Method for preparing lithium carbonate

Abstract

Provided is a method for preparing lithium carbonate, comprising the steps of: removing sulfur from lithium-containing brine; removing magnesium and calcium from the lithium-containing brine; removing boron and calcium from the lithium-containing brine; removing sodium and potassium from the lithium-containing brine; and extracting lithium carbonate from the lithium-containing brine.

Description

Method for manufacturing lithium carbonate

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

[0002] Lithium carbonate produced from brine is obtained by removing impurities to increase the purity of the lithium carbonate. To obtain high-purity lithium carbonate of battery grade, the extracted low-purity lithium carbonate is first slurried, then converted into a lithium bicarbonate (LiHCO3) solution using CO2 gas, then further removed divalent impurities (Ca, Mg) using an ion exchange method, and the lithium carbonate is reprecipitated by raising the temperature to produce high-purity lithium carbonate of battery grade.

[0003] The objective of the present invention is to provide a method for producing high-purity lithium carbonate by omitting the bicarbonate oxidation process.

[0004] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0005] In one embodiment of the present invention, a method for producing lithium carbonate is provided, comprising the steps of: removing sulfur from a lithium-containing brine; removing magnesium and calcium from a lithium-containing brine; removing boron and calcium from a lithium-containing brine; removing sodium and potassium from a lithium-containing brine; and extracting lithium carbonate from a lithium-containing brine.

[0006] Sulfur can be removed by removing the CaSO4 generated by adding a calcium-containing auxiliary material to the above lithium-containing brine.

[0007] Magnesium and calcium can be removed by introducing a carbonate ion source into the above lithium-containing brine to remove the generated MgCO3 or CaCO3.

[0008] Boron and calcium can be removed from the above lithium-containing brine using an ion exchange resin.

[0009] Sodium and potassium can be removed by precipitating them through the above lithium-containing brine by evaporating it under high temperature and reduced pressure.

[0010] The lithium-containing brine can be evaporated at high temperature and reduced pressure so that 40 to 60 wt% of the sodium or potassium content in the lithium-containing brine is removed.

[0011]

[0012] The above method for manufacturing lithium carbonate can extract lithium carbonate by introducing a carbonate ion source into the lithium-containing brine.

[0013] The method for manufacturing the lithium carbonate described above further includes the step of concentrating the lithium-containing brine, and the lithium-containing brine may be the concentrated lithium-containing brine.

[0014] The above method for manufacturing lithium carbonate may further include a step of separating the lithium carbonate and then washing it to remove impurities.

[0015] The above method for manufacturing lithium carbonate may not additionally perform a bicarbonate step.

[0016] In the above method for manufacturing lithium carbonate, the purity of the lithium carbonate in the resulting product obtained after separating and washing the extracted lithium carbonate may be 99.2 wt% or higher.

[0017]

[0018] In one embodiment of the present invention, solid lithium carbonate with a purity of 99.0 wt% or higher can be obtained according to the method for producing lithium carbonate, without additionally performing a bicarbonation step.

[0019] According to the above method for manufacturing lithium carbonate, high-purity lithium carbonate can be obtained, so the bicarbonate oxidation process can be omitted.

[0020] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0021] Figure 1 is a flowchart of the method for manufacturing the lithium carbonate.

[0022] FIG. 2 shows a schematic diagram of a method for manufacturing lithium carbonate according to one embodiment of the present invention.

[0023] Figures 3 and 4 are process schematic diagrams designed to simulate a method for extracting lithium carbonate.

[0024] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0025] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0026] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0027] In this specification, lithium, sulfur, magnesium, calcium, sodium, potassium, etc., may be in a form that exists in raw materials, extracts, or precipitates, and are collectively referred to as types of elements without being limited to a specific form, such as metal atoms, atoms, ions, or salts, and when distinction is necessary, they may be understood as being in a state that exists according to the laws of nature.

[0028] In one embodiment of the present invention:

[0029] Step of removing sulfur from lithium-containing brine;

[0030] Step of removing magnesium and calcium from lithium-containing brine;

[0031] Step of removing boron and calcium from lithium-containing brine;

[0032] Step of removing sodium and potassium from lithium-containing brine; and

[0033] A method for producing lithium carbonate is provided, comprising the step of extracting lithium carbonate from a lithium-containing brine.

[0034] By the above method for manufacturing lithium carbonate, impurities can be efficiently removed from brine, and the desired lithium carbonate can be obtained with high purity. By the above method for manufacturing lithium carbonate, high-purity lithium carbonate of battery grade can be obtained. Therefore, the above method for manufacturing lithium carbonate may not require an additional bicarbonation process to obtain high-purity lithium carbonate of battery grade. In other words, the above method for manufacturing lithium carbonate can produce high-purity battery-grade lithium carbonate without additionally performing a bicarbonation process.

[0035] The above method for manufacturing lithium carbonate can perform each of the above steps sequentially. FIG. 1 is a flowchart of the method for manufacturing lithium carbonate.

[0036] In the step (S10) of removing sulfur, sulfur can be removed by removing CaSO4 generated by adding a calcium-containing auxiliary material to the lithium-containing brine.

[0037] The calcium-containing auxiliary raw material may be a compound capable of forming a precipitate with sulfate ions, for example, CaCl2, CaO, Ca(OH)2, etc., and one or more of these may be used. The calcium-containing auxiliary raw material may be added in an amount equivalent to one equivalent of sulfur (S) contained in the lithium-containing brine. After adding the calcium-containing auxiliary raw material, the calcium content in the brine may increase, but it can be precipitated as CaCO3 in a subsequent step or removed using an ion exchange resin.

[0038] In the step (S20) of removing magnesium and calcium, magnesium and calcium can be removed by adding a carbonate ion source to the lithium-containing brine to remove the generated MgCO3 and CaCO3.

[0039] The above carbonate ion source may use a carbonate compound capable of forming precipitates of magnesium ions and / or calcium ions and MgCO3 and / or CaCO3, for example, Na2CO3, K2CO3, Li2CO3, etc., and one or more of these may be used.

[0040] In the step (S30) of removing boron and calcium, boron and calcium can be removed from the lithium-containing brine using an ion exchange resin. An ion exchange resin capable of adsorbing boron and / or calcium can be used, and the boron and / or calcium contained in the lithium-containing brine can be removed by adsorbing them onto the ion exchange resin through contact with the lithium-containing brine.

[0041] In one embodiment, in the step (S30) of removing boron and calcium, the boron content can be removed to about 40 to 60 wt%.

[0042] In the step (S40) of removing sodium and potassium, the lithium-containing brine can be removed by precipitating the sodium and potassium by evaporating it at high temperature and reduced pressure. When the brine is evaporated at high temperature and reduced pressure in a concentration crystallization facility, the sodium ions and potassium ions in the brine crystallize and precipitate in the form of, for example, NaCl or KCl, so they can be removed by solid-liquid separation.

[0043] In one embodiment, in the step (S40) of removing sodium and potassium, the lithium-containing brine may be evaporated at high temperature and reduced pressure to a degree such that 40 to 60 wt% is removed based on sodium content.

[0044] In one embodiment, in the step (S40) of removing sodium and potassium, the lithium-containing brine may be evaporated at high temperature and reduced pressure to a degree such that 40 to 60 wt% is removed based on potassium content.

[0045] After the step (S40) of removing sodium and potassium, a portion of the condensate may be added back into the lithium-containing brine to dilute it. By diluting in this way, the concentrated lithium concentration can be adjusted to a level similar to the concentration immediately before the step (S40) of removing sodium and potassium.

[0046] In the step (S50) of extracting lithium carbonate from the lithium-containing brine, lithium carbonate can be extracted by introducing a carbonate ion source into the lithium-containing brine. The carbonate ion source can be introduced in an amount corresponding to 1 equivalent of the lithium (Li) contained in the lithium-containing brine.

[0047] The above carbonate ion source may use a carbonate compound capable of forming lithium ions and Li2CO3, for example, Na2CO3, K2CO3, Li2CO3, etc., and one or more of these may be used.

[0048] The method for producing the lithium carbonate described above may further include a step of concentrating the lithium-containing brine before the step of removing the sulfur (S10). Accordingly, the lithium-containing brine may be a concentrated lithium-containing brine. The method of concentrating the lithium-containing brine may be by a method known to evaporate water to increase the concentration of lithium or lithium ions, for example, by natural evaporation, but is not limited thereto.

[0049] For example, in the step of concentrating the lithium-containing brine, the lithium-containing brine can be concentrated 2 to 50 times.

[0050] The above method for manufacturing lithium carbonate may further include a step of separating the lithium carbonate and then washing it to remove impurities.

[0051] For example, the extracted lithium carbonate can be separated into a slurry form, and the purity can be increased by further lowering the content of impurities that are easy to remove by washing with water, such as Na and K.

[0052] After performing a decarburization process on the filtrate from which lithium carbonate is extracted and separated, it can be recirculated to the step (S10) of removing sulfur from the lithium-containing brine.

[0053] FIG. 2 shows a schematic diagram of a method for manufacturing lithium carbonate according to one embodiment of the present invention.

[0054] In one embodiment, the product obtained by extracting lithium carbonate and separating solids and liquids may have a sodium content of 1.23 wt% or less before washing.

[0055] In one embodiment, the product obtained by extracting lithium carbonate and separating solids and liquids may have a potassium content of 0.29 wt% or less after washing.

[0056] In one embodiment, the product obtained by extracting lithium carbonate and separating solids and liquids may have a potassium content of 0.29 wt% or less before washing.

[0057] Among the results obtained after separating and washing the lithium carbonate extracted by the above method for manufacturing lithium carbonate, the purity of the lithium carbonate may be 99.2 wt% or higher.

[0058] In one embodiment of the present invention, solid lithium carbonate with a purity of 99.0 wt% or higher is provided, which is obtained according to the method for producing the lithium carbonate and is obtained without additionally performing a bicarbonation step.

[0059]

[0060] Examples and comparative examples of the present invention are described below. The following examples are merely embodiments of the present invention, and the present invention is not limited to the following examples.

[0061]

[0062] (Example)

[0063] The process of extracting lithium carbonate from the brine of Example 1 and Comparative Example 1 was simulated using a process simulation program, and the concentration of the element contained in the brine was calculated at each step.

[0064] Example 1

[0065] A method for extracting lithium carbonate was simulated in the process sequence shown in Figure 3.

[0066] (1) The brine was concentrated twice.

[0067] (2) S removal (S10): 35 wt% CaCl2 was added in an amount equal to 1 equivalent of S, so the S concentration increased from 2.25 to 1.63 g / L and the Ca concentration increased from 15.4 to 17.2 g / L.

[0068] (3) Mg / Ca removal (S20): 172.96 g of 25 wt% Na2CO3 solution was used in 1 L of concentrated brine. (Li loss due to water loss 0.77 wt%)

[0069] (4) B / Ca ion exchange (S30)

[0070] (5) Na / K removal (concentration crystallization) (S40): After removing 50 wt% of Na by mass, it was assumed that 50 wt% of K by mass was removed by further concentration.

[0071] (6) Dilution: Diluted to a Li concentration of 12 g / L.

[0072] (7) Lithium carbonate extraction (S50): Na2CO3 was added in an amount equal to 1 equivalent of Li. The moisture content was assumed to be 20 wt%.

[0073] (8) Washing: Washed with three times the amount of hot water. The moisture content was assumed to be 20 wt% even after washing.

[0074]

[0075] The concentration was calculated after each step using the OLI program, and the results are shown in Table 1 below. After separating the extracted lithium carbonate, the component ratios before and after washing are shown in Table 2.

[0076]

[0077] g / L 1st Concentration 2nd Concentration After S Removal Mg / Ca Removal LC Extract Stock Solution (Before Dilution After Concentration and Crystallization) LC Extract Filtrate pH 7.0 10.96 10.87 9.86 12.18 11.27 Li 1.93 12.000 11.80 7 10.012 12.000 1.250 Mg 4.57 0.025 0.024 0.0000.0000.000 Ca 0.51 11 15.39 217.179 0.1000.002 0.0 02Na96.568.28766.80673.2599.10356.311K1842.15441.47635.17121.0771 3.396B1.292.8742.8282.3980.8890.565S2.992.2531.6281.3801.6551.052

[0078] (wt.%) Before washing After washing Li 18.06 18.73 (Lithium carbonate) (96.16) (99.68) Mg 4.67 * 10 -9 3.00*10 -10 Ca3.34*10 -5 2.15*10 -6 Na1.230.08K0.290.02B0.017.96*10 -4 S0.021.48*10 -3

[0079] Comparative Example 1

[0080] A method for extracting lithium carbonate was simulated in the process sequence shown in Fig. 4.

[0081] (1) The brine was concentrated twice.

[0082] (2) Mg / Ca removal: 154.87 g of 25 wt% Na2CO3 solution was used in 1 L of concentrated brine. (Li loss due to water loss 0.69 wt%)

[0083] (3) Ca ion exchange: It was assumed that 98 wt% of Ca and Mg would be removed. Since the OLI program could only remove cations, they were removed in the form of CaO and MgO, which resulted in a decrease in pH.

[0084] (4) Lithium carbonate extraction: 1 equivalent of Li was added as Na2CO3. The moisture content was assumed to be 20 wt%.

[0085] (5) Washing: Washed with three times the amount of hot water. The moisture content was assumed to be 20 wt% even after washing.

[0086]

[0087] The concentration was calculated after each step using the OLI program, and the results are shown in Table 3 below. After separating the extracted lithium carbonate, the component ratios before and after washing are shown in Table 4.

[0088]

[0089] (g / L) 1st Concentration 2nd Concentration Mg / Ca After Removal Ca After Ion Exchange LC Extraction Filtrate pH 7.0 10.96 9.86 9.62 10.53 Li 1.93 12.000 10.296 10.296 1.275 Mg 4.57 0.025 0.0000.0000.000 Ca 0.51 115.39 20.1000.002 0.001 Na 9.56 8.287 73.635 73.6339 5.439 K 184 2.154 36.166 36.165 24.335 B 1.290 2.874 2.466 2.466 1.659 S 2.990 2.253 1.933 1.933 1.300

[0090] (wt.%) Before Wash After Wash Li 15.59 18.68 (Lithium Carbonate) (93.63) (99.46) Mg 3.78 * 10 -8 2.49*10 -9 Ca2.69*10 -5 1.77*10 -6 Na1.910.13K0.490.03B0.032.19*10 -3 S0.031.71*10 -3

[0091] Comparing the simulation results of Example 1 and Comparative Example 1, Table 2 shows that the purity of lithium carbonate before and after washing in Example 1 was 96.16 wt% and 99.68 wt%, respectively, which is superior to the purity of lithium carbonate before and after washing in Comparative Example 1 in Table 4, which was 93.63 wt% and 99.46 wt%. In Example 1 in Table 2, it can be confirmed that the impurity concentration of B was further reduced compared to Comparative Example 1 in Table 4, and the concentrations of other impurities S, Na, and K were also all further reduced in Example 1. However, although the purity of lithium carbonate in Comparative Example 1 was lower than that of Example 1 in the simulation results, an even lower value was obtained when the process was actually carried out. Therefore, in the actual results of Comparative Example 1, the purity dropped significantly, so a bicarbonation step was required to further increase the purity.

[0092] Although the present invention has been described above with reference to embodiments, the present invention is not limited by the embodiments disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. Step of removing sulfur from lithium-containing brine; Step of removing magnesium and calcium from lithium-containing brine; Step of removing boron and calcium from lithium-containing brine; Step of removing sodium and potassium from lithium-containing brine; and A step of extracting lithium carbonate from a lithium-containing brine; Method for manufacturing lithium carbonate.

2. In Paragraph 1, Sulfur is removed by removing CaSO4 generated by adding calcium-containing auxiliary materials to the above lithium-containing brine. Method for manufacturing lithium carbonate.

3. In Paragraph 1, Removing magnesium and calcium by removing MgCO3 or CaCO3 generated by adding a carbonate ion source to the above lithium-containing brine. Method for manufacturing lithium carbonate.

4. In Paragraph 1, Removal of boron and calcium from the above lithium-containing brine using an ion exchange resin Method for manufacturing lithium carbonate.

5. In Paragraph 1, The above lithium-containing brine is evaporated at high temperature and reduced pressure to precipitate and remove sodium and potassium. Method for manufacturing lithium carbonate.

6. In Paragraph 1, Evaporating the lithium-containing brine at high temperature and reduced pressure so that 40 to 60 wt% of the sodium or potassium content in the lithium-containing brine is removed. Method for manufacturing lithium carbonate.

7. In Paragraph 1, Lithium carbonate is extracted by adding a carbonate ion source to the above lithium-containing brine. Method for manufacturing lithium carbonate.

8. In Paragraph 1, Performing the above steps sequentially Method for manufacturing lithium carbonate.

9. In Paragraph 1, The above includes a step of further concentrating the lithium-containing brine, wherein the lithium-containing brine is a concentrated lithium-containing brine. Method for manufacturing lithium carbonate.

10. In Paragraph 1, A step of separating lithium carbonate and then washing to remove impurities is further included. Method for manufacturing lithium carbonate.

11. In Paragraph 1, Not performing an additional bicarbonate step Method for manufacturing lithium carbonate.

12. In Paragraph 11, Among the results obtained after separating and washing the extracted lithium carbonate above, the purity of the lithium carbonate is 99.2 wt% or higher Method for manufacturing lithium carbonate.

13. Solid lithium carbonate with a purity of 99.0 wt% or higher, obtained according to the method for producing lithium carbonate of claim 1 and without additionally performing a bicarbonation step.

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