A method for preparing battery-grade manganese sesquioxide using a manganese sulfate solution

Abstract

The application discloses a method for preparing battery-grade trimanganese tetraoxide by using a manganese sulfate solution and belongs to the technical field of preparation of manganese-based precursors of battery positive materials. The method comprises the following four steps: preparation of a solution, preparation of manganese carbonate particles, slurry mixing and oxygen pressure conversion of the manganese carbonate particles, and filtration, washing and drying to obtain trimanganese tetraoxide. The method can realize stable preparation of battery-grade trimanganese tetraoxide by using manganese salt, and the prepared product has the characteristics of low impurity content, small particle size, high specific surface area, high tap density and large spherical particles. The method has the advantages of short process flow, low cost and good product quality.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of manganese-based precursors for battery cathode materials, specifically relating to a method for preparing battery-grade manganese tetroxide using manganese sulfate solution. Background Technology

[0002] Manganese tetroxide (Mn3O4) is primarily used as a basic raw material in the production of manganese-zinc ferrites. In recent years, its applications have gradually expanded to other fields such as lithium manganese oxide batteries and the pigment industry. Mn3O4 is a high-quality raw material for preparing LiMn2O4 battery cathode materials, outperforming manganese dioxide. Therefore, the synthesis of LiMn2O4 using Mn3O4 as a raw material has gained increasing attention, and extensive research has been conducted on novel methods for synthesizing Mn3O4. The goal is to synthesize Mn3O4 products with characteristics such as small particle size, high specific surface area, low impurity content, and high tap density, meeting the specific quality requirements of LiMn2O4 production. Currently, using Mn3O4 to replace manganese dioxide in LiMn2O4 production is a major trend. Therefore, how to obtain qualified Mn3O4 raw materials at low cost is a crucial research focus that cannot be ignored in reducing the cost of LiMn2O4 battery cathode materials.

[0003] Currently, the purity of manganese tetroxide (Mn3O4) used to prepare battery cathode materials needs to be above 99%. Only battery cathode materials made from high-purity Mn3O4 exhibit significant advantages such as good capacity performance, high compaction density, and good cycle performance. Methods for producing battery-grade Mn3O4 with a purity of over 99% include electrolytic manganese oxidation and manganese salt oxidation, and these technologies are becoming increasingly mature. The main advantage of electrolytic manganese suspension oxidation is its relatively simple raw material and mature process. However, because this method uses electrolytic manganese as a raw material, the raw material cost accounts for about 80%, resulting in a high cost of Mn3O4. The manganese salt thermal oxidation method directly prepares Mn3O4 from manganese sulfate solution without electrolysis, eliminating the complex manganese electrolysis process, saving energy, and possessing a better price competitiveness. However, research on the manganese salt method for preparing Mn3O4 has not yet been industrialized, mainly because it has high requirements for raw materials and stringent control conditions; the prepared Mn3O4 is difficult to meet the required physical properties. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing battery-grade manganese tetroxide using manganese sulfate solution, so as to solve the technical problems of high raw material cost and harsh control conditions in the existing preparation process of battery-grade manganese tetroxide, which makes it difficult to achieve stable industrial production.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing battery-grade manganese tetroxide using manganese sulfate solution includes the following steps:

[0007] (1) Preparation of the solution: Prepare manganese sulfate solution to obtain backup solution A, and then prepare ammonium bicarbonate solution B.

[0008] (2) Preparation of manganese carbonate particles: Add an appropriate amount of deionized water as the base liquid to the reactor, add ethanol as the dispersant, and then add ammonium bicarbonate to control the pH value of the base liquid to 8.0-9.0. Stir and heat to control the temperature to 30-40℃. Add the backup liquid A and backup liquid B slowly to the reactor while stirring. Adjust the pH value of backup liquid B to control the reaction value to 7.5-8.5. The reaction time is 10-12h. After the addition is completed, control the final pH value of the reaction to 8.0-10.0. Continue stirring and aging for 5-8h before filtering.

[0009] (3) Oxygen pressure conversion of manganese carbonate particles: The manganese carbonate obtained in the filtration step (2) is washed with deionized water and then added to a high-pressure reactor. Deionized water / ammonium chloride / ammonia water or sodium hydroxide is added. The high-pressure reactor is started to stir and heat. Oxygen is continuously introduced at a pressure of 0.2-1.0 MPa and a heating temperature of 130-160°C. The reaction time is 2-6 hours.

[0010] (4) The liquid obtained in the filtration step (3) is filtered. The filtered solid manganese tetroxide is washed several times with deionized water. The filtered product is dried to obtain battery-grade manganese tetroxide.

[0011] More preferably, in step (1), the backup solution A is prepared by mixing high-purity manganese sulfate or purified manganese sulfate solution with ultrapure water, and the manganese ion concentration of the prepared backup solution A is 0.5 to 1.0 mol / L.

[0012] More preferably, in step (2), after slowly adding the backup solution A and backup solution B into the reaction vessel while stirring, the pH value of the reaction is adjusted to 8.0 by the backup solution B, the concentration of the backup solution B is 1.0 to 2.0 mol / L, and the concentration of the dispersant in the system is 2 to 5 g / L.

[0013] More preferably, in step (3), deionized water is added to control the liquid-solid ratio of manganese carbonate particles to 3:1 to 4:1, the concentration of ammonium chloride in the reaction system is 5 to 10 g / L, and the amount of ammonia or sodium hydroxide added in the reaction system is 1 to 2 g / L.

[0014] More preferably, in step (3), the manganese carbonate obtained in step (2) is washed with deionized water at least twice.

[0015] More preferably, the relevant parameters of the battery-grade manganese tetroxide obtained in step (4) are: particle size D50 of 6.0±1.5μm; tap density >2.2g / cm³. 3S% content < 0.02%; Mn% content > 70.5%; specific surface area < 2.0 m² 2 / g; its microstructure is spherical or near-spherical.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Through small-scale, pilot-scale, and large-scale studies, this invention has found that the technical solution provided by this invention, by introducing manganese carbonate as an intermediate step and high-pressure oxidation, can achieve stable preparation of battery-grade manganese tetroxide from manganese salts. The prepared product has characteristics such as low impurity content, small particle size, high specific surface area, high tap density, and large spherical particles. The basic parameters of the product are: particle size D50 of 6.0±1.5μm; tap density >2.2g / cm³. 3 S% content < 0.02%; Mn% content > 70.5%; specific surface area < 2.0 m² 2 / g; the microstructure is spherical or near-spherical, meeting the requirements of YB / T 4736-2019 standard.

[0018] 2. The processing technology of this invention has the advantages of short process, low cost and good product quality. Detailed Implementation

[0019] The present invention will be further described below with reference to various embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0020] Example 1

[0021] This embodiment describes a small-scale trial operation for preparing battery-grade manganese tetroxide using manganese sulfate solution, including the following steps:

[0022] (1) Mix 100g of manganese sulfate and 1L of deionized water to prepare a manganese sulfate solution; prepare 60g of ammonium bicarbonate into a 500ml solution;

[0023] (2) Add 500ml of deionized water as the base liquid and 2ml of ethanol as the dispersant to the reaction beaker, then add 5g of ammonium bicarbonate, stir and heat to control the temperature at 30-40℃; adjust the stirrer speed to 600-800r / min, and slowly add the prepared manganese sulfate solution and ammonium bicarbonate solution to the reaction vessel while stirring, control the reaction pH to 8.0, and the reaction time to 10h; after the addition is completed, control the final reaction pH to 9.0, continue stirring and aging for 5h, and then filter.

[0024] (3) The manganese carbonate obtained from the filtration step was washed twice with deionized water and then added to a high-pressure reactor. 500 ml of deionized water, 5 g / L of ammonium chloride, and 1 g of sodium hydroxide were added. The high-pressure reactor was started with stirring and heating. Oxygen was continuously introduced. The reaction pressure was 0.6 MPa, the heating temperature was 160°C, the stirring speed was 500 r / min, and the reaction time was 4 h.

[0025] (4) After the reaction, the solid manganese tetroxide was filtered and washed several times with deionized water. The filtered product was dried to obtain battery-grade manganese tetroxide. The particle size D50 of the manganese tetroxide precursor was 7.5 μm; the tap density was 2.2 g / cm³. 3 S% content < 0.01%; Mn% content 70.5%; specific surface area < 2.0 m² 2 / g; It is not difficult to see that the microstructure of the product prepared in this embodiment is spherical.

[0026] Example 2

[0027] This embodiment describes a pilot-scale operation for preparing battery-grade manganese tetroxide using manganese sulfate solution, including the following steps:

[0028] (1) Mix 50 kg of manganese sulfate and 0.5 cubic meters of deionized water to prepare a manganese sulfate solution; prepare 30 kg of ammonium bicarbonate into a 200 L solution;

[0029] (2) Add 200L of deionized water as the base liquid and 5L of ethanol as the dispersant to the reaction vessel, then add 5kg of ammonium bicarbonate, stir and heat to control the temperature at 30-40℃; adjust the stirrer speed to 600-800r / min, and slowly add the prepared manganese sulfate solution and ammonium bicarbonate solution to the reaction vessel while stirring, control the reaction pH to 8.0, and the reaction time to 12h; after the addition is completed, control the final reaction pH to 9.0, continue stirring and aging for 10h, and then filter.

[0030] (3) The manganese carbonate obtained from the filtration step is washed twice with deionized water and then added to the high-pressure reactor. 200L of deionized water, 2kg / L of ammonium chloride, and 1kg of sodium hydroxide are added. The high-pressure reactor is started with stirring and heating. Oxygen is continuously introduced at a pressure of 1.0Mpa and a heating temperature of 160℃. The stirring speed is 500r / min and the reaction time is 4h.

[0031] (4) After the reaction, the solid manganese tetroxide was filtered and washed several times with deionized water. The filtered product was dried to obtain battery-grade manganese tetroxide. The particle size D50 of the manganese tetroxide precursor was 7.0 μm; the tap density was 2.15 g / cm³. 3 S% content 0.01%; Mn% content 70.4%; specific surface area 2.0 m² 2 / g; It is not difficult to see that the microstructure of the product prepared in this embodiment is spherical.

[0032] Example 3

[0033] This embodiment describes a scale-up operation for preparing battery-grade manganese tetroxide using manganese sulfate solution, including the following steps:

[0034] (1) Prepare a manganese sulfate solution by mixing 200L of 150g / L manganese sulfate solution with 1.0 cubic meter of deionized water; prepare a 300L solution by mixing 40kg of ammonium bicarbonate.

[0035] (2) Add 0.5 cubic meters of deionized water as the base liquid to the reaction vessel, add 10 L of ethanol as the dispersant, and then add 10 kg of ammonium bicarbonate. Stir and heat to control the temperature at 30-40 °C. Adjust the stirrer speed to 800 r / min, and slowly add the prepared manganese sulfate solution and ammonium bicarbonate solution to the reaction vessel while stirring. Control the reaction pH to 8.0 and the reaction time to 10 h. After the addition is complete, control the final reaction pH to 9.0, continue stirring and aging for 12 h, and then filter.

[0036] (3) The manganese carbonate obtained from the filtration step is washed twice with deionized water and then added to a high-pressure reactor. 500L of deionized water, 30kg of ammonium chloride, and 20L of ammonia water are added. The high-pressure reactor is started with stirring and heating. Oxygen is continuously introduced at a pressure of 1.0Mpa and a heating temperature of 160℃. The stirring speed is 500r / min and the reaction time is 6h.

[0037] (4) After the reaction, the solid manganese tetroxide was filtered and washed several times with deionized water. The filtered product was dried to obtain battery-grade manganese tetroxide. The particle size D50 of the manganese tetroxide precursor was 7.0 μm; the tap density was 2.2 g / cm³. 3 S% content 0.005%; Mn% content 70.6%; specific surface area 2.0 m² 2 / g; It is not difficult to see that the microstructure of the product prepared in this embodiment is spherical.

[0038] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for preparing battery-grade manganese tetroxide using manganese sulfate solution, characterized in that, Includes the following steps: (1) Preparation of the solution: Prepare a manganese sulfate solution to obtain a backup solution A. The backup solution A is prepared by mixing high-purity manganese sulfate or purified manganese sulfate solution with ultrapure water. The manganese ion concentration of the prepared backup solution A is 0.5~1.0 mol / L. Then prepare ammonium bicarbonate as backup solution B. (2) Preparation of manganese carbonate particles: Add an appropriate amount of deionized water as the base liquid to the reactor and add ethanol as the dispersant. The concentration of the dispersant in the system is 2~5 g / L. Then add ammonium bicarbonate to control the pH value of the base liquid to 8.0~9.

0. Stir and heat to control the temperature at 30~40°C. Add the backup liquid A and backup liquid B slowly to the reactor while stirring. The concentration of backup liquid B is 1.0~2.0 mol / L. Adjust the backup liquid B to control the pH value of the reaction to 7.5~8.

5. The reaction time is 10~12 h. After the addition is completed, control the final pH value of the reaction to 8.0~10.

0. Continue stirring and aging for 5~8 h before filtering. (3) Oxygen pressure conversion of manganese carbonate particles: The manganese carbonate obtained in the filtration step (2) is washed with deionized water in a slurry, and the washing is repeated at least twice. Then it is added to a high-pressure reactor, and deionized water / ammonium chloride / ammonia water or sodium hydroxide is added. The liquid-solid ratio of deionized water to manganese carbonate particles is controlled at 3:1~4:

1. The concentration of ammonium chloride in the reaction system is 5~10g / L, and the amount of ammonia water or sodium hydroxide added in the reaction system is 1~2g / L. The high-pressure reactor is started to stir and heat, and oxygen is continuously introduced at a pressure of 0.2~1.0MPa. The heating temperature is 130~160°C, and the reaction time is 2~6h. (4) The filtrate obtained in step (3) is filtered. The filtered solid manganese tetroxide is washed several times with deionized water. The filtered product is dried to obtain battery-grade manganese tetroxide. The relevant parameters of the obtained battery-grade manganese tetroxide are: particle size D50 is 6.0±1.5μm; tap density >2.2g / cm³; S% content <0.02%; Mn% content >70.5%; specific surface area is <2.0m² / g; and the microstructure is spherical or near-spherical.