Superfine lithium carbonate and preparation method and device thereof

Abstract

The invention belongs to the field of material preparation, and discloses superfine lithium carbonate and a preparation method and device thereof. The preparation method of the superfine lithium carbonate comprises the following steps: respectively introducing a lithium-containing solution and a sodium carbonate solution into a reaction kettle for reaction, and starting a stirring shaft to drive a ball milling medium to move while reacting; after the reaction is completed, sequentially aging, screening, washing and drying to obtain the superfine lithium carbonate. In the process of preparing the lithium carbonate, the reaction and the particle refining process are synchronously carried out, the particle characteristics of the lithium carbonate can be effectively regulated and controlled while the production efficiency is improved, the finally prepared solid particles are uniformly dispersed and fine, sodium impurities can be conveniently washed, the sodium content in the product can be effectively reduced, the requirement for the sodium content in a battery-grade product is met, and the product quality is improved. The impurity removal cost is reduced. And the process flow is simple and easy to control, the production equipment investment is low, continuous production can be realized, and the production benefit is increased while the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material preparation, and relates to a preparation method of lithium salt, in particular to superfine lithium carbonate and a preparation method and device thereof. BACKGROUND

[0002] In recent years, with the explosive growth of market demand for lithium ion batteries, the lithium battery industry has developed more and more rapidly, and has driven the rapid expansion of the upstream and downstream industry chains. Lithium carbonate is the most important basic lithium salt for preparing various lithium compounds, and is widely used in the fields of batteries, medicines, chemical industry and the like.

[0003] At present, in the process of producing lithium carbonate, whether the lithium carbonate is prepared by ore extraction or lithium is extracted from salt lake brine, the commonly used lithium precipitation method is sodium carbonate precipitation method. The principle of preparing lithium carbonate by using sodium carbonate precipitation method is to utilize Li + and CO3 2- to combine to generate Li2CO3 precipitate which is slightly soluble in water. Since the solubility of lithium carbonate in water decreases with the increase of temperature, but the solubility of other alkali metal carbonates is much greater than that of lithium carbonate, lithium ions in the solution are extracted in the form of lithium carbonate precipitate. However, due to the sodium salt existing in the ore and salt lake and the sodium salt compound introduced in the lithium precipitation process, the sodium content in the lithium carbonate product exceeds the standard, and additional cost is brought for subsequent sodium removal.

[0004] In addition, in the traditional synthesis process of lithium carbonate, the high-temperature precipitation environment will cause the crystal to grow rapidly, and coarse particles of dozens of microns to several millimeters are easily formed. At the same time, the precipitation product under high temperature is dominated by monoclinic lithium carbonate, which is easy to grow into dense block or spherical agglomerates, which leads to the problem of coarse crystal particle size of lithium carbonate product. Moreover, the low porosity structure, surface adsorption wrapping and high compressibility of the lithium carbonate large particles will cause the problem of difficult washing of impurities in the lithium carbonate particles.

[0005] In order to solve the problems of large particle size and difficult washing of lithium carbonate particles, the commonly used method in industrial production is to first optimize the process to synthesize lithium carbonate, and then to obtain lithium carbonate products meeting the particle size requirements through crushing treatment. However, this method has the disadvantages of high energy consumption and long process flow, especially in the case of serious reduction of market price of battery-grade lithium carbonate, the cost input increases and the benefit decreases. SUMMARY

[0006] In view of the defects and deficiencies of the prior art, in a first aspect, the present application provides a preparation method of superfine lithium carbonate; in a second aspect, the present application provides superfine lithium carbonate; and in a third aspect, the present application provides a device for preparing superfine lithium carbonate.

[0007] In a first aspect, the present application provides a preparation method of superfine lithium carbonate, comprising: feeding lithium-containing solution and sodium carbonate solution into a reaction kettle for reaction, and driving ball milling medium to move by starting stirring shaft at the same time of reaction; and sequentially aging, screening, washing and drying after the reaction is completed, so that the superfine lithium carbonate is obtained.

[0008] Preferably, the lithium-containing solution is any one or more than two of lithium sulfate, lithium chloride and lithium nitrate solution.

[0009] Preferably, the molar ratio of lithium ions in the lithium-containing solution to carbonate ions in the sodium carbonate is 1:0.5-0.6.

[0010] Preferably, the lithium ion concentration of the lithium-containing solution is 15-25 g / L; the sodium carbonate solution concentration is 100-200 g / L; the flow rate of the lithium-containing solution is 0.1-0.5 L / min, and the flow rate of the sodium carbonate solution is 0.1-0.5 L / min.

[0011] Preferably, the stirring shaft rotates at a speed of 100-500 rpm.

[0012] Preferably, the reaction temperature is 80-95℃, and the reaction time is 0.1-5 h.

[0013] Preferably, the diameter of the ball milling medium is 3-10 mm, and the volume ratio of the ball milling medium to the reaction kettle body is 0.3-0.5:1.

[0014] Preferably, the ball milling medium is any one or both of zirconia balls and zirconium silicate ceramic balls.

[0015] Preferably, deionized water is used for washing, the temperature of the deionized water is 80-100℃, the washing is performed 2-6 times, and the solid-liquid ratio during washing is 1-5 g / mL.

[0016] In a second aspect, the present application provides a superfine lithium carbonate prepared by the above preparation method.

[0017] Preferably, the superfine lithium carbonate is in the form of rhombic blocks, and the superfine lithium carbonate is uniformly distributed.

[0018] Preferably, the particle size of the superfine lithium carbonate is 0.01-15 μm.

[0019] Preferably, the sodium content in the superfine lithium carbonate is 0.001-0.025%.

[0020] In a third aspect, a reaction kettle body, a stirring shaft, stirring blades and ball milling media are included, the ball milling media is located in the reaction kettle body, the stirring shaft is rotationally connected to the reaction kettle body, the stirring blades are fixedly connected to the stirring shaft, the reaction kettle body is loaded with a plurality of spherical grinding media, and a driving member for driving the stirring shaft to rotate is arranged on the reaction kettle body; when the stirring shaft rotates, the stirring blades drive the grinding media to move in the reaction kettle body.

[0021] Preferably, the rotation axis of the stirring shaft and the center line of the reaction kettle body overlap; the stirring blades are arranged in multiple groups, and the multiple groups of stirring blades are arranged at intervals along the length direction of the stirring shaft; each group of the stirring blades is arranged in multiple, and the multiple stirring blades are uniformly arranged at intervals along the circumferential direction of the stirring shaft.

[0022] Preferably, the driving member is a driving motor connected with the stirring shaft through a shaft coupling.

[0023] Preferably, a top cover is detachably connected to the reaction kettle body, and the top cover is provided with a feeding pipe and an observation port in communication with the reaction kettle body.

[0024] Preferably, a discharge pipe is arranged at the upper portion of the reaction kettle body, a sieve plate is arranged in the discharge pipe, and a back flushing device is arranged on the discharge pipe.

[0025] Preferably, the reaction kettle body includes an outer shell, a thermal insulation layer, a steam jacket layer and an inner shell, and the inner shell, the steam jacket layer, the thermal insulation layer and the outer shell are arranged from inside to outside.

[0026] Compared with the prior art, the present application has the following obvious beneficial effects: (1) In the process of preparing lithium carbonate, the reaction and the particle refinement process are carried out synchronously, which can effectively control the particle characteristics of lithium carbonate, improve the production efficiency, and ultimately obtain solid particles with uniform dispersion and small particle size, which is beneficial to washing sodium impurities, can effectively reduce the sodium content in the product, meet the sodium content requirement of battery-grade products, and reduce the cost of impurity removal. The process is simple and easy to control, the production equipment investment is low, and continuous production can be realized, which reduces the production cost and increases the production benefit.

[0027] (2) The present application provides a reaction kettle device for preparing ultra-fine lithium carbonate, which has a simple structure and is beneficial to preparing ultra-fine lithium carbonate material with small particle size and uniform distribution. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The overall structure schematic diagram of the device for preparing ultra-fine lithium carbonate provided for Example 1 is shown in the figure. Figure 2SEM images of lithium carbonate prepared for Example 2 and Comparative Example 1.

[0029] Label explanation: 1, reaction kettle body; 2, stirring shaft; 3, stirring blade; 4, outer shell; 5, insulation layer; 6, steam jacket layer; 7, inner shell; 8, reaction cavity; 9, ball milling medium; 10, steam pipeline; 11, steam valve; 12, top cover; 13, feeding pipe; 14, observation port; 15, driving part; 16, discharge pipe; 17, sieve plate; 18, back flushing device; 19, mounting seat. DETAILED DESCRIPTION

[0030] The present application provides the following specific technical solutions.

[0031] In a first aspect, the present application provides a method for preparing ultrafine lithium carbonate, comprising: introducing lithium-containing solution and sodium carbonate solution into a reaction kettle for reaction, and simultaneously starting a stirring shaft to drive the ball milling medium to move; and after the reaction is completed, sequentially aging, sieving, washing and drying to obtain the ultrafine lithium carbonate.

[0032] The inventors have found that the existing process for preparing lithium carbonate has problems of excessive sodium content, particle agglomeration and coarse particles. In the preparation method provided by the present application, the stirring shaft drives the ball milling medium to move at high speed in the reaction kettle, which forms strong shearing, impact and mixing effects on the lithium-containing solution and sodium carbonate solution, breaks the diffusion limit of the liquid interface, and makes the two reactants contact more quickly and uniformly, thereby accelerating the reaction rate and shortening the reaction time. The process of the reaction interferes with the distribution of particles, avoids particle agglomeration and growth, and helps to obtain ultrafine lithium carbonate products with smaller particle size and more uniform distribution, thereby improving the specific surface area and reactivity. Uniform mixing and continuous grinding can reduce the phenomenon of excessive local concentration or incomplete reaction, ensure that the lithium ions in the solution combine more fully with the carbonate ions, and improve the raw material utilization rate and the yield of lithium carbonate.

[0033] That is, the reaction and the particle refinement process are carried out simultaneously, which can effectively regulate the particle properties of lithium carbonate while improving the production efficiency, and the finally obtained solid particles are uniformly dispersed and small in size, which is beneficial to washing sodium impurities, can effectively reduce the sodium content in the product, meet the sodium content requirement of battery-grade products, and reduce the cost of impurity removal. Moreover, the process is simple and easy to control, the production equipment investment is low, and continuous production can be realized, thereby reducing the production cost and increasing the production benefit.

[0034] Preferably, the lithium-containing solution is any one or two or more of lithium sulfate, lithium chloride and lithium nitrate.

[0035] Preferably, the molar ratio of lithium ions to carbonate ions in the sodium carbonate is 1:0.5-0.6.

[0036] In practical application, the molar ratio of lithium ions to sodium carbonate added into the reaction kettle can be 1:0.5, 1:0.55, 1:0.6.

[0037] Preferably, the lithium ion concentration of the lithium-containing solution is 15-25 g / L; the sodium carbonate concentration in the sodium carbonate solution is 100-200 g / L; the flow rate of the lithium-containing solution is 0.1-0.5 L / min, and the flow rate of the sodium carbonate solution is 0.1-0.5 L / min.

[0038] In the process of lithium precipitation, the sodium carbonate solution is added in excess to ensure sufficient precipitation of lithium ions; the lithium ion concentration of the lithium-containing solution, the carbonate ion concentration in the sodium carbonate solution, the flow rate of the lithium-containing solution and the flow rate of the sodium carbonate solution are further controlled, and the stirring ball milling process is used to make the reaction proceed smoothly, thereby obtaining uniform and fine lithium carbonate products.

[0039] In practical application, the lithium ion concentration of the lithium-containing solution can be 15 g / L, 20 g / L, 25 g / L; the carbonate ion concentration in the sodium carbonate solution can be 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 200 g / L; the flow rate of the lithium-containing solution can be 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min; and the flow rate of the sodium carbonate solution can be 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min.

[0040] Preferably, the stirring speed is 100-500 rpm.

[0041] In the lithium precipitation process, the stirring speed significantly affects the particle size distribution, morphology and purity of lithium carbonate particles, therefore, a suitable stirring speed needs to be selected, too low or too high will bring negative effects. If the stirring speed is too low, the sodium carbonate solution and lithium-containing solution are not mixed uniformly, the local supersaturation is too high, leading to explosive nucleation and disordered growth of particles; at the same time, the ion diffusion rate is slow, the crystal growth is mainly controlled by diffusion, the growth rate is slow and uneven, resulting in large particle size and uneven distribution of lithium carbonate particles, and agglomeration. In addition, under low speed stirring, the slow crystal growth rate will give impurity ions enough time to embed into the crystal lattice defects and vacancies, at the same time, impurity ions are easily adsorbed on the crystal surface and wrapped in the mother liquor inside the gap between large particles, leading to increased impurity content and reduced product purity. If the stirring speed is too high, the high shear will break the crystals, which are easy to be nucleated and grown again; under high speed, forced convection will make the saturation degree consume quickly, so that the nucleation rate is greater than the growth rate, making the particles more fine; but fast nucleation will lead to more crystal defects, impurities are easy to adsorb or embed; at the same time, high shear force will accelerate the collision and friction of crystals, leading to local heating, forming a microcrystalline-recrystallization process, impurity redistribution; in addition, high speed stirring will exacerbate the wear of impeller and shaft sleeve, ball milling medium, introducing other impurities or particulate matter.

[0042] In practical application, the stirring speed can be 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm.

[0043] Preferably, the reaction temperature is 80-95℃, and the reaction time is 0.1-5h.

[0044] In the lithium precipitation process, the reaction temperature is a key control parameter, which directly affects the reaction rate, crystallization behavior and impurity removal. If the reaction temperature is too low, the ion diffusion rate is insufficient, the reaction rate decreases, and the yield also decreases, accompanied by slow nucleation rate, part of the crystal is coarse and uneven; the solubility of impurity ions decreases at low temperature, which is easy to co-precipitate with lithium carbonate or adsorbed on the crystal surface, and sodium sulfate crystals are easy to mix into lithium carbonate product. If the reaction temperature is too high, the solubility of lithium carbonate will abnormally rise when the temperature exceeds 100℃, the yield will decrease; the dissolution process of lithium carbonate is endothermic, high temperature will promote dissolution; under high temperature, carbonate ions are partially decomposed, which will produce bubbles to interfere with the crystallization process; in addition, in high temperature and alkaline environment, the equipment corrosion will increase, and the energy consumption will also increase.

[0045] In practical application, the reaction temperature can be 80℃, 85℃, 90℃, 95℃; the reaction time can be 0.1h, 1h, 2h, 3h, 4h, 5h.

[0046] Preferably, the diameter of the ball milling medium is 3-10mm, and the volume ratio of the ball milling medium to the reaction kettle body is 0.3-0.5:1.

[0047] Preferably, the ball milling medium is any one or both of zirconium oxide balls and zirconium silicate ceramic balls.

[0048] Preferably, deionized water is used for washing, the temperature of the deionized water is 80-95℃, the washing is performed 2-6 times, and the solid-liquid ratio during washing is 1-5 g / mL.

[0049] In actual application, the temperature of the deionized water can be 80℃, 85℃, 90℃, 95℃, or 100℃, the washing can be performed 2, 3, 4, 5, or 6 times, and the solid-liquid ratio during washing can be 1 g / mL, 2 g / mL, 3 g / mL, 4 g / mL, or 5 g / mL.

[0050] In the second aspect, the application provides ultrafine lithium carbonate prepared by the above preparation method.

[0051] Preferably, the ultrafine lithium carbonate is in the form of rhombic blocks, and the ultrafine lithium carbonate is uniformly distributed.

[0052] Preferably, the particle size of the ultrafine lithium carbonate is 0.01-15 μm.

[0053] Preferably, the sodium content in the ultrafine lithium carbonate is 0.001-0.025%.

[0054] In the third aspect, the application provides a device for preparing ultrafine lithium carbonate, which comprises a reaction kettle body, a stirring shaft, and stirring blades, the stirring shaft is rotatably connected to the reaction kettle body, the stirring blades are fixedly connected to the stirring shaft, a plurality of grinding media in the form of balls are loaded in the reaction kettle body, and a driving member for driving the stirring shaft to rotate is arranged on the reaction kettle body; when the stirring shaft rotates, the stirring blades drive the grinding media to move in the reaction kettle body.

[0055] In the preparation of lithium carbonate material, lithium-containing solution and sodium carbonate solution are respectively fed into the reaction kettle body, then the driving member is started to drive the stirring shaft to rotate, and the lithium is precipitated while the ball milling is stirred, and the particle size of the lithium carbonate product is effectively controlled by optimizing the parameters in the reaction and crystallization process, thereby preparing the ultrafine lithium carbonate product.

[0056] Preferably, the rotation axis of the stirring shaft and the center line in the reaction kettle body overlap; the stirring blades are arranged in multiple groups, and the multiple groups of stirring blades are arranged at intervals along the length direction of the stirring shaft; each group of the stirring blades is arranged in multiple, and the multiple stirring blades are uniformly arranged at intervals along the circumferential direction of the stirring shaft.

[0057] The stirring blades are arranged in multiple groups, which strengthens the action on the ball milling medium and is conducive to improving the ball milling effect.

[0058] Preferably, the driving member is a driving motor connected with the stirring shaft through a shaft coupling.

[0059] Preferably, a top cover is detachably connected to the reactor body, and the top cover is provided with a feeding pipe and an observation hole in communication with the reactor body.

[0060] The observation hole is beneficial to observe the material in the reactor body.

[0061] Preferably, the upper portion of the reactor body is provided with a discharge pipe, the discharge pipe is provided with a sieve plate, and the discharge pipe is provided with a back blowing device.

[0062] The sieve plate is beneficial to perform the reaction and the screening in the same device, so that the process of transferring the material is omitted and the process is simplified. The back blowing device is arranged on the discharge pipe, and the blowing direction of the back blowing device is from the discharge pipe to the inside of the reactor.

[0063] Preferably, the reactor body comprises an outer shell, a heat preservation layer, a steam jacket layer and an inner shell, and the inner shell, the steam jacket layer, the heat preservation layer and the outer shell are sequentially arranged from inside to outside.

[0064] The steam jacket is used for heating the material in the reactor body, and the heat preservation layer is beneficial to reduce the error of the reaction temperature.

[0065] In order to make the technical problems, technical solutions and technical advantages of the present application more clear, the following will be described in detail with specific examples, but the protection scope of the present application is not limited to the following specific examples.

[0066] Unless otherwise defined, all the professional terms used in the following have the same meaning as that understood by the person skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific examples, and are not intended to limit the protection scope of the present application.

[0067] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0068] Example 1: A device for preparing ultrafine lithium carbonate, referring to Figure 1, including a reaction kettle body 1, a stirring shaft 2, stirring blades 3 and ball milling media 9 located in the reaction kettle body 1. The reaction kettle body 1 comprises an outer shell 4, a thermal insulation layer 5, a steam jacket layer 6 and an inner shell 7, which are sequentially arranged from inside to outside. The inner shell 7 forms a reaction cavity 8 in which the ball milling media 9 are loaded. The steam jacket layer 6 is hollow, and the outer shell 4 is provided with a steam pipeline 10 communicating with the steam jacket layer 6. The steam pipeline 10 is provided with a steam valve 11 for opening and closing the steam pipeline 10.

[0069] An opening is formed at the top of the reaction kettle body 1, and a top cover 12 is detachably connected to the top opening of the reaction kettle body 1. The top cover 12 is fixedly connected and communicated with a feeding pipe 13. In the embodiment, two feeding pipes 13 are provided, one of which is a lithium-containing solution feeding pipe 13, and the other is a sodium carbonate solution feeding pipe 13. An observation hole 14 is arranged on the top cover 12, which is used to observe the material condition in the reaction cavity 8.

[0070] The stirring shaft 2 is rotatably connected to the top cover 12, and the rotation axis of the stirring shaft 2 overlaps with the center line of the reaction kettle body 1 when the top cover 12 is installed on the reaction kettle body 1. The stirring shaft 2 is fixedly connected with the stirring blades 3. The stirring blades 3 are provided in multiple groups, and the multiple groups of stirring blades 3 are arranged at intervals along the length direction of the stirring shaft 2. Each group of stirring blades 3 is fixedly connected with multiple stirring blades 3, and the multiple stirring blades 3 are uniformly and intervaliy arranged along the circumferential direction of the stirring shaft 2. A mounting seat 19 is fixedly connected to the top cover 12, and a driving member 15 for driving the stirring shaft 2 to rotate is fixedly connected to the mounting seat 19. The driving member 15 is a speed reducer driving motor, and the driving motor and the stirring shaft 2 are connected through a shaft coupling. When the stirring shaft 2 rotates, the stirring blades 3 drive the grinding media to move in the reaction kettle body 1.

[0071] A discharge pipe 16 is arranged at the upper part of the reaction kettle body 1, and a sieve plate 17 is arranged in the discharge pipe 16. The sieve plate 17 is arranged at the joint between the inner shell 7 and the discharge pipe 16, and the pore size of the sieve plate 17 is 0.01-15 μm. A back blowing device 18 is arranged on the discharge pipe 16, and the air direction of the back blowing device 18 is from the discharge pipe 16 to the reaction kettle body 1. The back blowing device 18 is arranged on the discharge pipe 16, and the air blowing direction is from the discharge pipe 16 to the reaction kettle body 1. If the sieve plate 17 is blocked, the back blowing device 18 can be started to clean the material.

[0072] In the embodiment, the back blowing device 18 comprises a plurality of blow nozzles arranged on the inner wall of the discharge pipe 16, the blow nozzles are arranged on the outer side of the sieve plate (the side of the sieve plate 17 connected with the reaction cavity 8 is the inner side), the blowing ends of the blow nozzles are directed to the sieve plate 17, if the sieve plate 17 is blocked to affect the discharge, the back blowing device 18 is started, the gas in the blow nozzles is blown to the sieve plate 17, the sieve plate 17 is dredged by the gas flow, the material blocking the sieve plate 17 is blown back to the reaction cavity, and the material not meeting the requirements is re-entered into the reaction cavity 8 for continuous reaction.

[0073] In the lithium precipitation process, fine lithium carbonate particles have good dispersibility due to surface tension, charge repulsion and the like, the specific surface area of the small particles is large, the contact area with the liquid is large, and the viscous resistance is stronger, so that the settling speed is significantly lower than that of large particles, and a suspension state is easily formed and gathered in the upper layer or the upper-middle layer of the solution. The discharge pipe 16 is arranged at the upper part of the reaction kettle body 1, most of the lithium carbonate particles entering the discharge pipe 16 for screening are fine, the material is preliminarily screened by using the physical properties of the material, and then the material meeting the particle size requirement is screened out by using the sieve plate 17, so that the possibility of blocking the sieve plate 17 is reduced.

[0074] Embodiment 2 A method for preparing ultrafine lithium carbonate, comprising: Step 1, lithium sulfate solution and sodium carbonate solution are respectively introduced into the reaction kettle through the feed pipe for reaction, the lithium concentration in the lithium-containing solution is 20 g / L, the concentration of the sodium carbonate solution is 150 g / L, the feeding rate of the lithium-containing solution and the sodium carbonate solution is 0.5 L / min, and the feeding time of the lithium solution and the sodium carbonate solution is controlled to be the same. The driving motor is started at the same time when the feeding is started, the stirring speed is controlled to be 300 rpm, the temperature in the reaction kettle body is controlled to be 90℃, and the ball milling medium is a 3 mm zirconia ball.

[0075] Step 2, after the reaction is completed, the material is aged for 1 h, and then the material after aging is discharged through the discharge pipe and screened by the sieve plate.

[0076] Step 3, the screened material is washed three times with deionized water at a temperature of 100℃, the liquid-solid ratio of the deionized water and the material is 3 g / mL during washing, and the obtained solid particles are dried at 105℃ for 12 h to obtain the ultrafine lithium carbonate.

[0077] Embodiment 3 A method for preparing ultrafine lithium carbonate, comprising: Step 1, lithium nitrate solution and sodium carbonate solution are respectively fed into the reactor through the feed pipe for reaction, the lithium concentration in the lithium-containing solution is 15 g / L, the concentration of sodium carbonate solution is 100 g / L, the feeding rate of lithium-containing solution and sodium carbonate solution is 0.3 L / min, and the feeding time of lithium solution and sodium carbonate solution is controlled to be the same. Start the driving motor at the same time of starting the feeding, control the stirring speed to be 100 rpm, control the temperature in the reactor body to be 90℃. The ball milling medium is 3mm zirconia ball.

[0078] Step 2, after the reaction is completed, the material is aged for 3h, and then discharged through the discharge pipe. The material entering the discharge pipe is screened through the sieve plate.

[0079] Step 3, the screened material is washed with deionized water at a temperature of 100℃ for 3 times, the liquid-solid ratio of deionized water and material is 1g / mL, and the obtained solid particles are dried at 105℃ for 12h to obtain the superfine lithium carbonate.

[0080] Example 4: A method for preparing superfine lithium carbonate, comprising: Step 1, lithium sulfate solution and sodium carbonate solution are respectively fed into the reactor through the feed pipe for reaction, the lithium concentration in the lithium-containing solution is 25 g / L, the concentration of sodium carbonate solution is 200 g / L, the feeding rate of lithium-containing solution and sodium carbonate solution is 0.4 L / min, and the feeding time of lithium solution and sodium carbonate solution is controlled to be the same. Start the driving motor at the same time of starting the feeding, control the stirring speed to be 400 rpm, control the temperature in the reactor body to be 90℃. The ball milling medium is 3mm zirconia ball.

[0081] Step 2, after the reaction is completed, the material is aged for 1h, and then discharged through the discharge pipe. The material entering the discharge pipe is screened through the sieve plate.

[0082] Step 3, the screened material is washed with deionized water at a temperature of 100℃ for 3 times, the liquid-solid ratio of deionized water and material is 5g / mL, and the obtained solid particles are dried at 105℃ for 12h to obtain the superfine lithium carbonate.

[0083] Example 5: A method for preparing superfine lithium carbonate, comprising: Step 1, lithium sulfate solution and sodium carbonate solution are respectively fed into the reactor through the feed pipe for reaction, the lithium concentration in the lithium-containing solution is 20 g / L, the concentration of sodium carbonate solution is 160 g / L, the feeding rate of lithium-containing solution and sodium carbonate solution is 0.2 L / min, and the feeding time of lithium solution and sodium carbonate solution is controlled to be the same. Start the driving motor at the same time of starting the feeding, control the stirring speed to be 500 rpm, control the temperature in the reactor body to be 90℃. The ball milling medium is 3mm zirconia ball.

[0084] Step 2, after the reaction is completed, the aged material is discharged through the discharge pipe, and the material entering the discharge pipe is screened through the sieve plate.

[0085] Step 3, the screened material is washed 3 times with deionized water at a temperature of 100℃, the liquid-solid ratio of deionized water and material is 4g / mL, and the obtained solid particles are the ultra-fine lithium carbonate.

[0086] Comparative Example 1: A method for preparing lithium carbonate, comprising: Step 1, lithium sulfate solution and sodium carbonate solution are respectively introduced into the reaction kettle through the feed pipe for reaction, the lithium concentration in the lithium-containing solution is 20g / L, the concentration of carbonate ions in the sodium carbonate is 150g / L, the feed rate of lithium-containing solution and sodium carbonate solution is 0.5L / min, and the feed time of lithium solution and sodium carbonate solution is controlled to be the same. Start the driving motor at the same time of starting the feed, control the stirring speed to be 300rpm, and control the temperature in the reaction kettle body to be 90℃.

[0087] Step 2, after the reaction is completed, the aged material is discharged through the discharge pipe, and the material entering the discharge pipe is screened through the sieve plate.

[0088] Step 3, the screened material is washed 3 times with deionized water at a temperature of 100℃, the liquid-solid ratio of deionized water and material is 4g / mL, and the obtained solid particles are the ultra-fine lithium carbonate.

[0089] Examples 2-5 are prepared using the ultra-fine lithium carbonate device described in Example 1, and stirring and ball milling are performed simultaneously during the reaction; Comparative Example 1 uses a commonly used reaction kettle for reaction, and only stirring treatment is performed during the reaction.

[0090] Figure 2 SEM images of lithium carbonate prepared in Example 2 and Comparative Example 1, wherein Figure (1) and Figure (2) are SEM images observed at different magnifications of Comparative Example 1, as shown in the figures, the lithium carbonate prepared in Comparative Example 1 is in block shape, the particle size is mostly in the range of 15-30μm, and the agglomeration is serious; Figure (3) and Figure (4) are SEM images observed at different magnifications of Example 2, as shown in the figures, the lithium carbonate is in rhombic block shape, the surface is smooth, the particle size is in the range of 0.1-10μm, and part of the fine particles is only a few hundred nanometers. It can be proved that the preparation process provided in the present application can prepare lithium carbonate products with finer particle size, which meets the requirements of producing battery-grade lithium carbonate.

[0091] The sodium content of lithium carbonate prepared in Examples 2-5 and Comparative Example 1 is detected, and the detection data is shown in Table 1.

[0092] Table 1: Sodium content and particle size of lithium carbonate prepared in Examples 2-5 and Comparative Example 1 As can be seen from the data in Table 1, the sodium content of the lithium carbonate products synthesized by the method of the present application all meet the requirement of the sodium content of battery-grade lithium carbonate (≤250 ppm). Compared with the sodium impurity content of the lithium carbonate prepared in Comparative Example 1, the lithium carbonate synthesized by the preparation process provided in the present application has a smaller particle size and is easier to wash the sodium impurities, thereby reducing the impurity content of the product.

[0093] The above examples are merely preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes within the technical scope of the present application according to the technical solution and concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for preparing ultrafine lithium carbonate, characterized in that, include: The lithium-containing solution and sodium carbonate solution are separately introduced into the reaction vessel for reaction. At the same time, the stirring shaft is started to drive the ball milling media to move. After the reaction is completed, the mixture is aged, sieved, washed and dried in sequence to obtain the ultrafine lithium carbonate.

2. The method for preparing ultrafine lithium carbonate as described in claim 1, characterized in that, The lithium-containing solution is any one or more of lithium sulfate, lithium chloride, and lithium nitrate; the molar ratio of lithium ions added to the reaction vessel to carbonate ions in sodium carbonate is 1:0.5~0.

6.

3. The method for preparing ultrafine lithium carbonate as described in claim 1, characterized in that, The lithium ion concentration of the lithium-containing solution is 15~25 g / L; the sodium carbonate solution concentration is 100~200 g / L; the flow rate of the lithium-containing solution is 0.1~0.5 L / min, and the flow rate of the sodium carbonate solution is 0.1~0.5 L / min.

4. The method for preparing ultrafine lithium carbonate as described in claim 1, characterized in that, The stirring shaft rotates at 100~500 rpm; the reaction temperature is 80~95℃; and the reaction time is 0.1~5h.

5. The method for preparing ultrafine lithium carbonate as described in claim 1, characterized in that, The diameter of the milling media is 3~10mm; the volume ratio of the milling media to the reaction vessel is 0.3~0.5∶1; the milling media is any one or two of zirconia balls and zirconium silicate ceramic balls.

6. An ultrafine lithium carbonate, characterized in that, It was prepared by the above method.

7. An ultrafine lithium carbonate, characterized in that, The ultrafine lithium carbonate is in the form of rhomboid blocks and is uniformly distributed; the particle size of the ultrafine lithium carbonate is 0.01~15μm; the sodium content in the ultrafine lithium carbonate is 0.001~0.025%.

8. An apparatus for preparing ultrafine lithium carbonate, characterized in that, The reactor includes a reactor body (1), a stirring shaft (2), stirring blades (3), and grinding media (9). The grinding media (9) is located inside the reactor body (1). The stirring shaft (2) is rotatably connected to the reactor body (1). The stirring blades (3) are fixedly connected to the stirring shaft (2). The reactor body (1) contains a plurality of grinding media arranged in a spherical shape. The reactor body (1) is provided with a drive unit (15) for driving the stirring shaft (2) to rotate. When the stirring shaft (2) rotates, the stirring blades (3) drive the grinding media to move inside the reactor body (1).

9. The apparatus for preparing ultrafine lithium carbonate as described in claim 8, characterized in that, The rotation axis of the stirring shaft (2) overlaps with the center line of the reactor body (1); multiple sets of stirring blades (3) are provided, and multiple sets of stirring blades (3) are spaced apart along the length direction of the stirring shaft (2); multiple stirring blades (3) are provided in each set, and multiple stirring blades (3) are evenly spaced apart along the circumferential direction of the stirring shaft (2); the driving component (15) is a driving motor, and the driving motor is connected to the stirring shaft (2) through a coupling.

10. The apparatus for preparing ultrafine lithium carbonate as described in claim 8 or 9, characterized in that, The reactor body (1) includes an outer shell (4), a heat insulation layer (5), a steam jacket layer (6), and an inner shell (7). The inner shell (7), the steam jacket layer (6), the heat insulation layer (5), and the outer shell (4) are arranged sequentially from the inside to the outside. A steam pipe (10) communicating with the steam jacket layer (6) is provided on the outer shell (4). A top cover (12) is detachably connected to the reactor body (1). A feed pipe (13) communicating with the reactor body (1) and an observation port (14) are provided on the top cover (12). A discharge pipe (16) is provided at the top of the reactor body (1). A sieve plate (17) is provided in the discharge pipe (16). A backflushing device (18) is provided on the discharge pipe (16).

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