A method for preparing lithium carbonate based on a high gravity reactor, lithium carbonate

Abstract

The application belongs to the field of new energy, and discloses a method for preparing lithium carbonate based on a supergravity reactor, which comprises the following steps: step 1: adding a soluble carbonate solution as a bottom liquid into the supergravity reactor; step 2: continuously adding a first solution containing lithium ions into the supergravity reactor; step 3: introducing the product of step 2 into a reaction kettle, continuously adding a second solution containing lithium ions while stirring, and obtaining lithium carbonate after the reaction is completed. The method adopts the supergravity reactor to perform preliminary crystallization operation, obtains liquid with uniform initial particle size, then transfers the liquid with preliminary crystallization into the reaction kettle to further increase the crystal, and through the method, the particle size distribution range of the lithium carbonate can be effectively controlled, and the impurity content is low. Meanwhile, the application also discloses lithium carbonate.

Description

Technical Field

[0001] This invention relates to the field of new energy, specifically to a method for preparing lithium carbonate based on a supergravity reactor, and lithium carbonate. Background Technology

[0002] The uniformity and particle size of lithium battery cathode materials directly affect battery performance. Therefore, lithium battery cathode material manufacturers reduce the content of large particles in lithium carbonate by shearing, sieving, and air jet milling to improve the quality of lithium carbonate products. Existing technologies disclose the use of hypergravity reactors to prepare high-quality lithium carbonate. For example, CN110817907A discloses a method for purifying high-purity lithium carbonate. This method only discloses the removal of impurities through a hypergravity reactor, which does not participate in any crystallization process, resulting in lithium carbonate with a wide particle size distribution. CN110304643A discloses a hypergravity method for preparing battery-grade ultrafine lithium carbonate. This method uses high-lithium brine and sodium carbonate aqueous solution as raw materials. The hypergravity reactor is started, and the rotation speed of the turntable is adjusted to control the hypergravity acceleration. The dispersed material is radially thrown away by centrifugal force and impacts the inner wall of the reactor. The finally collected liquid flows out from the liquid outlet under the influence of gravity and is collected in a product storage tank. After aging, alcohol washing, and filtration, battery-grade ultrafine lithium carbonate powder is obtained. However, the crystallization process involving only the hypergravity reactor results in a high content of sodium and potassium ions, leading to lower purity of the prepared lithium carbonate.

[0003] Therefore, the technical problem to be solved in this case is: how to prepare lithium carbonate with high purity and narrow particle size distribution. Summary of the Invention

[0004] The main objective of this invention is to provide a method for preparing lithium carbonate based on a supergravity reactor. This method uses a supergravity reactor for preliminary crystallization to obtain a liquid with uniform initial particle size. Then, the pre-crystallized liquid is transferred to a reaction vessel to further increase the size of the crystals. This method can effectively control the particle size distribution range of lithium carbonate and reduce the impurity content.

[0005] In addition, the present invention also discloses a lithium carbonate.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing lithium carbonate based on a supergravity reactor includes the following steps:

[0008] Step 1: Add a soluble carbonate solution as the base liquid to the centrifugal reactor;

[0009] Step 2: The first solution containing lithium ions is continuously added to the hypergravity reactor to obtain a solution containing seed crystals;

[0010] Step 3: Pour the solution from Step 2 into the reaction vessel, and continuously add a second solution containing lithium ions while stirring. After the reaction is complete, lithium carbonate is obtained.

[0011] Preferably, the molar amount of carbonate ions in the soluble carbonate solution is 0.5 to 0.8 times the sum of the molar amounts of lithium ions in the first solution and the second solution; the molar ratio of lithium ions in the first solution to lithium ions in the second solution is 5 to 60: 40 to 95.

[0012] In some specific embodiments of the present invention, the molar amount of carbonate ions in the soluble carbonate solution can be selected as 0.5, 0.6, 0.7 or 0.8 times the sum of the molar amounts of lithium ions in the first solution and the second solution;

[0013] The molar amount of lithium ions in the first solution and the molar ratio of lithium ions in the second solution can be selected as 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65 or 40:60, 60:40;

[0014] In the above-mentioned method for preparing lithium carbonate based on a supergravity reactor, both the first solution and the second solution are lithium-containing brines;

[0015] As a commonly used brine in this field, brine can be selected from salt lake brine, salt lake intercrystalline brine, and underground brine;

[0016] As potential raw materials, brine can also be selected from oilfield water, coalbed methane field produced water, salt lake brine, salt lake intercrystalline brine, geothermal water, underground brine, seawater, and lithium-rich eluent after extraction and treatment.

[0017] Regardless of the raw materials, the impurities in the brine are mainly sodium ions and / or potassium ions;

[0018] Some raw materials also contain calcium ions, manganese ions, etc. If the raw materials contain these metal ions that easily react with carbonate ions to form carbonate precipitates, these metal ions should be removed in advance (such as by using oxalic acid or oxalate for precipitation, using complexing agents for complexation, or a combination of multiple methods) to ensure the normal progress of subsequent reactions.

[0019] In the above-described method for preparing lithium carbonate based on a supergravity reactor, the first solution is a lithium salt solution, and more specifically, the metal ions in the lithium salt solution are only lithium ions. The phrase "only" here includes cases where trace amounts of other metal elements that cannot be completely removed are present; the second solution is brine.

[0020] During the experiment, it was found that if the metal ions in the first solution were only lithium ions, the particle size distribution range was narrower. The possible reason is that, without the interference of other impurity metal ions, the seed crystal is purer and its particle size distribution is more uniform. The particle size of this uniformly distributed particles increases in size in the reaction vessel, and its particle size distribution is narrower, resulting in a product with better specifications.

[0021] In the above-described method for preparing lithium carbonate based on a supergravity reactor, the concentration of sodium ions in the brine is 0–70 g / L, the concentration of potassium ions is 0–15 g / L, and / or the concentration of lithium ions in the brine is 0.01–8 g / L.

[0022] In some specific embodiments of the present invention, the concentration of sodium ions in the brine can be selected as 5 g / L, 10 g / L, 15 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L or 70 g / L.

[0023] In some specific embodiments of the present invention, the concentration of potassium ions can be selected as 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 8 g / L, 10 g / L, 12 g / L or 15 g / L;

[0024] In the above-described method for preparing lithium carbonate based on a supergravity reactor, the independent reaction temperatures in steps 2 to 3 are 50–99°C; preferably, the independent reaction temperatures in steps 2 to 3 are 55–95°C; more preferably, the independent reaction temperatures in steps 2 to 3 are 70–90°C.

[0025] Preferably, the first solution is added over a period of 0.1 to 2 hours;

[0026] Preferably, the second solution is added over a period of 0.5 to 3 hours;

[0027] And / or, in step 3, after the second solution is added, continue the reaction for 1-3 hours;

[0028] In some specific embodiments of the present invention, the first solution addition time in step 2 can be selected as 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2.0h;

[0029] In some specific embodiments of the present invention, the time for adding the second solution in step 3 can be selected as 0.5h, 1h, 1.5h, 2h, 2.5h or 3h;

[0030] In some specific embodiments of the present invention, the independent reaction temperatures in steps 2 to 3 are 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 99°C.

[0031] In the above-described method for preparing lithium carbonate based on a supergravity reactor, the concentration of carbonate in the bottom solution is 10–32 wt%; preferably, the concentration of carbonate in the bottom solution is 12–30 wt%; more preferably, the concentration of carbonate in the bottom solution is 15–25 wt%.

[0032] In some embodiments of the present invention, the concentration of carbonate in the base solution can be selected as 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, or 32wt%.

[0033] The carbonate is sodium carbonate and / or potassium carbonate.

[0034] In the above method for preparing lithium carbonate based on a hypergravity reactor, the stirring speed of the hypergravity reactor is 2000–5000 r / min. Preferably, the stirring speed of the hypergravity reactor is 2500–4500 r / min; more preferably, the stirring speed of the hypergravity reactor is 3000–4000 r / min.

[0035] In the above-mentioned method for preparing lithium carbonate based on a supergravity reactor, the molar amount of carbonate ions in the soluble carbonate solution is 0.55 to 0.75 times the sum of the molar amounts of lithium ions in the first solution and the second solution; the molar ratio of lithium ions in the first solution to lithium ions in the second solution is 10 to 25:75 to 90.

[0036] In the above-mentioned method for preparing lithium carbonate based on a supergravity reactor, in step 3, after the reaction is completed, a slurry containing lithium carbonate is obtained.

[0037] The specific steps for separating solid lithium carbonate from a lithium carbonate-containing slurry are as follows:

[0038] Filter the lithium carbonate-containing slurry, and wash the filter residue 2-4 times. The slurry-to-solid ratio is 2:1 to 10:1, the slurry water temperature is 50-99℃, and the washing time is 0.5-3h.

[0039] After washing, the solid is dispersed in water and washed a second time. Then it is filtered and rinsed once with clean water at a temperature of 50-99℃ to finally obtain lithium carbonate.

[0040] Meanwhile, the present invention also discloses a lithium carbonate with a particle size distribution of D10≥1μm, 5μm≤D50≤90μm, D90≤200μm, and a purity of battery-grade lithium carbonate.

[0041] Preferably, its particle size distribution is D10≥2μm, 5μm≤D50≤50μm, and D90≤100μm;

[0042] Preferably, the particle size distribution is D10≥2μm, 5μm≤D50≤8μm, and D90≤30μm.

[0043] The lithium carbonate described above is prepared using any of the methods described above.

[0044] One of the above-described technical solutions of the present invention has at least one of the following advantages or beneficial effects:

[0045] In this invention, a high-gravity reactor is used for preliminary crystallization to obtain a liquid with uniform initial particle size. The pre-crystallized liquid is then transferred to a reaction vessel to further increase the size of the crystals. This method can effectively control the particle size distribution range of lithium carbonate and result in low impurity content.

[0046] In a further preferred embodiment of the present invention, a relatively pure lithium salt solution is added to the supergravity reactor for reaction, resulting in purer seed crystals. After the crystal particle size increases in the reaction vessel, the particle size distribution is narrower, and the specifications of the obtained product are superior.

[0047] In this invention, the particle size distribution and impurity content of the product are optimized by controlling the distribution ratio of the first solution and the second solution. Experiments have shown that the closer the ratio is to 25:75, the better the particle size control and the lower the impurity content. The reason is that in the hypergravity reactor, sodium carbonate and lithium ions react to obtain seed crystals. The seed crystals enter the reaction vessel and grow larger. If the proportion of lithium ions is high in step 3, there are fewer seed crystals, and the crystal size is too large when growing in the reaction vessel. If the proportion of lithium ions is low in step 3, too many small-diameter crystals have the characteristic of aggregation, which increases the particle size. In this process, since it is not a normal particle size growth process, it will contain more impurities.

[0048] In this invention, a supergravity reactor can be used in conjunction with multiple reaction vessels to achieve scaled-up production and effectively improve production efficiency. Detailed Implementation

[0049] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0050] Part One

[0051] This section uses brine as a raw material for the preparation of seed crystals to produce lithium carbonate.

[0052] Example 1

[0053] A method for preparing lithium carbonate includes the following steps:

[0054] Step 1: Bottom liquid of the reactor: Using sodium carbonate as the bottom liquid, first prepare a sodium carbonate solution with a concentration of 25wt% in the reactor; the temperature of the sodium carbonate solution is 60℃;

[0055] Step 2: Add the bottom liquid to the high gravity reactor;

[0056] The specifications of the supergravity reactor are: 500L, 1500L / h;

[0057] The parameters of the hypergravity reactor were controlled as follows: 4000 r / min, 60℃, and atmospheric pressure.

[0058] The molar amount of sodium carbonate in the bottom liquid added to the hypergravity reactor is 0.6 times the molar amount of lithium ions in steps 3 and 4; the reaction temperature in the hypergravity reactor is 60℃.

[0059] Step 3: Pump the brine into the high gravity reactor using a metering pump over a period of 1 hour; after feeding, pump the reacted solution directly into the reaction vessel in Step 4 in one go.

[0060] Step 4: Using the solution from Step 3 as the base liquid, add the remaining brine through a metering pump; the feeding time is 1.5 hours, and the solution is kept warm for 2 hours after feeding is completed; the reaction temperature in the reactor is controlled at 90℃.

[0061] The main components of the brine in steps 3 and 4 are as follows:

[0062] Lithium sulfate 1 mol / L;

[0063] Sodium sulfate 1.2 mol / L;

[0064] Potassium sulfate 0.12 mol / L;

[0065] The brine molar ratio in steps 3 and 4 is 2:8, and the lithium ion molar ratio in both steps is 2:8.

[0066] Step 5: The product from Step 4 is filtered through a plate and frame filter press. The filter residue is pulped and washed three times. The pulping solution consists of lithium carbonate and pure water with a solid-to-weight ratio of 5:1. The pulping water temperature is 60°C and the washing time is 2 hours. After the second stirring and washing through the plate and frame filter press, it is rinsed once. The washing water is pure water at a temperature of 60°C. Finally, high-quality lithium carbonate with low potassium and low sodium is obtained.

[0067] Example 2

[0068] The process is largely the same as in Example 1, except that the brine molar ratio in steps 3 and 4 is 5:95, and the lithium ion molar ratio in both steps is 5:95.

[0069] Example 3

[0070] The process is largely the same as in Example 1, except that the brine molar ratio in steps 3 and 4 is 1:9, and the lithium ion molar ratio in both steps is 1:9.

[0071] Example 4

[0072] The process is largely the same as in Example 1, except that the brine molar ratio in steps 3 and 4 is 25:75, and the lithium ion molar ratio in both steps is 25:75.

[0073] Example 5

[0074] The process is largely the same as in Example 1, except that the brine molar ratio in steps 3 and 4 is 3:7, and the lithium ion molar ratio in both steps is 3:7.

[0075] Example 6

[0076] The process is largely the same as in Example 1, except that the molar ratio of brine in steps 3 and 4 is 4:6, and the molar ratio of lithium ions in both steps is 4:6.

[0077] Example 7

[0078] The process is largely the same as in Example 2, except that: 32wt% potassium carbonate is used to replace sodium carbonate in the base solution, with the molar amounts of both being equal; the reaction temperature in steps 1 to 5 is adjusted to 60℃; the feeding time in step 3 is 0.1h; the feeding time in step 4 is 0.5h, and the holding time is 1h; and the stirring speed of the supergravity reactor is 2000r / min.

[0079] Example 8

[0080] The process is largely the same as in Example 2, except that: the concentration of sodium carbonate in the bottom solution is 10 wt%; the reaction temperature of steps 1 to 5 is adjusted to 50°C; the feeding time in step 3 is 2 hours; the feeding time in step 4 is 3 hours, and the heat preservation time is 3 hours; and the stirring speed of the supergravity reactor is 5000 r / min.

[0081] Example 9

[0082] It is largely the same as Example 2, except that the molar ratio of sodium carbonate to lithium is 0.8:1.

[0083] Example 10

[0084] It is largely the same as Example 2, except that the molar ratio of sodium carbonate to lithium is 0.5:1.

[0085] Part Two

[0086] This section uses lithium sulfate solution as the raw material for preparing seed crystals to produce lithium carbonate.

[0087] Example 11

[0088] A method for preparing lithium carbonate includes the following steps:

[0089] Step 1: Bottom liquid of the reaction vessel: Using sodium carbonate as the bottom liquid, first prepare a sodium carbonate solution with a concentration of 25wt% in the reaction vessel; the temperature of the sodium carbonate solution is 90℃;

[0090] Step 2: Add the bottom liquid to the high gravity reactor;

[0091] The specifications of the supergravity reactor are: 500L, 1500L / h;

[0092] The parameters of the hypergravity reactor were controlled as follows: 4000 r / min, 90℃, and atmospheric pressure.

[0093] The molar amount of sodium carbonate in the bottom liquid added to the hypergravity reactor is 0.6 times the molar amount of lithium ions in steps 3 and 4; the reaction temperature in the hypergravity reactor is 90℃.

[0094] Step 3: Pump the lithium sulfate solution into the centrifugal reactor using a metering pump over a period of 1 hour; after the addition is complete, pump the reacted solution directly into the reaction vessel in Step 4.

[0095] The concentration of lithium sulfate is 1 mol / L;

[0096] Step 4: Using the slurry from Step 3 as the base liquid, add brine through a metering pump; the feeding time is 1.5 hours, and the mixture is kept warm for 2 hours after feeding; the reaction temperature in the reactor is controlled at 90℃.

[0097] The main components of the brine in step 4 are as follows:

[0098] Lithium sulfate 1 mol / L;

[0099] Sodium sulfate 1.2 mol / L;

[0100] Potassium sulfate 0.12 mol / L;

[0101] The ratio of lithium sulfate in steps 3 and 4 is 2:8.

[0102] Step 5: The product from Step 4 is filtered through a plate and frame filter press. The filter residue is pulped and washed three times with a pulping liquid-to-solid ratio of 5:1, pulping water temperature of 90℃, and washing time of 2 hours. After the second stirring and washing through the plate and frame filter press, it is rinsed once with washing water at 90℃. Finally, high-quality lithium carbonate with low potassium and low sodium is obtained.

[0103] Example 12

[0104] It is largely the same as Example 11, except that the ratio of lithium sulfate in steps 3 and 4 is 5:95.

[0105] Example 13

[0106] It is largely the same as Example 11, except that the ratio of lithium sulfate in steps 3 and 4 is 1:9.

[0107] Example 14

[0108] It is largely the same as Example 11, except that the ratio of lithium sulfate in steps 3 and 4 is 25:75.

[0109] Example 15

[0110] It is largely the same as Example 11, except that the ratio of lithium sulfate in steps 3 and 4 is 3:7.

[0111] Comparative Example 1

[0112] Step 1: Bottom liquid of the reactor: Using sodium carbonate as the bottom liquid, first prepare a sodium carbonate solution with a concentration of 25wt% in the reactor; the temperature of the sodium carbonate solution is 60℃;

[0113] Step 2: Add the bottom liquid to the high gravity reactor;

[0114] The specifications of the supergravity reactor are: 500L, 1500L / h;

[0115] The parameters of the hypergravity reactor were controlled as follows: 4000 r / min, 60℃, and atmospheric pressure.

[0116] The reaction temperature in the hypergravity reactor is 90℃; the molar amount of sodium carbonate in the bottom liquid added to the hypergravity reactor is 0.6 times the molar amount of lithium ions in step 3;

[0117] Step 3: Pump the brine solution into the centrifugal reactor using a metering pump over a period of 2 hours; after feeding, pump the reacted slurry directly into the reaction vessel in Step 4 in one go.

[0118] The main components of the brine in step 3 are as follows:

[0119] The concentration of lithium sulfate is 1 mol / L;

[0120] Sodium sulfate 1.2 mol / L;

[0121] Potassium sulfate 0.12 mol / L;

[0122] Step 4: Keep the reactor warm for 1 hour, and control the reaction temperature at 90℃;

[0123] Step 5: The product from Step 4 is filtered through a plate and frame filter press. The filter residue is pulped and washed three times with a pulping liquid-to-solid ratio of 5:1 and a pulping water temperature of 60°C for 2 hours. After the second stirring and washing through the plate and frame filter press, it is rinsed once with a washing water temperature of 60°C to finally obtain lithium carbonate.

[0124] Comparative Example 2

[0125] The reaction is roughly the same as Comparative Example 1, except that potassium carbonate is used to replace sodium carbonate in the base solution, and the molar amounts of both are equal; the reaction temperature of steps 1 to 5 is adjusted to 60°C.

[0126] Comparative Example 3

[0127] It is roughly the same as Comparative Example 1, except that the molar amount of sodium carbonate in the bottom liquid added to the supergravity reactor is 0.5 times the molar amount of lithium ions in step 3.

[0128] Comparative Example 4

[0129] Step 1: Bottom liquid of the reactor: Using sodium carbonate as the bottom liquid, first prepare a sodium carbonate solution with a concentration of 25wt% in the reactor; the temperature of the sodium carbonate solution is 60℃;

[0130] Step 2: Add the base liquid to the reaction vessel;

[0131] The molar amount of sodium carbonate in the bottom solution added to the reactor is 0.6 times the molar amount of lithium ions in step 3; the reaction temperature in the reactor is 60℃.

[0132] Step 3: Pump the brine solution into the reactor using a metering pump over a period of 2 hours; after feeding, keep the reactor warm for 1 hour, maintaining the reaction temperature at 90°C.

[0133] The components of the brine in step 3 are as follows:

[0134] The concentration of lithium sulfate is 1 mol / L;

[0135] Sodium sulfate 1.2 mol / L;

[0136] Potassium sulfate 0.12 mol / L;

[0137] Step 4: The product from Step 3 is filtered through a plate and frame filter press. The filter residue is pulped and washed three times with a pulping liquid-to-solid ratio of 5:1, pulping water temperature of 60°C, and washing time of 2 hours. After the second stirring and washing through the plate and frame filter press, it is rinsed once with washing water at 60°C to finally obtain lithium carbonate.

[0138] Performance testing

[0139] Test item 1: Impurity content, mainly testing the K and Na content in the dried lithium carbonate;

[0140] The specific method is as follows: ICP detection method is used for detection. 1g of sample is dissolved in 5ml of nitric acid and diluted to 100ml with pure water.

[0141] Detection conditions: Argon inlet pressure 0.6-0.8 MPa, RF power 1.2 kW, stabilization time 15 s, nebulizer flow rate 0.7 L / min, plasma gas flow rate 15 L / min, calibration fitting: linear, auxiliary gas flow rate 1.0 L / min, supplementary gas flow rate 0 L / min, number of repetitions 3, pump speed 12 rpm, rise delay 15 s, reading time 5 s;

[0142] Test item 2: Particle size detection, mainly to detect the particle size distribution of lithium carbonate.

[0143] The specific method is as follows: 0.2g of sample is added to 20ml of ethanol, sonicated for 2min, and then partially injected into the laser particle size analyzer.

[0144] The test results are shown in Table 1 below;

[0145] Table 1 Test Results

[0146]

[0147]

[0148] Results analysis:

[0149] 1. Through Examples 1-6, as the ratio of lithium sulfate in steps 3 and 4 changes, the closer it gets to 25:75, the better the particle size control and the lower the impurity content. The reason is that in the hypergravity reactor, sodium carbonate and lithium ions react to obtain seed crystals. The seed crystals enter the reaction vessel and grow larger. In the hypergravity reactor, if the proportion of lithium ions is higher, the number of crystals is greater, and the resulting particle size will be smaller and the particle size distribution will be more uniform. If the proportion of lithium ions is low in step 3, there are fewer seed crystals, and the particle size will be too large when growing in the reaction vessel.

[0150] However, the ratio of lithium sulfate in steps 3 and 4 cannot exceed 4:6. When the ratio is close to 4:6, the sodium and potassium ion content in Example 6 increases sharply compared to Example 5, and the particle size also increases significantly. The possible reason is that during the particle size ripening process in the reactor, too many small-diameter crystals have the characteristic of agglomeration, which increases the particle size. In this process, since it is not a normal particle size growth process, it contains more impurities.

[0151] 2. As can be seen from Examples 1-6 and Examples 11-15, the lithium sulfate solution used as seed crystal generally exhibits superior performance in all aspects. Although this method reduces production efficiency, it is beneficial for controlling product quality. The most likely reason for this phenomenon is the low number of impurity metal ions and seed crystals, leading to synchronous crystal growth and further reducing the amount of impurities within the crystal.

[0152] 3. As can be seen from Examples 1, 7, 10 and Comparative Examples 1-3, the performance change trend is consistent when the relevant process parameters are changed.

[0153] 4. As seen in Examples 2 and 7-10, the more sodium carbonate, the narrower the particle size distribution and the fewer impurities; the reason for this is currently unclear. A comparison between Examples 2 and 7 shows that sodium carbonate is the preferred base liquid; the reason for the performance difference between sodium carbonate and potassium carbonate is currently unclear.

[0154] 3. As can be seen from Comparative Examples 1 and 4, the overall effect of using a hypergravity reactor is better than that of a conventional reactor. As can be seen from Examples 1, 1, and 4, combining a hypergravity reactor with a conventional reactor and using seed crystals to hatch crystals can significantly reduce the particle size distribution range and reduce impurity content.

[0155] Additionally, it should be noted that the brine used in the embodiments and comparative examples of this invention is the same type of brine. This is due to the limitation of a single source of raw materials, as demonstrated in the first embodiment above.

[0156] The verification of different proportions of brine used in the first solution and the second solution demonstrates the influence trend of the relevant influencing factors of the present invention on the reaction results. For those skilled in the art, brine from different sources can produce similar trend changes when using the method of the present invention. Therefore, the selection of brine in the embodiments is not intended to limit the method of the present invention in any way.

[0157] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing lithium carbonate based on a supergravity reactor, characterized in that, Includes the following steps: Step 1: Add a soluble carbonate solution as the base liquid to the centrifugal reactor; Step 2: The first solution containing lithium ions is continuously added to the hypergravity reactor to obtain a solution containing seed crystals; Step 3: Pour the solution from Step 2 into the reaction vessel, and continuously add a second solution containing lithium ions while stirring. After the reaction is complete, lithium carbonate is obtained. The second solution is a lithium-containing brine; The molar amount of carbonate ions in the soluble carbonate solution is 0.5 to 0.8 times the sum of the molar amounts of lithium ions in the first solution and the second solution; the molar ratio of lithium ions in the first solution to lithium ions in the second solution is 5 to 35: 65 to 95.

2. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, Both the first solution and the second solution are lithium-containing brines.

3. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, The first solution is a lithium salt solution; the second solution is a lithium-containing brine.

4. The method for preparing lithium carbonate based on a supergravity reactor according to claim 2 or 3, characterized in that, The concentration of sodium ions in the brine is 0~70 g / L, and the concentration of potassium ions is 0~15 g / L. And / or, the lithium ion concentration in the brine is 0.01~8 g / L.

5. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, The independent reaction temperatures in steps 2 and 3 are 50-99℃. And / or, the first solution is added over a period of 0.1 to 2 hours; And / or, the second solution is added over a period of 0.5 to 3 hours; And / or, in step 3, after the second solution is added, continue the reaction for 1-3 hours.

6. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, The concentration of carbonate in the substrate is 10-32 wt%. The carbonate is sodium carbonate and / or potassium carbonate.

7. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, The stirring speed of the supergravity reactor is 2000~5000 r / min.

8. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, The molar amount of carbonate ions in the soluble carbonate solution is 0.55 to 0.75 times the sum of the molar amounts of lithium ions in the first solution and the second solution; the molar ratio of lithium ions in the first solution to lithium ions in the second solution is 10 to 25: 75 to 90.

9. The method for preparing lithium carbonate based on a supergravity reactor according to claim 1, characterized in that, In step 3, after the reaction is completed, a slurry containing lithium carbonate is obtained; The specific steps for separating solid lithium carbonate from a lithium carbonate-containing slurry are as follows: Filter the lithium carbonate-containing slurry, and wash the filter residue 2-4 times. The slurry-to-solid ratio is 2:1 to 10:1, the slurry water temperature is 50-99℃, and the washing time is 0.5-3h. After washing, the solid is dispersed in water and washed a second time. Then it is filtered and rinsed once with clean water at a temperature of 50-99℃ to finally obtain lithium carbonate.

10. A lithium carbonate, characterized in that, The lithium carbonate is prepared by any one of the methods described in claims 1 to 9, and its particle size distribution is D10≥1μm, 5μm≤D50≤90μm, D90≤200μm, and its purity is battery grade.

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