Methods for preparing lithium carbonate
By combining calcination and sulfuric acid leaching with carbonate reaction, the problems of complex processes and low purity in the recycling of lithium battery cathode materials have been solved, achieving efficient and low-cost lithium carbonate preparation and improving purity and recovery rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GANZHOU HANRUI NEW ENERGY TECH CO LTD
- Filing Date
- 2023-12-06
- Publication Date
- 2026-05-26
AI Technical Summary
In the existing technology, the process of recycling lithium battery cathode materials to prepare lithium carbonate is complicated, resulting in high cost and low purity of lithium carbonate, and the extraction agent residue may introduce impurities.
The process involves roasting a mixture of black powder and coke to produce lithium carbonate-containing calcined sand. Lithium ions are then separated by sulfuric acid leaching and pH adjustment. Lithium carbonate is generated by reacting with a carbonate solution, avoiding the need for additional extractants and achieving heavy metal precipitation. This simplifies the process and reduces costs.
It improves the purity and recovery rate of lithium carbonate, simplifies the process, reduces preparation costs, and avoids the introduction of impurities by the extractant.
Smart Images
Figure CN117509689B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery material recycling technology, specifically to a method for preparing lithium carbonate. Background Technology
[0002] Currently, methods for recovering lithium-ion battery cathode materials to prepare lithium carbonate include: ammonia roasting to convert lithium cobalt oxide into sulfate, using organic extractants to recover cobalt, precipitation to recover lithium from the residual liquid, and finally recovering lithium as lithium carbonate. The extraction and separation process and equipment are relatively complex, which is not conducive to reducing recovery costs. Furthermore, the extraction and separation process may leave extractant residues, which is detrimental to improving the purity of lithium carbonate. Summary of the Invention
[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing lithium carbonate that is conducive to reducing preparation costs and improving purity.
[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:
[0005] A method for preparing lithium carbonate includes the following steps:
[0006] Step 1: Mix black powder and coke to obtain a mixture, wherein the black powder includes lithium salt cathode material and graphite anode material, wherein the lithium salt cathode material includes at least one element selected from cobalt, manganese or nickel, and place the mixture in an air atmosphere calcining kiln to obtain calcined sand, wherein the calcined sand includes Li2CO3, the calcination temperature is 550-650℃, and the calcination time is 40-100 minutes;
[0007] Step 2: Take a portion of the roasted sand and prepare it into a first slurry. Use sulfuric acid aqueous solution to leach the Li ions in the first slurry. Adjust the pH value to 6-7 to obtain a second slurry. After solid-liquid separation of the second slurry, obtain a first leachate and a first leaching residue.
[0008] Step 3: Take the first leachate and a portion of the new roasted sand to make a slurry, adjust the pH value to 10-11 to obtain the third slurry, and then separate the solid and liquid of the third slurry to obtain the second leachate and the second leaching residue.
[0009] Step 4: After heating the second leachate to a temperature greater than 90°C, add it to the carbonate solution to obtain a lithium carbonate mixture. The temperature of the carbonate solution is 80-90°C.
[0010] In some possible implementations, step four further includes:
[0011] The lithium carbonate mixture is reacted at a temperature of 80-90℃ for 60-90 minutes.
[0012] In some possible implementations, the ratio of the black powder to the coke is 4:1 to 6:1 by weight.
[0013] In some possible implementations, the calcination temperature is 550-600°C and the calcination time is 40-60 minutes.
[0014] In some possible implementations, in step two, the concentration of the sulfuric acid aqueous solution is 1.5-2 mol / L and the concentration of Li ions is 18-24 g / L; in step four, the concentration of the carbonate solution is 340-360 g / L.
[0015] In some possible implementations, the ratio of the second slurry to the roasted sand in step three is 5:1 to 6:1 by mass.
[0016] In some possible implementations, in step four, the continuous addition time of the second leachate is controlled to be 60-90 minutes.
[0017] In some possible implementations, step three further includes:
[0018] The second leaching residue was washed with an aqueous sulfuric acid solution to obtain slag and washing liquid;
[0019] The preparation method further includes:
[0020] Return the washing liquid to step two to use it to prepare the calcined sand into a slurry, and repeat steps two through four.
[0021] In some possible implementations, in step three, the concentration of the sulfuric acid aqueous solution is 0.15-0.2 mol / L, and the ratio of the second leaching residue to the sulfuric acid aqueous solution is 1:5 by mass.
[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0023] In this application, the black powder obtained from dismantling lithium batteries includes graphite anode material and lithium salt cathode material. The lithium salt cathode material includes at least one element selected from cobalt, manganese, or nickel. After reduction roasting of the black powder and coke, calcined ore containing lithium carbonate is obtained. A portion of the calcined ore reacts with sulfuric acid to leach cations (including L1 ions) from the calcined ore, resulting in a reaction slurry. The reaction slurry undergoes a displacement reaction with a portion of the new calcined ore, allowing heavy metal elements (such as cobalt, manganese, or nickel) to precipitate as carbonates, thereby improving the purity of the final lithium carbonate. Furthermore, this application uses calcined ore containing lithium carbonate as a heavy metal removal agent without the need for additional extractants or precipitants, thus avoiding the introduction of other impurities and reducing the production cost of lithium carbonate.
[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0025] Figure 1 A flowchart illustrating a method for preparing lithium carbonate according to an embodiment of this application. Detailed Implementation
[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0027] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0028] Reference Figure 1 One embodiment of this application provides a method for preparing lithium carbonate, comprising the following steps:
[0029] Step 1: Mix black powder and coke to obtain a mixture. The black powder includes lithium salt cathode material and graphite anode material. The lithium salt cathode material includes at least one heavy metal element selected from cobalt, manganese, or nickel. Place the mixture in an air-atmosphere calcining kiln to obtain calcined sand. The calcination temperature is 550-650℃, and the calcination time is 40-100 minutes. The calcined sand includes Li₂CO₃. In this step, the lithium salt of the cathode material is converted into Li₂CO₃. For example, the black powder can be obtained by dismantling used lithium batteries. For example, the lithium salt cathode material can include at least one of lithium cobalt oxide, lithium manganese oxide, or lithium nickel cobalt manganese oxide. That is, after calcination, lithium cobalt oxide, lithium manganese oxide, or lithium nickel cobalt manganese oxide can be converted into Li₂CO₃.
[0030] In some embodiments, the ratio of the black powder to the coke by weight is 4:1 to 6:1, and this ratio is beneficial to improving the conversion rate of the lithium salt cathode material.
[0031] Furthermore, the calcination temperature is 550-600℃, and the calcination time is 40-60 minutes. At this temperature and time, Li in the black powder can fully react to form Li2CO3. Too high a temperature will lead to the volatilization loss of Li and material caking, while too low a temperature will significantly prolong the reaction time.
[0032] Step Two: Take a portion of the roasted sand and prepare a slurry to obtain a first slurry. For example, pure water can be used to prepare the slurry with the roasted sand. For example, the mass ratio of pure water to roasted sand can be between 2:1 and 3:1. Leach the Li ions from the first slurry using a sulfuric acid aqueous solution, adjusting the pH to 6-7 to obtain a second slurry. After solid-liquid separation of the second slurry, a first leaching solution and a first leaching residue are obtained. In this step, Li₂CO₃ reacts with sulfuric acid to generate lithium sulfate. The second slurry includes trace amounts of heavy metal ions dissolved in the sulfuric acid aqueous solution, such as at least one of nickel (Ni), cobalt (Co), or manganese (Mn). Therefore, the first leaching solution may include lithium sulfate and heavy metal ions. For example, both the sulfuric acid aqueous solution and the first slurry can be added to the leaching tank for reaction. Stirring can be performed during the reaction. For example, the stirring time can be 8-12 hours.
[0033] In some embodiments, during the solid-liquid separation process, the first leaching residue can be washed with pure water, and the ratio of pure water to the first leaching residue by mass can be 5:1.
[0034] In some embodiments, in this step, the concentration of the sulfuric acid aqueous solution is 1.5–2 mol / L, and the concentration of Li ions is 18–24 g / L.
[0035] Step 3: The first leachate is mixed with a portion of the fresh roasted sand to form a slurry, and the pH is adjusted to 10-11 to obtain a third slurry. The third slurry is then separated into solid and liquid components to obtain a second leachate and a second leaching residue. In this step, carbonate ions have a greater tendency to bind with heavy metal ions, leading to the exchange of heavy metal ions with lithium ions to precipitate corresponding heavy metal carbonates. Therefore, the second leaching residue contains heavy metal carbonates, and the second leachate is enriched with lithium salts.
[0036] In some embodiments, the ratio of the second slurry to the roasted sand used in this step is 5:1 to 6:1 by mass. This ratio helps to increase the precipitation rate of heavy metals, thereby helping to reduce the heavy metal content of the final lithium carbonate product.
[0037] In some embodiments, the second leaching residue is washed with an aqueous sulfuric acid solution to obtain slag and washing liquid. The washing liquid is returned to step two for slurry preparation of the roasted sand. The surface of the second leaching residue may carry some lithium ions, and returning the washing liquid to step two helps to further improve the lithium ion recovery rate.
[0038] In some embodiments, in this step, the concentration of the sulfuric acid aqueous solution is 0.15-0.2 mol / L, and the ratio of the second leaching residue to the sulfuric acid aqueous solution in this step is 1:5 by mass.
[0039] Step 4: After heating the second leachate to a temperature greater than 90°C, add it to the carbonate solution to obtain a lithium carbonate mixture. The temperature of the carbonate solution is 80-90°C. For example, the carbonate solution may include at least one of Na₂CO₃ solution or K₂CO₃ solution. The temperature setting in Step 4 is beneficial for increasing the amount of lithium carbonate precipitated.
[0040] In some embodiments, the concentration of the carbonate solution in this step is 340-360 g / L, and controlling the concentration is beneficial to further increase the amount of lithium carbonate precipitated.
[0041] In some embodiments, the continuous addition time of the second leachate is controlled to be 60-90 minutes. Through the synergistic effect of reactant concentration and reaction time, the amount of lithium carbonate precipitated is further increased.
[0042] In some embodiments, this step further includes: reacting the lithium carbonate mixture at a temperature of 80-90°C for 60-90 minutes. The amount of lithium carbonate precipitated can be further increased through this reaction.
[0043] When the washing liquid is generated in step three, the preparation method further includes: returning the washing liquid to step two to slurry the calcined sand with the washing liquid, and repeating steps two to four so that lithium ions in the washing liquid can also be precipitated.
[0044] When it is necessary to prepare lithium carbonate powder, the lithium carbonate mixture can be subjected to solid-liquid separation to obtain lithium carbonate filter residue. The lithium carbonate filter residue can be dried to obtain lithium carbonate powder.
[0045] In this application, the black powder obtained from dismantling lithium batteries includes graphite anode material and lithium salt cathode material. The lithium salt cathode material includes at least one element selected from cobalt, manganese, or nickel. After reduction roasting of the black powder and coke, calcined ore containing lithium carbonate is obtained. A portion of the calcined ore reacts with sulfuric acid to leach metal ions (including Li ions) from the calcined ore, resulting in a reaction slurry. The reaction slurry undergoes a displacement reaction with a portion of the new calcined ore, allowing heavy metal elements (such as cobalt, manganese, or nickel) to precipitate as carbonates, thereby improving the purity of the final lithium carbonate. Furthermore, this application uses calcined ore containing lithium carbonate as a heavy metal removal agent without the need for additional extractants or precipitants, thus avoiding the introduction of other impurities and reducing the production cost of lithium carbonate.
[0046] Specifically:
[0047] Example 1:
[0048] (1) Lithium-ion batteries with NCM523 positive electrode material were selected for lithium carbonate recycling, and lithium batteries with graphite (C) as negative electrode material were used as recycling raw materials. The black powder obtained from the dismantling of waste lithium batteries was thoroughly mixed with coke to obtain a mixture. The mass ratio of black powder to coke was 5:1. Specifically, the mass of black powder was 100g and the mass of coke was 20g. The mixture was placed in an air atmosphere roasting kiln and roasted to obtain calcined sand. The roasting time was 60 minutes and the roasting temperature was 600℃, that is, the calcined sand included Li2CO3.
[0049] (2) First-stage pulping and leaching: A portion of the roasted sand is mixed with pure water to obtain a first slurry. Specifically, in this step, the mass of roasted sand is 113.1 g and the mass of water is 200 g. Li ions in the first slurry are leached with a 2 mol / L sulfuric acid aqueous solution to obtain a second slurry. The first slurry and the sulfuric acid aqueous solution are stirred and reacted in a leaching tank for 12 hours, and the pH is adjusted to 6. Specifically, the concentration of Li ions is 17.2 g / L. In this step, the ratio of the total mass of pure water and sulfuric acid aqueous solution to the roasted sand is 1:2. The second slurry is then separated into a first leaching solution and a first leaching residue. The first leaching residue is washed with pure water, and the solid-liquid ratio of the first leaching residue to pure water is 1:5.
[0050] (3) Second-stage pulping and leaching: The first leachate is mixed with a portion of the new roasted sand to form a pulp, and the pH is adjusted to 10.4 to obtain a third pulp. Specifically, the mass of the first leachate is 67.8 g, and the mass of the roasted sand is 22.6 g, such that, by mass, the ratio of the second pulp to the roasted sand used in this step is 5:1. After solid-liquid separation, the third pulp yields a second leachate and a second leaching residue. The second leaching residue is washed with 2 mol / L sulfuric acid to obtain slag and washing liquid. In this step, by mass, the solid-liquid ratio of the sulfuric acid aqueous solution to the second leaching residue is 1:5. The washing liquid is returned to the first-stage pulping and leaching process and mixed with new roasted sand.
[0051] (4) Lithium precipitation: The second leaching solution was heated to 95°C and then added to a Na2CO3 solution at 90°C with a concentration of 360 g / L. The addition time of the second leaching solution was controlled at 60 minutes, and the volume ratio of the second leaching solution to the Na2CO3 solution was controlled at 4:1. After the second leaching solution was added, the system was kept at a constant temperature and stirred for 60 minutes.
[0052] After the washing liquid is returned to the first stage of pulping leaching and new roasted sand slurry preparation, the entire process of the first stage of pulping leaching can be completed, and steps three and four can be repeated.
[0053] Example 2:
[0054] The difference from Example 1 is that the mixture is placed in an air atmosphere roasting kiln to obtain roasted sand, and the roasting time is 40 minutes. During the first stage of pulping and leaching, the pH is adjusted to 7.
[0055] Example 3:
[0056] The difference from Example 1 is that the pH was adjusted to 7 during a pulping and leaching process.
[0057] Example 4:
[0058] The difference from Example 1 is that lithium carbonate is recycled from spent NCM523, NCM811 and lithium cobalt oxide lithium-ion batteries.
[0059] Comparative Example 1:
[0060] (1) Lithium carbonate was recycled from lithium-ion batteries using NCM523 cathode material and graphite (C) anode material. The waste lithium batteries were dismantled to obtain black powder, which was then thoroughly mixed with coke to obtain a mixture. The mass ratio of black powder to coke was 5:1, specifically, 100g of black powder and 20g of coke. The mixture was then placed in an air-atmosphere roasting kiln to obtain calcined sand. The roasting time was 60 minutes, and the roasting temperature was 600℃.
[0061] (2) First-stage pulping and leaching: A portion of the roasted sand is mixed with pure water to obtain a first slurry. Specifically, in this step, the mass of roasted sand is 113.1 g and the mass of water is 200 g. Li ions in the first slurry are leached with a 2 mol / L sulfuric acid aqueous solution to obtain a second slurry. The first slurry and the sulfuric acid aqueous solution are stirred and reacted in a leaching tank for 12 hours, and the pH is adjusted to 6. Specifically, the concentration of Li ions is 17.2 g / L. In this step, the ratio of the total mass of pure water and sulfuric acid aqueous solution to the roasted sand is 1:2. The second slurry is then separated into a first leaching solution and a first leaching residue. The first leaching residue is washed with pure water, and the solid-liquid ratio of the first leaching residue to pure water is 1:5.
[0062] (3) Lithium precipitation: The first leachate was heated to 95°C and then added to a Na2CO3 solution at 90°C with a concentration of 360 g / L. The second leachate was added over a period of 60 minutes, with a volume ratio of 4:1 to the Na2CO3 solution. After adding the second leachate, the system was kept at this temperature and stirred for 60 minutes.
[0063] The difference between this example and Example 1 is that the two-stage leaching and pulping step is omitted, and the first leaching solution is used as the pre-lithiation solution.
[0064] Comparative Example 2:
[0065] The difference from Example 1 is that in step (1), the mixture is placed in an air atmosphere calcining kiln and calcined to obtain calcined sand at a calcination temperature of 800 minutes.
[0066] Comparative Example 3:
[0067] The difference from Example 1 is that in step (1), the mixture is placed in an air atmosphere roasting kiln to obtain roasted sand, and the roasting time is 120 minutes.
[0068] Comparative Example 4:
[0069] The difference from Example 1 is that in step (2), the pH of the first slurry was adjusted to 9 by leaching it with a 2 mol / L sulfuric acid aqueous solution.
[0070] This application uses an inductively coupled plasma atomic emission spectrometer (ICP-Avio200) to test the Li ion content in a Li-containing solution, and employs acid-base titration to test the lithium recovery rate and lithium carbonate content.
[0071] The test results of the above embodiments and comparative examples are shown in the table below.
[0072]
[0073] Based on the above test results, it can be seen that the preparation method of this application has a good recovery rate of Li in lithium-ion batteries and the product has high purity. The leachate obtained by this process can be used as a pre-liquid for Li precipitation to prepare battery-grade Li2CO3 products.
[0074] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A method for preparing lithium carbonate, characterized in that, Includes the following steps: Step 1: Mix black powder and coke to obtain a mixture, wherein the black powder includes lithium salt cathode material and graphite anode material, wherein the lithium salt cathode material includes at least one element selected from cobalt, manganese or nickel, and place the mixture in an air atmosphere calcining kiln to obtain calcined sand, wherein the calcined sand includes Li2CO3, the calcination temperature is 550-650℃, and the calcination time is 40-100 minutes; Step 2: Take a portion of the roasted sand and prepare it into a first slurry. Use sulfuric acid aqueous solution to leach the Li ions in the first slurry. Adjust the pH value to 6-7 to obtain a second slurry. After solid-liquid separation of the second slurry, obtain a first leachate and a first leaching residue. Step 3: Take the first leachate and a portion of the new roasted sand to make a slurry, adjust the pH value to 10-11 to obtain the third slurry, and then separate the solid and liquid of the third slurry to obtain the second leachate and the second leaching residue. Step 4: After heating the second leachate to a temperature greater than 90°C, add it to the carbonate solution to obtain a lithium carbonate mixture. The temperature of the carbonate solution is 80-90°C.
2. The method for preparing lithium carbonate as described in claim 1, characterized in that, Step four also includes: The lithium carbonate mixture is reacted at a temperature of 80-90°C for 60-90 minutes.
3. The method for preparing lithium carbonate as described in claim 1, characterized in that, The ratio of the black powder to the coke by weight is 4:1 to 6:
1.
4. The method for preparing lithium carbonate as described in claim 3, characterized in that, The roasting temperature is 550-600℃ and the roasting time is 40-60 minutes.
5. The method for preparing lithium carbonate as described in claim 1, characterized in that, In step two, the concentration of the sulfuric acid aqueous solution is 1.5–2 mol / L, and the concentration of Li ions is 18–24 g / L. In step four, the concentration of the carbonate solution is 340–360 g / L.
6. The method for preparing lithium carbonate as described in claim 5, characterized in that, The ratio of the second slurry to the roasted sand in step three is 5:1 to 6:1 by mass.
7. The method for preparing lithium carbonate as described in claim 6, characterized in that, In step four, the continuous addition time of the second leachate is controlled to be 60-90 minutes.
8. The method for preparing lithium carbonate according to any one of claims 1 to 7, characterized in that, Step three also includes: The second leaching residue was washed with an aqueous sulfuric acid solution to obtain slag and washing liquid; The preparation method further includes: Return the washing liquid to step two to use it to prepare the calcined sand into a slurry, and repeat steps two through four.
9. The method for preparing lithium carbonate as described in claim 8, characterized in that, In step three, the concentration of the sulfuric acid aqueous solution is 0.15-0.2 mol / L, and the ratio of the second leaching residue to the sulfuric acid aqueous solution is 1:5 by mass.