Device and method for preparing lithium carbonate micropowder

Abstract

The application provides a device and method for preparing lithium carbonate micro powder, and belongs to the field of lithium carbonate preparation. The preparation device comprises a carbonization reaction box, a carbon dioxide bubble generating device and a feeder connected with the carbonization reaction box, a stirring device and a foam scraping device arranged in the carbonization reaction box. The preparation method comprises the following steps: pumping lithium hydroxide solution and a foaming agent into the carbonization reaction box, pumping micro-nano CO2 bubbles into the carbonization reaction box by the carbon dioxide bubble generating device, and starting the stirring device; after the carbonization is completed, the foam scraping device is started to scrape out and collect the lithium carbonate micro powder suspension; and the lithium carbonate large particle suspension is collected at the bottom of the carbonization reaction box. In the application, a large amount of bubbles is generated in the carbonization process of the lithium hydroxide solution by adding the foaming agent, the agglomeration and crystallization growth of the lithium carbonate are inhibited, the small particle size lithium carbonate micro powder is taken out by the aid of the bubbles, a small amount of large particle size lithium carbonate is deposited at the bottom of the device, and the lithium carbonate micro powder and the large particle size lithium carbonate product are prepared.

Description

Technical Field

[0001] This invention belongs to the field of lithium carbonate preparation technology, and specifically relates to an apparatus and method for preparing lithium carbonate micro powder. Background Technology

[0002] Lithium is the lightest known metal, possessing unique and excellent physicochemical properties. Lithium and its compounds are widely used in ceramics, glass, aerospace materials, nuclear industry, and new energy materials. In recent years, due to the rapid development of the new energy vehicle industry, lithium prices have soared. Lithium carbonate is one of the basic lithium compounds, which can be converted into various industrial lithium raw materials and is also a major lithium product demanded by the lithium-ion battery industry. Industrial production sources of lithium carbonate include lithium extraction from lithium ore (spodumene, lepidolite) and brine extraction from salt lakes. To produce lithium carbonate, the downstream process of both typically involves carbonizing the extracted refined lithium salt solutions (lithium sulfate, lithium chloride, lithium hydroxide solutions, etc.). Carbonization is usually achieved by adding carbonates. To avoid introducing new impurities and to produce high-purity lithium carbonate, carbon dioxide gas is often introduced into the lithium hydroxide solution.

[0003] The main applications of lithium carbonate in lithium-ion battery materials are as a lithium source for cathode materials and an additive for electrolytes. Both require lithium carbonate products to have a small particle size, so lithium carbonate micro powder is the main form requirement. Currently, the preparation method of lithium carbonate micro powder usually involves repeatedly grinding and crushing the prepared large-particle-size lithium carbonate products until the particle size meets the requirements. This process is lengthy and costly.

[0004] Currently, lithium carbonate is prepared using the carbonization method. During the carbonization process, crystal growth and powder agglomeration are very likely to occur, resulting in large particle size of the prepared lithium carbonate micro powder. Subsequent crushing processes are often required to reduce the particle size of the product, which greatly increases the complexity and cost of the process. Summary of the Invention

[0005] Therefore, the present invention aims to provide an apparatus and method for preparing lithium carbonate micro powder, in order to solve at least one of the technical problems in the background art.

[0006] This invention is implemented as follows:

[0007] An apparatus for preparing lithium carbonate micro powder, characterized in that the apparatus comprises:

[0008] In the carbonization reaction chamber, lithium hydroxide solution and carbon dioxide undergo a carbonization reaction and form foam, which in turn forms a lithium carbonate micro powder suspension and a lithium carbonate large particle suspension.

[0009] A carbon dioxide bubble generator is used to generate carbon dioxide gas into micro-nano-scale bubbles and deliver them to the carbonization reaction chamber. The carbon dioxide bubble generator is connected to the side wall of the carbonization reaction chamber.

[0010] A feeder is used to mix lithium hydroxide solution with a foaming agent and pump it into the carbonization reaction tank. The feeder is connected to the feed port of the carbonization reaction tank.

[0011] A stirring device, which is vertically installed inside the carbonization reaction chamber, is used to accelerate the carbonization reaction rate;

[0012] A skimming device is installed inside the carbonization reaction chamber and above the stirring device. The skimming device is used to skim the lithium carbonate micro powder suspension out of the carbonization reaction chamber. The lithium carbonate micro powder suspension is the foam that adsorbs lithium carbonate microparticles.

[0013] Furthermore, a pH sensor is installed inside the carbonization reaction chamber.

[0014] Furthermore, the carbon dioxide bubble generating device includes a CO2 storage container, an aeration pump, and a bubble generator connected sequentially by pipes. The outlet of the bubble generator is connected to the side wall of the carbonization reaction chamber. The working process of the carbon dioxide bubble generating device is as follows: the aeration pump introduces carbon dioxide gas from the CO2 storage container into the bubble generator, where it mixes with water to form micro-nano-sized CO2 bubbles. These bubbles are then transported through pipes to a microporous foaming mesh and uniformly bubbled into the carbonization reaction chamber, where they undergo a carbonization reaction with the lithium hydroxide solution.

[0015] Furthermore, the bubble generator is an ultra-micro nano bubble generator.

[0016] Furthermore, a microporous foaming mesh is provided inside the side wall of the carbonization reaction chamber, and the outlet pipe of the bubble generator penetrates the inner wall of the carbonization reaction chamber and is connected to the microporous foaming mesh; the carbon dioxide bubbles generated by the bubble generator enter the carbonization reaction chamber through the microporous foaming mesh.

[0017] Furthermore, the foam scraping device includes several sets of parallel foam scrapers, each comprising a motor, an impeller, and several scraping blades. The motor drives the impeller to rotate, which in turn drives the scraping blades to rotate, thereby moving the foam. The upper sidewall of the carbonization reaction chamber is provided with a through hole for the discharge of the lithium carbonate micro powder suspension. The first set of foam scrapers transfers the upper foam to the next set of foam scrapers, and the last set of foam scrapes the foam through the through hole into a collection box. The last set of foam scrapers is located near the through hole, and the collection box is located outside the carbonization reaction chamber and connected to the through hole.

[0018] Furthermore, a discharge channel for discharging large lithium carbonate particle suspension is provided at the bottom of the carbonization reaction chamber.

[0019] Furthermore, the inner walls of the carbonization reaction chamber are all coated with anti-corrosion and anti-stick coatings.

[0020] The present invention also provides a method for preparing lithium carbonate micro powder, using the above-described apparatus for preparing lithium carbonate micro powder, comprising the following steps:

[0021] Prepare the raw materials by mixing lithium hydroxide and water in a feeder to form a lithium hydroxide solution, and then mix the lithium hydroxide solution with a foaming agent.

[0022] Carbonization foaming: Lithium hydroxide solution and foaming agent are mixed and pumped into the carbonization reaction tank. The carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonization reaction tank. While the carbonization reaction is underway, the stirring device is turned on. The lithium hydroxide solution and CO2 undergo carbonization reaction to generate solid lithium carbonate. Most of the solid lithium carbonate avoids agglomeration and crystal growth under the action of foam and thus exists mainly in the form of lithium carbonate micro powder. A small part of the solid lithium carbonate aggregates and deposits at the bottom of the carbonization reaction tank to form large lithium carbonate particles.

[0023] Lithium carbonate is collected by suspending lithium carbonate micropowder on the surface of the liquid in the carbonation reaction tank under the action of foam to form a lithium carbonate micropowder suspension. After carbonation is completed, the foam scraping device is turned on to scrape the lithium carbonate micropowder suspension outside the carbonation reaction tank and collect it; large lithium carbonate particle suspension is collected at the bottom of the carbonation reaction tank.

[0024] Furthermore, the preparation method also includes:

[0025] The lithium carbonate micro powder suspension is filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which is then dried and pulverized to obtain lithium carbonate micro powder.

[0026] The lithium carbonate large particle suspension is filtered by a centrifuge to collect the wet lithium carbonate large particles, which are then dried and pulverized to obtain lithium carbonate powder.

[0027] Furthermore, the foaming agent is a water-soluble foaming agent that has a foaming effect under alkaline conditions; the foaming agent is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and sodium fatty alcohol polyoxyethylene ether sulfate, and the amount of the foaming agent is 1~10g / kg of lithium hydroxide dry material.

[0028] Furthermore, in order to avoid the formation of a large amount of lithium bicarbonate, the endpoint pH value of the carbonization reaction needs to be controlled. The endpoint pH value is the basis for the end of the carbonization reaction, and the endpoint pH value is 9~10.

[0029] The growth of lithium carbonate grains during carbonization is due to crystal growth and agglomeration. Suppressing the agglomeration and crystal growth of lithium carbonate during carbonization can yield small-particle-size lithium carbonate micropowder. To address the problems of long reaction time and low efficiency in traditional carbonization devices, which lead to crystal growth and agglomeration, this invention proposes a scraper with a rotating impeller design in a novel device, utilizing foam to scrape out and collect the lithium carbonate micropowder that has not grown or agglomerated during carbonization. The particles scraped out by the scraper are small-particle-size lithium carbonate micropowder, while the particles not scraped out at the bottom of the device are large-particle lithium carbonate due to the long aging time.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The novel device and method provided by the present invention have the functions of carbonization and particle size selection. During the carbonization process of lithium hydroxide solution, a large amount of foam is used to carry out and collect lithium carbonate micro powder, and the lithium carbonate micro powder does not grow and agglomerate further, resulting in small particle size.

[0032] 2. The lithium carbonate deposited at the bottom of the device of the present invention is a grown-up particle, which can simultaneously produce 1-3μm micro powder lithium carbonate and 5-7μm large particle lithium carbonate products.

[0033] 3. The novel device and method provided by this invention carry out small lithium carbonate particles through foam. The lithium carbonate micro powder foam has low water content, high filtration efficiency, less agglomeration, fast drying, low crushing cost, and simple operating conditions, and has broad prospects for large-scale application. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the apparatus for preparing lithium carbonate micropowder according to the present invention.

[0035] Illustration: 1-CO2 storage container, 2-air pump, 3-bubble generator, 4-microporous foaming mesh cover, 5-carbonization reaction chamber, 6-feeder, 7-first skimmer, 8-second skimmer, 9-collection box, 10-through hole, 11-stirring equipment, 12-discharge channel, 13-pH sensor. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] Example 1

[0038] like Figure 1As shown, the apparatus for preparing lithium carbonate micro powder includes a carbonation reaction chamber 5, a carbon dioxide bubble generator and a feeder 6 connected to the carbonation reaction chamber 5, a stirring device 11 and a skimmer installed inside the carbonation reaction chamber 5.

[0039] The carbonization reaction and foaming process of lithium hydroxide solution with carbon dioxide are carried out in carbonization reaction chamber 5. The lithium hydroxide solution reacts with CO2 to produce lithium carbonate solid. Under the action of foam, most of the lithium carbonate solid is attached to the foam surface in the form of micro powder, and a small part of the lithium carbonate solid agglomerates and crystals grow to form large lithium carbonate particles. The carbon dioxide bubble generating device makes carbon dioxide gas into micro-nano-scale bubbles and transports them to the carbonization reaction chamber 5. Specifically, the carbon dioxide bubble generating device is connected to the side wall of the carbonization reaction chamber 5. The feeder 5 is connected to the feed inlet of the carbonization reaction tank 6. The lithium hydroxide solution and foaming agent can be mixed in the feeder 6 first and then pumped into the carbonization reaction tank 5 by the feed pump (not marked in the figure). The stirring device 11 is vertically installed in the carbonization reaction tank 5 to accelerate the carbonization reaction rate. The skimmer is installed inside the carbonization reaction tank and above the stirring device 11. The skimmer is used to skim the lithium carbonate micro powder suspension out of the carbonization reaction tank 5. The lithium carbonate micro powder suspension is foam that adsorbs lithium carbonate micro powder. Under the action of the foam, the lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 to form a lithium carbonate micro powder suspension. The upper side wall of the carbonization reaction tank 5 is provided with a through hole 10 for the discharge of the lithium carbonate micro powder suspension. The through hole 10 is close to the skimmer.

[0040] The bottom of the carbonation reaction chamber 5 is equipped with a discharge channel 12 for discharging a suspension of large lithium carbonate particles. This suspension refers to the large lithium carbonate particles that have settled at the bottom of the carbonation reaction chamber 5 after aging. The discharge channel 12 is located on one side of the lower part of the carbonation reaction chamber 5 and penetrates the chamber wall. The discharge channel 12 is equipped with a mechanical switch device (such as a valve) to control its opening and closing. The carbonation reaction chamber 5 is connected to the outside world through the discharge channel 12. After carbonation is completed, the suspension of large lithium carbonate particles is discharged from the device.

[0041] The carbon dioxide bubble generating device includes a CO2 storage container 1, an aeration pump 2, and a bubble generator 3 connected sequentially by pipes. The outlet of the bubble generator 3 is connected to the side wall of the carbonization reaction chamber 5. A microporous foamed mesh cover 4 is installed on the inner wall of the side wall of the carbonization reaction chamber 5, which is essentially embedded and fixed to the side wall of the carbonization reaction chamber 5. The outlet pipe of the bubble generator 3 penetrates the inner wall of the carbonization reaction chamber 5 and is connected to the microporous foamed mesh cover 4. The carbon dioxide bubbles generated by the bubble generator 3 enter the carbonization reaction chamber 5 through the microporous foamed mesh cover 4. The microporous foamed mesh cover 4 can be installed near the lower inner side of the carbonization reaction chamber 5, which can increase the bubble generation rate and improve the carbonization rate.

[0042] In some preferred embodiments, the bubble generator 3 is an ultra-micro nano bubble generator. Bubbles in water with a size of ten to tens of micrometers are called micron bubbles; bubbles with a size of less than hundreds of nanometers are called nano bubbles; and the mixed state of bubbles between the two is called ultra-micro nano bubbles. In this embodiment, the ultra-micro nano bubble generator is used to make the carbon dioxide bubbles micro-nano level bubbles, which have a large specific surface area and a very slow rising speed in the solution. Therefore, they can stay in the lithium hydroxide solution for a longer time, indirectly improving the carbonization efficiency.

[0043] The stirring device 11 can use a conventional stirrer, which may include a drive system, a stirring shaft, and stirring blades installed on the outer wall of the stirring shaft. The drive system drives the stirring shaft to rotate, thereby driving the stirring blades to rotate, so that CO2 and lithium hydroxide can quickly undergo a carbonization reaction, and at the same time, the foam is evenly distributed in the carbonization reaction chamber 5. The drive system is installed at the bottom of the carbonization reaction chamber 5. The stirring shaft is connected to the drive system. The stirring blades can be selected from one of the following: paddle type, frame type, anchor type, ribbon type, turbine type stirring blades. The height of the stirring shaft is the same as or slightly lower than the upper end of the microporous foaming mesh cover 4.

[0044] The foam scraping device includes several sets of parallel scrapers. The first set of scrapers transfers the upper foam to the next set of scrapers, and the last set of scrapers scrapes the foam through the through hole 10 into the collection box 9. The last set of scrapers is located near the through hole 10. In this embodiment, two sets are provided, namely a first scraper 7 and a second scraper 8. Both the first scraper 7 and the second scraper 8 include a motor, an impeller, and several scraping blades. In this embodiment, the scraper is provided with 4-6 scraping blades. The motor drives the impeller to rotate, which in turn drives the scraping blades to rotate. The scraping blades are evenly arranged around the outer wall of the impeller, thereby driving the foam to move. The first scraper 7 transfers the upper foam to the second scraper 8, and the second scraper 8 scrapes the foam through the through hole 10 into the collection box 9. The second scraper 8 is located near the through hole 10. The collection box 9 is located outside the carbonization reaction box 5 and is connected to the through hole 10. Specifically, the collection box 9 is located diagonally below the through hole 10 and installed on the upper outer side of the carbonization reaction box 5. During operation, the first foam scraper 7 transfers the upper foam to the second foam scraper 8, which then scrapes the foam through the through hole 10 into the collection box 9. Carbonization ends when the pH value in the carbonization reaction box 5 reaches the carbonization endpoint pH value, and the product contained in the collection box 9 is then discharged.

[0045] In some preferred embodiments, a pH sensor 13 can be installed inside the carbonization reaction chamber 5 to monitor the pH value inside the chamber 5 in real time and convert it into a corresponding usable output signal to facilitate the determination of the end time of the carbonization reaction. To avoid the formation of a large amount of lithium bicarbonate, the endpoint pH value of the carbonization reaction needs to be controlled, and the endpoint pH value is 9-10.

[0046] In some preferred embodiments, the inner wall of the carbonization reaction chamber 5 is provided with a coating that is both corrosion-resistant and non-sticky, in order to prevent foam from sticking together and being difficult to remove, while also improving service life. The coating can be formed by spraying any anti-corrosion and non-sticky paint permitted in the art, such as a polytetrafluoroethylene coating.

[0047] Example 2

[0048] The preparation of lithium carbonate micropowder using the apparatus of Example 1 specifically includes the following steps:

[0049] (1) Prepare raw materials. In the feeder 6, prepare lithium hydroxide and water in proportion to form a lithium hydroxide solution of 40g / L. Select sodium dodecylbenzenesulfonate as foaming agent and mix the foaming agent with the lithium hydroxide solution at a ratio of 1g / kg dry lithium hydroxide.

[0050] (2) Carbonization foaming: The lithium hydroxide solution is mixed with the foaming agent and pumped into the carbonization reaction box 5. At the same time, the carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonization reaction box 5 to carry out the carbonization reaction. The stirring device 11 is turned on at the same time. The working process of the carbon dioxide bubble generator is as follows: the air pump 2 introduces carbon dioxide gas from the CO2 storage container 1 into the bubble generator 3 and mixes it with water to form micro-nano-level CO2 bubbles. Then, it is transported through the pipeline to the microporous foaming mesh 4 and evenly blown into the carbonization reaction box 5. The CO2 bubbles react with the lithium hydroxide solution to generate lithium carbonate solid. Under the action of the foaming agent, a large amount of foam is formed. Most of the lithium carbonate solid avoids agglomeration and crystal growth under the action of the foam and exists in the form of lithium carbonate micro powder. A small part of the lithium carbonate solid aggregates and deposits at the bottom of the carbonization reaction box 5 to form large lithium carbonate particles.

[0051] (3) Lithium carbonate collection: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 under the action of foam to form a lithium carbonate micro powder suspension. When the pH value in the carbonization reaction tank 5 is 9, the carbonization ends. After the carbonization ends, the foam scraping device is turned on. The first foam scraper 7 transfers the upper foam to the second foam scraper 8. The second foam scraper 8 scrapes the foam through the through hole 10 into the collection tank 9. After the carbonization ends, the lithium carbonate micro powder suspension is collected in the collection tank 9, and the lithium carbonate large particle suspension is collected in the unloading channel 12 of the carbonization reaction tank 5.

[0052] For lithium carbonate micron powder suspensions and lithium carbonate large particle suspensions, conventional processes can be used for fine treatment, such as:

[0053] The lithium carbonate micro powder suspension was filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which was then dried at 80℃ for 12 hours and crushed to obtain lithium carbonate micro powder with a particle size D50 of 3μm.

[0054] The lithium carbonate large particle suspension was filtered through a centrifuge to collect the wet lithium carbonate large particles, which were then dried at 80°C for 12 hours and crushed to obtain lithium carbonate powder with a particle size D50 of 6 μm.

[0055] Example 3

[0056] The preparation of lithium carbonate micropowder using the apparatus of Example 1 specifically includes the following steps:

[0057] (1) Prepare raw materials. In the feeder 6, prepare lithium hydroxide and water in proportion to form a lithium hydroxide solution of 40 g / L. Select a mixture of sodium dodecylbenzenesulfonate and sodium dodecyl sulfate as a foaming agent. Mix the foaming agent with the lithium hydroxide solution at a ratio of 10 g / kg dry lithium hydroxide.

[0058] (2) Carbonization foaming: The lithium hydroxide solution is mixed with the foaming agent and pumped into the carbonization reaction box 5. At the same time, the carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonization reaction box 5 to carry out the carbonization reaction. The stirring device 11 is turned on at the same time. The working process of the carbon dioxide bubble generator is as follows: the air pump 2 introduces carbon dioxide gas from the CO2 storage container 1 into the bubble generator 3 and mixes it with water to form micro-nano-level CO2 bubbles. Then, it is transported through the pipeline to the microporous foaming mesh 4 and evenly blown into the carbonization reaction box 5. The CO2 bubbles react with the lithium hydroxide solution to generate lithium carbonate solid. Under the action of the foaming agent, a large amount of foam is formed. Most of the lithium carbonate solid avoids agglomeration and crystal growth under the action of the foam and exists in the form of lithium carbonate micro powder. A small part of the lithium carbonate solid aggregates and deposits at the bottom of the carbonization reaction box 5 to form large lithium carbonate particles.

[0059] (3) Lithium carbonate collection: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 under the action of foam to form a lithium carbonate micro powder suspension. When the pH value in the carbonization reaction tank 5 is 10, the carbonization ends. After the carbonization ends, the foam scraping device is turned on. The first foam scraper 7 transfers the upper foam to the second foam scraper 8. The second foam scraper 8 scrapes the foam through the through hole 10 into the collection tank 9. After the carbonization ends, the lithium carbonate micro powder suspension is collected in the collection tank 9, and the lithium carbonate large particle suspension is collected in the unloading channel 12 of the carbonization reaction tank 5.

[0060] For lithium carbonate micron powder suspensions and lithium carbonate large particle suspensions, conventional processes can be used for fine treatment, such as:

[0061] The lithium carbonate micro powder suspension was filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which was then dried at 80°C for 12 hours and crushed to obtain lithium carbonate micro powder with a particle size D50 of 1 μm.

[0062] The lithium carbonate large particle suspension was filtered through a centrifuge to collect the wet lithium carbonate large particles, which were then dried at 80°C for 12 hours and crushed to obtain lithium carbonate powder with a particle size D50 of 5 μm.

[0063] Example 4

[0064] (1) Prepare raw materials. In the feeder 6, prepare lithium hydroxide and water in proportion to form a lithium hydroxide solution of 40g / L. Select a mixture of sodium dodecylbenzenesulfonate and sodium fatty alcohol polyoxyethylene ether sulfate as a foaming agent. Mix the foaming agent with the lithium hydroxide solution at a ratio of 5g / kg dry lithium hydroxide.

[0065] (2) Carbonization foaming: The lithium hydroxide solution is mixed with the foaming agent and pumped into the carbonization reaction box 5. At the same time, the carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonization reaction box 5 to carry out the carbonization reaction. The stirring device 11 is turned on at the same time. The working process of the carbon dioxide bubble generator is as follows: the air pump 2 introduces carbon dioxide gas from the CO2 storage container 1 into the bubble generator 3 and mixes it with water to form micro-nano-level CO2 bubbles. Then, it is transported through the pipeline to the microporous foaming mesh 4 and evenly blown into the carbonization reaction box 5. The CO2 bubbles react with the lithium hydroxide solution to generate lithium carbonate solid. Under the action of the foaming agent, a large amount of foam is formed. Most of the lithium carbonate solid avoids agglomeration and crystal growth under the action of the foam and exists in the form of lithium carbonate micro powder. A small part of the lithium carbonate solid aggregates and deposits at the bottom of the carbonization reaction box 5 to form large lithium carbonate particles.

[0066] (3) Lithium carbonate collection: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 under the action of foam to form a lithium carbonate micro powder suspension. When the pH value in the carbonization reaction tank 5 is 9.5, the carbonization ends. After the carbonization ends, the foam scraping device is turned on. The first foam scraper 7 transfers the upper foam to the second foam scraper 8. The second foam scraper 8 scrapes the foam through the through hole 10 into the collection tank 9. After the carbonization ends, the lithium carbonate micro powder suspension is collected in the collection tank 9, and the lithium carbonate large particle suspension is collected in the unloading channel 12 of the carbonization reaction tank 5.

[0067] For lithium carbonate micron powder suspensions and lithium carbonate large particle suspensions, conventional processes can be used for fine treatment, such as:

[0068] The lithium carbonate micro powder suspension was filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which was then dried at 80℃ for 12 hours and crushed to obtain lithium carbonate micro powder with a particle size D50 of 2μm.

[0069] The lithium carbonate large particle suspension was filtered through a centrifuge to collect the wet lithium carbonate large particles, which were then dried at 80°C for 12 hours and crushed to obtain lithium carbonate powder with a particle size D50 of 6 μm.

[0070] Example 5

[0071] (1) Prepare raw materials. In feeder 6, prepare lithium hydroxide and water in proportion to form a lithium hydroxide solution of 40g / L. Select a mixture of sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate as foaming agent. Mix the foaming agent with the lithium hydroxide solution at a ratio of 5g / kg dry lithium hydroxide.

[0072] (2) Carbonization foaming: The lithium hydroxide solution is mixed with the foaming agent and pumped into the carbonization reaction box 5. At the same time, the carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonization reaction box 5 to carry out the carbonization reaction. The stirring device 11 is turned on at the same time. The working process of the carbon dioxide bubble generator is as follows: the air pump 2 introduces carbon dioxide gas from the CO2 storage container 1 into the bubble generator 3 and mixes it with water to form micro-nano-level CO2 bubbles. Then, it is transported through the pipeline to the microporous foaming mesh 4 and evenly blown into the carbonization reaction box 5. The CO2 bubbles react with the lithium hydroxide solution to generate lithium carbonate solid. Under the action of the foaming agent, a large amount of foam is formed. Most of the lithium carbonate solid avoids agglomeration and crystal growth under the action of the foam and exists in the form of lithium carbonate micro powder. A small part of the lithium carbonate solid aggregates and deposits at the bottom of the carbonization reaction box 5 to form large lithium carbonate particles.

[0073] (3) Lithium carbonate collection: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 under the action of foam to form a lithium carbonate micro powder suspension. When the pH value in the carbonization reaction tank 5 is 9, the carbonization ends. After the carbonization ends, the foam scraping device is turned on. The first foam scraper 7 transfers the upper foam to the second foam scraper 8. The second foam scraper 8 scrapes the foam through the through hole 10 into the collection tank 9. After the carbonization ends, the lithium carbonate micro powder suspension is collected in the collection tank 9, and the lithium carbonate large particle suspension is collected in the unloading channel 12 of the carbonization reaction tank 5.

[0074] For lithium carbonate micron powder suspensions and lithium carbonate large particle suspensions, conventional processes can be used for fine treatment, such as:

[0075] The lithium carbonate micro powder suspension was filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which was then dried at 80℃ for 12 hours and crushed to obtain lithium carbonate micro powder with a particle size D50 of 2μm.

[0076] The lithium carbonate large particle suspension was filtered through a centrifuge to collect the wet lithium carbonate large particles, which were then dried at 80°C for 12 hours and crushed to obtain lithium carbonate powder with a particle size D50 of 7 μm.

[0077] Example 6

[0078] (1) Prepare raw materials. In the feeder 6, prepare lithium hydroxide and water in proportion to form a lithium hydroxide solution of 40g / L. Select a mixture of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate and sodium fatty alcohol polyoxyethylene ether sulfate as foaming agent. Mix the foaming agent with the lithium hydroxide solution at a ratio of 8g / kg dry lithium hydroxide.

[0079] (2) Carbonization foaming: The lithium hydroxide solution is mixed with the foaming agent and pumped into the carbonization reaction box 5. At the same time, the carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonization reaction box 5 to carry out the carbonization reaction. The stirring device 11 is turned on at the same time. The working process of the carbon dioxide bubble generator is as follows: the air pump 2 introduces carbon dioxide gas from the CO2 storage container 1 into the bubble generator 3 and mixes it with water to form micro-nano-level CO2 bubbles. Then, it is transported through the pipeline to the microporous foaming mesh 4 and evenly blown into the carbonization reaction box 5. The CO2 bubbles react with the lithium hydroxide solution to generate lithium carbonate solid. Under the action of the foaming agent, a large amount of foam is formed. Most of the lithium carbonate solid avoids agglomeration and crystal growth under the action of the foam and exists in the form of lithium carbonate micro powder. A small part of the lithium carbonate solid aggregates and deposits at the bottom of the carbonization reaction box 5 to form large lithium carbonate particles.

[0080] (3) Lithium carbonate collection: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 under the action of foam to form a lithium carbonate micro powder suspension. When the pH value in the carbonization reaction tank 5 is 9.3, the carbonization ends. After the carbonization ends, the foam scraping device is turned on. The first foam scraper 7 transfers the upper foam to the second foam scraper 8. The second foam scraper 8 scrapes the foam through the through hole 10 into the collection tank 9. After the carbonization ends, the lithium carbonate micro powder suspension is collected in the collection tank 9, and the lithium carbonate large particle suspension is collected in the unloading channel 12 of the carbonization reaction tank 5.

[0081] For lithium carbonate micron powder suspensions and lithium carbonate large particle suspensions, conventional processes can be used for fine treatment, such as:

[0082] The lithium carbonate micro powder suspension was filtered using a microporous filter device to collect the wet lithium carbonate micro powder, which was then dried at 80℃ for 12 hours and crushed to obtain lithium carbonate micro powder with a particle size D50 of 1.5μm.

[0083] The lithium carbonate large particle suspension was filtered through a centrifuge to collect the wet lithium carbonate large particles, which were then dried at 80°C for 12 hours and crushed to obtain lithium carbonate powder with a particle size D50 of 6 μm.

[0084] Example 7

[0085] (1) Prepare raw materials. In the feeder 6, prepare lithium hydroxide and water in proportion to form a lithium hydroxide solution of 40g / L. Select a mixture of fatty alcohol polyoxyethylene ether sodium sulfate as a foaming agent. Mix the foaming agent with the lithium hydroxide solution at a ratio of 2g / kg dry lithium hydroxide.

[0086] (2) Carbonation foaming: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonation reaction tank 5 under the action of foam. The lithium hydroxide solution is mixed with the foaming agent and pumped into the carbonation reaction tank 5. At the same time, the carbon dioxide bubble generator pumps micro-nano-level CO2 bubbles into the carbonation reaction tank 5 to carry out the carbonation reaction. The stirring device 11 is turned on at the same time. The working process of the carbon dioxide bubble generator is as follows: the air pump 2 introduces carbon dioxide gas from the CO2 storage container 1 into the bubble generator 3 and mixes it with water to form micro-nano-level CO2 bubbles. Then, it is transported through the pipeline to the microporous foaming mesh 4 and evenly blown into the carbonation reaction tank 5. The CO2 bubbles react with the lithium hydroxide solution to generate lithium carbonate solid. Under the action of the foaming agent, a large amount of foam is formed. Most of the lithium carbonate solid avoids agglomeration and crystal growth under the action of foam and thus exists in the form of lithium carbonate micro powder. A small part of the lithium carbonate solid aggregates and deposits at the bottom of the carbonation reaction tank 5 to form large lithium carbonate particles.

[0087] (3) Lithium carbonate collection: Lithium carbonate micro powder is suspended on the surface of the liquid in the carbonization reaction tank 5 under the action of foam to form a lithium carbonate micro powder suspension. When the pH value in the carbonization reaction tank 5 is 9.7, the carbonization ends. After the carbonization ends, the foam scraping device is turned on. The first foam scraper 7 transfers the upper foam to the second foam scraper 8. The second foam scraper 8 scrapes the foam through the through hole 10 into the collection tank 9. After the carbonization ends, the lithium carbonate micro powder suspension is collected in the collection tank 9, and the lithium carbonate large particle suspension is collected in the unloading channel 12 of the carbonization reaction tank 5.

[0088] For lithium carbonate micron powder suspensions and lithium carbonate large particle suspensions, conventional processes can be used for fine treatment, such as:

[0089] The lithium carbonate micro powder suspension was filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which was then dried at 80℃ for 12 hours and crushed to obtain lithium carbonate micro powder with a particle size D50 of 2μm.

[0090] The lithium carbonate large particle suspension was filtered through a centrifuge to collect the wet lithium carbonate large particles, which were then dried at 80°C for 12 hours and crushed to obtain lithium carbonate powder with a particle size D50 of 6.5 μm.

[0091] Comparative Example 1

[0092] The foaming agent in step (1) of Example 2 was removed, and the other steps were the same as in Example 2. The final product was lithium carbonate powder with a particle size D50 of 20 μm, which was collected from the unloading channel 12. It can be seen that during the carbonation process in this comparative example, lithium carbonate agglomeration and crystal growth occurred, so the resulting products were all lithium carbonate powders with a relatively large particle size.

[0093] Comparative Example 2

[0094] In step (2) of Example 2, ordinary carbon dioxide gas was pumped into the carbonization reaction chamber 5. The other steps were the same as in Example 2. The time taken to reach the final pH value of carbonization was longer, indicating that the carbonization rate of this example was lower than that of Example 2.

[0095] Comparative Example 3

[0096] In step (3) of Example 2, carbonization ended when the pH value in carbonization reaction chamber 5 reached 8. The other steps were the same as in Example 2. After collecting the lithium carbonate micropowder suspension and the lithium carbonate large particle suspension, the solution in carbonization reaction chamber 5 was tested and found to contain a large amount of lithium bicarbonate. The reactions that occurred included:

[0097] CO2 + 2LiOH == Li2CO3 (precipitate) + H2O; Li2CO3 + CO2 + H2O == 2LiHCO3 (soluble).

[0098] It is evident that the carbonization reaction in this embodiment was excessive, leading to the production of the byproduct lithium bicarbonate.

[0099] Comparative Example 4

[0100] In step (3) of Example 2, carbonization ended when the pH value in the carbonization reaction chamber 5 was 11. Other steps were the same as in Example 2. After collecting the lithium carbonate micro powder suspension and the lithium carbonate large particle suspension, the solution in the carbonization reaction chamber 5 was tested. There was still a large amount of LiOH, indicating that the carbonization reaction in this example was incomplete.

[0101] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing lithium carbonate micro powder, characterized in that, The method includes the following steps: Prepare the raw materials by mixing lithium hydroxide and water in a feeder to form a lithium hydroxide solution, and then mix the lithium hydroxide solution with a foaming agent. Carbonization foaming involves mixing a lithium hydroxide solution with a foaming agent and pumping the mixture into a carbonization reaction chamber. A carbon dioxide bubble generator pumps micro-nano-sized CO2 bubbles into the chamber. Simultaneously, a stirring device is activated, and the lithium hydroxide solution reacts with CO2 to produce solid lithium carbonate. Under the influence of foaming, the solid lithium carbonate primarily exists in the form of lithium carbonate micropowder. A small amount of solid lithium carbonate aggregates and deposits at the bottom of the carbonization reaction chamber, forming larger lithium carbonate particles. A pH sensor is installed inside the carbonization reaction chamber, and the endpoint pH value is used to determine the end of the carbonization reaction. The endpoint pH value of the carbonization reaction is 9-10 to avoid the formation of lithium bicarbonate. Lithium carbonate is collected by suspending lithium carbonate micropowder on the surface of the liquid in the carbonization reaction tank under the action of foam to form a lithium carbonate micropowder suspension. After carbonization, the foam scraping device is turned on to scrape the lithium carbonate micropowder suspension outside the carbonization reaction tank and collect it. A lithium carbonate large particle suspension is collected at the bottom of the carbonization reaction tank. At the same time, lithium carbonate micropowder with a size of 1μm-3μm and lithium carbonate large particle products with a size of 5μm-7μm are prepared.

2. The method for preparing lithium carbonate micro powder according to claim 1, characterized in that, The method further includes: The lithium carbonate micro powder suspension is filtered using a microporous filtration device to collect the wet lithium carbonate micro powder, which is then dried and pulverized to obtain lithium carbonate micro powder. The lithium carbonate large particle suspension is filtered by a centrifuge to collect the wet lithium carbonate large particles, which are then dried and pulverized to obtain lithium carbonate powder.

3. The method for preparing lithium carbonate micro powder according to claim 1, characterized in that, The foaming agent is a water-soluble foaming agent that has a foaming effect under alkaline conditions; the foaming agent is one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and sodium fatty alcohol polyoxyethylene ether sulfate, and the amount of foaming agent used is 1~10g / kg of lithium hydroxide dry material.

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