Preparation method of cobaltosic oxide with high apparent density
By setting cobalt carbonate seeds at the bottom of the reaction vessel and reacting under liquid feeding, and then calcining at high temperature, the loose density of cobalt tetroxide was successfully improved, the problem of insufficient density in the existing technology was solved, and solid fuel was met High density requirements for batteries.
Patent Information
- Application Number
- CN202411522173.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-29
- Publication Date
- 2025-02-07
AI Technical Summary
It is difficult to produce cobalt tetroxide with high loose density, especially in applications where cobalt is cobalt tetroxide in solid fuel cell connecting sheets, the loose density requirements are high.
By setting cobalt carbonate seeds at the bottom of the reaction vessel, and feeding ammonium bicarbonate solution and cobalt sulfate solution by liquid feeding, the reaction raw materials can directly reach the bottom of the reaction vessel for reaction, so that the carbonic acid grown on the cobalt carbonate seeds is made Cobalt is tighter. Then calcination was carried out at 820-850°C to obtain high-volume cobalt tetroxide.
The loose density of cobalt tetroxide has been increased to above 1.35g/cm3, and can easily reach 1.5g/cm3, meeting the high loose density requirements of cobalt in solid fuel cell connection sheets.
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Figure HDA0005108292790000011 
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of material preparation, in particular to a method for preparing cobalt oxide with high bulk density. Background Art
[0002] Spinel transition metal oxide Co3O4 is widely used in battery materials, magnetic materials, catalysts, thermistors and varistors, biosensors and other fields. In these applications, the bulk density of Co3O4 is not required or is required to be less than 0.7g / cm 3 The solid fuel cell connector uses lanthanum strontium cobalt manganese (LSCM) material in which the cobalt is cobalt tetroxide and requires a high bulk density. Summary of the invention
[0003] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing cobalt tetroxide with high bulk density. The preparation method provided by the present invention can produce cobalt tetroxide with a bulk density greater than 1.3 g / cm 3 of cobalt tetroxide.
[0004] The present invention provides a method for preparing cobalt tetroxide, comprising:
[0005] S1) arranging cobalt carbonate seed crystals at the bottom of a reaction vessel, feeding an ammonium bicarbonate solution and a cobalt sulfate solution to the bottom of the reaction vessel for reaction, and growing cobalt carbonate on the cobalt carbonate seed crystals;
[0006] S2) calcining the cobalt carbonate obtained in step S1) at 820-850° C. to obtain cobalt tetroxide.
[0007] The present invention feeds ammonium bicarbonate solution and cobalt sulfate solution to the bottom of the reaction container for reaction, specifically, feeds ammonium bicarbonate solution and cobalt sulfate solution to the bottom of the reaction container for reaction at a flow rate ratio of (2.5-3.5):1. In certain embodiments of the present invention, the concentration of the ammonium bicarbonate solution is 180-210 g / L; the concentration of the cobalt sulfate solution is 100-130 g / L. In the present invention, the feeding method of feeding the reaction raw materials to the bottom of the reaction container is a submerged feeding method. By the submerged feeding method, the ammonium bicarbonate solution and the cobalt sulfate solution are directly fed to the bottom of the reaction container for reaction, so that the cobalt carbonate grown on the cobalt carbonate seed crystals arranged at the bottom of the reaction container can be more compact.
[0008] In step S1) of the present invention, the ammonium bicarbonate solution and the cobalt sulfate solution are fed to the bottom of the reaction container for reaction, the reaction time is 2 to 4 hours, the reaction temperature is 45 to 55°C, and the reaction is carried out at a pH of 7.5 to 8.5. The present invention feeds the ammonium bicarbonate solution and the cobalt sulfate solution to the bottom of the reaction container and mixes them to start the reaction, so the reaction of the present invention specifically includes feeding the ammonium bicarbonate solution and the cobalt sulfate solution to the bottom of the reaction container while performing a mixed reaction, and continuing the aging reaction after the feeding is completed, the mixing reaction time is 1.5 to 2.5 hours, the mixing reaction temperature is 45 to 55°C; the aging reaction time is 0.5 to 1.5 hours, and the aging reaction temperature is 45 to 55°C.
[0009] After the cobalt carbonate is grown on the cobalt carbonate seed crystal to obtain the cobalt carbonate, the obtained cobalt carbonate is calcined at 820-850°C. Specifically, the obtained cobalt carbonate is calcined in the first zone, the second zone, the third zone, the fourth zone, the fifth zone and the sixth zone in sequence to obtain cobalt tetroxide; wherein the first zone is a dehydration decomposition zone, the second zone, the third zone and the fourth zone are all heat preservation sintering zones, and the fifth zone and the sixth zone are all cooling zones; the temperature for calcination in the first zone is 770-800° C., and the time is 2-3 hours; the temperature for calcination in the second zone is 820-850° C., and the time is 2-3 hours; the temperature for calcination in the third zone is 820-850° C., and the time is 2-3 hours; the temperature for calcination in the fourth zone is 820-850° C., and the time is 2-3 hours; the temperature for calcination in the fifth zone is 720-750° C., and the time is 3 hours or more, preferably 3-5 hours, and more preferably 4 hours; the temperature for calcination in the sixth zone is 270-300° C., and the time is 3 hours or more, preferably 3-5 hours, and more preferably 4 hours. In certain embodiments of the present invention, the present invention feeds the cobalt carbonate into a rotary kiln through a screw feeder and calcines in the above six temperature zones in sequence, with a feeding frequency of 10 to 15 Hz, a kiln feeding frequency of 40 to 50 Hz, a kiln drum frequency of 10 to 20 Hz, and an inlet wind speed of 0.4 to 0.8 m / s.
[0010] The present invention also includes washing the obtained cobalt carbonate with water before calcining until the conductivity of the washed water is less than 5ms / cm, at which time the impurity sulfur element in the cobalt carbonate is less than 50ppm, and then drying and calcining. In certain embodiments of the present invention, the drying temperature is 80-120°C and the drying time is 1-3h. The present invention dries the material before the cobalt carbonate is put into the kiln for calcining, thereby avoiding clogging the kiln exhaust duct.
[0011] Step S1) of the present invention is specifically as follows: S1a) adding ammonium bicarbonate solution and cobalt sulfate solution to the bottom of a reaction container for reaction to obtain a reaction solution containing cobalt carbonate seed precipitates, and extracting the reaction solution, wherein the amount of the reaction solution extracted is 1 / 3 to 1 / 2 of the total volume of the reaction solution;
[0012] S1b) feeding ammonium bicarbonate solution and cobalt sulfate solution into the bottom of the reaction vessel in step S1a) to react, and growing cobalt carbonate on the cobalt carbonate seed crystals to obtain cobalt carbonate.
[0013] Step S1a) of the present invention is a step of setting cobalt carbonate seeds at the bottom of the reaction vessel, that is, feeding ammonium bicarbonate solution and cobalt sulfate solution to the bottom of the reaction vessel for reaction to obtain a reaction solution containing cobalt carbonate seed precipitates, and the reaction solution is pumped away. More specifically, 400 to 600 L of water is added to the reaction vessel, and ammonium bicarbonate solution and cobalt sulfate solution are fed to the bottom of the reaction vessel at a flow rate ratio of (2.5 to 3.5): 1 to react to obtain a reaction solution containing cobalt carbonate seed precipitates, and the reaction solution is pumped away. The concentrations of the ammonium bicarbonate solution and the cobalt sulfate solution of the present invention are the same as those described above and will not be repeated. The reaction described in step S1a) of the present invention is a cobalt carbonate seed synthesis reaction, which is the same as the reaction performed in the above step S1) to grow cobalt carbonate on the cobalt carbonate seeds and will not be repeated.
[0014] After obtaining the reaction solution containing the cobalt carbonate seed precipitate, the reaction solution needs to be pumped out, and the amount of the reaction solution pumped out is 1 / 3 to 1 / 2 of the total volume of the reaction solution. After the seed crystals are synthesized, they need to be left to stand so that the seed crystals are precipitated at the bottom of the reaction container. At this time, the supernatant is pumped out, that is, the reaction solution is pumped out, which increases the proportion of seed crystals in the subsequent reaction system, thereby increasing the collision between the cobalt carbonate crystals, making the cobalt carbonate more compact.
[0015] The present invention also provides cobalt tetroxide obtained by any of the above-mentioned preparation methods. The method of the present invention can increase the bulk density of cobalt tetroxide prepared to 1.35 g / cm 3 Above, can easily reach 1.5g / cm 3 In one embodiment of the present invention, the bulk density of the cobalt oxide prepared by the method of the present invention is increased to 1.7 g / cm 3 .
[0016] The present invention provides a method for preparing cobalt tetroxide with high bulk density. The method for preparing cobalt tetroxide with high bulk density provided by the present invention arranges cobalt carbonate seeds at the bottom of the reaction vessel, and combines the method of underwater feeding to allow the reaction raw materials to directly reach the bottom of the reaction vessel for reaction, thereby making the cobalt carbonate grown on the cobalt carbonate seeds more compact. When the cobalt carbonate seeds are arranged at the bottom of the reaction vessel, the present invention also adopts the method of underwater feeding to allow the reaction raw materials to directly reach the bottom of the reaction vessel for seed synthesis reaction, thereby making the synthesized cobalt carbonate seeds more compact, and by pumping out the supernatant, the seed ratio of the reaction system is increased, thereby making the cobalt carbonate subsequently grown on the seeds more compact. The method of the present invention increases the bulk density of the prepared cobalt tetroxide to 1.35 g / cm 3 Above, can easily reach 1.5g / cm 3 . BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 The figure is a schematic flow chart of the method for preparing cobalt tetroxide with high bulk density according to the present invention;
[0018] Figure 2 The present invention is a schematic diagram of the device for preparing the high bulk density cobalt tetroxide. DETAILED DESCRIPTION
[0019] The present invention discloses a method for preparing cobalt trioxide with high bulk density. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to realize and apply the technology of the present invention.
[0020] The present invention Figure 1 The process shown is used to prepare cobalt tetroxide with high bulk density. Figure 1 The present invention is a schematic flow chart of the method for preparing cobalt oxide with high bulk density.
[0021] The present invention adopts Figure 2 The device shown is used to prepare cobalt tetroxide with high bulk density. Figure 2The schematic diagram of the device for the method for preparing cobalt tetroxide with high bulk density of the present invention, wherein ① is the upper liquid feed valve of the CoSO4 solution tank, through which CoSO4 can be fed to the liquid surface of the solution tank; ② is the lower liquid feed valve of the CoSO4 solution tank, through which CoSO4 can be fed to the stirring paddle of the solution tank; ③ is the upper liquid feed valve of the NH4HCO3 solution tank, through which NH4HCO3 can be fed to the liquid surface of the solution tank; ④ is the upper liquid feed valve of the NH4HCO3 solution tank, through which NH4HCO3 can be fed to the liquid surface of the solution tank; ⑤ is the stirring paddle; ⑥ is the center position of the stirring paddle. If CoSO4 and NH4HCO3 are fed to the liquid surface of the solution tank through ① and ③, the feeding method is upper liquid feeding; if CoSO4 and NH4HCO3 are fed to the stirring paddle of the solution tank through ② and ④, the feeding method is lower liquid feeding.
[0022] The present invention will be further described below in conjunction with embodiments:
[0023] Example 1
[0024] 1. Seed preparation: add 500L pure water into the reactor, start stirring (speed 40Hz), heat to 53°C, add 100L ammonium bicarbonate to adjust the pH of the solution in the reactor to 8.0, and then add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio of 3:1) in a submerged feeding manner at the same time. After adding for 2h, continue aging reaction for 1h. After the end, stop stirring and let it stand, pump out the supernatant (1 / 2 of the total volume), and use cobalt carbonate A in the reactor as seed;
[0025] 2. Synthesis reaction: After stirring, add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio is 3:1) into the reactor in the seed crystal A simultaneously by submerged feeding, control the temperature at 53°C and pH=8.0 during the feeding process, continue aging reaction for 1 hour after 2 hours of feeding, and obtain cobalt carbonate B;
[0026] 3. Centrifugal washing: The cobalt carbonate B in step 2 is pumped into the centrifuge through the mortar (the equipment is adjusted to 600rpm / min feeding) for solid-liquid separation. After the liquid is fed, it is dried at high speed and then centrifuged at 2m 3 / h rate of pure water, washing until the outlet water conductivity is 3ms / cm (the impurity sulfur element in the cobalt carbonate is measured to be less than 50ppm), and drying and dehydration to obtain cobalt carbonate C;
[0027] 4. Drying: The cobalt carbonate C obtained in step 3 is placed in a vacuum oven and dried at 105° C. for 2 h to obtain dry cobalt carbonate D;
[0028] 5. Calcination: The cobalt carbonate D obtained in step 4 is fed into the rotary kiln through a spiral feeder, the feeding frequency is 15Hz, and the kiln feeding frequency is 45Hz. The temperature zones of the kiln are set as follows: Zone 1, 800℃; Zone 2, 820℃; Zone 3, 820℃; Zone 4, 820℃; Zone 5, 750℃; Zone 6, 300℃; the drum frequency of the kiln is 20Hz, the air inlet speed is 0.5m / s, and the cobalt tetroxide is obtained by discharging the kiln tail. The sample is sent for analysis and the bulk ratio of cobalt tetroxide is 1.7g / cm 3 .
[0029] The concentration of the ammonium bicarbonate used above is 200 g / L; the concentration of the cobalt sulfate solution is 120 g / L.
[0030] Example 2
[0031] 1. Seed preparation: add 400L pure water into the reactor, start stirring (speed 30Hz), heat to 45°C, add 60L ammonium bicarbonate to adjust the pH of the solution in the reactor to 8.0, and then add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio of 3.5:1) by submerged feeding at the same time. After adding for 2h, continue aging reaction for 1h. After the end, stop stirring, pump out the supernatant (1 / 3 of the total volume), and use cobalt carbonate A in the reactor as seed;
[0032] 2. Synthesis reaction: After stirring the reactor in the seed crystal A, add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio is 3.5:1) in a submerged feeding manner. During the feeding process, the temperature is controlled at 45°C and the pH is controlled at 8.0. After 2 hours of feeding, the aging reaction is continued for 1 hour to obtain cobalt carbonate B;
[0033] 3. Centrifugal washing: The cobalt carbonate B in step 2 is pumped into the centrifuge through the mortar (the equipment is adjusted to 600rpm / min feeding) for solid-liquid separation. After the liquid is fed, it is dried at high speed and then centrifuged at 2m 3 / h rate of pure water, washing until the outlet water conductivity is 5ms / cm (the impurity sulfur element in the cobalt carbonate is measured to be less than 50ppm), and drying and dehydration to obtain cobalt carbonate C;
[0034] 4. Drying: The cobalt carbonate C obtained in step 3 is placed in a vacuum oven and dried at 105° C. for 2 h to obtain dry cobalt carbonate D;
[0035] 5. Calcination: The cobalt carbonate D obtained in step 4 is fed into the rotary kiln through a spiral feeder, the feeding frequency is 12Hz, and the kiln feeding frequency is 45Hz. The temperature zones of the kiln are set as follows: Zone 1, 800℃; Zone 2, 820℃; Zone 3, 820℃; Zone 4, 820℃; Zone 5, 750℃; Zone 6, 300℃; the drum frequency of the kiln is 15Hz, the air inlet speed is 0.8m / s, and the cobalt tetroxide is obtained by discharging the kiln tail. The sample analysis test shows that the bulk ratio of cobalt tetroxide is 1.35g / cm3 .
[0036] The concentration of the ammonium bicarbonate used above is 210 g / L; the concentration of the cobalt sulfate solution is 130 g / L.
[0037] Comparative Example 1
[0038] 1. Seed preparation: add 500L pure water to the reactor, start stirring (speed 40Hz), heat to 53°C, add 100L ammonium bicarbonate to adjust the pH of the solution in the reactor to 8.0, and then add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio of 3:1) by liquid feeding at the same time. After adding materials for 2h, continue aging reaction for 1h. After the end, stop stirring and let it stand, pump out the supernatant (1 / 2 of the total volume), and use cobalt carbonate A in the reactor as seed;
[0039] 2. Synthesis reaction: After stirring, add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio is 3:1) into the reactor in the seed crystal A simultaneously by liquid feeding, control the temperature at 53°C and pH=8.0 during the feeding process, continue aging reaction for 1 hour after 2 hours of feeding, and obtain cobalt carbonate B;
[0040] 3. Centrifugal washing: The cobalt carbonate B in step 2 is pumped into the centrifuge through the mortar (the equipment is adjusted to 600rpm / min feeding) for solid-liquid separation. After the liquid is fed, it is dried at high speed and then centrifuged at 2m 3 / h rate of pure water, washing until the outlet water conductivity is 3ms / cm (the impurity sulfur element in the cobalt carbonate is measured to be less than 50ppm), and drying and dehydration to obtain cobalt carbonate C;
[0041] 4. Drying: The cobalt carbonate C obtained in step 3 is placed in a vacuum oven and dried at 105° C. for 2 h to obtain dry cobalt carbonate D;
[0042] 5. Calcination: The cobalt carbonate D obtained in step 4 is fed into the rotary kiln through a spiral feeder, the feeding frequency is 15Hz, and the kiln feeding frequency is 45Hz. The temperature zones of the kiln are set as follows: Zone 1, 800℃; Zone 2, 820℃; Zone 3, 820℃; Zone 4, 820℃; Zone 5, 750℃; Zone 6, 300℃; the drum frequency of the kiln is 20Hz, the air inlet speed is 0.5m / s, and the cobalt tetroxide is obtained by discharging the kiln tail. The sample is sent for analysis and the loose ratio of cobalt tetroxide is 1.0g / cm 3 .
[0043] The concentration of the ammonium bicarbonate used above is 200 g / L; the concentration of the cobalt sulfate solution is 120 g / L.
[0044] Comparative Example 2
[0045] 1. Seed preparation: add 500L pure water into the reactor, start stirring (speed 40Hz), heat to 53°C, add 100L ammonium bicarbonate to adjust the pH of the solution in the reactor to 8.0, and then add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio of 3:1) in a submerged feeding manner at the same time. After adding for 2h, continue aging reaction for 1h. After the end, stop stirring and let it stand, pump out the supernatant (1 / 2 of the total volume), and use cobalt carbonate A in the reactor as seed;
[0046] 2. Synthesis reaction: After stirring, add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio is 3:1) into the reactor in the seed crystal A simultaneously by submerged feeding, control the temperature at 53°C and pH=8.0 during the feeding process, continue aging reaction for 1 hour after 2 hours of feeding, and obtain cobalt carbonate B;
[0047] 3. Centrifugal washing: The cobalt carbonate B in step 2 is pumped into the centrifuge through the mortar (the equipment is adjusted to 600rpm / min feeding) for solid-liquid separation. After the liquid is fed, it is dried at high speed and then centrifuged at 2m 3 / h rate of pure water, washing until the outlet water conductivity is 3ms / cm (the impurity sulfur element in the cobalt carbonate is measured to be less than 50ppm), and drying and dehydration to obtain cobalt carbonate C;
[0048] 4. Drying: The cobalt carbonate C obtained in step 3 is placed in a vacuum oven and dried at 105° C. for 2 h to obtain dry cobalt carbonate D;
[0049] 5. Calcination: The cobalt carbonate D obtained in step 4 is fed into the rotary kiln through a spiral feeder, the feeding frequency is 15Hz, and the kiln feeding frequency is 45Hz. The temperature zones of the kiln are set as follows: Zone 1, 500℃; Zone 2, 620℃; Zone 3, 620℃; Zone 4, 620℃; Zone 5, 550℃; Zone 6, 300℃; the drum frequency of the kiln is 20Hz, the air inlet speed is 0.5m / s, and the cobalt tetroxide is obtained by discharging the kiln tail. The sample is sent for analysis and the bulk ratio of cobalt tetroxide is 0.9g / cm 3 .
[0050] The concentration of the ammonium bicarbonate used above is 200 g / L; the concentration of the cobalt sulfate solution is 120 g / L.
[0051] Example 3
[0052] 1. Seed preparation: add 500L pure water into the reactor, start stirring (speed 40Hz), heat to 53°C, add 100L ammonium bicarbonate to adjust the pH of the solution in the reactor to 8.0, and then add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio of 3:1) in a submerged feeding manner at the same time. After adding for 2h, continue aging reaction for 1h. After the end, stop stirring and let it stand. Cobalt carbonate A in the reactor is used as seed;
[0053] 2. Synthesis reaction: After stirring, add ammonium bicarbonate solution and cobalt sulfate solution (flow rate ratio is 3:1) into the reactor in the seed crystal A simultaneously by submerged feeding, control the temperature at 53°C and pH=8.0 during the feeding process, continue aging reaction for 1 hour after 2 hours of feeding, and obtain cobalt carbonate B;
[0054] 3. Centrifugal washing: The cobalt carbonate B in step 2 is pumped into the centrifuge through the mortar (the equipment is adjusted to 600rpm / min feeding) for solid-liquid separation. After the liquid is fed, it is dried at high speed and then centrifuged at 2m 3 / h rate of pure water, washing until the outlet water conductivity is 3ms / cm (the impurity sulfur element in the cobalt carbonate is measured to be less than 50ppm), and drying and dehydration to obtain cobalt carbonate C;
[0055] 4. Drying: The cobalt carbonate C obtained in step 3 is placed in a vacuum oven and dried at 105° C. for 2 h to obtain dry cobalt carbonate D;
[0056] 5. Calcination: The cobalt carbonate D obtained in step 4 is fed into the rotary kiln through a spiral feeder, the feeding frequency is 15Hz, and the kiln feeding frequency is 45Hz. The temperature zones of the kiln are set as follows: Zone 1, 800℃; Zone 2, 820℃; Zone 3, 820℃; Zone 4, 820℃; Zone 5, 750℃; Zone 6, 300℃; the drum frequency of the kiln is 20Hz, the air inlet speed is 0.5m / s, and the cobalt tetroxide is obtained by discharging the kiln tail. The sample analysis test shows that the bulk ratio of cobalt tetroxide is 1.65g / cm 3 .
[0057] Furthermore, the concentration of ammonium bicarbonate used above is 200 g / L; the concentration of cobalt sulfate solution is 120 g / L.
[0058] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A method for preparing cobalt tetroxide, characterized in that: include: S1) arranging cobalt carbonate seed crystals at the bottom of a reaction vessel, feeding an ammonium bicarbonate solution and a cobalt sulfate solution to the bottom of the reaction vessel for reaction, and growing cobalt carbonate on the cobalt carbonate seed crystals; S2) calcining the cobalt carbonate obtained in step S1) at 820-850° C. for 6-9 hours to obtain cobalt tetroxide.
2. The preparation method according to claim 1, characterized in that: In step S1), the ammonium bicarbonate solution and the cobalt sulfate solution are added to the bottom of the reaction container at a flow rate ratio of (2.5-3.5):1 to react; The concentration of the ammonium bicarbonate solution is 180-210 g / L; the concentration of the cobalt sulfate solution is 100-130 g / L.
3. The preparation method according to claim 1, characterized in that: In step S1), the reaction time is 2 to 4 hours, and the reaction temperature is 45 to 55°C.
4. The preparation method according to claim 1, characterized in that: In step S1), the reaction is carried out at a pH of 7.5 to 8.
5.
5. The preparation method according to claim 1, characterized in that: Step S2) specifically comprises: calcining the cobalt carbonate obtained in step S1) in the first zone, the second zone, the third zone, the fourth zone, the fifth zone and the sixth zone in sequence to obtain cobalt tetroxide; The calcination temperature in the first zone is 770-800°C and the time is 2-3h; The calcination temperature in the second zone is 820-850°C and the time is 2-3 hours; The calcination temperature in the three zones is 820-850°C and the calcination time is 2-3 hours; The calcination temperature in the fourth zone is 820-850°C and the time is 2-3h; The calcination temperature in the fifth zone is 720-750° C. and the calcination time is more than 3 hours; The calcination temperature in the sixth zone is 270-300° C. and the calcination time is more than 3 hours.
6. The preparation method according to claim 1, characterized in that: In step S2), before calcination, the cobalt carbonate obtained in step S1) is washed with water until the conductivity of the washed water is less than 5 ms / cm.
7. The preparation method according to any one of claims 1 to 6, characterized in that: Step S1) is specifically: S1a) adding an ammonium bicarbonate solution and a cobalt sulfate solution to the bottom of a reaction vessel for reaction to obtain a reaction solution containing cobalt carbonate seed precipitates, and removing the reaction solution, wherein the amount of the reaction solution removed is 1 / 3 to 1 / 2 of the total volume of the reaction solution; S1b) feeding ammonium bicarbonate solution and cobalt sulfate solution into the bottom of the reaction vessel in step S1a) to react, and growing cobalt carbonate on the cobalt carbonate seed crystals to obtain cobalt carbonate.
8. The preparation method according to claim 7, characterized in that: In step S1a), the ammonium bicarbonate solution and the cobalt sulfate solution are added to the bottom of the reaction container at a flow rate ratio of (2.5-3.5):1 to react; The concentration of the ammonium bicarbonate solution is 180-210 g / L; the concentration of the cobalt sulfate solution is 100-130 g / L.
9. The preparation method according to claim 7, characterized in that: In step S1a), the reaction time is 2 to 4 hours, and the reaction temperature is 45 to 55°C.
10. The preparation method according to claim 7, characterized in that: In step S1a), the reaction is carried out at a pH of 7.5 to 8.5.