CN115849414B - Method for preparing ultrapure lithium carbonate with uniform and stable granularity - Google Patents
Method for preparing ultrapure lithium carbonate with uniform and stable granularity Download PDFInfo
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- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 title claims abstract description 86
- 229910052808 lithium carbonate Inorganic materials 0.000 title claims abstract description 86
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000000197 pyrolysis Methods 0.000 claims abstract description 59
- HQRPHMAXFVUBJX-UHFFFAOYSA-M lithium;hydrogen carbonate Chemical compound [Li+].OC([O-])=O HQRPHMAXFVUBJX-UHFFFAOYSA-M 0.000 claims abstract description 50
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 20
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 20
- 239000013078 crystal Substances 0.000 claims abstract description 11
- 238000005406 washing Methods 0.000 claims abstract description 11
- 238000001354 calcination Methods 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims description 33
- 239000002245 particle Substances 0.000 claims description 19
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 238000003763 carbonization Methods 0.000 claims description 14
- 239000012535 impurity Substances 0.000 claims description 13
- 238000003756 stirring Methods 0.000 claims description 13
- 238000005342 ion exchange Methods 0.000 claims description 12
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000003729 cation exchange resin Substances 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 7
- 238000005119 centrifugation Methods 0.000 claims description 6
- 239000002002 slurry Substances 0.000 claims description 6
- 239000003957 anion exchange resin Substances 0.000 claims description 4
- 239000011347 resin Substances 0.000 claims description 4
- 229920005989 resin Polymers 0.000 claims description 4
- 238000012360 testing method Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims 1
- 230000000007 visual effect Effects 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 6
- 230000001276 controlling effect Effects 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention discloses a method for preparing ultrapure lithium carbonate with uniform and stable granularity, which comprises the following steps: preparing lithium bicarbonate solution; pyrolysis is carried out by adopting an improved pyrolysis device; centrifuging; washing with water and centrifuging again; and (5) calcining. According to the invention, carbon dioxide is introduced into the pyrolysis kettle, the visual appearance is that the pressure in the kettle is increased, and the pressure in the kettle of the pyrolysis kettle is kept constant in a pressure release mode of the exhaust valve, so that crystals are uniformly separated out and grown, the granularity of the obtained ultra-pure lithium carbonate is stable and uniform, the condition that granularity index is suddenly high and suddenly low is avoided, and the industrial standard is met.
Description
Technical Field
The invention relates to the technical field of lithium carbonate preparation, in particular to a method for preparing ultrapure lithium carbonate with uniform and stable granularity.
Background
At present, the requirements of various industries on lithium carbonate serving as a lithium base material are more and more severe, particularly the requirements on the quality of ultrapure lithium carbonate in special industries such as high-end chips are shown in the requirements on chemical indexes and the severe requirements on physical indexes. Wherein, the requirements of chemical indexes comprise that the main content reaches more than 99.999 percent, and the requirements of physical indexes mainly comprise the requirements of granularity, wherein, lithium carbonate D10 is more than or equal to 1, D50 is more than or equal to 3 and less than or equal to 8, D90 is more than or equal to 9 and less than or equal to 15 in YS/T582-2013 standard. However, in the existing preparation method of lithium carbonate, the method of obtaining ultrapure lithium carbonate cannot be stabilized in the requirement of YS/T582-2013 standard, and similarly, the purity of the lithium carbonate with the granularity stabilized in the requirement of YS/T582-2013 standard can be obtained and is less than 99.999%.
Disclosure of Invention
The invention aims to solve the technical problem that the existing lithium carbonate preparation method cannot simultaneously consider the purity of more than 99.999% and the granularity requirement in YS/T582-2013 standard, and provides a method for preparing ultrapure lithium carbonate with uniform and stable granularity.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for preparing ultrapure lithium carbonate having uniform and stable particle size, comprising the steps of:
step one, preparing and purifying lithium bicarbonate solution: injecting pure water into a carbonization kettle, starting stirring, adding battery-grade lithium carbonate, then introducing carbon dioxide for full reaction, testing the Li content in the lithium bicarbonate solution when the solution is clear and transparent, and purifying when the Li content is 8g/L, wherein the purified solution is a qualified lithium bicarbonate solution;
purifying lithium bicarbonate solution: (1) and (3) carrying out four-stage precise filtration on the qualified lithium bicarbonate liquid prepared in the step (I). First, the lithium bicarbonate solution was passed through a 0.5 μm filter bag to filter out impurities having larger particles. The small particle impurities were then filtered further through a 0.05 micron filter. Finally, the mixture passes through a 2-channel 0.01-micrometer filter element continuously. (2) The filtered lithium bicarbonate solution in the step (1) is firstly passed through cation exchange resin, and the cation exchange resin is mixed with several resins with strong specific ion exchange capacity and added into an ion exchange column for use (such as Ca, mg and other impurity ions which are difficult to remove). Then, SO is removed by anion exchange resin 4 2- . (3) The lithium bicarbonate after ion exchange passes through a filter element of 0.01 mu m again, and the qualified lithium bicarbonate solution is obtained.
Step two, pyrolysis is carried out by adopting a pyrolysis device: the pyrolysis device comprises a pyrolysis kettle body, wherein the top of the pyrolysis kettle body is provided with a liquid inlet, a steam pipe and a stirring device, the bottom of the pyrolysis kettle body is provided with a liquid outlet, and the liquid outlet is communicated with a centrifugal machine; the pyrolysis kettle body is also provided with an air inlet, an air outlet, a temperature sensor and a pressure gauge, wherein the air inlet and CO 2 The air source is communicated, the air outlet is sequentially communicated with the air dryer and the carbonization kettle, and the air inlet and the air outlet are respectively provided with an air inlet valve and an air outlet valve; the pressure gauge is electrically connected with a signal input end of the PLC, and a signal output end of the PLC is electrically connected with the air inlet valve and the air outlet valve respectively;
the pyrolysis operation is as follows:
starting a stirring device, and injecting the qualified lithium bicarbonate solution in the first step into a pyrolysis kettle body until the liquid level of the lithium bicarbonate solution rises to 2/3 of the volume of the pyrolysis kettle; at 1Kg/m 3 Adding ultrapure lithium carbonate with the purity of more than 99.999 percent as seed crystal into the adding amount of the lithium bicarbonate solution, and then adding carbon dioxide into the pyrolysis kettle body through an air inlet to ensure that the air pressure in the kettle reaches 0.5-5Mpa; the steam is introduced into the kettle through the steam pipe to start heating, the temperature in the kettle is monitored by the temperature sensor to be higher than 90 ℃, the solution becomes turbid gradually in the heating process, and the lithium carbonate is separated out to release a large amount of carbon dioxide and must pass throughThe PLC controls the opening and closing of the air inlet valve and the air outlet valve, so that the pressure in the kettle is kept at 0.5-5Mpa; when the temperature in the kettle is increased to 95 ℃ and the pressure in the kettle is unchanged after 20min, manually opening an exhaust valve, drying the gas in the kettle through a gas dryer, and then introducing the gas into a carbonization kettle for preparing lithium bicarbonate solution, discharging lithium carbonate slurry from a liquid outlet of a pyrolysis kettle to a centrifugal machine for centrifugation, and when no water drops from a liquid outlet of the centrifugal machine, closing the centrifugal machine to obtain wet lithium carbonate;
step three, washing and centrifuging again: washing wet lithium carbonate in the second step with water, centrifuging again, and controlling the water content in the centrifuged lithium carbonate to be less than or equal to 5%;
step four, calcining: calcining the centrifuged lithium carbonate in the third step for 2 hours at 400-600 ℃ to obtain the ultrapure lithium carbonate with the purity of more than or equal to 99.999%.
As a preferable mode of the technical scheme of the invention, the purity of the battery grade lithium carbonate is 99.5%.
Preferably, in the first step, the reaction time is 2-4h.
Preferably, in the second step, the temperature rising rate is 0.5-1 ℃/min, preferably 1 ℃/min.
Preferably, in the second step, the moisture of the wet lithium carbonate after centrifugation is less than or equal to 5 percent.
Preferably, in the third step, the solid-to-liquid ratio of wet lithium carbonate water washing is 1:5.
Compared with the existing lithium carbonate preparation method, the method has the following beneficial effects:
1. according to the invention, the pressure in the pyrolysis kettle body is kept constant in a carbon dioxide supplementing and exhaust valve decompression mode, the granularity of the obtained ultrapure lithium carbonate is stable and uniform, the condition that granularity index is suddenly high and suddenly low is avoided, and the requirement of YS/T582-2013 standard on the granularity of the ultrapure lithium carbonate is met.
2. LiHCO according to lithium bicarbonate pyrolytic chemical reaction equation 2 3 =Li 2 CO 3 +CO 2 +H 2 O is known that a large amount of carbon dioxide is generated when the reaction proceeds forward, and lithium carbonate is precipitated and crystals grow. If a large amount of crystals are precipitated and grown up instantaneously, the grain size of the crystals is not uniformEven, resulting in the inability of ultra-pure lithium carbonate to be used. The applicant thinks that lithium carbonate is uniformly precipitated to form a long crystal in a unit time by controlling the forward progress rate of the reaction. The means of controlling the forward reaction rate is to regulate the amount of carbon dioxide in the pyrolysis kettle, and the more products, the slower the forward reaction rate, and the trend of the reverse reaction is seen from the factors influencing the reaction rate. Therefore, carbon dioxide is introduced into the pyrolysis kettle, the intuitive increase of the air pressure in the kettle is shown, and the effect of controlling the forward reaction rate can be achieved by controlling the pressure in the reaction kettle to be a constant value, so that crystals are uniformly separated out and grown up, the stable and uniform granularity of the ultra-pure lithium carbonate is ensured, and the industrial requirements are met.
Drawings
FIG. 1 is a schematic view of a pyrolysis apparatus used in the present invention;
reference numerals: 1. a pyrolysis kettle body; 2. a liquid inlet; 3. a liquid outlet; 4. a centrifuge; 5. an air inlet; 6. an exhaust port; 7. a pressure gauge; 8. CO 2 A gas source; 9. a gas dryer; 10. a carbonization kettle; 11. a temperature sensor; 12. a steam pipe; 13. and a stirring device.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples.
In the following embodiment, the adopted continuous pyrolysis device is shown in fig. 1, and comprises a pyrolysis kettle body 1, wherein the top of the pyrolysis kettle body 1 is provided with a liquid inlet 2, a steam pipe 12 and a stirring device 13, the bottom of the pyrolysis kettle body is provided with a liquid outlet 3, and the liquid outlet 3 is communicated with a centrifugal machine 4; the pyrolysis kettle body 1 is also provided with an air inlet 5, an air outlet 6, a temperature sensor 11 and a pressure gauge 7, wherein the air inlet 5 and CO 2 The air source 8 is communicated, the air outlet 6 is sequentially communicated with the air dryer 9 and the carbonization kettle 10, and the air inlet 5 and the air outlet 6 are respectively provided with an air inlet valve and an air outlet valve; the pressure gauge 7 is electrically connected with a signal input end of the PLC, and a signal output end of the PLC is electrically connected with the air inlet valve and the air outlet valve respectively.
The pyrolysis operation is as follows: starting a stirring device 13, injecting qualified lithium bicarbonate solution into the pyrolysis kettle body 1, and directlyThe liquid level of the lithium bicarbonate solution is raised to 2/3 of the volume of the pyrolysis kettle; at 1Kg/m 3 Adding ultrapure lithium carbonate with the purity of more than 99.999 percent as seed crystal into the adding amount of the lithium bicarbonate solution, and then adding carbon dioxide into the pyrolysis kettle body 1 through the air inlet 5, so that the air pressure in the kettle reaches 0.5-5Mpa; the steam is introduced into the kettle through the steam pipe 12 to start heating, the temperature in the kettle is monitored by the temperature sensor 11 and is increased to more than 90 ℃, in the heating process, the solution becomes turbid gradually, lithium carbonate is separated out, a large amount of carbon dioxide is released, the opening and closing of the air inlet valve and the air outlet valve are controlled by the PLC controller, and the pressure in the kettle is kept at 0.5-5Mpa, which is as follows: presetting a pressure value in the pyrolysis kettle by a PLC (programmable logic controller), transmitting a signal to the PLC when the pressure gauge 7 measures that the pressure in the kettle exceeds the preset value, and controlling an exhaust valve on an exhaust port 6 to be opened by the PLC to release pressure; when the pressure gauge 7 measures that the pressure in the kettle is smaller than a preset value, a signal is transmitted to the PLC, the PLC controls the air inlet valve on the air inlet 5 to be opened, and carbon dioxide is supplemented, so that the pressure is constant at the preset value. Finally, when the temperature in the kettle is increased to 95 ℃ and the pressure in the kettle is unchanged after 20min, an exhaust valve is manually opened, gas in the kettle is dried by a gas dryer 9 and then is introduced into a carbonization kettle 10 for preparing lithium bicarbonate solution, lithium carbonate slurry is discharged from a liquid outlet 3 of a pyrolysis kettle to a centrifugal machine 4 for centrifugation, and when no water drops from a liquid outlet of the centrifugal machine 4, the centrifugal machine 4 is closed to obtain wet lithium carbonate.
Example 1:
the method for preparing the ultra-pure lithium carbonate with uniform and stable granularity provided by the embodiment comprises the following steps:
(1) Will be 5m 3 Is injected with pure water of 8m 3 In the carbonization kettle, stirring is started, 237.6kg of battery-grade lithium carbonate (purity: 99.5%, moisture: 10%) is taken, a small amount of lithium carbonate is added into the carbonization kettle for multiple times, then carbon dioxide is introduced for reaction, the Li content in the lithium bicarbonate solution is tested when the solution is clear and transparent, and the solution is purified when the Li content is 8g/L, and the purified solution is qualified lithium bicarbonate solution; purifying lithium bicarbonate solution: (1) and (3) carrying out four-stage precise filtration on the qualified lithium bicarbonate liquid prepared in the step (I). Firstly, passing the lithium bicarbonate solution through a filter bag of 0.5 mu m,filtering out impurities with larger particles. The small particle impurities were then filtered further through a 0.05 micron filter. Finally, the mixture passes through a 2-channel 0.01-micrometer filter element continuously. (2) The filtered lithium bicarbonate solution in the step (1) is firstly passed through cation exchange resin, and the cation exchange resin is mixed with several resins with strong specific ion exchange capacity and added into an ion exchange column for use (such as Ca, mg and other impurity ions which are difficult to remove). Then, SO is removed by anion exchange resin 4 2- . (3) And (3) passing the lithium bicarbonate after ion exchange through a filter element with the diameter of 0.01 mu m again to obtain qualified lithium bicarbonate solution.
(2) The pyrolysis kettle stirring device 13 is started, and the temperature of the pyrolysis kettle is 2m 3 Injecting the qualified lithium bicarbonate solution into a pyrolysis kettle, and adding 2kg of ultrapure lithium carbonate with the purity of more than 99.999% as seed crystals; then adding carbon dioxide into the closed pyrolysis kettle to ensure that the air pressure in the kettle reaches 3.5Mpa; heating is started, the temperature is finally increased to 95 ℃ according to the temperature of 1 ℃/min, and the pressure in the pyrolysis kettle is controlled to be kept at 3.5Mpa all the time. When the temperature is raised to 95 ℃, the air pressure in the kettle is kept unchanged within 20min, an exhaust valve is manually opened, the gas in the kettle is dried by a gas dryer 9 and then is introduced into a carbonization kettle 10 for preparing lithium bicarbonate solution, lithium carbonate slurry is discharged from a liquid outlet 3 of a pyrolysis kettle to a centrifugal machine 4 for centrifugation, when no water drops from a liquid outlet of the centrifugal machine 4, the centrifugal machine 4 is closed, so that wet lithium carbonate is obtained, and the water content of the wet lithium carbonate is 4.9%.
(3) Wet lithium carbonate is washed with water in a solid-to-liquid ratio of 1:5, the washing temperature is 90 ℃, and the washing time is 30min. And then centrifuging again, wherein the water content of the centrifuged lithium carbonate is 5%.
(4) And calcining the centrifuged lithium carbonate for 2 hours at the temperature of 450 ℃. The test purity after drying is 99.9992%, D10:2.2 μm, D50:4.6 μm, D90:10.8 μm.
Examples 2 to 12
Example 2-example 12 experimental procedure and the like were the same as example 1 except that carbon dioxide was introduced to change the pressure in the pyrolysis reactor. The data pair is shown in table 1.
TABLE 1 pressure in pyrolysis reactor and ultrapure lithium carbonate index for examples 2-12
As can be seen from the data in Table 1, as the amount of carbon dioxide replenished in the pyrolysis kettle increases, the granularity of the prepared ultrapure lithium carbonate becomes smaller and smaller as the pressure in the kettle increases, and the YS/T582-2013 standard is continuously trended. When the pressure is increased to 3.5Mpa, the granularity index completely accords with YS/T582-2013 standard, and the granularity change is not obvious when the pressure is continuously increased. Considering that too much pressure slows down the pyrolysis rate, which affects the production efficiency and the safety of the production. When pyrolyzing 2m of carbonized liquid, the ultrapure lithium carbonate is separated out under the condition of 3.5Mpa by preferentially selecting the pressure, and the granularity of the prepared ultrapure lithium carbonate meets YS/T582-2013 standard. The purity is also above 99.999 percent, and the chemical index is also stable.
Examples 13 to 18
Examples 13-18 the other steps were repeated as in example 1 except that example 1 was repeated to verify whether the purity and particle size index of the ultrapure lithium carbonate obtained by the particle size control process by introducing carbon dioxide were stable, and the results are shown in Table 2.
TABLE 2 ultra-pure lithium carbonate index in examples 13-18
From the data in Table 2, the ultra-pure lithium carbonate prepared by the method has uniform and stable granularity, the granularity index accords with YS/T582-2013 standard after repeated times, and the purity index is also stabilized above 99.999%.
Comparative example 1: the pressure is regulated by the traditional process without introducing carbon dioxide
(1) Injecting pure water with the grain of 5m into a carbonization reaction kettle with the grain of 8m, starting stirring, taking 237.6kg of battery-grade lithium carbonate (purity: 99.5%, moisture: 10%), adding a small amount of lithium carbonate into the carbonization kettle for multiple times, introducing carbon dioxide for reaction, testing the Li content in the lithium bicarbonate solution when the solution is clear and transparent, and purifying and removing impurities by using ion exchange resin when the Li content is 8g/L, thereby purifyingAnd obtaining qualified lithium bicarbonate solution after the chemical treatment. Purifying lithium bicarbonate liquid: (1) and (3) carrying out four-stage precise filtration on the qualified lithium bicarbonate liquid prepared in the step (I). First, the lithium bicarbonate solution was passed through a 0.5 μm filter bag to filter out impurities having larger particles. The small particle impurities were then filtered further through a 0.05 micron filter. Finally, the mixture passes through a 2-channel 0.01-micrometer filter element continuously. (2) The filtered lithium bicarbonate solution in the step (1) is firstly passed through cation exchange resin, and the cation exchange resin is mixed with several resins with strong specific ion exchange capacity and added into an ion exchange column for use (such as Ca, mg and other impurity ions which are difficult to remove). Then, SO is removed by anion exchange resin 4 2- . (3) The lithium bicarbonate after ion exchange passes through a filter element of 0.01 mu m again, and the purified qualified lithium bicarbonate solution is obtained.
(2) And (3) starting the pyrolysis reaction kettle for stirring, injecting the 2 m-wave qualified lithium bicarbonate solution into the pyrolysis kettle, and adding 2kg of seed crystal. And (3) introducing steam into the top of the pyrolysis kettle to start heating, wherein the temperature is finally raised to 95 ℃ at 1 ℃/min, and preserving heat for 20min after the temperature in the kettle is raised to 95 ℃. The lithium carbonate slurry is then discharged from the pyrolysis kettle.
(3) And (3) carrying out solid-liquid separation on the lithium carbonate slurry in the step (2), separating by using a centrifugal machine, and closing the centrifugal machine when no water drops flow at a liquid outlet of the centrifugal machine, so as to obtain wet lithium carbonate, and ensuring that the water content of the wet lithium carbonate is 4.7%.
(4) Washing the wet lithium carbonate in the step (3) with water according to the solid-to-liquid ratio of 1:5, wherein the washing temperature is 90 ℃, and the washing time is 30min. And then centrifuging again, wherein the water content of the centrifuged lithium carbonate is 4.9%.
(5) And (3) centrifuging the lithium carbonate in the step (4), and calcining for 2 hours at the temperature of 450 ℃. The index of the obtained ultra-pure lithium carbonate is shown in Table 3.
Comparative examples 2 to 6
Comparative examples 2 to 6 the other steps are the same as those of comparative example 1 except that comparative example 1 was repeated to verify whether the purity and particle size index of the ultrapure lithium carbonate prepared by the conventional process are stable, and the results are shown in table 3.
TABLE 3 ultra-pure lithium carbonate index in comparative examples 1-6
As can be seen from the data in Table 3, the ultra-pure lithium carbonate prepared by conventional pyrolysis means has unstable particle size index and suddenly changes in height, and does not meet YS/T582-2013 standard. And when the granularity is larger, the impurities are more wrapped, so that the purity of the prepared ultra-pure lithium carbonate is unstable and sometimes lower than the index of 99.999%.
Claims (6)
1. A method for preparing ultrapure lithium carbonate with uniform and stable particle size, which is characterized by comprising the following steps:
step one, preparing and purifying lithium bicarbonate solution: injecting pure water into a carbonization kettle, starting stirring, adding battery-grade lithium carbonate, then introducing carbon dioxide for full reaction, testing the Li content in the lithium bicarbonate solution when the solution is clear and transparent, and purifying when the Li content is 8g/L, wherein the purified solution is a qualified lithium bicarbonate solution; the purifying operation is as follows: (1) passing lithium bicarbonate solution with Li content of 8g/L through four-stage precise filtration, firstly passing the lithium bicarbonate solution through a filter bag with the granularity of 0.5 mu m, filtering out impurities with larger particles, then passing through a filter core with the granularity of 0.05 mu m, continuously filtering out small particle impurities, and finally continuously passing through a filter core with the granularity of 0.01 mu m for 2 times; (2) the filtered lithium bicarbonate solution in the step (1) is firstly passed through cation exchange resin, the cation exchange resin is used as the resin with strong ion exchange capacity for Ca and Mg, and is mixed and added into an ion exchange column for use, and then SO is removed by anion exchange resin 4 2- The method comprises the steps of carrying out a first treatment on the surface of the (3) The lithium bicarbonate after ion exchange passes through a filter element of 0.01 mu m again, and then qualified lithium bicarbonate solution can be obtained;
step two, pyrolysis is carried out by adopting a pyrolysis device: the pyrolysis device comprises a pyrolysis kettle body (1), wherein a liquid inlet (2), a steam pipe (12) and a stirring device (13) are arranged at the top of the pyrolysis kettle body (1), a liquid outlet (3) is arranged at the bottom of the pyrolysis kettle body, and the liquid outlet (3) is communicated with a centrifugal machine (4); an air inlet (5), an air outlet (6) and a temperature transmitter are also arranged on the pyrolysis kettle body (1)A sensor (11) and a pressure gauge (7), the air inlet (5) and CO 2 The air source (8) is communicated, the air outlet (6) is sequentially communicated with the air dryer (9) and the carbonization kettle (10), and the air inlet (5) and the air outlet (6) are respectively provided with an air inlet valve and an air outlet valve; the pressure gauge (7) is electrically connected with a signal input end of the PLC, and a signal output end of the PLC is electrically connected with the air inlet valve and the air outlet valve respectively;
the pyrolysis operation is as follows:
starting a stirring device (13), and injecting the qualified lithium bicarbonate solution in the first step into the pyrolysis kettle body (1) until the liquid level of the lithium bicarbonate solution rises to 2/3 of the volume of the pyrolysis kettle; at 1Kg/m 3 Adding ultrapure lithium carbonate with the purity of more than 99.999 percent as seed crystal into the adding amount of the lithium bicarbonate solution, and then adding carbon dioxide into the pyrolysis kettle body (1) through the air inlet (5) to ensure that the air pressure in the kettle reaches 3.5-5Mpa; introducing steam into the kettle through a steam pipe (12) to start heating, monitoring through a temperature sensor (11), and heating the kettle to more than 90 ℃, wherein in the heating process, a PLC (programmable logic controller) controls the opening and closing of an air inlet valve and an air outlet valve to keep the pressure in the kettle constant; when the temperature in the kettle is increased to 95 ℃ and the pressure in the kettle is unchanged after 20min, an exhaust valve is manually opened, gas in the kettle is dried by a gas dryer (9) and then is introduced into a carbonization kettle (10) for preparing lithium bicarbonate solution, lithium carbonate slurry is discharged from a liquid outlet (3) of a pyrolysis kettle to a centrifugal machine (4) for centrifugation, and when no water drops from the liquid outlet of the centrifugal machine (4), the centrifugal machine (4) is closed to obtain wet lithium carbonate;
step three, washing and centrifuging again: washing wet lithium carbonate in the second step with water, centrifuging again, and controlling the water content in the centrifuged lithium carbonate to be less than or equal to 5%;
step four, calcining: calcining the centrifuged lithium carbonate in the third step for 2 hours at 400-600 ℃ to obtain the ultrapure lithium carbonate with the purity of more than or equal to 99.999 percent and meeting YS/T582-2013 standard requirements.
2. A method of preparing ultra-pure lithium carbonate of uniform and stable particle size according to claim 1, wherein the battery grade lithium carbonate has a purity of 99.5%.
3. The method for preparing ultrapure lithium carbonate having uniform and stable particle size according to claim 1, wherein in the second step, the temperature rising rate is 0.5-1 ℃/min.
4. A method for preparing ultrapure lithium carbonate having a uniform and stable particle size according to claim 3, wherein the temperature rise rate is 1 ℃/min.
5. The method for preparing ultrapure lithium carbonate having a uniform and stable particle size according to any one of claims 1 to 4, wherein in the second step, the moisture content of the wet lithium carbonate after centrifugation is not more than 5%.
6. A method for producing ultrapure lithium carbonate having a uniform and stable particle size according to any one of claims 1 to 4, wherein in the third step, the wet lithium carbonate is washed with water at a solid-to-liquid ratio of 1:5.
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| CN202211654559.7A CN115849414B (en) | 2022-12-22 | 2022-12-22 | Method for preparing ultrapure lithium carbonate with uniform and stable granularity |
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| CN202211654559.7A CN115849414B (en) | 2022-12-22 | 2022-12-22 | Method for preparing ultrapure lithium carbonate with uniform and stable granularity |
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| CN115849414B true CN115849414B (en) | 2023-05-09 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4124684A (en) * | 1976-08-10 | 1978-11-07 | Ministere Des Richesses Naturelles, Gouvernement Du Quebec | Continuous production of lithium carbonate |
| CN103833053A (en) * | 2014-01-21 | 2014-06-04 | 四川天齐锂业股份有限公司 | Method of preparing high-purity lithium carbonate of the 5 N grade |
| CN106365182A (en) * | 2016-08-30 | 2017-02-01 | 荆门市格林美新材料有限公司 | Method for preparing battery grade lithium carbonate by using impulse type hydrogenated industrial grade lithium carbonate |
| WO2018234614A1 (en) * | 2017-06-22 | 2018-12-27 | Outotec (Finland) Oy | Method of extracting lithium compound(s) |
| CN114477245A (en) * | 2022-02-24 | 2022-05-13 | 宁夏天霖新材料科技有限公司 | Method for preparing lithium carbonate of battery by continuously carbonizing industrial-grade lithium carbonate |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4124684A (en) * | 1976-08-10 | 1978-11-07 | Ministere Des Richesses Naturelles, Gouvernement Du Quebec | Continuous production of lithium carbonate |
| CN103833053A (en) * | 2014-01-21 | 2014-06-04 | 四川天齐锂业股份有限公司 | Method of preparing high-purity lithium carbonate of the 5 N grade |
| CN106365182A (en) * | 2016-08-30 | 2017-02-01 | 荆门市格林美新材料有限公司 | Method for preparing battery grade lithium carbonate by using impulse type hydrogenated industrial grade lithium carbonate |
| WO2018234614A1 (en) * | 2017-06-22 | 2018-12-27 | Outotec (Finland) Oy | Method of extracting lithium compound(s) |
| CN114477245A (en) * | 2022-02-24 | 2022-05-13 | 宁夏天霖新材料科技有限公司 | Method for preparing lithium carbonate of battery by continuously carbonizing industrial-grade lithium carbonate |
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