carbonate as the carbonate compound, the weight ratio of sodium carbonate, sodium percarbonate, and calcium carbonate may be x:(5-x):5 (0 <x<5), 구체적인 일 예로 상기 탄산 화합물에서 탄산나트륨, 과탄산나트륨, 및 탄산칼슘의 중량비는 2:3:5 일 수 있다.

[0066] The sulfuric acid compound may be a sulfate containing an alkali metal, an alkaline earth metal, or a transition metal, and for example, the sulfuric acid compound may include sodium sulfate, aluminum sulfate, calcium sulfate, magnesium sulfate, iron sulfate, potassium sulfate, or a combination thereof. As a specific example, the sulfuric acid compound may include sodium sulfate, calcium sulfate, potassium sulfate, or a combination thereof.

[0067] For example, when the sodium sulfate and the calcium sulfate are used together as the sulfuric acid compound, the weight ratio of sodium sulfate and calcium sulfate may be 4:6 to 6:4.

[0068] For example, when sodium sulfate, calcium sulfate, and potassium sulfate are used as the sulfuric acid compounds, the weight ratio of sodium sulfate, calcium sulfate, and potassium sulfate may be y:(5-y):5 (0 <y<5), 구체적인 일 예로 상기 황산 화합물에서 황산나트륨, 황산칼슘, 및 황산칼륨의 중량비는 2:3:5 일 수 있다.

[0069] The phosphoric acid compound may be a phosphate containing an alkali metal, an alkaline earth metal, or a transition metal, and as an example, the phosphoric acid compound may include sodium phosphate, sodium hydrogen phosphate (sodium phosphate monobasic), sodium dihydrogen phosphate (sodium phosphate dibasic), calcium phosphate, potassium phosphate, or a combination thereof. As a specific example, the phosphoric acid compound may include sodium phosphate, sodium hydrogen phosphate, calcium phosphate, or a combination thereof.

[0070] For example, when the sodium phosphate and the sodium hydrogen phosphate are used together as the phosphoric acid compound, the weight ratio of the sodium phosphate and the sodium hydrogen phosphate may be 4:6 to 6:4.

[0071] For example, when using the sodium phosphate, the sodium hydrogen phosphate, and the calcium phosphate as the phosphoric acid compound, the weight ratio of sodium phosphate, sodium hydrogen phosphate, and calcium phosphate may be y:(5-y):5 (0 <y<5), 구체적인 일 예로 상기 인산 화합물에서 인산나트륨, 인산수소나트륨, 및 인산칼슘의 중량비는 2:3:5 일 수 있다.

[0072] For example, the extractant may include a coagulant mixture including not only the carbonic acid compound, the sulfuric acid compound, or the phosphoric acid compound, but also an anionic polymer and an alkaline coagulant, thereby effectively flocculating the lithium compound in the form of coagulated colloidal particles to produce a lithium compound in the form of flocs.

[0073] For example, for the extractant, the mixing weight ratio of the carbonic acid compound, sulfuric acid compound, phosphoric acid compound, or a combination thereof and the coagulant mixture may be 4:6 to 6:4, for example, 4:6 to 5:5, or 5:5 to 6:4.

[0074] When the above numerical range is satisfied, the lithium compound can be effectively coagulated and the lithium compound can be agglomerated in a short period of time to form a lithium compound in the form of a large particle size floc.

[0075] For example, the anionic polymer may include an acrylamide-based polymer, and the anionic polymer may include a copolymer having acrylamide, sodium acrylate, sodium methacrylate, sodium-2-acrylamide-2-methylpropane sulfonate, or a combination thereof as a structural unit.

[0076] As another example, the anionic polymer may include carboxymethylcellulose (CMC), hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof, or a combination thereof.

[0077] As a specific example, ZipFloc AN-series from Sungchang Co., Ltd. can be used as the anionic polymer, and ZipFloc AN-570F can be used as an example.

[0078] For example, the alkaline coagulant may include sodium aluminate.

[0079] For example, in the coagulant mixture, the anionic polymer and the alkaline coagulant may be included in a weight ratio of 1:5 to 1:10, for example, in a weight ratio of 1:7 to 1:10, or 1:8 to 1:10.

[0080] For example, in the step (S30) of generating the lithium compound, an extractant in the form of a mixture of a carbonate compound, a sulfuric acid compound, a phosphoric acid compound, or a combination thereof; and a coagulant mixture may be added to the brine. If the above components are not all mixed and added to the brine at different times, it may be difficult for the coagulation and agglomeration reaction of the lithium compound to occur effectively.

[0081] In the step (S30) of generating the lithium compound, the first stirring process may be a step of uniformly mixing LiCl in the brine and the introduced extractant so that an ion exchange reaction and an adsorption reaction occur. Through the first stirring process, the LiCl in the brine and the carbonate compound, sulfuric acid compound, or phosphoric acid compound contained in the extractant may undergo an ion exchange reaction, so that the lithium compound may coagulate and become colloidal particles. The lithium compound coagulated through the reaction may exist in the brine in the form of a colloid.

[0082] The lithium compound generated in the above step (S30) may include lithium carbonate, lithium sulfate, lithium phosphate, or a combination thereof.

[0083] For example, when the extractant contains sodium carbonate, the lithium compound produced may be lithium carbonate, and the reaction formula for forming lithium carbonate is as follows.

[0084] [Reaction Formula 1]

[0085] 2LiCl + Na2CO3→ Li2CO3+ 2NaCl

[0086] For example, when the extractant includes calcium carbonate, the lithium compound produced may be lithium carbonate, and the reaction formula for forming lithium carbonate is as follows.

[0087] [Reaction Formula 2]

[0088] 2LiCl + CaCO3 → Li2CO3+ CaCl2

[0089] For example, when the extractant contains sodium sulfate, the lithium compound produced may be lithium sulfate, and the reaction formula for forming lithium sulfate is as follows.

[0090] [Reaction Formula 3]

[0091] 2LiCl + Na2SO4→ Li2SO4+ 2NaCl

[0092] For example, when the extractant contains sodium phosphate, the lithium compound produced may be lithium phosphate, and the reaction formula for forming lithium phosphate is as follows.

[0093] [Reaction Formula 4]

[0094] 3LiCl + Na3PO4→ Li3PO4+ 3NaCl

[0095] For example, in the first stirring process, the stirring speed may be 240 rpm / min to 380 rpm / min, and the stirring time may be 1 minute to 5 minutes, or 1 minute to 3 minutes. When the speed and time of the first stirring are as described above, the lithium compound can be effectively coagulated.

[0096] The step (S40) of adjusting the pH of the brine in which the lithium compound is produced to 8.5 to 14.0 may be a step for fixing the colloidal lithium compound produced in the previous step (S30). When the pH of the brine in which the lithium compound is produced is adjusted to be alkaline, the reverse reaction in which lithium is re-dissolved in the brine in the above reaction formulas 1 to 4 is prevented from occurring, thereby allowing the lithium compound to be obtained more effectively.

[0097] For example, the step (S40) may be a step of adjusting the brine to exhibit alkalinity by adding a second pH adjuster to the brine in which the lithium compound is produced, and the second pH adjuster may include an alkaline compound.

[0098] For example, the alkaline compound may include sodium aluminate, sodium hydroxide, calcium hydroxide, sodium carbonate, potassium hydroxide, or a combination thereof.

[0099]

[0100] The step (S50) of obtaining a coagulated lithium compound by secondarily stirring the brine in which the lithium compound is produced may be a step in which the colloidal lithium compound flocculates to form a lithium compound in the form of flocs.

[0101] In the step (S50) of obtaining the above-described aggregated lithium compound, the coagulant mixture including the above-described anionic polymer and alkaline coagulant effectively coagulates the colloidal lithium compound, thereby forming a lithium compound in the form of flocs having a relatively large particle size. When the lithium compound in the form of flocs having a large particle size is formed, gravity dehydration of the treated brine in the separation step (S60) described later is possible, thereby providing the advantage of economically obtaining a large amount of lithium compound in a short period of time.

[0102] For example, the particle size of the lithium compound in the form of a flock may be 2 mm or more, such as 3 mm or more, 5 mm or more, or 10 mm or more.

[0103] Referring to FIG. 2, the step of coagulating the lithium compound (S50) may include a first coagulation step (S51) and a second coagulation step (S52), and the step of coagulating the lithium compound (S50) may first perform the first coagulation step (S51) and then perform the second coagulation step (S52).

[0104] The first coagulation step (S51) may be a step in which most of the lithium compound in colloidal form coagulates. The stirring speed in the first coagulation step (S51) may be 120 rpm / min to 240 rpm / min, and the stirring time may be 1 minute to 5 minutes, or 1 minute to 3 minutes.

[0105] The second coagulation step is a step in which a secondary coagulation reaction is performed so that fine colloidal particles that were not coagulated in the first coagulation step can be adsorbed to the flocs. Compared to the first coagulation step, the stirring speed may be relatively slow and the stirring time may be relatively short.

[0106] For example, the stirring speed in the second coagulation step (S52) may be 60 rpm / min to 180 rpm / min, and the stirring time may be 1 minute to 3 minutes.

[0107] For example, the sum of the first stirring time and the second stirring time in the step (S30) of generating a brine containing a lithium compound by first stirring and the step (S50) of coagulating the lithium compound by second stirring the brine containing the lithium compound may be referred to as the reaction time, and the reaction time may mean the time taken from the start of step S30 to the end of step S50. For example, the reaction time may be 3 to 20 minutes, for example, 3 to 13 minutes, 5 to 10 minutes, or 5 to 8 minutes.

[0108] The step (S60) of separating the lithium compound and the treatment brine by solid-liquid separation of the above-mentioned coagulated lithium compound may be a step of separating the lithium compound in the form of a floc obtained in the coagulation step (S50) from the treatment brine.

[0109] For example, in the step S60, a solid-state lithium compound and a liquid-state treatment brine can be separated from each other, and a device equipped with a mesh can be used for the solid-liquid separation. For example, a sieve screen, belt thickener, drum mesh screen, or vibrating screen having a pore size of 0.3 mm to 0.7 mm can be used for the solid-liquid separation.

[0110] For example, since the lithium compound in the form of flocs aggregated in the above-described agglomeration step (S50) has a relatively large particle size, solid-liquid separation can be easily achieved when the lithium compound and the treatment brine pass through the devices having the mesh installed.

[0111] The step (S70) of dehydrating the separated lithium compound may be a step of compressing and dehydrating the separated lithium compound to obtain a first lithium compound, which is a final lithium compound, and a dewatering solution.

[0112] The above dehydration step (S70) can be performed using a screw press dehydrator, a belt press dehydrator, or a filter press dehydrator.

[0113] In the above dehydration step, the first lithium compound can be obtained and the remaining leached liquid can be generated, and the leached liquid can be reintroduced into the step (S50) of obtaining the aggregated lithium compound, thereby further increasing the lithium production amount.

[0114]

[0115] Referring to FIG. 3, the separated treatment brine in the step (S60) can be reprocessed through a step (S80) of adjusting the pH of the separated treatment brine to 7.5 to 11.5 to re-agglomerate the lithium compound; a step (S90) of separating the re-agglomerated lithium compound from the re-agglomerated lithium compound by solid-liquid separation; and a step (S100) of dehydrating the separated re-agglomerated lithium compound to obtain a second lithium compound and the leached liquid.

[0116] Since the separated treated brine contains some lithium compounds that were not aggregated in the S50 step, the re-agglomeration step (S80) may be additionally performed to extract the remaining lithium compounds, thereby further increasing the lithium extraction rate.

[0117] The above S80 step can re-agglomerate the residual lithium compound by simply adjusting the pH of the treated brine to 7.5 to 11.5 without additionally adding the aforementioned extractant to the treated brine.

[0118] At this time, in the step of adjusting the pH of the treated brine, a third pH adjusting agent may be added, and the third pH adjusting agent may include polyaluminum chloride (PAC), aluminum sulfate, ferric sulfate, ferric chloride, sodium aluminate, sodium hydroxide, calcium hydroxide, sodium carbonate, potassium hydroxide, or a combination thereof.

[0119] Next, the step (S90) of separating the re-agglomerated lithium compound from the re-processed brine by subjecting the re-agglomerated lithium compound to solid-liquid separation can be performed by the same method as in the step S60 described above, so a detailed description thereof is omitted here.

[0120] For example, the pH of the reprocessed brine separated through the S90 step may be 7.0 to 9.0, and accordingly, the reprocessed brine can be discharged as is, which has the advantage of being environmentally friendly.

[0121] Next, a step (S100) can be performed to dehydrate the separated re-agglomerated lithium compound to obtain a second lithium compound and the above-described liquid. Since the step S100 can be dehydrated in the same manner as the step S70 described above, a detailed description thereof is omitted here.

[0122] Referring to FIG. 3, the first lithium compound can be obtained through steps S10 to S70 described above, and the second lithium compound can be obtained through steps S80 to S100 for the remaining treated brine after obtaining the first lithium compound.

[0123] The first lithium compound and the second lithium compound may each independently be lithium carbonate, lithium sulfate, lithium phosphate, or a combination thereof, and the first lithium compound and the second lithium compound may be the same or different lithium compounds.

[0124] For example, by the method of directly extracting lithium contained in the brine, the production amount of the extracted lithium compound when treating 1 ton of brine may be 3.8 kg or more, for example, 4.0 kg or more, 4.5 kg or more, 5.0 kg or more, 5.5 kg or more, or 6.0 kg or more (based on a lithium solubility of 1300 mg / L in brine).

[0125] For example, one extraction device comprising a method for directly extracting lithium contained in brine according to one embodiment can process at least 40 tons of brine per hour, for example, 50 tons. In this case, the amount of lithium compound produced per hour from one extraction device may be at least 200 kg / hr, for example, at least 220 kg / hr, or at least 240 kg / hr (based on a lithium solubility of 1300 mg / L in brine).

[0126] The method for directly extracting lithium contained in brine according to the above-described embodiment corresponds to the Direct Lithium Extraction (DLE) method. Since lithium can be extracted directly from brine, it does not require the large land required to build a pond used in the natural evaporation method. In addition, the treated brine after extraction can be released back into the water, which prevents the depletion of groundwater resources caused by the use of the natural evaporation method and has the advantage of being an environmentally friendly method. Furthermore, since a single extraction process can be completed within 20 minutes, it is economical and efficient, enabling mass production of lithium. Furthermore, lithium production can be further increased by repeating the re-extraction process for the treated brine and the separated liquid generated during the process.

[0127] Lithium extracted through the method according to the above-described embodiment can be used as a cathode active material of a lithium secondary battery. For example, the cathode active material may be at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. For example, the composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese oxide, or combinations thereof. Using the method according to the embodiment, lithium can be mass-produced in a short period of time in an environmentally friendly manner, so there is an advantage in that the demand for lithium, which is a key material of lithium secondary batteries, can be effectively met.

[0128]

[0129] Hereinafter, examples and comparative examples of the present invention are described. The following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0130]

[0131] Example

[0132] Example 1

[0133] First, lithium hydroxide is dissolved in 1 L of 3% salinity brine at 7000 mg / L to prepare a brine containing lithium as shown in Fig. 4. When the lithium content (mg / L) in the brine is measured using inductively coupled plasma-optical emission spectroscopy (ICP-OES), it can be confirmed to be 1300 mg / L (lithium solubility value of brine before lithium extraction).

[0134] Next, aluminum sulfate is added to the prepared brine to adjust the pH to approximately 3.0.

[0135] Next, for 1 L of the above brine, about 21 g of an extractant, which is a mixture of sodium carbonate and sodium sulfate in a weight ratio of 4:6 and a coagulant mixture in a weight ratio of 5:5, is added. At this time, the coagulant mixture is prepared by mixing an anionic polymer, ZipFloc AN-570F (Seongchang Co., Ltd.), and an alkaline coagulant, sodium aluminate, in a weight ratio of 1:5.

[0136] The mixture of the above-mentioned extractant added to the above-mentioned brine is mixed at a primary stirring speed of 240 rpm / min for 3 minutes to coagulate the lithium compound and form colloid particles. Referring to Fig. 5, it can be confirmed that a lithium compound coagulated in the form of colloid particles is produced at this stage.

[0137] Sodium aluminate is added to the brine in which the lithium compound is produced to adjust the pH of the brine to approximately 13.0.

[0138] Next, the brine is stirred a second time to coagulate the lithium compound. Specifically, the brine is stirred at a speed of 180 rpm / min for approximately 2 minutes to coagulate the lithium compound for the first time, and then stirred at a speed of 90 rpm / min for approximately 2 minutes to coagulate the lithium compound for the second time, coagulating the lithium compound in the form of flocs. Referring to Fig. 6, it can be confirmed that large-particle-sized flocs of lithium compounds are coagulated at this stage.

[0139] Next, the brine is passed through a drum screen to separate the lithium compound and the treated brine into solid and liquid. The obtained lithium compound is compressed and dehydrated in a screw press dehydrator to obtain extracted particles containing the lithium compound according to Example 1, as shown in FIG. 7.

[0140] Example 2

[0141] Extraction particles according to Example 2 are obtained in the same manner as Example 1, except that about 22 g of an extractant, which is a mixture of sodium phosphate and sodium sulfate in a weight ratio of 4:6 per 1 L of brine and a mixture of the coagulant prepared in Example 1 in a weight ratio of 5:5, is added.

[0142] Example 3

[0143] Extraction particles according to Example 3 are obtained in the same manner as in Example 1, except that about 18 g of an extractant, which is a mixture of sodium phosphate and sodium carbonate in a weight ratio of 4:6 per 1 L of brine and a mixture of the coagulant prepared in Example 1 in a weight ratio of 5:5, is added.

[0144] Example 4

[0145] Extraction particles according to Example 4 are obtained in the same manner as in Example 1, except that about 18 g of an extractant, which is a mixture of sodium carbonate and the coagulant prepared in Example 1, is added in a weight ratio of 5:5 to 1 L of brine.

[0146] Example 5

[0147] Extraction particles according to Example 5 are obtained in the same manner as in Example 1, except that about 26 g of an extractant, which is a mixture of sodium sulfate and the coagulant prepared in Example 1, is added in a weight ratio of 5:5 to 1 L of brine.

[0148] Example 6

[0149] Extraction particles according to Example 6 are obtained in the same manner as in Example 1, except that about 18 g of an extractant, which is a mixture of sodium phosphate and the coagulant prepared in Example 1, is added in a weight ratio of 5:5 to 1 L of brine.

[0150] Example 7

[0151] In the above Example 1, the pH of the treated brine separated from the solid and liquid is adjusted to about 9.0 to re-agglomerate the lithium compound, and the re-agglomerated lithium compound is further separated from the solid and liquid and dehydrated, thereby obtaining the extracted particles according to Example 7.

[0152] Example 8

[0153] In the above Example 2, the pH of the separated brine is adjusted to about 9.0 to re-agglomerate the lithium compound, and the re-agglomerated lithium compound is further dehydrated by solid-liquid separation, thereby obtaining the extracted particles according to Example 8.

[0154] Example 9

[0155] In the above Example 3, the pH of the separated brine is adjusted to about 9.0 to re-agglomerate the lithium compound, and the re-agglomerated lithium compound is further dehydrated by solid-liquid separation, thereby obtaining the extracted particles according to Example 9.

[0156] Examples 10 to 12

[0157] Extracted particles according to Examples 10 to 12 were obtained in the same manner as in Example 1, except that the reaction time was changed as shown in Table 2 below.

[0158] The above reaction time means the sum of the first stirring time and the second stirring time, and the second stirring time means the sum of the first coagulation stirring time and the second coagulation stirring time.

[0159] Specifically, in the case of Example 10, the first stirring time is 1 minute / the first coagulation stirring time is 1 minute / the second coagulation stirring time is 1 minute. (Reaction time: 3 minutes)

[0160] Specifically, in the case of Example 11, the first stirring time is 1 minute / the first coagulation stirring time is 2 minutes / the second coagulation stirring time is 2 minutes. (Reaction time: 5 minutes)

[0161] Specifically, in the case of Example 12, the first stirring time is 4 minutes / the first coagulation stirring time is 4 minutes / the second coagulation stirring time is 4 minutes. (Reaction time: 12 minutes)

[0162]

[0163] Evaluation example: Production of lithium compounds

[0164] The weights of the extracted particles obtained according to Examples 1 to 12 are shown in Tables 1 and 2 below. Next, the content ratio (%) of lithium per 1 kg of the extracted particles was measured through ICP-OES analysis and shown in Tables 1 and 2 below.

[0165] Next, the content ratio (%) of lithium compounds contained per 1 kg of extracted particles is calculated using the content ratio (%) of lithium measured above and lithium carbonate equivalent (LCE) according to the following [Formula 1] and is shown in Tables 1 and 2.

[0166] [Formula 1]

[0167] Content of lithium compounds in the extracted particles (%) = 5.32 x Content of lithium in the extracted particles (%)

[0168] In addition, for each example, the amount of lithium compound produced when 1 ton of brine is processed per device is calculated according to [Formula 2] below and shown in Tables 1 and 2.

[0169] [Formula 2]

[0170] Lithium compound production (kg, based on processing 1 ton of brine) = Weight of extracted particles (kg) x Content of lithium compound in extracted particles (%) x 1000

[0171] In addition, for Example 1 and Examples 10 to 12, which have different reaction times (sum of the first and second stirring times), the production amount (kg) of lithium compounds when 1 ton of brine is treated according to the reaction time is shown in a graph in Figure 8.

[0172] Weight of extracted particles (kg) Content of lithium in extracted particles (%, per 1 kg) Content of lithium compound in extracted particles (%, per 1 kg) Lithium compound production (kg) (based on treatment of 1 ton of brine) Example 10.0492 kg 2.02% 2.02 x 5.32 = 10.746% 5.287 kg Example 20.0456 kg 1.83% 1.83 x 5.32 = 9.736% 4.44 kg Example 30.0436 kg 1.83% 1.83 x 5.32 = 9.736% 4.25 kg Example 40.0504 kg 1.97% 1.97 x 5.32 = 10.481% 5.282 kg Example 50.0488 kg 1.85% 1.85 x 5.32 = 9.842%4.80kgExample 60.0443kg1.93%1.93 x 5.32 = 10.267%4.55kgExample 7 (1st extraction)0.0492kg2.02%2.02 x 5.32 = 10.746%5.287kgTotal 6.539kg(2nd extraction)0.0122kg1.93%1.93 x 5.32 = 10.267%1.252kgExample 8 (1st extraction)0.0456kg1.83%1.83 x 5.32 = 9.736%4.44kgTotal 4.928kg(2nd extraction)0.0069kg1.33%1.33 x 5.32 = 7.075%0.488kgExample 9 (1st extraction)0.0436kg1.83%1.83 x 5.32 = 9.736%4.25kgTotal5.594kg(2nd extraction)0.0160kg1.58%1.58 x 5.32 = 8.405%1.344kg

[0173]

[0174] Referring to Table 1, it can be confirmed that the lithium compound production (kg) is 4.25 kg or more when 1 ton of brine is treated in Examples 1 to 6, and it can be confirmed that the lithium compound production is particularly high in Examples 1 and 4.

[0175] In addition, in the case of Examples 7, 8, and 9, a second extraction (re-extraction) was performed on Examples 1, 2, and 3, respectively, and it was confirmed that the sum of the lithium compound production amounts in the first and second extractions was significantly higher than that in the first extraction.

[0176] Weight of extracted particles (kg) Content of lithium in extracted particles (%, per 1 kg) Content of lithium compound in extracted particles (%, per 1 kg) Production of lithium compound (kg) (based on treatment of 1 ton of brine) Example 10 (Reaction time: 3 minutes) 0.0345 kg 2.08% 2.08 kg x 5.32 = 11.065% 3.817 kg Example 11 (Reaction time: 5 minutes) 0.0502 kg 1.90% 1.90 kg x 5.32 = 10.108% 5.074 kg Example 1 (Reaction time: 7 minutes) 0.0492 kg 2.02% 2.02 kg x 5.32 = 10.746% 5.287 kg Example 12 (Reaction time: 12 minutes) 0.0488kg 1.85% 1.85kg x 5.32 = 9.842% 4.802kg

[0177] Referring to Table 2 and Figure 8, it can be confirmed that when the reaction time is 3 to 12 minutes, the production amount (kg) of lithium compounds is about 3.8 kg or more when 1 ton of brine is treated, and in particular, it can be confirmed that the production amount (kg) of lithium compounds is high in Example 1 (reaction time: 7 minutes) and Example 11 (reaction time: 5 minutes).

[0178]

[0179] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

[0180]

[0181]

[0182]

[0183]

[0184] [Explanation of symbols]

[0185] S10: Preparation of brine containing lithium

[0186] S20: Brine pH adjustment step

[0187] S30: Step of adding an extractant to brine and stirring it for the first time to produce brine containing a lithium compound.

[0188] S40: pH adjustment step of brine in which lithium compounds are produced

[0189] S50: Step of obtaining a coagulated lithium compound by secondary stirring of the brine in which the lithium compound is produced.

[0190] S51: First coagulation stage

[0191] S52: Second coagulation stage

[0192] S60: A step for separating the lithium compound and the treatment brine by separating the solid and liquid of the coagulated lithium compound.

[0193] S70: Step of dehydrating the separated lithium compound to obtain a first lithium compound and a separation solution.

[0194] S80: Step of re-agglomerating lithium compounds by adjusting the pH of the separated treatment brine.

[0195] S90: A step of separating the re-agglomerated lithium compound from the re-processed brine by separating the re-agglomerated lithium compound from the solid and liquid.

[0196] S100: Step of dehydrating the separated re-agglomerated lithium compound to obtain a second lithium compound and a separation solution.

Claims

1. A step of preparing a brine containing lithium; A step of adjusting the pH of the brine containing the lithium to be 1.0 to 6.0; A step of first stirring the brine containing lithium by adding an extractant including a carbonate compound, a sulfuric acid compound, a phosphoric acid compound, or a combination thereof, and a coagulant mixture including an anionic polymer and an alkaline coagulant to the brine containing lithium, thereby generating a brine containing a lithium compound; A step of adjusting the pH of the brine containing the lithium compound to 8.5 to 14.0; A step of obtaining a coagulated lithium compound by secondarily stirring the brine containing the lithium compound; A step of separating the lithium compound and the treatment brine by solid-liquid separation of the above-mentioned coagulated lithium compound; and A method for directly extracting lithium contained in brine, comprising a step of dehydrating the separated lithium compound to obtain a first lithium compound and a separation solution.

2. In paragraph 1, The method for directly extracting lithium contained in the brine comprises the steps of: adjusting the pH of the separated treated brine to 7.5 to 11.5 to re-agglomerate the lithium compound; A step of separating the re-agglomerated lithium compound from the re-processed brine by solid-liquid separation; and A method for directly extracting lithium contained in brine, further comprising the step of dehydrating the separated and re-agglomerated lithium compound to obtain a second lithium compound and the above-desorbed liquid.

3. In paragraph 1, In the step of preparing the brine containing the lithium, A method for directly extracting lithium contained in brine, wherein the solubility of lithium in the brine is 300 mg / L to 3000 mg / L.

4. In paragraph 1, In the step of adjusting the pH of the brine containing lithium to 1.0 to 6.0, A method for directly extracting lithium contained in brine, wherein a first pH adjusting agent comprising polyaluminum chloride (PAC), aluminum sulfate, ferric sulfate, ferric chloride, or a combination thereof is added.

5. In paragraph 1, A method for directly extracting lithium contained in a brine, wherein the carbonate compound comprises sodium carbonate, sodium percarbonate, calcium carbonate, potassium carbonate, manganese carbonate, iron carbonate, copper carbonate, zinc carbonate, magnesium carbonate, nickel carbonate, or a combination thereof.

6. In paragraph 1, A method for directly extracting lithium contained in a brine, wherein the sulfuric acid compound comprises sodium sulfate, aluminum sulfate, calcium sulfate, magnesium sulfate, iron sulfate, potassium sulfate, or a combination thereof.

7. In paragraph 1, A method for directly extracting lithium contained in a brine, wherein the phosphoric acid compound comprises sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, calcium phosphate, potassium phosphate, or a combination thereof.

8. In paragraph 5, A method for directly extracting lithium contained in a brine, wherein the carbonate compound comprises sodium carbonate and sodium percarbonate in a weight ratio of 4:6 to 6:

4.

9. In paragraph 5, The above carbonic acid compound is x:(5-x):5 (0) of the sodium carbonate, the sodium percarbonate, and the calcium carbonate. <x<5)의 중량비로 포함하는, 염수에 포함된 리튬을 직접 추출하는 방법.

10. In paragraph 6, A method for directly extracting lithium contained in a brine, wherein the sulfuric acid compound comprises sodium sulfate and calcium sulfate in a weight ratio of 4:6 to 6:

4.

11. In paragraph 6, The above sulfuric acid compound is y:(5-y):5 (0) of the sodium sulfate, the calcium sulfate, and the potassium sulfate. <y<5)의 중량비로 포함하는, 염수에 포함된 리튬을 직접 추출하는 방법.

12. In paragraph 7, A method for directly extracting lithium contained in a brine, wherein the phosphoric acid compound comprises sodium phosphate and sodium hydrogen phosphate in a weight ratio of 4:6 to 6:

4.

13. In paragraph 7, The above phosphoric acid compound is the sodium phosphate, the sodium hydrogen phosphate, and the calcium phosphate in the ratio y:(5-y):5 (0 <y<5)의 중량비로 포함하는, 염수에 포함된 리튬을 직접 추출하는 방법.

14. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the extractant comprises the carbonate compound and the sulfuric acid compound in a weight ratio of 4:6 to 6:

4.

15. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the extractant comprises the phosphoric acid compound and the sulfuric acid compound in a weight ratio of 4:6 to 6:

4.

16. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the extractant comprises the phosphoric acid compound and the carbonic acid compound in a weight ratio of 4:6 to 6:

4.

17. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the carbonate compound, sulfuric acid compound, phosphoric acid compound, or a combination thereof and the coagulant mixture are included in a weight ratio of 4:6 to 6:

4.

18. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the anionic polymer and the alkaline coagulant are included in a weight ratio of 1:3 to 1:10 in the coagulant mixture.

19. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the stirring speed in the first stirring process is 240 rpm / min to 380 rpm / min and the stirring time is 1 to 5 minutes.

20. In paragraph 1, In the step of adjusting the pH of the above brine to 8.5 to 14.0, A method for directly extracting lithium contained in brine by adding a second pH adjusting agent containing an alkaline compound.

21. In paragraph 20, A method for directly extracting lithium contained in brine, wherein the alkaline compound comprises sodium aluminate, sodium hydroxide, calcium hydroxide, sodium carbonate, potassium hydroxide, or a combination thereof.

22. In paragraph 1, A method for directly extracting lithium contained in a brine, wherein the step of obtaining a coagulated lithium compound by secondarily stirring the brine in which the lithium compound is produced includes a first coagulation step and a second coagulation step, and the stirring speed of the first coagulation step is faster than the stirring speed of the second coagulation step.

23. In paragraph 22, The stirring speed of the first coagulation step is 120 rpm / min to 240 rpm / min, A method for directly extracting lithium contained in brine, wherein the stirring speed of the second coagulation step is 60 rpm / min to 180 rpm / min.

24. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the step of separating the above-mentioned treated brine includes a solid-liquid separation step using a sieve screen, a belt thickener, a drum screen, or a vibrating screen.

25. In paragraph 1, The step of dehydrating the lithium compound is a method for directly extracting lithium contained in brine using a screw press dehydrator, belt press dehydrator, or filter press dehydrator.

26. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the above-mentioned separation solution is reintroduced into the step of obtaining the above-mentioned coagulated lithium compound.

27. In paragraph 1, A method for directly extracting lithium contained in brine, wherein the production amount of the extracted lithium compound is 5.0 kg or more when processing 1 ton of brine based on a lithium solubility of 1300 mg / L in the brine by the method for directly extracting lithium contained in the brine.

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