A high-density small-particle cobalt carbonate and its preparation method and application

Abstract

The present invention provides a method for preparing high-density small-particle cobalt carbonate, prepares a cobalt salt solution and an ammonium bicarbonate solution, adds them to a reaction vessel in a continuous feeding manner and reacts; in the initial stage of the continuous feeding stage, stops feeding at intervals and performs aging treatment, and continues to react after several agings until the seed crystal grows to a certain particle size; stops settling, siphons the supernatant, and then adopts a one-time feeding method to add the reaction solution to the reaction vessel, and continues to react under closed conditions to obtain a cobalt carbonate slurry; after washing, separation and drying, a high-density small-particle cobalt carbonate is obtained. The present invention is regularly aged at the initial stage of the reaction, effectively improving the defects of the seed crystal such as loose structure and poor density in the generation stage; adopts a combination of a continuous feeding method and a one-time feeding method, and in the crystal growth stage, the reaction time is effectively shortened by a one-time feeding, the production efficiency is improved, and the density and particle size consistency of the particles are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of cobalt carbonate preparation, and in particular relates to a high-density small-particle cobalt carbonate and a preparation method thereof, and also relates to the application of the high-density small-particle cobalt carbonate. Background Art

[0002] As an important inorganic chemical raw material, cobalt carbonate is widely used in battery materials, catalysts, ceramic materials and other fields. There are precipitation method, sol-gel method, hydrothermal method and so on for preparing cobalt carbonate. Among them, precipitation method is widely used in industrial production because of its advantages such as simple process, low cost and stable product quality. However, the small particles of cobalt carbonate prepared by this method often have the problem of low density due to factors such as fast nucleation rate and insufficient particle growth. Small particles of cobalt carbonate with higher density are used in battery materials to improve battery energy density; they are used in catalysts to improve catalytic activity and stability; they are also used in ceramic materials to improve ceramic performance.

[0003] Based on this, providing a high-density small-particle cobalt carbonate and a preparation method thereof to better meet the application needs of different scenarios is a technical problem that needs to be solved urgently. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for preparing high-density small-particle cobalt carbonate with good particle size distribution consistency and high tap density.

[0005] The second object of the present invention is to provide a high-density small-particle cobalt carbonate with good particle size distribution consistency and high tap density.

[0006] The third object of the present invention is to provide an application of high-density small-particle cobalt carbonate with good particle size distribution consistency and high tap density.

[0007] The technical solution adopted by the present invention to achieve one of the purposes is: to provide a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: S1, prepare a cobalt salt solution with a cobalt ion concentration of 110-140g / L and an ammonium bicarbonate solution with a concentration of 220-260g / L; S2, using a continuous feeding method, the cobalt salt solution and the ammonium bicarbonate solution are simultaneously added to a reaction vessel with a bottom water temperature of 40-50°C and a stirring speed of 280-340r / min according to a flow ratio of 1: (1.5-2.2), and the pH of the reaction system is controlled to be 7.0-7.5; in the initial stage of the continuous feeding, the feeding is stopped and aged once at regular intervals, and the single aging time is 30-60min. After 3-5 cumulative agings, the reaction is continued until the seed particle size reaches 2.4-2.7μm; S3, stopping the kettle for sedimentation, siphoning the supernatant; then using a one-time feeding method, adding the cobalt salt solution and the ammonium bicarbonate solution into the reaction container at a volume ratio of 1: (1.5-2.2), and continuing the reaction for 3-8 hours at a temperature of 40-50° C., a rotation speed of 20-50 r / min, and a sealed condition to obtain a cobalt carbonate slurry; S4. The cobalt carbonate slurry is washed, solid-liquid separated and dried to obtain highly dense small particles of cobalt carbonate.

[0008] The general idea of ​​the present invention is as follows: In order to prepare small-particle cobalt carbonate with high density, the present invention mainly makes the following two improvements in the preparation process of cobalt carbonate: on the one hand, the present invention performs regular aging at the initial stage of the reaction, which effectively improves the defects of the seed crystals in the generation stage, such as loose structure and poor density; on the other hand, the preparation method adopts a combination of a continuous feeding method and a one-time feeding method. In the crystal growth stage, the reaction time is effectively shortened by a one-time feeding, thereby improving the production efficiency.

[0009] Among them, the present invention sets the aging at the initial stage of seed generation, which can guide the growth direction of the crystal and help improve the crystal nucleus structure. According to the Ostwald ripening mechanism, small crystal particles have high surface energy and cannot exist stably in the solution, so the small particles will gradually dissolve, and the dissolved substances will recrystallize on the surface of larger crystal particles. The initial stage of continuous feeding is the seed generation stage. Multiple aging provides sufficient time for the crystal to grow and rearrange its structure. With the dissolution of small particles and the redeposition of solutes on large particles, the internal structure of the crystal will gradually become more compact.

[0010] In addition, the present invention adopts a combination of continuous feeding method and one-time feeding method, which can also improve the density and particle size consistency of crystal particles. In the seed generation stage, the continuous feeding method is adopted in combination with the aging method, and the crystal can be made more dense through the action of mechanical force; in the later stage, the one-time feeding method is adopted and the crystal is ensured to be in a sealed state, which provides a stable and consistent environment for the crystal, makes the growth rate of each crystal similar, and is conducive to forming particles with consistent particle size and high density.

[0011] Furthermore, in step S1, the cobalt salt in the cobalt salt solution includes cobalt sulfate and / or cobalt chloride.

[0012] Furthermore, in step S2, the flow rate of the cobalt salt solution is 30-38 mL / min, and the flow rate of the ammonium bicarbonate solution is 52-60 mL / min. The flow rate of the cobalt salt solution is controlled to be 30-38 mL / min, so that the growth rate of the seed crystal can be controlled; and the pH of the reaction system is controlled within a suitable range by adjusting the flow rate of the ammonium bicarbonate solution.

[0013] Further, for the aging process of step S2, it has been found that when the aging frequency is too high, the growth and dissolution balance of the seed crystal itself will be broken, and the crystal structure may collapse, and it is impossible to maintain its originally relatively ordered lattice state; and if the aging frequency is too low, the crystal structure cannot be optimized in time, affecting the overall quality of the seed crystal. For a single aging time, if it is set too short, the crystal growth and dissolution will be insufficient, and if the aging time is too long, the crystal will be subjected to excessive mechanical stress, causing scratches and cracks on the surface. Based on the above analysis, preferably, the first 4 hours of the continuous feeding, the feeding is stopped and aged every 1 hour, the single aging time is 30-60min, and the reaction is continued after 4 cumulative agings until the seed crystal particle size reaches 2.4-2.7μm.

[0014] Preferably, the aging temperature is 5-10°C lower than the reaction temperature, and low-speed intermittent stirring is used during aging. Stir for 10-20 minutes, stop for 4-6 minutes, and the stirring speed is set to 100-150r / min. In the lower temperature environment, the crystal growth rate slows down, and the ions have more time to find a suitable position for arrangement, making the crystal structure more compact; the low-speed intermittent stirring method can avoid the structure of the seed crystal being destroyed due to excessive stirring, and at the same time make the concentration of the solute around the seed crystal more uniform, which is conducive to the uniform growth of the crystal and improves the density of the seed crystal.

[0015] Furthermore, in step S2, the reaction time is 22-30 hours, and the aging time is not included in the reaction time.

[0016] Furthermore, in step S3, the kettle is stopped for sedimentation, and the supernatant is siphoned off until the volume of the slurry in the kettle remains at 20%-30%.

[0017] In the late stage of seed growth of step S3 of the present invention, the reaction conditions are set as follows: stirring speed of 20-50r / min, temperature of 40-50°C, and reaction in a sealed environment for 3-8h. In a hydrothermal environment with a certain temperature and pressure, the solute ions diffuse and rearrange fully, so that the crystals can be better arranged into a regular crystal structure during growth, and it is beneficial for the crystals to grow at a similar rate, thereby forming particles with a narrow particle size distribution and relatively uniform size. The present invention sets the stirring speed to 20-50r / min at this stage. If the stirring speed is too high, the mechanical force generated will affect the stability of this environment; if the stirring speed is too low or the stirring is stopped, the bottom crystals will be squeezed by the mother liquor and other crystals, resulting in abnormal growth rate.

[0018] Furthermore, in step S4, the cobalt carbonate slurry is washed with pure water at a temperature of 60-80°C; and the temperature of the drying treatment is 60-80°C.

[0019] The technical solution adopted by the present invention to achieve the second purpose is: to provide a high-density small-particle cobalt carbonate, which is prepared by the preparation method according to one of the purposes of the present invention; the particle size D50 of the high-density small-particle cobalt carbonate is 5.019-5.982 μm, the consistency is 0.259-0.312, and the tap density TD is 2.0-2.7 g / m 3 .

[0020] The technical solution adopted by the present invention to achieve the third purpose is: to provide an application of the high-density small-particle cobalt carbonate described in the second purpose of the present invention in battery materials, catalysts or ceramic materials.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a method for preparing highly dense small-particle cobalt carbonate. Periodic aging is performed in the initial stage of the reaction, which can effectively improve the defects of the seed crystals in the generation stage, such as loose structure and poor density. A continuous feeding method and a one-time feeding method are combined. In the crystal growth stage, the one-time feeding method is used to effectively shorten the reaction time, improve production efficiency, and further improve the density and particle size consistency of the particles.

[0022] (2) The particle size D50 of the high-density small-particle cobalt carbonate prepared by the present invention is 5.019-5.982 μm, the consistency is 0.259-0.312, and the tap density TD is 2.0-2.7 g / m 3 , and has broad prospects for promotion and application in battery materials, catalysts or ceramic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the XRD diagram of the high-density small-particle cobalt carbonate prepared in Example 1 of the present invention; Figure 2 This is a SEM image of the highly dense small-particle cobalt carbonate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0026] The present invention will be further described below in conjunction with specific embodiments, but they are not intended to be limiting of the present invention.

[0027] The embodiment of the present invention provides a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: Step 1: preparing a cobalt salt solution with a cobalt ion concentration of 110-140 g / L and an ammonium bicarbonate solution with a concentration of 220-260 g / L; the cobalt salt in the cobalt salt solution includes cobalt sulfate and / or cobalt chloride.

[0028] Step 2: Add bottom water to the reactor. The bottom water is a mixture of ammonium bicarbonate and pure water in a volume ratio of 1: (10-12). The amount of bottom water is enough to submerge the stirring blade. When the bottom water temperature rises to 42°C, the cobalt salt solution and the ammonium bicarbonate solution are added simultaneously in a flow ratio of 1: (1.5-2.2) to the reaction vessel with a bottom water temperature of 40-50°C and a stirring speed of 280-340r / min by continuous feeding. The flow rate of the ammonium bicarbonate solution is adjusted to control the pH of the reaction system to 7.0-7.5. Among them, the flow rate of the cobalt salt solution is 30-38mL / min. The flow rate of the ammonium bicarbonate solution is 52-60 mL / min; in the first 4 hours of the continuous feeding, the feeding is stopped and the aging is performed once every 1 hour, the single aging time is 30-60 minutes, and the reaction is continued after 4 cumulative agings until the seed particle size reaches 2.4-2.7 μm; the aging temperature is 5-10° C. lower than the reaction temperature, and a low-speed intermittent stirring method of 100-150 r / min is adopted during the aging process, and the stirring is stopped for 4-6 minutes every 10-20 minutes; the cumulative reaction time of step 2 is 22-30 hours, and the aging time is not included in the reaction time.

[0029] Step 3: Stop the kettle and let it settle, siphon the supernatant until the volume of the slurry in the kettle remains 20%-30%; then, add the cobalt salt solution and ammonium bicarbonate solution into the reaction vessel at a volume ratio of 1: (1.5-2.2) in a one-time feeding manner, and continue the reaction for 3-8 hours at a temperature of 40-50°C, a rotation speed of 20-50r / min, and a sealed condition to obtain cobalt carbonate slurry.

[0030] Step 4: Wash the cobalt carbonate slurry with pure water at a temperature of 60-80°C, and then separate the solid and liquid, and then dry the wet cobalt carbonate at 60-80°C to obtain highly dense small particles of cobalt carbonate.

[0031] Example 1 This embodiment provides a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: Step 1: Using cobalt chloride hexahydrate and ammonium bicarbonate as raw materials, prepare a cobalt salt solution with a cobalt ion concentration of 110 g / L and an ammonium bicarbonate solution with a concentration of 220 g / L.

[0032] Step 2: Add bottom water to the reactor to submerge the stirring blade. When the bottom water temperature rises to 42°C, use a continuous feeding method to add a cobalt salt solution at a flow rate of 38 mL / min and an ammonium bicarbonate solution at a flow rate of 60 mL / min to a reaction vessel with a bottom water temperature of 42°C and a stirring speed of 330 r / min through a metering pump, and control the pH of the reaction system to be 7.3; in the first 4 hours of the continuous feeding, stop feeding and age once every 1 hour, the single aging time is 40 minutes, and continue to react after 4 cumulative agings until the seed particle size reaches 2.7 μm; the aging process is cooled to 35°C, and a low-speed intermittent stirring method of 150 r / min is used during the aging, and the stirring is stopped for 5 minutes every 15 minutes; the cumulative reaction time of step 2 is 24 hours, and the aging time is not included in the reaction time.

[0033] Step 3: Stop the kettle for sedimentation, siphon the supernatant until the volume of the slurry in the kettle remains at 25%; then, adopt a one-time feeding method to add the cobalt salt solution and ammonium bicarbonate solution into the reaction vessel at a volume ratio of 1:2. At this time, the material in the kettle accounts for about 85% of the total volume of the kettle. Continue the reaction for 5 hours at a temperature of 42°C, a rotation speed of 30r / min and sealed conditions to obtain cobalt carbonate slurry.

[0034] Step 4: Wash the cobalt carbonate slurry with pure water at a temperature of 60°C, and then separate the solid from the liquid, and then dry the wet cobalt carbonate at 70°C to obtain highly dense small particles of cobalt carbonate.

[0035] The XRD pattern and scanning electron microscope image of the highly dense small particle cobalt carbonate prepared in this embodiment are shown as follows: Figure 1 and 2 After testing, the particle size D50 of the high-density small-particle cobalt carbonate prepared in Example 1 is 5.532 μm, the consistency is 0.259, and the tap density TD is 2.7 g / m 3 .

[0036] Example 2 This embodiment provides a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: Step 1: Using cobalt sulfate dodecahydrate and ammonium bicarbonate as raw materials, a cobalt salt solution with a cobalt ion concentration of 110 g / L and an ammonium bicarbonate solution with a concentration of 220 g / L are prepared.

[0037] Step 2: Add bottom water to the reactor to submerge the stirring blade. When the bottom water temperature rises to 43°C, use a continuous feeding method to add a cobalt salt solution at a flow rate of 35 mL / min and an ammonium bicarbonate solution at a flow rate of 57 mL / min to a reaction vessel with a bottom water temperature of 43°C and a stirring speed of 310 r / min through a metering pump, and control the pH of the reaction system to be 7.2; in the first 4 hours of the continuous feeding, stop feeding and age once every 1 hour, the single aging time is 30 minutes, and continue to react after 4 cumulative agings until the seed particle size reaches 2.5 μm; the aging process is cooled to 36°C, and a low-speed intermittent stirring method of 130 r / min is used during the aging, and the stirring is stopped for 5 minutes every 15 minutes; the cumulative reaction time of step 2 is 26 hours, and the aging time is not included in the reaction time.

[0038] Step 3: Stop the kettle for sedimentation, siphon the supernatant until the volume of the slurry in the kettle remains at 22%; then, the cobalt salt solution and ammonium bicarbonate solution are added into the reaction vessel at a volume ratio of 1:1.9 in a one-time feeding manner. At this time, the material in the kettle accounts for about 87% of the total volume of the kettle. The reaction is continued for 7 hours at a temperature of 42°C, a rotation speed of 30 r / min and sealed conditions to obtain cobalt carbonate slurry.

[0039] Step 4: Wash the cobalt carbonate slurry with pure water at a temperature of 60°C, and then separate the solid from the liquid, and then dry the wet cobalt carbonate at 70°C to obtain highly dense small particles of cobalt carbonate.

[0040] After testing, the particle size D50 of the high-density small-particle cobalt carbonate prepared in Example 2 is 5.154 μm, the consistency is 0.293, and the tap density TD is 2.4 g / m 3 .

[0041] Example 3 This embodiment provides a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: Step 1: Using cobalt chloride hexahydrate and ammonium bicarbonate as raw materials, prepare a cobalt salt solution with a cobalt ion concentration of 130 g / L and an ammonium bicarbonate solution with a concentration of 260 g / L.

[0042] Step 2: Add bottom water to the reactor to submerge the stirring blade. When the bottom water temperature rises to 40°C, use a continuous feeding method to add a cobalt salt solution at a flow rate of 30 mL / min and an ammonium bicarbonate solution at a flow rate of 52 mL / min into a reaction vessel with a bottom water temperature of 40°C and a stirring speed of 340 r / min through a metering pump, and control the pH of the reaction system to be 7.1; in the first 4 hours of the continuous feeding, stop feeding and age once every 1 hour, the single aging time is 60 minutes, and continue to react after accumulating 5 agings until the seed particle size reaches 2.4 μm; the aging process is cooled to 33°C, and a low-speed intermittent stirring method of 120 r / min is used during the aging, and the stirring is stopped for 5 minutes every 15 minutes; the cumulative reaction time of step 2 is 30 hours, and the aging time is not included in the reaction time.

[0043] Step 3: Stop the kettle for sedimentation, siphon the supernatant until the volume of the slurry in the kettle remains at 23%; then, the cobalt salt solution and ammonium bicarbonate solution are added into the reaction vessel at a volume ratio of 1:1.5 in a one-time feeding manner. At this time, the material in the kettle accounts for about 88% of the total volume of the kettle. The reaction is continued for 3 hours at a temperature of 40°C, a rotation speed of 50 r / min and sealed conditions to obtain cobalt carbonate slurry.

[0044] Step 4: Wash the cobalt carbonate slurry with pure water at a temperature of 60°C, and then separate the solid from the liquid, and then dry the wet cobalt carbonate at 70°C to obtain highly dense small particles of cobalt carbonate.

[0045] After testing, the particle size D50 of the high-density small-particle cobalt carbonate prepared in Example 3 is 5.891 μm, the consistency is 0.308, and the tap density TD is 2.1 g / m 3 .

[0046] Example 4 This embodiment provides a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: Step 1: Using cobalt chloride hexahydrate and ammonium bicarbonate as raw materials, prepare a cobalt salt solution with a cobalt ion concentration of 110 g / L and an ammonium bicarbonate solution with a concentration of 220 g / L.

[0047] Step 2: Add bottom water to the reactor to submerge the stirring blade. When the bottom water temperature rises to 50°C, use a continuous feeding method to add a cobalt salt solution at a flow rate of 30 mL / min and an ammonium bicarbonate solution at a flow rate of 60 mL / min into a reaction vessel with a bottom water temperature of 50°C and a stirring speed of 340 r / min through a metering pump, and control the pH of the reaction system to be 7.0; in the first 4 hours of the continuous feeding, stop feeding and age once every 1 hour, the single aging time is 50 minutes, and continue to react after 4 cumulative agings until the seed particle size reaches 2.7 μm; the aging process is cooled to 40°C, and a low-speed intermittent stirring method of 150 r / min is used during the aging, and the stirring is stopped for 5 minutes every 15 minutes; the cumulative reaction time of step 2 is 25 hours, and the aging time is not included in the reaction time.

[0048] Step 3: Stop the kettle for sedimentation, siphon the supernatant until the volume of the slurry in the kettle remains 20%; then, the cobalt salt solution and ammonium bicarbonate solution are added into the reaction vessel at a volume ratio of 1:2.2 in a one-time feeding manner. At this time, the material in the kettle accounts for about 85% of the total volume of the kettle. The reaction is continued for 8 hours at a temperature of 50°C, a rotation speed of 20r / min and sealed conditions to obtain cobalt carbonate slurry.

[0049] Step 4: Wash the cobalt carbonate slurry with pure water at a temperature of 60°C, and then separate the solid from the liquid, and then dry the wet cobalt carbonate at 70°C to obtain highly dense small particles of cobalt carbonate.

[0050] After testing, the particle size D50 of the high-density small-particle cobalt carbonate prepared in Example 4 is 5.982 μm, the consistency is 0.312, and the tap density TD is 2.2 g / m 3 .

[0051] Example 5 This embodiment provides a method for preparing high-density small-particle cobalt carbonate, comprising the following steps: Step 1: Using cobalt chloride hexahydrate and ammonium bicarbonate as raw materials, prepare a cobalt salt solution with a cobalt ion concentration of 120 g / L and an ammonium bicarbonate solution with a concentration of 240 g / L.

[0052] Step 2: Add bottom water to the reactor to submerge the stirring blade. When the bottom water temperature rises to 45°C, use a continuous feeding method to add a cobalt salt solution at a flow rate of 30 mL / min and an ammonium bicarbonate solution at a flow rate of 60 mL / min into a reaction vessel with a bottom water temperature of 45°C and a stirring speed of 280 r / min through a metering pump, and control the pH of the reaction system to be 7.5; in the first 4 hours of the continuous feeding, stop feeding and age once every 1 hour, the single aging time is 30 minutes, and continue to react after accumulating 3 agings until the seed particle size reaches 2.4 μm; the aging process is cooled to 38°C, and a low-speed intermittent stirring method of 130 r / min is used during the aging, and the stirring is stopped for 5 minutes every 15 minutes; the cumulative reaction time of step 2 is 22 hours, and the aging time is not included in the reaction time.

[0053] Step 3: Stop the kettle for sedimentation, siphon the supernatant until the volume of the slurry in the kettle remains at 23%; then, the cobalt salt solution and ammonium bicarbonate solution are added into the reaction vessel at a volume ratio of 1:2 in a one-time feeding manner. At this time, the material in the kettle accounts for about 82% of the total volume of the kettle. The reaction is continued for 5 hours at a temperature of 40°C, a rotation speed of 50 r / min and sealed conditions to obtain cobalt carbonate slurry.

[0054] Step 4: Wash the cobalt carbonate slurry with pure water at a temperature of 65°C, and then separate the solid from the liquid, and then dry the wet cobalt carbonate at 75°C to obtain highly dense small particles of cobalt carbonate.

[0055] After testing, the particle size D50 of the high-density small-particle cobalt carbonate prepared in Example 5 is 5.019 μm, the consistency is 0.289, and the tap density TD is 2.0 g / m 3 .

[0056] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-density small-particle cobalt carbonate, characterized in that: The following steps are involved: S1, prepare a cobalt salt solution with a cobalt ion concentration of 110-140g / L and an ammonium bicarbonate solution with a concentration of 220-260g / L; S2, using a continuous feeding method, the cobalt salt solution and the ammonium bicarbonate solution are simultaneously added to a reaction vessel with a bottom water temperature of 40-50°C and a stirring speed of 280-340r / min according to a flow ratio of 1: (1.5-2.2), and the pH of the reaction system is controlled to be 7.0-7.5; in the initial stage of the continuous feeding, the feeding is stopped and aged once at regular intervals, and the single aging time is 30-60min. After 3-5 cumulative agings, the reaction is continued until the seed particle size reaches 2.4-2.7μm; S3, stopping the kettle for sedimentation, siphoning the supernatant; then using a one-time feeding method, adding the cobalt salt solution and the ammonium bicarbonate solution into the reaction container at a volume ratio of 1: (1.5-2.2), and continuing the reaction for 3-8 hours at a temperature of 40-50° C., a rotation speed of 20-50 r / min, and a sealed condition to obtain a cobalt carbonate slurry; S4. The cobalt carbonate slurry is washed, solid-liquid separated and dried to obtain highly dense small particles of cobalt carbonate.

2. The preparation method according to claim 1, characterized in that: In step S1, the cobalt salt in the cobalt salt solution includes cobalt sulfate and / or cobalt chloride.

3. The preparation method according to claim 1, characterized in that: In step S2, the flow rate of the cobalt salt solution is 30-38 mL / min, and the flow rate of the ammonium bicarbonate solution is 52-60 mL / min.

4. The preparation method according to claim 1, characterized in that: In step S2, during the first 4 hours of continuous feeding, the feeding is stopped and the aging is performed once every 1 hour. The single aging time is 30-60 minutes. After accumulating 4 aging times, the reaction is continued until the seed crystal particle size reaches 2.4-2.7 μm.

5. The preparation method according to claim 4, characterized in that: The aging temperature is 5-10°C lower than the reaction temperature. During the aging, low-speed intermittent stirring is adopted. Stir for 10-20 minutes and stop for 4-6 minutes. The stirring speed is set to 100-150r / min.

6. The preparation method according to claim 1, characterized in that: In step S2, the reaction time is 22-30 hours, and the aging time is not included in the reaction time.

7. The preparation method according to claim 1, characterized in that: In step S3, the kettle is stopped for sedimentation, and the supernatant is siphoned until the volume of the slurry in the kettle remains at 20%-30%.

8. The preparation method according to claim 1, characterized in that: In step S4, the cobalt carbonate slurry is washed with pure water at a temperature of 60-80°C; the temperature of the drying treatment is 60-80°C.

9. A highly dense small particle cobalt carbonate, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8; the particle size D50 of the high-density small-particle cobalt carbonate is 5.019-5.982 μm, the consistency is 0.259-0.312, and the tap density TD is 2.0-2.7 g / m 3 .

10. Use of the high-density small-particle cobalt carbonate according to claim 9 in battery materials, catalysts or ceramic materials.

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