Preparation process of manganese dioxide by solvothermal method
The manganese dioxide solution was treated by the solvent-thermal method, and the hot concentrated hydrochloric acid solvent was used and stirred or oscillated at high temperatures was solved, and the preparation of high-concentration manganese dioxide crystals was achieved.
Patent Information
- Application Number
- CN202510033945.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-02-14
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In the prior art, the crystal concentration of manganese dioxide is lowered by direct calcination and thermal decomposition method during the preparation process of manganese dioxide.
By using the solvent-thermal method, the reaction is equilibrium by mixing the manganese dioxide solution with a hot concentrated hydrochloric acid solvent, stirring or oscillation at high temperature, and then cooling and high concentration of manganese dioxide crystals are obtained by evaporation crystallization.
The concentration of manganese dioxide crystals is increased to obtain a purer manganese dioxide crystal, which solves the problem of lower crystal concentration in the prior art.
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Figure CN119430287A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of manganese dioxide preparation, in particular to a solvent thermal method for preparing manganese dioxide. Background Art
[0002] Manganese dioxide has many uses and functions, mainly including the following aspects: (1) Catalyst: Manganese dioxide can be used as a catalyst in chemical reactions to accelerate the reaction rate without changing the equilibrium position of the reaction. For example, in the reaction of potassium chlorate decomposition to produce oxygen, manganese dioxide exists as a catalyst; (2) Battery material: Due to its good conductivity and stability, manganese dioxide is widely used as a positive electrode material for lithium-ion batteries, which can improve the energy density and cycle life of the battery. In addition, manganese dioxide can also be used to manufacture high-performance batteries such as dry batteries and nickel-hydrogen batteries; (3) Magnetic material: Some manganese dioxide has ferromagnetism or paramagnetism, making it an important raw material for manufacturing permanent magnets or electromagnetic devices; (4) Adsorbent: Manganese dioxide particles have a large surface area and can effectively adsorb organic and inorganic substances in water, including heavy metal ions, and can be used for water treatment and air purification; (5) Manganese dioxide is also used to manufacture metallic manganese, special alloys, gas masks, electronic materials ferrite, etc. In addition, it can also be used in the rubber industry to increase the viscosity of rubber and as a catalyst in chemical experiments.
[0003] However, in the actual preparation process, the inventors found that the following problems still exist: in the process of preparing manganese dioxide in the prior art, pyrolusite is subjected to multiple steps to obtain a manganese dioxide product, but in the preparation process, the manganese dioxide product is obtained by direct roasting and thermal decomposition, and the direct roasting and thermal decomposition only evaporates the evaporable part in the solution, and the crystal concentration of the obtained manganese dioxide is low.
[0004] Based on this, the present invention provides a solvent thermal process for preparing manganese dioxide. Summary of the invention
[0005] In view of the deficiencies in the prior art, the present invention provides a solvothermal method for preparing manganese dioxide, which has the advantages of improving the purification process by solvothermal method, thereby increasing the concentration of manganese dioxide crystals, and solves the problems raised in the background technology.
[0006] The present invention provides the following technical solution: a solvent thermal method for preparing manganese dioxide, comprising the following steps: (1) Mixed roasting: In the manganese carbonate method, finely crushed pyrolusite and coal powder are evenly mixed, and then the high-valent manganese is reduced to manganese monoxide through reduction roasting; (2) Deslagging and precipitation: The generated manganese monoxide product is first leached with nitric acid and then with sulfuric acid. When the pH value of the manganese sulfate solution obtained by the sulfuric acid leaching is neutralized to 4-6, the leached manganese sulfate solution is poured into a new container, and the slag is removed by filtering with a filter during the pouring process. The manganese sulfate solution after the slag is removed enters the interior of the new container to precipitate impurities; (3) Filter pressing operation: the filtrate of the manganese sulfate solution in the new container is purified by adding sodium sulfide, and then the purified manganese sulfate solution is filtered by a filter press; (4) Manganese carbonate precipitation: Add ammonium bicarbonate and seed crystals to the filtered manganese sulfate solution to generate manganese carbonate precipitation; (5) Calcination thermal decomposition: The manganese carbonate precipitate is calcined and thermally decomposed at about 450°C in the air through water vapor to generate manganese dioxide; (6) Solution generation: The remaining manganese carbonate and low-valent manganese oxide are dissolved with sulfuric acid, heavyened with sodium chlorate, and then washed to obtain manganese dioxide solution; (7) Solvothermal treatment: Add hot concentrated hydrochloric acid solvent to the inside of the manganese dioxide solution, dissolve it in the solvent by stirring or shaking, heat the solution to 150°C, the reaction speed is accelerated under the action of high temperature, the reaction reaches equilibrium, cool the reaction liquid, and obtain pure manganese dioxide crystals by evaporation and crystallization; (8) Crystal crushing: The manganese dioxide crystals are crushed into powder using a hammer crusher.
[0007] Preferably, the pyrolusite may also be substituted with manganese carbonate ore, and the preparation process remains unchanged, and the pyrolusite is finely crushed by a hammer crusher.
[0008] Preferably, the mass ratio of the finely crushed pyrolusite to the coal powder is 80%-85%:15%-20%, for example, the mass ratio of the finely crushed pyrolusite is 80g-85g:15g-20g.
[0009] Preferably, the reduction roasting consists of two processes, preheating and reduction, using corresponding preheating furnaces and reduction furnaces. The charge is dried by a drum dryer to make the moisture content of the charge less than 4% to 5%. The dried material is preheated by a preheating furnace and then heated to a certain temperature in a reduction furnace for water gas reduction.
[0010] Preferably, the filtering steps of the filter net are divided into three layers, initially using a filter with a pore diameter of 0.5nm for primary screening and slag removal, then using a filter with a pore diameter of 0.25nm for secondary filtering and slag removal, and then using a filter with a pore diameter of 0.1nm for the final step of filtering and slag removal.
[0011] Preferably, the volume ratio of the nitric acid to the sulfuric acid is 1:1, and the ratio used in a single preparation process is a fixed value, for example, 500 ml of nitric acid and 500 ml of sulfuric acid.
[0012] Compared with the prior art, the present invention has the following beneficial effects: The solvent thermal method for preparing manganese dioxide adopts a solvent thermal method, uses a hot concentrated hydrochloric acid solvent to mix with a manganese dioxide solution, and uses stirring or oscillation in the mixing process to fully dissolve the two, and then uses high temperature to quickly react to reach equilibrium, and then cools the reaction liquid, and uses the property that manganese dioxide can dissolve in hot concentrated hydrochloric acid to produce chlorine gas, so as to further purify the manganese dioxide solution, and then the purified liquid is evaporated and crystallized to obtain purer manganese dioxide crystals. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 Schematic diagram of the process for preparing manganese dioxide of the present invention. DETAILED DESCRIPTION
[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.
[0015] See also Figure 1 , a solvothermal method for preparing manganese dioxide, comprising the following steps: (1) Mixed roasting: In the manganese carbonate method, finely crushed pyrolusite and coal powder are evenly mixed, and then the high-valent manganese is reduced to manganese monoxide through reduction roasting; (2) Deslagging and precipitation: The generated manganese monoxide product is first leached with nitric acid and then with sulfuric acid. When the pH value of the manganese sulfate solution obtained by the sulfuric acid leaching is neutralized to 4-6, the leached manganese sulfate solution is poured into a new container, and the slag is removed by filtering with a filter during the pouring process. The manganese sulfate solution after the slag is removed enters the interior of the new container to precipitate impurities; (3) Filter pressing operation: the filtrate of the manganese sulfate solution in the new container is purified by adding sodium sulfide, and then the purified manganese sulfate solution is filtered by a filter press; (4) Manganese carbonate precipitation: Add ammonium bicarbonate and seed crystals to the filtered manganese sulfate solution to generate manganese carbonate precipitation; (5) Calcination thermal decomposition: The manganese carbonate precipitate is calcined and thermally decomposed at about 450°C in the air through water vapor to generate manganese dioxide; (6) Solution generation: The remaining manganese carbonate and low-valent manganese oxide are dissolved with sulfuric acid, heavyened with sodium chlorate, and then washed to obtain manganese dioxide solution; (7) Solvothermal treatment: Add hot concentrated hydrochloric acid solvent to the inside of the manganese dioxide solution, dissolve it in the solvent by stirring or shaking, heat the solution to 150°C, the reaction speed is accelerated under the action of high temperature, the reaction reaches equilibrium, cool the reaction liquid, and obtain pure manganese dioxide crystals by evaporation and crystallization; (8) Crystal crushing: The manganese dioxide crystals are crushed into powder using a hammer crusher.
[0016] The solvent thermal method is adopted, and hot concentrated hydrochloric acid solvent is mixed with manganese dioxide solution. The mixing process is stirred or oscillated to fully dissolve the two, and then the high temperature is used to quickly react to reach equilibrium. The reaction liquid is then cooled, and the manganese dioxide solution is further purified by using the property that manganese dioxide can dissolve in hot concentrated hydrochloric acid to produce chlorine. The purified liquid is then evaporated and crystallized to obtain purer manganese dioxide crystals.
[0017] Wherein, pyrolusite can also be substituted with manganese carbonate ore, and the preparation process remains unchanged, and the pyrolusite is finely crushed by a hammer crusher.
[0018] Among them, the mass ratio of finely crushed pyrolusite to coal powder is 80%-85%:15%-20%, for example, the mass ratio of finely crushed pyrolusite is 80g-85g:15g-20g.
[0019] Among them, reduction roasting consists of two processes: preheating and reduction. The corresponding preheating furnace and reduction furnace are used. The charge is dried by a drum dryer to make the moisture content of the charge less than 4% to 5%. The dried material is preheated by a preheating furnace and then heated to a certain temperature in the reduction furnace for water gas reduction.
[0020] Among them; the filtering steps of the filter net are divided into three layers. The initial screening and slag removal are carried out using a filter net with a hole diameter of 0.5nm, and then the secondary filtering and slag removal is carried out using a filter net with a hole diameter of 0.25nm, and then the final filtering and slag removal is carried out using a filter net with a hole diameter of 0.1nm.
[0021] Among them, the volume ratio of nitric acid and sulfuric acid is 1:1, and the ratio used once in the preparation process is a fixed value, for example: nitric acid is 500ml and sulfuric acid is 500ml.
[0022] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.
[0023] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A solvothermal method for preparing manganese dioxide, characterized in that: The following steps are involved: (1) Mixed roasting: In the manganese carbonate method, finely crushed pyrolusite and coal powder are evenly mixed, and then the high-valent manganese is reduced to manganese monoxide through reduction roasting; (2) Deslagging and precipitation: The generated manganese monoxide product is first leached with nitric acid and then with sulfuric acid. When the pH value of the manganese sulfate solution obtained by the sulfuric acid leaching is neutralized to 4-6, the leached manganese sulfate solution is poured into a new container, and the slag is removed by filtering with a filter during the pouring process. The manganese sulfate solution after the slag is removed enters the interior of the new container to precipitate impurities; (3) Filter pressing operation: the filtrate of the manganese sulfate solution in the new container is purified by adding sodium sulfide, and then the purified manganese sulfate solution is filtered by a filter press; (4) Manganese carbonate precipitation: Add ammonium bicarbonate and seed crystals to the filtered manganese sulfate solution to generate manganese carbonate precipitation; (5) Calcination thermal decomposition: The manganese carbonate precipitate is calcined and thermally decomposed at about 450°C in the air through water vapor to generate manganese dioxide; (6) Solution generation: The remaining manganese carbonate and low-valent manganese oxide are dissolved with sulfuric acid, heavyened with sodium chlorate, and then washed to obtain manganese dioxide solution; (7) Solvothermal treatment: Add hot concentrated hydrochloric acid solvent to the inside of the manganese dioxide solution, dissolve it in the solvent by stirring or shaking, heat the solution to 150°C, the reaction speed is accelerated under the action of high temperature, the reaction reaches equilibrium, cool the reaction liquid, and obtain pure manganese dioxide crystals by evaporation and crystallization; (8) Crystal crushing: The manganese dioxide crystals are crushed into powder using a hammer crusher.
2. A solvothermal method for preparing manganese dioxide according to claim 1, characterized in that: The pyrolusite can also use manganese carbonate ore as a substitute raw material, and the preparation process remains unchanged. The pyrolusite is finely crushed by a hammer crusher.
3. A solvothermal method for preparing manganese dioxide according to claim 1, characterized in that: The mass ratio of the finely crushed pyrolusite to the coal powder is 80%-85%:15%-20%, for example, the mass ratio of the finely crushed pyrolusite is 80g-85g:15g-20g.
4. A solvothermal method for preparing manganese dioxide according to claim 1, characterized in that: The reduction roasting consists of two processes, preheating and reduction. The corresponding preheating furnace and reduction furnace are used. The charge is dried by a drum dryer to make the moisture content of the charge less than 4% to 5%. The dried material is preheated by a preheating furnace and then heated to a certain temperature in the reduction furnace for water gas reduction.
5. The process for preparing manganese dioxide by a solvothermal method according to claim 1, characterized in that: The filtering steps of the filter net are divided into three layers. The filter net with a pore diameter of 0.5nm is used for initial screening and slag removal, and then the filter net with a pore diameter of 0.25nm is used for secondary filtration and slag removal. Finally, the filter net with a pore diameter of 0.1nm is used for the final step of filtration and slag removal.
6. A solvothermal method for preparing manganese dioxide according to claim 1, characterized in that: The volume ratio of the nitric acid to the sulfuric acid is 1:1, and the ratio used once in the preparation process is a fixed value, for example, 500 ml of nitric acid and 500 ml of sulfuric acid.