Preparation method of metal oxide capable of accurately controlling particle size

Abstract

The invention discloses a preparation method of a metal oxide capable of accurately controlling particle size, which comprises the following steps: (1) reacting raw materials to obtain an intermediate solution containing metal oxide particles; (2) the intermediate solution is pumped into a multi-stage U-shaped pipe for sedimentation, a solution containing metal oxide particles with different particle sizes is obtained in each stage of U-shaped pipe, a valve is arranged at the bottom of each stage of U-shaped pipe, and a solution containing metal oxide particles with the target particle size is obtained through the valves; and (3) aging the solution of the metal oxide particles with the target particle size. According to the preparation method of the metal oxide, continuous synthesis and preparation of the metal oxide are achieved, meanwhile, precise control over the particle size range of the synthesized metal oxide is achieved, and the problems that in an existing process, the amount of produced wastewater is large, and the particle size and the impurity content are uncontrollable are solved.

Description

Technical Field

[0001] The invention relates to the technical field of metal oxide material preparation, and in particular to a method for preparing a metal oxide with accurately controlled particle size. Background Art

[0002] With the rapid development of new energy and the continuous development of battery types, positive electrode materials have put forward higher and higher requirements on the morphology and particle size of solid particles, because the tap density determines the size of the battery discharge capacity per unit volume. At present, in industry, the control of the particle size of metal oxide synthesis is mainly achieved through chemical means, such as adjusting the pH value of the solution, the concentration of the material, the feeding speed, the stirring intensity, the type of complexing agent, and ultrasonic synthesis. However, these methods will affect the morphology of solid particles when adjusting the solid particle size, and it is impossible to accurately control the particle size range during the synthesis process. Summary of the invention

[0003] The present invention provides a method for preparing a metal oxide with accurately controlled particle size, so as to solve the technical problem of poor particle size control effect in the existing metal oxide preparation process mentioned in the background technology.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is: A method for preparing a metal oxide with accurately controlled particle size comprises the following steps: (1) mixing the raw materials for preparing the metal oxide in a certain ratio to form a reaction system for reaction, introducing an oxidant into the reaction system during the reaction, and obtaining an intermediate solution containing metal oxide particles after a set reaction time; (2) pumping the intermediate solution into a multi-stage U-shaped tube for sedimentation, and obtaining solutions containing metal oxide particles of different particle sizes in each stage of the U-shaped tube, wherein a valve is provided at the bottom of each stage of the U-shaped tube, and a solution of particles of the target particle size is obtained through the valve; (3) Aging the solution of particles of the target particle size to obtain the metal oxide product of the target particle size.

[0005] The design idea of ​​the above technical solution is that the present invention adopts a multi-stage U-shaped tube to classify the metal oxide particles of different particle sizes in the intermediate solution, utilizes the difference in the sedimentation speed of the metal oxides of different particle sizes to distribute the metal oxide particles of different particle sizes in each stage of the U-shaped tube, and selects the solution of the U-shaped tube where the metal oxide of the target particle size required for production is located to carry out the next aging operation, so as to achieve precise control of the particle size of the metal oxide product, which can effectively avoid the problem that the single-tank reaction such as the existing metal salt oxidation method and the metal corrosion method cannot accurately control the particle size of the solid particles, and effectively prevent the excessive growth of solid particles.

[0006] As a further preferred embodiment of the above technical solution, in step (2), solutions of metal oxide particles of different particle sizes are obtained in each stage of the U-shaped tube by controlling the pumping rate of the intermediate solution, the vertical height of each stage of the U-shaped tube and the number of stages of the multi-stage U-shaped tube.

[0007] As a further preferred embodiment of the above technical solution, the pumping rate is 20-200 r / min; the height of each level of U-shaped tube is 5-30 cm, and the diameter of each level of U-shaped tube is 1-5 cm. As a further preferred embodiment of the above technical solution, in step (2), before the intermediate solution is pumped into the multi-stage U-shaped tube, the multi-stage U-shaped tube is filled with the solution.

[0008] As a further preferred embodiment of the above technical solution, in step (2), the pumping rate of the intermediate solution into the multi-stage U-shaped tube is greater than the sedimentation rate of the metal oxide particles.

[0009] As a further preferred embodiment of the above technical solution, the sum of the discharge rates of each stage of the U-shaped tube is less than the feed rate of the multi-stage U-shaped tube.

[0010] As a further preferred embodiment of the above technical solution, the sum of the discharge volumes of the U-shaped tubes at each stage is greater than or equal to the sum of the added volumes of the prepared raw materials.

[0011] As a further preferred embodiment of the above technical solution, the raw materials for preparing the metal oxide in step (1) include sulfate, alkali solution and a complexing agent; the sulfate includes at least one of manganese sulfate, nickel sulfate and cobalt sulfate; the alkali solution includes at least one of sodium hydroxide solution and potassium hydroxide solution; and the complexing agent is aqueous ammonia.

[0012] As a further preferred embodiment of the above technical solution, the oxidant in step (1) includes at least one of oxygen and air.

[0013] As a further preferred embodiment of the above technical solution, in the reaction process of preparing the raw materials in step (1), the pH of the reaction system is first controlled to be 10-12, and then the pH of the reaction system is adjusted to 8-10. The pH of the reaction system is first controlled to be 10-12 to form a large number of seed crystals in the reaction system, and then the pH is adjusted to 8-10 to inhibit the crystallization process and strengthen the growth of seed crystals.

[0014] As a further preferred embodiment of the above technical solution, the number of stages of the multi-stage U-shaped tube is 2 to 10, and the solution obtained in the last stage of the U-shaped tube is a clear liquid, which does not contain metal oxide particles. By controlling the number of U-shaped tubes, the preparation of different metal oxides can be achieved, and the complete separation of solids and liquids can be achieved, thereby reducing the amount of wastewater generated during the preparation process.

[0015] As a further preferred embodiment of the above technical solution, the reaction time of the reaction system in step (1) is controlled so that the particle size of the particles in the obtained intermediate solution is less than or equal to the particle size of the target particle size, and the solution with a particle size smaller than the target particle size obtained in the multi-stage U-shaped tube in step (2) is returned to the reaction system in step (1) for further reaction. By controlling the reaction time so that the particle size of the particles in the solution entering the multi-stage U-shaped tube is less than or equal to the target particle size, and then the solution with a particle size smaller than the target particle size obtained in the multi-stage U-shaped tube is re-entered into the kettle for reaction until it grows to the target particle size, continuous feeding, continuous growth and continuous output of metal oxides can be achieved, so that the process of the present invention has the feasibility of industrial scale-up and continuous production.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of the metal oxide of the present invention realizes the continuous synthesis and preparation of the metal oxide and also realizes the precise control of the particle size range of the synthesized metal oxide, effectively preventing the excessive growth of solid particles, and solving the problems of large amount of wastewater discharge, uncontrollable particle size and impurity content in the existing process. The prepared metal oxide has a high tap density and can be used to make batteries with high performance requirements.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a SEM image of metal oxide particles of the intermediate solution obtained in Example 1 of the present invention; Figure 2 is a SEM image of metal oxide particles of the intermediate solution obtained in Example 1 of the present invention; Figure 3 The particle size distribution result of the intermediate solution obtained in step (1) of Example 1 of the present invention; Figure 4 The particle size distribution result of the metal oxide particles in the solution in the first stage U-shaped tube of the multi-stage U-shaped tube in step (2) of Example 1 of the present invention; Figure 5 This is the particle size distribution result of the metal oxide particles in the solution in the second stage U-shaped tube in the multi-stage U-shaped tube in step (2) of Example 1 of the present invention. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0020] Embodiment 1: The method for preparing the metal oxide with accurately controlled particle size of the present embodiment comprises the following steps: (1) A manganese sulfate solution, a sodium hydroxide solution and an ammonia solution were prepared, and added to a reaction synthesis kettle using a metering pump according to a reaction molar ratio (manganese sulfate: sodium hydroxide: ammonia solution = 1:2:0.0025) to obtain a reaction system. The pH of the reaction system was adjusted to 11, and the reaction was carried out at 50°C for 30 minutes. The pH of the reaction system was then adjusted to 8.7, and air was blown into the reaction system to continue the reaction for 16 hours to obtain an intermediate solution. The metal oxide particles in the intermediate solution were subjected to SEM analysis and particle size distribution test, and the results were as follows: Figure 1-Figure 3 As shown; (2) The intermediate solution was pumped into a three-stage U-shaped tube filled with the supernatant of the reaction reactor by a peristaltic pump for sedimentation (a valve was opened at the bottom of each stage of the U-shaped tube). The pumping rate of the intermediate solution was 45 r / min, and the vertical height of the three-stage U-shaped tube was 8.3 cm. Solutions with metal oxide particles of different particle sizes were obtained in each stage of the U-shaped tube. The particle size of the metal oxide particles in the solution in the first stage of the U-shaped tube was analyzed. The results are as follows: Figure 4 As shown; the particle size of the metal oxide particles in the solution in the second-stage U-tube was analyzed, and the results are as follows Figure 5 As shown; (3) The solution in the first-stage U-shaped tube is sent to the aging kettle through a valve for aging for 5 hours to obtain metal oxide manganese tetraoxide with concentrated particle size distribution. The solutions in the second and third-stage U-shaped tubes are returned to the reaction synthesis kettle through valves for further reaction, and a clear liquid is obtained at the end of the third-stage U-shaped tube.

[0021] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application. The above are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a metal oxide with accurately controlled particle size, characterized in that: The following steps are involved: (1) mixing the raw materials for preparing the metal oxide in a certain ratio to form a reaction system for reaction, introducing an oxidant into the reaction system during the reaction, and obtaining an intermediate solution containing metal oxide particles after a set reaction time; (2) pumping the intermediate solution into a multi-stage U-shaped tube for sedimentation, and obtaining solutions containing metal oxide particles of different particle sizes in each stage of the U-shaped tube, wherein a valve is provided at the bottom of each stage of the U-shaped tube, and a solution of particles of the target particle size is obtained through the valve; (3) Aging the solution of particles of the target particle size to obtain the metal oxide product of the target particle size.

2. The method for preparing a metal oxide with accurately controlled particle size according to claim 1, characterized in that: In step (2), solutions of particles of different particle sizes are obtained in each stage of the U-shaped tube by controlling the pumping rate of the intermediate solution, the vertical height of each stage of the U-shaped tube, the diameter of each stage of the U-shaped tube and the number of stages of the multi-stage U-shaped tube.

3. The method for preparing a metal oxide with accurately controlled particle size according to claim 2, characterized in that: The pumping rate is 20-200 r / min; the height of each level of the U-shaped tube is 5-30 cm, and the diameter of each level of the U-shaped tube is 1-5 cm.

4. The method for preparing a metal oxide with accurately controlled particle size according to claim 1, characterized in that: In step (2), before the intermediate solution is pumped into the multi-stage U-shaped tube, the multi-stage U-shaped tube is filled with a reaction system without particles.

5. The method for preparing a metal oxide with accurately controlled particle size according to claim 1, characterized in that: In step (2), the pumping rate of the intermediate solution into the multi-stage U-shaped tube is greater than the sedimentation rate of the metal oxide particles.

6. The method for preparing a metal oxide with accurately controlled particle size according to any one of claims 1 to 5, characterized in that: The raw materials for preparing the metal oxide in step (1) include sulfate, alkali solution and a complexing agent; the sulfate includes at least one of manganese sulfate, nickel sulfate and cobalt sulfate; the alkali solution includes at least one of sodium hydroxide solution and potassium hydroxide solution; and the complexing agent is aqueous ammonia.

7. The method for preparing a metal oxide with accurately controlled particle size according to any one of claims 1 to 5, characterized in that: The oxidant in step (1) includes at least one of oxygen and air.

8. The method for preparing a metal oxide with accurately controlled particle size according to any one of claims 1 to 5, characterized in that: During the reaction process of preparing the raw materials in step (1), the pH of the reaction system is first controlled to be 10-12, and then the pH of the reaction system is adjusted to 8-10.

9. The method for preparing a metal oxide with accurately controlled particle size according to any one of claims 1 to 5, characterized in that: The number of stages of the multi-stage U-shaped tube is 2 to 4, and the solution obtained in the last stage of the U-shaped tube is a clear liquid, which does not contain metal oxide particles.

10. The method for preparing a metal oxide with accurately controlled particle size according to any one of claims 1 to 5, characterized in that: The reaction time of the reaction system in step (1) is controlled so that the particle size of the particles in the obtained intermediate solution is less than or equal to the particle size of the target particle size, and the solution with a particle size smaller than the target particle size obtained in the multi-stage U-shaped tube in step (2) is returned to the reaction system in step (1) to continue the reaction.

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