Separating method of lithium carbonate

Abstract

A separating method of lithium carbonate, according to the present invention, comprises the steps of: preparing a slurry containing a mixture of lithium carbonate and an oxide containing at least one element selected from the group consisting of Al and Si; injecting a hydrophobizing agent into the slurry so as to cause the particle surface of the lithium carbonate to be hydrophobic; injecting bubbles into the slurry and collecting suspended matter; and filtering the suspended matter so as to collect lithium carbonate.

Description

Method for separating lithium carbonate

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

[0002] With the advent of the electric vehicle era, the lithium-ion battery industry is growing rapidly, and as a result, the demand for lithium as a battery material is continuously increasing.

[0003] Lithium is primarily used industrially in the form of carbonates and hydroxides. For example, naturally occurring lithium is ionized through leaching, purified to remove impurities, and then carbonated or crystallized to produce lithium salts for industrial use.

[0004] However, some lithium carbonate exists in nature, and intermediates or byproducts containing lithium carbonate also exist.

[0005] At this time, in order to recover a small amount of lithium carbonate mixed with other substances, a method of leaching with acid to ionize lithium and then carbonating it again is generally used.

[0006] However, this method requires a large amount of processing equipment to recover a small amount of lithium, and there is a problem that many types of impurities are inevitably leached together when lithium is leached, so they must be purified again.

[0007] Therefore, there is a need for the development of a technology that can selectively separate lithium carbonate from a mixture containing a small amount of lithium carbonate.

[0008] The present invention aims to provide a method for separating lithium carbonate, which can selectively separate lithium carbonate from a mixture containing lithium carbonate, specifically from a mixture containing a small amount of lithium carbonate.

[0009] The present invention provides a method for separating lithium carbonate, comprising the steps of: preparing a slurry comprising a mixture of an oxide containing at least one element selected from the group consisting of Al and Si and lithium carbonate; adding a hydrophobic agent to the slurry to change the particle surface of the lithium carbonate to be hydrophobic; injecting bubbles into the slurry and recovering a suspended solid; and filtering the suspended solid to recover lithium carbonate.

[0010] The method for separating lithium carbonate according to the present invention has the advantage of being able to selectively and easily separate only lithium carbonate from a mixture containing a small amount of lithium carbonate.

[0011] Figure 1 is a diagram showing the results of a mineralogical analysis of a mixture containing lithium carbonate according to Example 1.

[0012] Figure 2 is a diagram showing the results of a mineral analysis of a floating substance according to Example 1.

[0013] Figure 3 is a diagram showing the lithium carbonate recovery rate according to pH in Example 2.

[0014] Figure 4 is a diagram showing the results of a mineralogical analysis of a mixture containing lithium carbonate manufactured from spodumene ore according to Example 3.

[0015] Figure 5 is a diagram showing the results of a mineralogical analysis of a mixture containing lithium carbonate manufactured from petalite ore according to Example 4.

[0016] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention. The present invention is defined solely by the scope of the claims set forth below.

[0017] In the present invention, when it is said that a member is located “on” another member, this includes not only cases where a member is in direct contact with another member, but also cases where another member is interposed between the two members.

[0018] 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.

[0019]

[0020] One aspect of the present invention relates to a method for separating lithium carbonate, comprising the steps of: preparing a slurry comprising a mixture of an oxide containing at least one element selected from the group consisting of Al and Si and lithium carbonate; adding a hydrophobic agent to the slurry to change the particle surface of the lithium carbonate to be hydrophobic; injecting bubbles into the slurry and recovering a suspended solid; and filtering the suspended solid to recover lithium carbonate.

[0021] The method for separating lithium carbonate according to the present invention has the advantage of being able to easily separate lithium carbonate even when a small amount of lithium carbonate is included by adding a hydrophobic agent that changes the particle surface of lithium carbonate to hydrophobicity and then performing flotation separation.

[0022]

[0023] Steps to prepare the slurry

[0024] A method for separating lithium carbonate according to the present invention comprises the step of preparing a slurry comprising a mixture of lithium carbonate and an oxide containing at least one element selected from the group consisting of Al and Si.

[0025]

[0026] In one embodiment of the present invention, the oxide containing one or more elements selected from the group consisting of Al and Si and the lithium carbonate may be derived from an ore containing lithium.

[0027] The method for separating lithium carbonate according to the present invention can selectively separate a small amount of lithium carbonate contained in an ore containing lithium.

[0028]

[0029] In another embodiment of the present invention, the lithium-containing ore may include at least one selected from the group consisting of spodumene, petalite, lepidolite, hectorite, eucryptite, jadarite, zinnwaldite, and amblygonite.

[0030] Specifically, the lithium-containing ore may be, but is not limited to, spodumene or petalite.

[0031] However, if the above lithium-containing ore is spodumene or petalite, it is preferable because it has the advantage of relatively reducing costs.

[0032]

[0033] The method for obtaining a mixture comprising an oxide containing at least one element selected from the group consisting of Al and Si and the lithium carbonate from the above lithium-containing ore is not limited in the present invention.

[0034] For example, a mixture can be obtained by calcining the above lithium-containing ore and then performing a sulfuric acid roasting process, leaching process, etc.

[0035] Alternatively, a slurry may be obtained by carbonating the above lithium-containing ore using a sodium carbonate solution.

[0036]

[0037] The above calcination may be performed at a temperature of 950 to 1,100°C for 5 minutes to 5 hours, preferably 10 minutes to 3 hours, but is not limited thereto.

[0038] When the above calcination is performed under conditions within the above range, the phase transition from the α phase to the β phase of the lithium-containing ore is sufficient, and the phenomenon of the lithium leaching rate being lowered due to micro-calcination or under-calcination can be suppressed, which is preferable.

[0039] When the above-mentioned lithium-containing ore is subjected to sulfuric acid roasting, the lithium in the ore can be transformed into the form of a water-soluble substance.

[0040] The above sulfuric acid oxidation can be performed at a temperature range of 175 to 250°C, preferably 200 to 250°C, for 30 minutes to 2 hours, preferably 30 minutes to 1 hour.

[0041] When the sulfuric acid oxidation is performed within the above-mentioned time range at the above-mentioned temperature range, it is preferable because the oxidation time and energy consumption can be minimized.

[0042] Thereafter, by mixing the above-described ore with a solvent and subjecting it to water leaching, a slurry including a mixture of an oxide containing at least one element selected from the group consisting of Al and Si and lithium carbonate can be obtained.

[0043] The above solvent may be pure water or distilled water, but is not limited thereto.

[0044] The solvent preferably does not contain acid substances such as sulfuric acid, but this is not limited to this. A solvent free of acid substances such as sulfuric acid is preferred because it is environmentally friendly. Furthermore, even if the solvent contains a small amount of acid within a complex process, recycling it without compromising the overall production process can be economically and environmentally beneficial.

[0045]

[0046] The carbonation can be performed by adding 0.3 to 1.5 L of the sodium carbonate solution to 100 g of the lithium-containing ore and reacting at 200 to 350°C, preferably 220 to 300°C, and more preferably 220 to 250°C for 30 to 90 minutes, preferably 30 to 60 minutes.

[0047] At this time, the lithium-containing ore may be calcined before carbonating the lithium-containing ore, but is not limited thereto.

[0048]

[0049] At this time, if necessary, a salt, hydroxide, or oxide containing aluminum such as Al(OH)3 may be further added. When a salt, hydroxide, or oxide containing aluminum is further added, the content of oxides such as NaAlSi2O6·H2O and HAlSi2O6 in the slurry described later increases, which is advantageous because it increases the production of lithium carbonate.

[0050]

[0051] In short, the oxide containing one or more elements selected from the group consisting of Al and Si may be a leaching residue in a slurry obtained by leaching an ore containing lithium.

[0052]

[0053] In another embodiment of the present invention, the oxide containing at least one element selected from the group consisting of Al and Si may include at least one element selected from the group consisting of NaAlSi2O6·H2O, HAlSi2O6 and SiO2.

[0054]

[0055] In another embodiment of the present invention, the lithium carbonate may be included in an amount of 35% by weight or less, specifically 30% by weight or less, based on the total weight of the mixture.

[0056] An oxide containing one or more elements selected from the group consisting of Al and Si may be included as a remainder to satisfy 100 wt% of the entire mixture.

[0057]

[0058] In another embodiment of the present invention, in the step of preparing the slurry, the slurry may have a concentration of 5 to 50 w / v%, preferably 10 to 40 w / v%, and more preferably 10 to 30 w / v%.

[0059]

[0060] In another embodiment of the present invention, the step of preparing a slurry including a mixture of an oxide containing at least one element selected from the group consisting of Al and Si and lithium carbonate may include a step of mixing the mixture of an oxide containing at least one element selected from the group consisting of Al and Si and lithium carbonate into a solvent.

[0061] The above solvent can be added so as to satisfy the concentration of the slurry described above.

[0062]

[0063] In another embodiment of the present invention, the solvent may include at least one selected from the group consisting of a solution of pure water, a lithium-containing carbonate, a lithium-containing chloride, and a lithium-containing hydroxide.

[0064] Preferably, the solvent may be a solution of a lithium-containing carbonate, a lithium-containing chloride or a lithium-containing hydroxide, and more preferably, the solvent may be a solution of a lithium-containing carbonate.

[0065] When the solvent is a solution of a carbonate containing lithium, the recovery rate of the lithium carbonate can be increased, which is preferable.

[0066]

[0067] In another embodiment of the present invention, in the step of preparing the slurry, the slurry may have a pH of 8 or higher, preferably 9 or higher, and more preferably 9 to 10.

[0068] When the pH of the above slurry satisfies the above range, it is preferable to increase the recovery rate of lithium carbonate.

[0069] The pH of the above slurry can be adjusted using, but is not limited to, hydrochloric acid or caustic soda.

[0070]

[0071] Step for changing the particle surface of lithium carbonate to hydrophobic

[0072] The method for separating lithium carbonate according to the present invention includes a step of adding a hydrophobic agent to the slurry to change the particle surface of the lithium carbonate to hydrophobic.

[0073]

[0074] In another embodiment of the present invention, the hydrophobic agent can change only the particle surface of the lithium carbonate into hydrophobic.

[0075] In another embodiment of the present invention, the hydrophobic agent may be at least one selected from the group consisting of oleic acid, sodium oleate, and sodium dodecyl sulfate.

[0076]

[0077] In another embodiment of the present invention, the hydrophobic agent may be added in an amount of 0.001 to 1.0%, preferably 0.01 to 0.08%, of the total volume of the slurry.

[0078] When the hydrophobic agent is included within the above range, the effect of changing the particle surface of the lithium carbonate to hydrophobic while minimizing the amount of the hydrophobic agent added is sufficient, so that the recovery rate of the lithium carbonate can be maximized in the flotation separation step of the lithium carbonate described later, which is preferable.

[0079]

[0080] After adding the hydrophobic agent to the slurry, the slurry can be stirred at 100 to 500 rpm for 1 to 10 minutes, preferably 2 to 8 minutes, and more preferably 2 to 5 minutes.

[0081] In short, the method for separating lithium carbonate according to the present invention may further include a step of stirring the slurry into which the hydrophobic agent has been added.

[0082] If the step of stirring the slurry is further included, the time for the particle surface of the lithium carbonate to change to hydrophobic can be shortened, and the phenomenon of the particle surface of the lithium carbonate changing to hydrophobic can be uniformly achieved throughout the lithium carbonate particles, which is preferable.

[0083]

[0084] Steps to recover floating objects

[0085] The method for separating lithium carbonate according to the present invention includes the steps of injecting bubbles into the slurry and recovering the floating matter.

[0086] The method for separating lithium carbonate according to the present invention can recover only lithium carbonate particles whose particle surfaces have been changed to be hydrophobic by injecting bubbles into the slurry to which the hydrophobic agent has been added, thereby causing the particles to rise to the top of the slurry together with the bubbles.

[0087]

[0088] In another embodiment of the present invention, the step of injecting bubbles into the slurry and recovering the floating matter may be a step of injecting air using a bubble generator and performing floating sorting.

[0089]

[0090] In another embodiment of the present invention, the floating selection can be performed for 1 to 10 minutes, preferably 1 to 6 minutes, and more preferably 1 to 3 minutes.

[0091] When the above-mentioned flotation is performed within the above-mentioned time range, the process time can be shortened while sufficiently flotating the lithium carbonate particles whose particle surfaces have been changed to be hydrophobic, thereby increasing the recovery rate of lithium carbonate, which is preferable.

[0092]

[0093] The step of recovering the above floating material may be performed at room temperature, but is not limited thereto.

[0094] The above-mentioned floating material may have a lithium carbonate content of 80 wt% or more, preferably 85 wt% or more, and more preferably 90 wt% or more, based on the total weight.

[0095]

[0096] Steps for recovering lithium carbonate

[0097] The method for separating lithium carbonate according to the present invention includes a step of filtering the floating matter to recover lithium carbonate.

[0098] The above filtration can be performed using a filter press, but is not limited thereto.

[0099] The method for separating lithium carbonate according to the present invention may further include a step of drying the filtered lithium carbonate.

[0100] Specifically, after obtaining the above-mentioned filtered lithium carbonate, it can be dried at a temperature of 80 to 100°C for 10 to 30 hours, preferably 15 to 28 hours, and more preferably 20 to 24 hours, but is not limited thereto.

[0101]

[0102] The method for separating lithium carbonate according to the present invention has the advantage of being able to easily separate lithium carbonate even when a small amount of lithium carbonate is included, by adding a hydrophobic agent to a slurry containing a mixture of lithium carbonate and an oxide containing at least one element selected from the group consisting of Al and Si, thereby changing only the particle surface of the lithium carbonate to hydrophobic, and then performing flotation and separation.

[0103]

[0104] Hereinafter, preferred embodiments and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0105]

[0106] Example 1

[0107] A mixture was prepared by mixing the residue (HAlSi2O6, CaSO4·2H2O, SiO2 as the main mineral phase) produced by calcination, roasting, leaching, and refining from spodumene ore and lithium carbonate at a weight ratio of 9:1. The lithium content of the lithium carbonate mixture is shown in Table 1 below, and the results of the mineralogical analysis according to XRD analysis are shown in Fig. 1.

[0108] The equipment capable of floating lithium carbonate is in the form of a cylindrical tube, and a glass filter is installed at the bottom of the tube to allow bubbles to be injected from the bottom.

[0109] 100 mL of saturated lithium carbonate solution was added to the equipment, 20 g of the above mixture was added, 0.2 mL of oleic acid was added, and the mixture was stirred at 500 rpm for 2 minutes. After reducing the stirring speed to 100 rpm, bubbles were injected from the bottom through a bubble generator for 3 minutes.

[0110] During the injection of bubbles, the material rising to the top of the solution along with the bubbles was recovered. All experiments were conducted at room temperature. The pH of the solution was adjusted to pH 10 using hydrochloric acid and caustic soda.

[0111] The recovered material was filtered, dried at 100°C for 24 hours, and then the lithium content was measured, and the results are shown in Table 1 below.

[0112] The lithium content of the lithium carbonate mixture was 1.8%, and the lithium content of the material recovered by floating (float) was 15.5%. In addition, Fig. 2 shows the mineral phase of the recovered material, in which the main mineral phase is lithium carbonate, some HAlSi2O6 and SiO2 are observed, and CaSO4·2H2O cannot be confirmed. From these results, it can be seen that lithium carbonate can be selectively recovered.

[0113]

[0114] Li content (%)Lithium carbonate mixture 1.8Recovered material (floating matter) 15.5

[0115] Example 2

[0116] In the same equipment as Example 1, 100 mL of a saturated lithium carbonate solution was added, 20 g of the mixture prepared in Example 1 was added, 0.2 mL of oleic acid was added, and the mixture was stirred at 500 rpm for 2 minutes. After reducing the stirring speed to 100 rpm, bubbles were injected from the bottom through a bubble generator for 3 minutes.

[0117] During the injection of bubbles, the material that rose to the top of the solution along with the bubbles was recovered. All experiments were conducted at room temperature. The pH of the solution was adjusted from 8 to 11.6 using hydrochloric acid and caustic soda, respectively.

[0118] The recovered materials were filtered and dried at 100°C for 24 hours according to pH, and the lithium carbonate recovery rate was measured. The results are shown in Fig. 3.

[0119] As shown in Fig. 3, the lithium carbonate recovery rate increased as the pH increased, and no significant change was observed at pH 10 or higher.

[0120]

[0121] Example 3

[0122] After calcining spodumene ore at 1,100°C for 1 hour, 200 g of the calcined ore was added to 1 L of a 10% Na2CO3 solution and reacted at 220°C for 1 hour to obtain a mixture slurry mainly composed of NaAlSi2O6·.H2O, SiO2, and Li2CO3. The mineral phase of the mixture slurry is as shown in Fig. 4.

[0123] 100 mL of the above slurry was added to the same equipment as Example 1, 0.2 mL of oleic acid was added, and the mixture was stirred at 500 rpm for 2 minutes. After reducing the stirring speed to 100 rpm, bubbles were injected from the bottom through a bubble generator for 3 minutes.

[0124] During the injection of air bubbles, the material rising to the top of the solution along with the bubbles was recovered. All experiments were conducted at room temperature. The pH of the slurry was adjusted to 10.

[0125] The recovered material was filtered, dried at 100°C for 24 hours, and then the lithium content was measured. The results are shown in Table 2 below. The lithium content of the lithium carbonate mixture was 2.5%, and the lithium content of the recovered material (float) recovered by floating was 15.5%. These results indicate that lithium carbonate can be selectively recovered.

[0126]

[0127] Li content (%)Lithium carbonate mixture 2.5Recovered material (floating matter) 15.5

[0128] Example 4

[0129] 300 g of petalite and 351 g of Al(OH) were added to 1 L of a 15% Na2CO3 solution and reacted at 250°C for 1 hour to obtain a mixture slurry mainly composed of NaAlSi2O6·.H2O, SiO2, and Li2CO3. The mineral phase of the mixture slurry is as shown in Fig. 5.

[0130] 100 mL of the above slurry was added to the same equipment as Example 1, 0.2 mL of oleic acid was added, and the mixture was stirred at 500 rpm for 2 minutes. After reducing the stirring speed to 100 rpm, bubbles were injected from the bottom through a bubble generator for 3 minutes.

[0131] During the injection of air bubbles, the material rising to the top of the solution along with the bubbles was recovered. All experiments were conducted at room temperature. At this time, the pH of the slurry was 10.

[0132] The recovered material (floating matter) was filtered, dried at 100°C for 24 hours, and then the lithium content was measured, and the results are shown in Table 3 below. The lithium content of the lithium carbonate mixture was 1.5%, and the lithium content of the floating and recovered material was 14.4%.

[0133]

[0134] Li content (%)Lithium carbonate mixture1.5Recovered material (floating matter)14.4

[0135] Referring to the singe example, the method for separating lithium carbonate according to the present invention has the advantage of being able to easily separate lithium carbonate even when a small amount of lithium carbonate is included.

[0136]

[0137] The present invention is not limited to the above-described embodiments, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A step of preparing a slurry comprising a mixture of an oxide containing one or more elements selected from the group consisting of Al and Si and lithium carbonate; A step of changing the particle surface of the lithium carbonate to hydrophobic by adding a hydrophobic agent to the slurry; A step of injecting bubbles into the above slurry and recovering floating matter; and A step of filtering the above floating matter to recover lithium carbonate; A method for separating lithium carbonate comprising:

2. In paragraph 1, A method for separating lithium carbonate, wherein the hydrophobic agent changes only the particle surface of the lithium carbonate into hydrophobic.

3. In paragraph 1, A method for separating lithium carbonate, wherein the hydrophobic agent is at least one selected from the group consisting of oleic acid, sodium oleate, and sodium dodecyl sulfate.

4. In paragraph 1, A method for separating lithium carbonate, wherein the hydrophobic agent is added in an amount of 0.001 to 1.0% based on the total volume of the slurry.

5. In paragraph 1, A method for separating lithium carbonate, wherein the oxide containing at least one element selected from the group consisting of Al and Si includes at least one element selected from the group consisting of NaAlSi2O6·H2O, HAlSi2O6 and SiO2.

6. In paragraph 1, A method for separating lithium carbonate, wherein the lithium carbonate is contained in an amount of 35 wt% or less based on the total weight of the mixture.

7. In paragraph 1, A method for separating lithium carbonate, wherein the oxide contains at least one element selected from the group consisting of Al and Si, and the lithium carbonate is derived from an ore containing lithium.

8. In paragraph 7, A method for separating lithium carbonate, wherein the lithium-containing ore comprises at least one selected from the group consisting of spodumene, petalite, lepidolite, hectorite, eucryptite, jadarite, zinnwaldite, and amblygonite.

9. In paragraph 1, The step of injecting bubbles into the above slurry and recovering the floating matter; A method for separating lithium carbonate, which comprises the steps of injecting air using a bubble generator and performing flotation separation.

10. In paragraph 9, A method for separating lithium carbonate, wherein the above floating selection is performed for 1 to 10 minutes.

11. In paragraph 1, A step of preparing a slurry comprising a mixture of an oxide containing one or more elements selected from the group consisting of Al and Si and lithium carbonate; A method for separating lithium carbonate, comprising the step of mixing a mixture of lithium carbonate and an oxide containing at least one element selected from the group consisting of Al and Si into a solvent.

12. In paragraph 11, A method for separating lithium carbonate, wherein the solvent comprises at least one selected from the group consisting of a solution of pure lithium, a lithium-containing carbonate, a lithium-containing chloride, and a lithium-containing hydroxide.

13. In paragraph 1, In the step of preparing the above slurry; A method for separating lithium carbonate, wherein the above slurry has a concentration of 5 to 50 w / v%.

14. In paragraph 1, In the step of preparing the above slurry; A method for separating lithium carbonate, wherein the above slurry has a pH of 8 or higher.

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