Method for recovering lithium

Abstract

The method for recovering lithium according to the present invention comprises: a step of physically screening and crushing waste lithium batteries to obtain a lithium source; a step of heat-treating the lithium source at a temperature of 100 to 1600 DEG C; a step of performing water immersion on the lithium source after heat treatment to separate a first lithium source residue and a lithium carbonate aqueous solution; recovering lithium carbonate from the lithium carbonate aqueous solution; a step of adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment; a step of subjecting the first lithium source residue after heat treatment to water immersion so as to separate a second lithium source residue and a lithium chloride aqueous solution; and a step for recovering lithium chloride from the aqueous lithium chloride solution.

Description

Technical Field

[0001] The present invention relates to a method for recovering lithium. Specifically, the present invention relates to a method for pre-recovering lithium from waste lithium batteries. Background Art

[0002] With the popularization of electric vehicles, the number of waste batteries is gradually increasing, especially lithium-ion batteries (LIBs). It is expected that from around 2030, approximately 80,000 waste batteries will be generated. The potential residual value of resources recovered from waste batteries of domestic electric vehicles in South Korea is expected to reach 200 billion won.

[0003] Therefore, research is actively underway to recover valuable metals from waste batteries. This means extracting rare metals such as nickel and cobalt that were originally completely dependent on imports to ensure a stable supply of materials, and it is expected that import substitution can be achieved.

[0004] Regarding the processes for recovering valuable metals from waste batteries at home and abroad, relevant recycling enterprises are commercializing based on dry / wet processes. For the dry process, Ni, Co, etc. can be recovered, but the difficult-to-reduce element lithium floats out in the form of slag, and there is a defect of difficult recovery. For the wet process, after recovering all other elements, lithium is recovered in the final stage, and lithium loss may occur during the recovery of other elements in the intermediate process.

[0005] Therefore, there is a current need to develop a lithium recovery process that can minimize lithium loss. Summary of the Invention

[0006] Technical Problem to be Solved

[0007] The present invention aims to provide a method for recovering lithium, which can pre-recover lithium through a pre-leaching process, thereby suppressing lithium loss.

[0008] Technical Solution

[0009] The present invention provides a method for recovering lithium, which includes: a step of heat-treating a lithium source at a temperature of 100 to 1600 °C; a step of water-leaching the heat-treated lithium source to separate it into a first lithium source residue and an aqueous lithium carbonate solution; a step of recovering lithium carbonate from the aqueous lithium carbonate solution; a step of adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment; a step of water-leaching the heat-treated first lithium source residue to separate it into a second lithium source residue and an aqueous lithium chloride solution; and a step of recovering lithium chloride from the aqueous lithium chloride solution.

[0010] Advantageous Effects

[0011] According to the method for recovering lithium of the present invention, by pre-leaching lithium, it has the advantage of being able to minimize lithium loss in the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a simulation result diagram showing that lithium carbonate and lithium aluminate (LiAlO2) are generated as lithium compounds when a lithium source is heat-treated. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. The scope of the present invention is defined by the claims.

[0014] In the present invention, when a component is described as being "above" another component, this includes not only the case where a component is in direct contact with another component, but also the case where other components are interposed between the two components.

[0015] In the present invention, when a part is described as "including" a certain component, unless otherwise stated to the contrary, it means that other components may also be included, and does not exclude other components.

[0016] One embodiment of the present invention relates to a method for recovering lithium, which includes: a step of heat-treating a lithium source at a temperature of 100 to 1600 °C; a step of water-leaching the heat-treated lithium source to separate it into a first lithium source residue and an aqueous solution of lithium carbonate (Li2CO3); a step of recovering lithium carbonate from the aqueous solution of lithium carbonate; a step of adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment; a step of water-leaching the heat-treated first lithium source residue to separate it into a second lithium source residue and an aqueous solution of lithium chloride (LiCl); and a step of recovering lithium chloride from the aqueous solution of lithium chloride.

[0017] When extracting lithium using existing waste lithium batteries, cathode material waste, and process waste, since lithium is extracted at the end of the process, there will inevitably be a problem of a certain degree of lithium loss. In addition, when extracting lithium from lithium ore, an excessive amount of sulfuric acid is used relative to the amount of lithium contained in the lithium ore, which is not ideal in terms of the environment and economy, and a process of pre-treating the lithium ore is also required, so it is not very ideal in terms of the process.

[0018] According to the method for recovering lithium of the present invention, the lithium recovered in the last step of the existing process is pre-leached using a dry process employing a chlorination method, so that the lithium lost in the process can be minimized, and after recovering lithium, the valuable metals contained in the lithium source can be recovered without loss, so it is very useful economically.

[0019] Step of heat-treating a lithium source

[0020] The method for recovering lithium according to the present invention includes: a step of heat-treating a lithium source at a temperature of 100 to 1600 °C.

[0021] In the present invention, the "lithium source" may refer to waste lithium battery scraps, cathode material scraps, process scraps, spodumene, etc. containing lithium.

[0022] The waste lithium battery scraps, cathode material scraps, process scraps, and spodumene can be understood as terms commonly interpreted in this industry.

[0023] The waste lithium battery may include a cathode material, an anode material, an electrolyte, etc.

[0024] For the spodumene, for example, it can be spodumene (LiAlSi2O6), petalite (LiAlSi4O 10 ), lepidolite (K(Li,Al)3(Si,Al)4O 10 (F,OH)2), eucryptite (LiAlSiO4), amblygonite ((Li,Na)AlPO4(F,OH)), or a mixture thereof, but not limited thereto.

[0025] Specifically, the spodumene can be spodumene.

[0026] The lithium source may include metal oxides composed of multiple metals.

[0027] The multiple metals may be lithium (Li), nickel (Ni), cobalt (Co), copper (Cu), manganese (Mn), etc., and the multiple metals may also be their composite metals.

[0028] The metal oxides may be lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (LiNiCoMnO2), lithium manganese oxide (LiMnO2), lithium copper oxide (LiCuO2), lithium iron phosphate (LiFePO4), lithium aluminate (LiAlO2), lithium fluoride (LiF), or lithium-containing spodumene (LiAlSi2O6), other lithium compounds, etc.

[0029] In short, the lithium source may include the metal oxides composed of multiple metals.

[0030] According to the method for recovering lithium of the present invention, before the step of heat-treating the lithium source, it may include, as needed, a step of physically screening and crushing the lithium source to obtain a lithium source in powder form, but not limited thereto. For example, when the lithium source is a waste lithium battery or spodumene, it may include, as needed, a step of physically screening and crushing the waste lithium battery or spodumene to obtain a lithium source in powder form.

[0031] In short, the lithium source may be in powder form.

[0032] The lithium source is heat-treated to produce lithium carbonate (Li2CO3). For example, the carbon contained in the lithium source reacts with 2LiMeO2 or a lithium compound to produce lithium carbonate. At this time, the reaction formula is as follows.

[0033] [Reaction formula]

[0034] 2LiMeO2 + 2C → Li2CO3 + 2Me + CO

[0035] In the reaction formula, Me is the plurality of metals.

[0036] Regarding the temperature of the heat treatment, it is preferably 200 to 1000 °C, and more preferably can be 400 to 1000 °C. When the temperature of the heat treatment is within this range, it has the advantage that the reaction efficiency is optimized, and thus it is ideal.

[0037] In one embodiment of the present invention, the step of heat-treating the lithium source can be carried out for 10 minutes to 24 hours, preferably 20 minutes to 600 hours, and more preferably 20 minutes to 400 minutes.

[0038] When the time of the heat treatment is within this range, it promotes the compounding of the residual carbon and lithium in the lithium source, and it is easy to produce lithium carbonate, and thus it is ideal.

[0039] In yet another embodiment of the present invention, the heat treatment step can be carried out in a fluidized furnace, a vertical furnace, a horizontal furnace or a rotary furnace, but is not limited thereto.

[0040] In yet another embodiment of the present invention, in the heat treatment step, the carbon source can be added to a stoichiometric ratio of Li:C of 1:0.5 or more, preferably 1:0.5 to 1:1.2, and more preferably 1:0.5 to 1:1.

[0041] When the carbon source is added to the lithium source and heat-treated together, according to the reaction formula, the production of lithium carbonate is promoted, and thus it is ideal. Specifically, when the lithium source is a waste cathode material, the carbon source can be added to the lithium source and heat-treated together.

[0042] The carbon source can be carbon-based powder, coke, CO gas or CO2 gas, but is not limited thereto.

[0043] Step of separating into a first lithium source residue and an aqueous lithium carbonate solution

[0044] The method for recovering lithium according to the present invention includes: a step of water-leaching the heat-treated lithium source to separate it into a first lithium source residue and an aqueous lithium carbonate solution.

[0045] The solubility of the lithium carbonate generated through the heat treatment step in water is 1.54 g / 100 ml (based on 0 °C). Therefore, the generated lithium carbonate is recovered into a solution by water leaching.

[0046] For the water leaching, it can be carried out with distilled water. In the present invention, the time of the water leaching, the amount of the distilled water, and the temperature of the distilled water are not limited.

[0047] By water leaching the lithium source after the heat treatment, the lithium carbonate generated in the heat treatment step dissolves in water to become an aqueous solution state, while the first lithium source residue still remains in a solid state.

[0048] The separation of the first lithium source residue and the lithium carbonate aqueous solution can be carried out using a filter press, a decanter, etc., but is not limited thereto.

[0049] Step of recovering lithium carbonate

[0050] The method for recovering lithium according to the present invention includes: a step of recovering lithium carbonate from the lithium carbonate aqueous solution.

[0051] The lithium carbonate can be recovered by water leaching.

[0052] The step of recovering the lithium carbonate may further include a step of heating and concentrating or vacuum distilling to promote the precipitation of the lithium carbonate.

[0053] The recovered lithium carbonate can be subjected to a washing step. For the lithium carbonate, the higher the water temperature, the lower the solubility in water. Therefore, it is preferred to raise the water temperature to 80 to 90 °C for washing.

[0054] The lithium carbonate after the washing step can be subjected to a drying step.

[0055] The drying step can be carried out using a dryer or an oven. In the present invention, the drying temperature, the drying time, etc. of the drying step are not limited.

[0056] The method for recovering lithium according to the present invention, since lithium is leached in advance in the form of lithium carbonate, has the advantage of being able to improve the lithium recovery rate compared with the conventional lithium recovery methods.

[0057] Step of adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment

[0058] The method for recovering lithium according to the present invention includes: a step of adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment.

[0059] In yet another embodiment of the present invention, the raw material for the chlorination reaction may be a chlorinating gas or one or more chlorides selected from CaCl2, FeCl3, MgCl2, NaCl, KCl, CuCl2, AlCl3, and MnCl x among others.

[0060] Based on the concentration of Li remaining in the first lithium source residue, the raw material for the chlorination reaction may be added in an equivalent ratio sufficient to prepare lithium chloride.

[0061] For example, based on 1 mole of Li remaining in the first lithium source residue, the raw material for the chlorination reaction may be included in a proportion of 0.01 to 0.5 moles, preferably 0.05 to 0.4 moles, and more preferably 0.1 to 0.4 moles.

[0062] Although not wishing to be bound by theory, it is theoretically possible to capture the lithium in the lithium source in the form of lithium carbonate. However, due to kinetic or reaction driving force issues, it is difficult to capture all the lithium in the lithium source as lithium carbonate, and the remaining lithium will remain in the form of compounds such as LiAlO2.

[0063] Figure 1 is a simulation result diagram showing the formation of lithium carbonate and lithium aluminate (LiAlO2) as lithium compounds when the lithium source is heat-treated. Refer to Figure 1 It can be seen that when the lithium source is heat-treated, although lithium carbonate is formed, lithium aluminate still remains. If the lithium aluminate remains, it causes a loss in lithium recovery, so dissociating the bond of lithium aluminate is an important factor.

[0064] In addition, when directly converting the lithium in the lithium source into lithium chloride, there are some problems with the cation elements of the added chlorides mixing into the formed lithium chloride.

[0065] Therefore, in the present invention, after heat-treating the lithium source to form lithium carbonate, water leaching is then carried out to recover the lithium carbonate, and chlorides are added to the remaining lithium source residue, followed by a dry heat-treatment chlorination reaction to recover the remaining lithium in the form of lithium chloride.

[0066] Thereby, not only can the loss of lithium be minimized to the greatest extent, but also the mixing of impurities caused by the added additional raw materials, such as chlorides, can be minimized to the greatest extent, thus having significant advantages.

[0067] In yet another embodiment of the present invention, the raw material for the chlorination reaction may be FeCl3. Specifically, in the present invention, the raw material for the chlorination reaction may be FeCl3.

[0068] The melting point (mp) of the FeCl3 is 306 °C and the boiling point (bp) is 315 °C, which is relatively low compared with other chlorides. For example, for CaCl2, since the melting point is 772 °C and the boiling point is 1935 °C, the reaction may be limited to high temperatures. Therefore, compared with other chlorides that require reactions at high temperatures, FeCl3 has the advantage of being able to produce lithium chloride at a relatively low temperature, and thus FeCl3 is preferably used as the raw material for the chlorination reaction.

[0069] The heat treatment can be carried out at a temperature of 100 to 1600 °C, preferably 200 to 1000 °C, more preferably 400 to 1000 °C.

[0070] When the temperature of the heat treatment is within the above range, it has the advantage of being able to improve the reaction efficiency, and thus is ideal.

[0071] The time of the heat treatment can be 10 minutes to 24 hours, preferably 20 minutes to 600 hours, more preferably 30 minutes to 400 minutes.

[0072] When the time of the heat treatment is within the above range, the chlorination reaction between the lithium remaining in the first lithium source residue and the raw material for the chlorination reaction is promoted, and thus lithium chloride is easily produced, and thus is ideal.

[0073] The step of heat-treating the first lithium source residue can utilize coke, CO gas or CO2 gas.

[0074] For example, the coke can be added together when adding the raw material for the chlorination reaction to the first lithium source residue.

[0075] In addition, for example, the step of heat-treating the first lithium source residue can be carried out in an atmosphere of CO gas or CO2 gas.

[0076] The coke, CO gas and CO2 gas can play a role in increasing the production rate of the lithium chloride. Specifically, the coke, CO gas and CO2 gas can act as reducing agents.

[0077] Relative to the molar ratio of the residual lithium contained in the first lithium source residue, 0.5 to 2 moles of the coke can be included, but it is not limited thereto.

[0078] However, when the content of the coke is within the above range, it is neither likely to act as an impurity nor has the effect of improving the production efficiency, and thus is ideal.

[0079] For the coke, the average particle size can be 100 to 400 μm, but it is not limited thereto. However, when the coke satisfies the range of the average particle size, the phenomenon of coke aggregation is suppressed, and it has an excellent effect of improving the production efficiency, and thus is ideal.

[0080] The flow rate of the CO gas or CO2 gas can vary according to the scale of the reaction heat treatment furnace, and thus can be supplied in an appropriate amount. For example, for the CO gas or CO2 gas, the supply flow rate can be 300 to 1500 sccm / minute, but is not limited thereto. However, when the flow rate of the CO gas or CO2 gas satisfies the above range, the production rate of the lithium chloride is sufficiently increased, and thus it is ideal.

[0081] The heat treatment of the first lithium source residue can be carried out in a fluidized furnace, a vertical furnace, a horizontal furnace or a rotary furnace, but is not limited thereto.

[0082] Step of separating into a second lithium source residue and an aqueous lithium chloride solution

[0083] The method for recovering lithium according to the present invention includes: a step of leaching the heat-treated first lithium source residue with water to separate it into a second lithium source residue and an aqueous lithium chloride solution.

[0084] The heat-treated first lithium source residue is in a state of generating lithium chloride, and the solubility of lithium chloride in water is relatively high, so it is recovered as a solution by leaching with water. For example, for the lithium chloride, the solubility can be 68.29 g / 100 mL at 0 °C and 74.48 g / 100 mL at 10 °C.

[0085] For the water leaching, it can be carried out with distilled water, and the time of the water leaching, the amount of the distilled water and the temperature of the distilled water are not limited in the present invention.

[0086] By leaching the heat-treated first lithium source residue with water, the lithium chloride generated in the step of heat-treating the first lithium source is dissolved in water to become an aqueous solution state, while the second lithium source residue still remains in a solid state.

[0087] The separation of the second lithium source residue and the aqueous lithium chloride solution can be carried out by using a filter press, a decanter, etc., but is not limited thereto.

[0088] In another embodiment of the present invention, the steps of adding a chlorination reaction raw material to the first lithium source residue and carrying out heat treatment can be carried out two or more times; and the step of leaching the heat-treated first lithium source residue with water to separate it into a second lithium source residue and an aqueous lithium chloride solution can be carried out.

[0089] In summary, after subjecting the heat-treated first lithium source residue to water leaching to separate it into a second lithium source residue and an aqueous lithium chloride solution, adding the chlorination reaction raw material to the separated second lithium source residue and performing heat treatment, and then performing water leaching, it can be separated into a third lithium source residue and an aqueous lithium chloride solution. In addition, after adding the chlorination reaction raw material to the third lithium source residue and performing heat treatment, it can be separated into a fourth lithium source residue and an aqueous lithium chloride solution by water leaching.

[0090] As described above, when performing the steps of adding the chlorination reaction raw material to the first lithium source residue and performing heat treatment two or more times; and separating into a second lithium source residue and an aqueous lithium chloride solution, the lithium recovery rate can be further increased, so it is ideal.

[0091] According to the method for recovering lithium of the present invention, since it includes the step of separating into a second lithium source residue and an aqueous lithium chloride solution, even the residual lithium that has not been recovered in the form of lithium carbonate can be recovered, and it has the advantage of minimizing lithium loss.

[0092] Step of recovering lithium chloride

[0093] The method for recovering lithium according to the present invention includes the step of recovering lithium chloride from the aqueous lithium chloride solution.

[0094] For the recovery of the lithium chloride, according to the process temperature, it can be divided into solid capture, liquid capture or gas capture.

[0095] In another embodiment of the present invention, the step of recovering lithium chloride can be carried out by a selective chlorination system.

[0096] For example, for the aqueous lithium chloride solution, it can be captured in gaseous form at a temperature of 1400 °C or higher. In this case, a gaseous lithium chloride capture zone can be formed above, and after being condensed in a condenser, it can be captured in solid form, or captured in liquid form by water leaching above, but it is not limited thereto.

[0097] Step of recovering valuable metals

[0098] The method for recovering lithium according to the present invention may further include the step of recovering valuable metals from the second lithium source residue.

[0099] The step of recovering the valuable metals is not limited in the present invention.

[0100] For example, after leaching the second lithium source residue from which the lithium chloride has been separated into a solution by sulfuric acid leaching, through an impurity purification process, solvent extraction is carried out in the order of Cu, Mn, Co, Ni, and recovery is carried out by this conventional method, but it is not limited thereto.

[0101] The method for recovering lithium according to the present invention is used for pre-extracting lithium in the process of recovering valuable metals from lithium sources such as waste lithium battery scraps, cathode material scraps, process scraps, and lithium ore (spodumene). Specifically, after first recovering lithium compounds in the form of lithium carbonate and then recovering lithium in the form of lithium chloride, by pre-leaching lithium, it has the advantage of minimizing the process loss of lithium. In addition, compared with the traditional wet process system using sulfuric acid, pretreatment is not required, and lithium compounds can be effectively recovered from ores, having the advantage of simplifying the process. In addition, valuable metals such as Ni, Co, Cu, and Mn can be recovered after first recovering lithium.

[0102] Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following embodiments are only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiments.

[0103] Example

[0104] The waste lithium batteries are physically screened and crushed using a crusher to obtain a lithium source in powder form.

[0105] The lithium source is heat-treated at a temperature of 600 °C for 6 hours. After leaching the heat-treated lithium source with distilled water, it is filtered using a filter press to be separated into a first lithium source residue and an aqueous lithium carbonate solution. The separated aqueous lithium carbonate solution is subjected to water leaching to recover it in the form of lithium carbonate.

[0106] FeCl3 is added to the first lithium source residue separated from the aqueous lithium carbonate solution, and it is heat-treated at a temperature of 600 °C for 6 hours. The heat-treated first lithium source residue is leached in distilled water and filtered using a filter press to be separated into a second lithium source residue and an aqueous lithium chloride solution. The separated aqueous lithium chloride solution is subjected to water leaching using a selective chlorination system at 1400 °C to recover lithium chloride, and this process is repeated 3 times in total. At this time, the addition amount of FeCl3 is changed each time (based on the concentration of residual lithium contained in each residue), and it is shown in Table 1 below.

[0107] The lithium recovery rates based on the lithium compounds recovered in each step are shown in Table 1.

[0108] For the lithium recovery rate, it is calculated by analyzing the lithium concentration in the aqueous lithium carbonate solution and the aqueous lithium chloride solution.

[0109]

Table 1

[0110]

[0111] As can be seen from Table 1, more than 99% of the total lithium in waste lithium batteries can be recovered. When the method of recovery in the form of LiCl is carried out once, the recovery rate can be 99.2%. When the method of recovery in the form of LiCl is further repeated twice, the recovery rate can be 99.83%.

[0112] The present invention can be implemented in various different ways and is not limited to the described embodiments. Those of ordinary skill in the technical field to which the present invention pertains can understand that the present invention can be implemented in other specific ways without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the above embodiments are exemplary in all aspects and are not used to limit the present invention.

Claims

1. A method for recovering lithium, comprising: heating a lithium source at a temperature of 100 to 1600 °C; leaching the heat-treated lithium source with water to separate it into a first lithium source residue and an aqueous lithium carbonate solution; recovering lithium carbonate from the aqueous lithium carbonate solution; adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment; leaching the heat-treated first lithium source residue with water to separate it into a second lithium source residue and an aqueous lithium chloride solution; and recovering lithium chloride from the aqueous lithium chloride solution.

2. The method for recovering lithium according to claim 1, wherein, The raw material for the chlorination reaction is a chlorinated gas or one or more chlorides selected from CaCl2, FeCl3, MgCl2, NaCl, KCl, CuCl2, AlCl3, and MnCl x ides above.

3. The method for recovering lithium according to claim 2, wherein, the chlorination reaction raw material is FeCl3.

4. The method for recovering lithium according to claim 1, wherein, in the heat treatment step, a carbon source is added such that the stoichiometric ratio of Li:C is 1:0.5 or more.

5. The method for recovering lithium according to claim 1, wherein, the step of adding a chlorination reaction raw material to the first lithium source residue and performing heat treatment; and the step of leaching the heat-treated first lithium source residue with water to separate it into a second lithium source residue and an aqueous lithium chloride solution are performed more than twice.

6. The method for recovering lithium according to claim 1, further comprising a step of recovering valuable metals from the second lithium source residue.

7. The method for recovering lithium according to claim 1, wherein, the step of heat-treating the lithium source is performed for 10 minutes to 24 hours.

8. The method for recovering lithium according to claim 1, wherein, the heat treatment step is performed in a fluidized furnace, a vertical furnace, a horizontal furnace or a rotary furnace.

9. The method for recovering lithium according to claim 1, wherein, the step of recovering lithium chloride is performed by a selective chlorination system.

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