Battery-grade chemical manganese dioxide, its preparation method and application

Abstract

The present application relates to a kind of battery-grade chemical manganese dioxide and its preparation method and application, with manganese ore as raw material, the manganese element in manganese ore is converted into the mixed solution of sulfate containing divalent manganese and trivalent manganese, then the mixed solution of sulfate containing divalent manganese and trivalent manganese is mixed with the low-density gamma crystal form chemical manganese dioxide prepared in advance, make trivalent manganese ion occur disproportionation reaction, the manganese dioxide product generated is deposited in the surface and internal pore of the low-density gamma crystal form chemical manganese dioxide, and the battery-grade chemical manganese dioxide is obtained after treatment.Compared with prior art, the present application solves the defects that chemical manganese dioxide (CMD) cannot be applied to battery industry due to low density, and can replace electrolytic manganese dioxide and be applied to the production of zinc-manganese battery.

Description

Technical Field

[0001] This invention relates to the field of battery material processing technology, specifically to a battery-grade chemical manganese dioxide, its preparation method, and its application. Background Technology

[0002] With the rapid development of the battery industry, the demand for manganese oxides is also increasing, and higher requirements are being placed on the quality of manganese oxides. Currently, zinc-manganese batteries and lithium-manganese batteries generally use electrolytic manganese dioxide (EMD) as a raw material, but electrolytic manganese dioxide (EMD) has disadvantages such as high investment, high energy consumption, and long production time.

[0003] Chemical manganese dioxide (CMD) has significant advantages in terms of investment, energy consumption, production time, and electrochemical performance. However, the low density of CMD makes it difficult to apply in the battery industry.

[0004] Therefore, it is urgent to find new synthesis methods or optimize traditional process conditions to improve the density of chemical manganese dioxide (CMD).

[0005] Patent CN1258643A discloses a method for the heavyification of chemically processed manganese dioxide. The method involves placing the primary manganese dioxide to be heavyified in an aqueous solution of manganese sulfate and permanganate for a chemical reaction. The resulting manganese dioxide is deposited on the surface and in the pores of the primary manganese dioxide particles. After filtration, a heavy manganese dioxide product is obtained. The heavy manganese dioxide obtained by this patent has a tap density exceeding 2.0 g / cm³. 3 It can be used not only as general chemical manganese dioxide, but also to meet the production needs of the battery industry. However, the permanganate in this patent will introduce a large amount of sodium or potassium ions, which will not only affect the purity of the product (high-density CMD), but also generate a large amount of industrial waste salt (sodium sulfate or potassium sulfate); moreover, potassium permanganate is expensive. Summary of the Invention

[0006] The purpose of this invention is to provide a battery-grade chemical manganese dioxide, its preparation method, and its application. The prepared battery-grade chemical manganese dioxide has high density and can replace electrolytic manganese dioxide in the production of zinc-manganese batteries.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] This invention provides a method for preparing battery-grade chemical manganese dioxide from manganese ore. Using manganese ore as raw material, the manganese element in the ore is converted into a mixed solution of sulfates containing divalent and trivalent manganese. Subsequently, the mixed solution of sulfates containing divalent and trivalent manganese is reacted with pre-prepared low-density γ-crystalline chemical manganese dioxide, causing a disproportionation reaction of trivalent manganese ions. The resulting manganese dioxide product is deposited on the surface and in the internal pores of the low-density γ-crystalline chemical manganese dioxide. After post-processing, the battery-grade chemical manganese dioxide is obtained.

[0009] Preferably, the manganese ore includes rhodochrosite.

[0010] Preferably, it includes the following steps:

[0011] S1. Crushing and grinding manganese ore to obtain mineral powder;

[0012] S2. Mix the mineral powder obtained in step S1 with pure water and stir evenly to obtain a mineral slurry;

[0013] S3. React the slurry obtained in step S2 with concentrated sulfuric acid in a sealed container, and maintain a certain pressure through a pressure relief valve. After the reaction is completed, add pure water, separate the solid and liquid, and obtain a crude manganese sulfate solution.

[0014] S4. The crude manganese sulfate solution obtained in step S3 and hydrogen peroxide are stirred in a sealed container to obtain a mixed solution. Then, lime milk is added in an anaerobic environment and under stirring to precipitate the iron, aluminum and silicon elements in the solution. After solid-liquid separation, the purified manganese sulfate solution is obtained.

[0015] S5. The purified manganese sulfate solution obtained in step S4 is stirred and reacted with ammonia water. During the reaction, air is continuously introduced as an oxidant and heating is maintained. After the reaction, manganese tetroxide precipitate is obtained by solid-liquid separation. The mother liquor obtained by separation is used for evaporation and crystallization to prepare agricultural grade ammonium sulfate.

[0016] S6. Stir the manganese tetroxide precipitate obtained in step S5 with dilute acid solution. After the reaction is complete, wash with pure water until neutral to remove impurities in manganese tetroxide. After solid-liquid separation, pure manganese tetroxide is obtained.

[0017] S7. The pure manganese tetroxide obtained in step S6 is stirred and reacted with dilute sulfuric acid to obtain a mixed solution of sulfates containing divalent and trivalent manganese.

[0018] S8. Stir the battery-grade manganese sulfate solution and γ-MnO2 seed crystals evenly, introduce ozone to react, and after the reaction is completed, separate the solid and liquid to obtain low-density γ-crystalline chemical manganese dioxide.

[0019] S9. The mixed solution of sulfate containing divalent and trivalent manganese obtained in step S7 is stirred and reacted with the low-density γ-crystalline chemical manganese dioxide obtained in step S8. During the reaction, the mixture is continuously heated to cause the trivalent manganese ions to undergo a disproportionation reaction. After the reaction is completed, solid-liquid separation is performed to obtain high-density γ-crystalline chemical manganese dioxide and battery-grade manganese sulfate solution.

[0020] S10. The high-density γ-crystalline chemical manganese dioxide obtained in step S9 is washed with pure water by vacuum filtration until the conductivity is 90-110 μS / cm, and then dried and ground until the particle size is <45 μm to obtain the battery-grade chemical manganese dioxide.

[0021] S11. 50wt% to 75wt% of the battery-grade manganese sulfate solution obtained in step S9 is recycled back to step S8 to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the remaining 50wt% to 25wt% of the battery-grade manganese sulfate solution is used for evaporation and crystallization to prepare battery-grade manganese sulfate.

[0022] S12. The sulfuric acid-containing mother liquor obtained after evaporation and crystallization in step S11 is recycled back to step S3 for the preparation of crude manganese sulfate solution.

[0023] Preferably, in step S1, the mineral powder has a mesh size of 200 to 300 mesh.

[0024] Preferably, in step S2, the mass ratio of pure water to mineral powder is 1.4 to 1.6:1.

[0025] Preferably, in step S3, the concentrated sulfuric acid has a mass fraction of 98 wt%, the mass ratio of concentrated sulfuric acid to mineral powder is 0.95–1.05:1, the mass ratio of the replenishing pure water to mineral powder is 0.9–1.1:1, the critical pressure of the pressure relief valve is 1.5–2.5 bar, and the reaction time is 30–40 min.

[0026] More preferably, the critical pressure of the pressure relief valve is 2 bar.

[0027] Preferably, in step S4, the mass ratio of hydrogen peroxide to iron in the crude manganese sulfate solution is 1.02 to 1.11:1, the concentration of hydrogen peroxide is 27.5 wt% to 30 wt%, the stirring reaction time is 4 to 10 min, and the pH at which iron, aluminum, and silicon elements form precipitates is 5.0 to 5.2.

[0028] Preferably, in step S4, the oxygen-free environment refers to the process of introducing an inert gas to expel oxygen from the sealed container.

[0029] More preferably, in step S4, the inert gas includes nitrogen.

[0030] Preferably, in step S5, the mass ratio of the ammonia water (calculated as 100% pure ammonia water) to the manganese element in the manganese sulfate purification solution is 1.3 to 1.4:1.

[0031] Preferably, in step S5, the heating temperature is controlled at 75-80°C, and the reaction time is 6.5-8.5 h.

[0032] Preferably, in step S5, the reaction also produces ammonium sulfate, which can act as a catalyst to accelerate the reaction rate.

[0033] Preferably, in step S6, the dilute acid solution is a hydrochloric acid or nitric acid solution with a pH of 1.9 to 2.1, the mass ratio of the dilute acid solution to the manganese tetroxide precipitate is 4-5:1, the reaction time is 70-90 minutes, and the cleaning method includes vacuum filtration washing.

[0034] Preferably, in step S7, the molar ratio of the pure manganese tetroxide to dilute sulfuric acid is 1:4.15-4.25, the concentration of the dilute sulfuric acid is 2.3-2.5 mol / L, and the reaction time is 20-30 min.

[0035] Preferably, in step S8, the battery-grade manganese sulfate solution is a battery-grade manganese sulfate aqueous solution.

[0036] More preferably, in step S8, at the start of the reaction, the battery-grade manganese sulfate solution is prepared by dissolving purchased battery-grade manganese sulfate in pure water, but the purchased battery-grade manganese sulfate is only used once, and is subsequently replaced by the battery-grade manganese sulfate solution provided in step S11.

[0037] More preferably, in step S8, the concentration of the battery-grade manganese sulfate solution prepared from purchased battery-grade manganese sulfate is 2.3 to 2.5 mol / L.

[0038] Preferably, in step S8, the manganese content in the battery-grade manganese sulfate solution is 1 / 3 to 1 / 2 of the manganese content in the mixed solution containing divalent and trivalent manganese sulfates.

[0039] Preferably, in step S8, the amount of γ-MnO2 seed crystals added is 3% to 5% of the mass of manganese sulfate added, and the reaction time is 2 to 2.5 hours.

[0040] Preferably, in step S8, the mass of the introduced ozone is 0.37 to 0.43 times the mass of the added manganese sulfate, and the concentration of the introduced ozone is 100 to 150 mg / L.

[0041] Preferably, in step S9, the amount of the mixed solution of divalent and trivalent manganese sulfate and the low-density γ-crystalline chemical manganese dioxide fed together are calculated based on the total number of moles of manganese contained therein, and the molar ratio is (2-3):1.

[0042] Preferably, in step S9, the heating temperature is 65-70°C and the reaction time is 40-50 min.

[0043] Preferably, in steps S2, S3, S5, S6, S7, S8 and S9, the stirring speed is 600 to 1200 rpm.

[0044] Furthermore, the solid-liquid separation methods in steps S3, S4, S5, S6, S8 and S9 include one or more of centrifugal separation, plate and frame filtration and vacuum filtration.

[0045] Preferably, the battery-grade chemical manganese dioxide obtained in step S10 can be used as γ-MnO2 seed crystals in step S8.

[0046] More preferably, in step S11, 50wt% to 75wt% of the battery-grade manganese sulfate solution obtained in step S9 can be used as the battery-grade manganese sulfate solution for preparing low-density γ-crystalline chemical manganese dioxide in step S8, and the remaining 50wt% to 25wt% of the battery-grade manganese sulfate solution can be used for evaporation crystallization to prepare battery-grade manganese sulfate.

[0047] Preferably, the method for preparing battery-grade chemical manganese dioxide from manganese ore specifically includes the following steps:

[0048] S1. Crush and grind rhodochrosite to obtain mineral powder;

[0049] S2. Mix the mineral powder obtained in step S1 with water and stir evenly to obtain a mineral slurry;

[0050] S3. The slurry obtained in step S2 and 98% concentrated sulfuric acid are stirred and reacted in a closed reaction vessel 1. During the reaction, a certain pressure is maintained through a pressure relief valve. After the reaction is completed, water is added and stirred evenly. Solid-liquid separation is performed to obtain a crude manganese sulfate solution.

[0051] S4. The crude manganese sulfate solution obtained in step S3 and hydrogen peroxide are stirred and reacted in a closed reaction vessel 2. Nitrogen gas is introduced to squeeze out the oxygen in the reaction vessel 2. Lime milk is added in an anaerobic environment and under stirring to precipitate and remove iron, aluminum and silicon elements in the solution. Solid-liquid separation is performed to obtain purified manganese sulfate solution.

[0052] S5. The purified manganese sulfate solution obtained in step S4 and ammonia water are stirred and reacted in reaction vessel 3. Air is continuously introduced during the reaction and heating is maintained. Solid-liquid separation is performed to obtain manganese tetroxide precipitate. The mother liquor is used for evaporation and crystallization to prepare agricultural grade ammonium sulfate.

[0053] S6. The manganese tetroxide obtained in step S5 is stirred and reacted with dilute acid solution in reaction vessel 4. After the reaction is completed, it is washed with pure water until neutral to remove impurities in manganese tetroxide. Solid-liquid separation is performed to obtain pure manganese tetroxide.

[0054] S7. The manganese tetroxide obtained in step S6 is reacted with dilute sulfuric acid in reaction vessel 5 by stirring thoroughly to obtain a mixed solution of divalent manganese and trivalent manganese sulfate.

[0055] S8. The battery-grade manganese sulfate solution and γ-MnO2 seed crystals are thoroughly stirred in the reaction vessel 6, and ozone is introduced to fully react and separate the solid and liquid to obtain low-density γ-crystalline chemical manganese dioxide (CMD).

[0056] S9. The mixed solution of divalent and trivalent manganese sulfate obtained in step S7 and the low-density γ-crystalline chemical manganese dioxide (CMD) obtained in step S8 are stirred and reacted in reactor 5. During the reaction, the mixture is continuously heated and the solid and liquid are separated to obtain high-density γ-crystalline chemical manganese dioxide (CMD) and battery-grade manganese sulfate solution.

[0057] S10. The high-density γ-crystalline chemical manganese dioxide (CMD) obtained in step S9 is washed with pure water by vacuum filtration until the conductivity is 90-110 μS / cm, then dried and ground until the particle size is <45 μm to obtain battery-grade chemical manganese dioxide, which can be used as seed crystals in step S8.

[0058] S11. 50wt% to 75wt% of the battery-grade manganese sulfate solution obtained in step S9 is recycled back to step S8 to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the remaining 50wt% to 25wt% of the battery-grade manganese sulfate solution is used for evaporation and crystallization to prepare battery-grade manganese sulfate.

[0059] S12. Return the sulfuric acid-containing mother liquor obtained in step S11 to step S3 for dissolving manganese ore.

[0060] The present invention also provides a battery-grade chemical manganese dioxide prepared by the method for preparing battery-grade chemical manganese dioxide from the aforementioned manganese ore, wherein the loose bulk density is 1.9–2.2 g / cm³. 3 .

[0061] The present invention also provides an application of the aforementioned battery-grade chemical manganese dioxide in the field of zinc-manganese battery preparation.

[0062] This invention addresses the problem of low density in existing chemical manganese dioxide (CMD) by providing a method for preparing battery-grade chemical manganese dioxide from manganese ore. The method involves generating manganese dioxide through the disproportionation reaction of trivalent manganese ions and depositing the newly generated manganese dioxide onto the surface and pores of low-density chemical manganese dioxide (CMD) particles, thereby increasing its density and preparing a high-density battery-grade chemical manganese dioxide.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] (1) The present invention provides a method for preparing battery-grade chemical manganese dioxide from manganese ore. The manganese dioxide generated by the disproportionation of trivalent manganese ions is deposited on the surface and pores of low-density chemical manganese dioxide (CMD) particles to obtain high-density chemical manganese dioxide (CMD). The high-density chemical manganese dioxide has the various performance indicators of battery-grade manganese dioxide and can replace electrolytic manganese dioxide in the production of zinc-manganese batteries.

[0065] (2) The battery-grade manganese dioxide prepared by this invention meets all the performance indicators of QB / T2629-2021 "Electrolytic Manganese Dioxide for Alkaline Zinc-Manganese Dioxide Batteries", and the highest loose packing density reaches 2.2 g / cm³. 3 It is superior to the standard.

[0066] (3) The present invention provides a method for preparing battery-grade chemical manganese dioxide from manganese ore, which uses air as an oxidant to prepare manganese tetroxide, and then uses sulfuric acid to dissolve manganese tetroxide to prepare trivalent manganese ions. The operating cost is low.

[0067] (4) The present invention uses the selective trivalent manganese ion disproportionation method to prepare high-density chemical manganese dioxide, which does not introduce impurity ions, resulting in high product purity and no industrial waste salt generated.

[0068] (5) The present invention provides a method for preparing battery-grade chemical manganese dioxide from manganese ore. While preparing battery-grade manganese dioxide, battery-grade manganese sulfate and agricultural-grade ammonium sulfate can be produced as by-products, which effectively improves the resource utilization rate and economic benefits of the entire production process.

[0069] (6) The battery-grade manganese sulfate solution obtained as a byproduct in this invention can be efficiently utilized in two parts. One part is recycled for step S8 to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the other part is used for evaporation and crystallization to prepare battery-grade manganese sulfate. The sulfuric acid-containing mother liquor generated after evaporation and crystallization can be further recycled back to step S3 to prepare crude manganese sulfate solution, thereby realizing resource recycling. Attached Figure Description

[0070] Figure 1 This is a process flow diagram of the present invention;

[0071] Figure 2 This is the manganese element material balance diagram of the present invention. Detailed Implementation

[0072] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0073] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0074] This invention provides a method for preparing battery-grade chemical manganese dioxide from manganese ore, such as... Figure 1-2 As shown, this is achieved through the following technical solution:

[0075] (1) Crush and grind rhodochrosite to 200-300 mesh to obtain mineral powder.

[0076] (2) Mix the mineral powder with 1.4 to 1.6 times the weight of the mineral powder in water and stir evenly to obtain a slurry.

[0077] (3) The slurry and 0.95 to 1.05 times the mass of the slurry and 98 wt% concentrated sulfuric acid were stirred in a closed reaction vessel 1 for 30 to 40 minutes. During the reaction, the critical pressure of the pressure relief valve was set to 2 bar. After the reaction was completed, 0.9 to 1.1 times the mass of the slurry and water were added and stirred evenly. The solid and liquid were separated to obtain a crude manganese sulfate solution.

[0078] (4) The above crude manganese sulfate solution and hydrogen peroxide (0.35 to 0.4 times the mass of iron in the crude manganese sulfate solution) are stirred and reacted in a closed reaction vessel 2. Nitrogen gas is introduced to squeeze out the oxygen in the reaction vessel 2. Lime milk is added to the pH 5.0 to 5.2 under anaerobic environment and stirring. Solid-liquid separation is performed to obtain purified manganese sulfate solution.

[0079] (5) The above-mentioned manganese sulfate purification solution and ammonia water with a manganese element mass of 1.3 to 1.4 times that of the manganese sulfate purification solution are stirred in the reaction vessel 3 for 6.5 to 8.5 hours. During the reaction, air is continuously introduced and the temperature is controlled at 75 to 80°C. Solid-liquid separation is performed to obtain manganese tetroxide precipitate. The solution after solid-liquid separation is used for evaporation and crystallization to prepare agricultural grade ammonium sulfate as a by-product.

[0080] (6) The above manganese tetroxide is stirred and reacted with hydrochloric acid or nitric acid solution with pH 1.9 to 2.1 in reaction vessel 4 for 70 to 90 minutes. After the reaction is completed, the manganese tetroxide is washed with pure water until neutral by vacuum filtration to remove impurities in the manganese tetroxide. Solid-liquid separation is performed to obtain pure manganese tetroxide.

[0081] (7) The above-mentioned pure manganese tetroxide and 2.3-2.5 mol / L dilute sulfuric acid are stirred in reaction vessel 5 at a molar ratio of 1:4.15-4.25 for 20-30 min to obtain a mixed solution of divalent and trivalent manganese sulfates.

[0082] (8) Prepare a battery-grade manganese sulfate solution with a manganese content of 1 / 3 to 1 / 2 and a concentration of 2.3 to 2.5 mol / L in the above-mentioned mixed solution of divalent and trivalent manganese sulfates and 3% to 5% γ-MnO2 seed crystals. Stir the solution thoroughly in the reaction vessel 6 and introduce ozone to react for 2 to 2.5 hours. Separate the solid and liquid to obtain low-density γ-crystalline chemical manganese dioxide (CMD).

[0083] (9) The above mixed solution of divalent manganese and trivalent manganese sulfate and the above low-density γ-crystalline chemical manganese dioxide (CMD) are stirred and reacted in reactor 5 for 40-50 min. The temperature is controlled at 65-70℃ during the reaction. Solid-liquid separation is performed to obtain high-density γ-crystalline chemical manganese dioxide (CMD) and battery-grade manganese sulfate solution.

[0084] (10) The above-mentioned high-density γ-crystalline chemical manganese dioxide (CMD) was washed with pure water by vacuum filtration until the conductivity reached 90-110 μS / cm, then dried and ground until the particle size was <45 μm, yielding a loose packing density of 1.9-2.2 g / cm³. 3 Battery-grade chemical manganese dioxide can be used as a seed crystal for recycling in step (8).

[0085] (11) 50 wt% to 75 wt% of the battery-grade manganese sulfate solution obtained in step (9) is recycled back to step (8) to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the remaining 50 wt% to 25 wt% of the battery-grade manganese sulfate solution is used for evaporation and crystallization to prepare battery-grade manganese sulfate.

[0086] (12) The sulfuric acid-containing mother liquor obtained in step (11) is returned to step S3 for dissolving manganese ore.

[0087] Solid-liquid separation methods include one or more of centrifugal separation, plate and frame filtration, and vacuum filtration.

[0088] Example 1

[0089] This embodiment provides a method for preparing battery-grade chemical manganese dioxide from manganese ore. The specific parameter settings in this embodiment are as follows:

[0090] (1) Crush and grind rhodochrosite to 200 mesh to obtain mineral powder.

[0091] (2) Mix the mineral powder with 1.4 times the weight of water and stir evenly to obtain a slurry.

[0092] (3) The slurry and 98% concentrated sulfuric acid of 1.05 times the mass of the slurry were stirred and reacted in a closed reactor 1 for 40 minutes. During the reaction, the critical pressure of the pressure relief valve was set to 2 bar. After the reaction was completed, 1.1 times the mass of the slurry was added and stirred evenly. The crude manganese sulfate solution was obtained by plate and frame filtration.

[0093] (4) The above crude manganese sulfate solution and hydrogen peroxide of 0.35 times the mass of iron in the crude manganese sulfate solution are stirred and reacted in a closed reaction vessel 2. Nitrogen gas is introduced to squeeze out the oxygen in the reaction vessel 2. Lime milk is added to pH 5.2 under anaerobic environment and stirring. After plate and frame filtration, purified manganese sulfate solution is obtained.

[0094] (5) The above purified manganese sulfate solution and ammonia water with a manganese element mass of 1.3 times that of the purified manganese sulfate solution were stirred and reacted in reactor 3 for 6.5 h. During the reaction, air was continuously introduced and the temperature was controlled at 80 °C. After plate and frame filtration, manganese tetroxide precipitate was obtained. The solution after plate and frame filtration was used for evaporation and crystallization to prepare agricultural grade ammonium sulfate as a by-product.

[0095] (6) The above manganese tetroxide and hydrochloric acid solution with pH 1.9 were stirred and reacted in reaction vessel 4 for 90 min. After the reaction was completed, the manganese tetroxide was washed with pure water until neutral by vacuum filtration to remove impurities. Pure manganese tetroxide was obtained by plate and frame filtration.

[0096] (7) The above-mentioned pure manganese tetroxide and 2.3 mol / L dilute sulfuric acid were stirred in reaction vessel 5 at a molar ratio of 1:4.25 for 30 min to obtain a mixed solution of divalent manganese and trivalent manganese sulfate.

[0097] (8) Prepare a battery-grade manganese sulfate solution with a manganese content of 1 / 3 and a concentration of 2.3 mol / L in the above-mentioned mixed solution of divalent and trivalent manganese sulfates and 3% γ-MnO2 seed crystals. Stir the solution thoroughly in the reaction vessel 6 and introduce ozone to react for 2 hours. After plate and frame filtration, obtain low-density γ-crystalline chemical manganese dioxide (CMD).

[0098] (9) The above mixed solution of divalent manganese and trivalent manganese sulfate and the above low-density γ-crystalline chemical manganese dioxide (CMD) were stirred and reacted in reactor 5 for 40 min. The temperature was controlled at 70℃ during the reaction. After plate and frame filtration, high-density γ-crystalline chemical manganese dioxide (CMD) and battery-grade manganese sulfate solution were obtained.

[0099] (10) The above-mentioned high-density γ-crystalline chemical manganese dioxide (CMD) was washed with pure water by vacuum filtration until the conductivity reached 90 μS / cm, then dried and ground until the particle size was <45 μm, yielding a loose packing density of 2.2 g / cm³.3 Battery-grade chemical manganese dioxide can be used as a seed crystal for recycling in step (8).

[0100] (11) 50 wt% of the battery-grade manganese sulfate solution obtained in step (9) is recycled back to step (8) to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the remaining 50 wt% of the battery-grade manganese sulfate solution is used for evaporation and crystallization to prepare battery-grade manganese sulfate.

[0101] (12) Return the sulfuric acid-containing mother liquor obtained in step (11) to step (3) for dissolving manganese ore.

[0102] The test results of the final product, battery-grade chemical manganese dioxide, are shown in Table 1.

[0103] Table 1. Detection results of battery-grade chemical manganese dioxide in Example 1.

[0104]

[0105]

[0106] The final product, battery-grade chemical manganese dioxide, meets all performance indicators of QB / T2629-2021 "Electrolytic Manganese Dioxide for Alkaline Zinc-Manganese Dioxide Batteries", and can replace electrolytic manganese dioxide in the production of zinc-manganese batteries.

[0107] Example 2

[0108] This embodiment provides a method for preparing battery-grade chemical manganese dioxide from manganese ore. The specific parameter settings in this embodiment are as follows:

[0109] (1) Crush and grind rhodochrosite to 300 mesh to obtain mineral powder.

[0110] (2) Mix the mineral powder with 1.6 times the weight of the mineral powder and water, and stir evenly to obtain a slurry.

[0111] (3) The slurry and 0.95 times the mass of 98% concentrated sulfuric acid were stirred and reacted in a closed reactor 1 for 30 minutes. During the reaction, the critical pressure of the pressure relief valve was set to 2 bar. After the reaction was completed, 0.9 times the mass of water was added and stirred evenly. After centrifugation, a crude manganese sulfate solution was obtained.

[0112] (4) The above crude manganese sulfate solution and hydrogen peroxide with the same mass of iron in 0.4 times the crude manganese sulfate solution were stirred and reacted in a closed reaction vessel 2. Nitrogen gas was introduced to squeeze out the oxygen in the reaction vessel 2. Lime milk was added to pH 5.0 under anaerobic environment and stirring. After centrifugation, a purified manganese sulfate solution was obtained.

[0113] (5) The above manganese sulfate purification solution and ammonia water with a manganese element mass of 1.4 times the manganese sulfate purification solution were stirred and reacted in reactor 3 for 8.5 hours. During the reaction, air was continuously introduced and the temperature was controlled at 75°C. After centrifugation, manganese tetroxide precipitate was obtained. The solution after centrifugation was used for evaporation and crystallization to prepare agricultural grade ammonium sulfate as a by-product.

[0114] (6) The above manganese tetroxide and nitric acid solution with pH 2.1 were stirred and reacted in reaction vessel 4 for 70 min. After the reaction was completed, the manganese tetroxide was washed with pure water until neutral by vacuum filtration to remove impurities. After centrifugation, pure manganese tetroxide was obtained.

[0115] (7) The above-mentioned pure manganese tetroxide and 2.5 mol / L dilute sulfuric acid were stirred in reaction vessel 5 at a molar ratio of 1:4.15 for 20 min to obtain a mixed solution of divalent manganese and trivalent manganese sulfate.

[0116] (8) Prepare a manganese sulfate solution with a manganese content of 1 / 2 and a concentration of 2.5 mol / L and 5% γ-MnO2 seed crystals in the above-mentioned mixed solution of divalent manganese and trivalent manganese sulfate. Stir the solution thoroughly in the reaction vessel 6 and introduce ozone to react for 2.5 h. After centrifugation, obtain low-density γ-crystalline chemical manganese dioxide (CMD).

[0117] (9) The above mixed solution of divalent manganese and trivalent manganese sulfate and the above low-density γ-crystalline chemical manganese dioxide (CMD) were stirred and reacted in the reaction vessel 5 for 50 min. The temperature was controlled at 65℃ during the reaction. After centrifugation, high-density γ-crystalline chemical manganese dioxide (CMD) and battery-grade manganese sulfate solution were obtained.

[0118] (10) The above-mentioned high-density γ-crystalline chemical manganese dioxide (CMD) was washed with pure water by vacuum filtration until the conductivity reached 110 μS / cm, then dried and ground until the particle size was <45 μm, yielding a loose packing density of 1.9 g / cm³. 3 Battery-grade chemical manganese dioxide can be used as a seed crystal for recycling in step (8).

[0119] (11) 75 wt% of the battery-grade manganese sulfate solution obtained in step (9) is recycled back to step (8) to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the remaining 25 wt% of the battery-grade manganese sulfate solution is used for evaporation and crystallization to prepare battery-grade manganese sulfate.

[0120] (12) Return the sulfuric acid-containing mother liquor obtained in step (11) to step (3) for dissolving manganese ore.

[0121] The test results of the final product, battery-grade chemical manganese dioxide, are shown in Table 2 below.

[0122] Table 2 shows the detection results of battery-grade chemical manganese dioxide in Example 1.

[0123]

[0124]

[0125] The final product, battery-grade chemical manganese dioxide, meets all performance indicators of QB / T2629-2021 "Electrolytic Manganese Dioxide for Alkaline Zinc-Manganese Dioxide Batteries", and can replace electrolytic manganese dioxide in the production of zinc-manganese batteries.

[0126] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing battery-grade chemical manganese dioxide from manganese ore, characterized in that, Using manganese ore as raw material, the manganese element in the manganese ore is converted into a mixed solution of sulfates containing divalent and trivalent manganese. Then, the mixed solution of sulfates containing divalent and trivalent manganese is mixed and reacted with a pre-prepared low-density γ-crystalline chemical manganese dioxide, causing the trivalent manganese ions to undergo a disproportionation reaction. The resulting manganese dioxide product is deposited on the surface and internal pores of the low-density γ-crystalline chemical manganese dioxide. After post-processing, the battery-grade chemical manganese dioxide is obtained. The preparation method includes the following steps: S1. Crushing and grinding manganese ore to obtain mineral powder; S2. Mix the mineral powder obtained in step S1 with pure water and stir evenly to obtain a mineral slurry; S3. React the slurry obtained in step S2 with concentrated sulfuric acid in a sealed container, and maintain a certain pressure through a pressure relief valve. After the reaction is completed, add pure water, separate the solid and liquid, and obtain a crude manganese sulfate solution. S4. The crude manganese sulfate solution obtained in step S3 and hydrogen peroxide are stirred in a sealed container to obtain a mixed solution. Then, lime milk is added in an anaerobic environment and under stirring to precipitate the iron, aluminum and silicon elements in the solution. After solid-liquid separation, the purified manganese sulfate solution is obtained. S5. The purified manganese sulfate solution obtained in step S4 is stirred and reacted with ammonia water. During the reaction, air is continuously introduced as an oxidant and heating is maintained. After the reaction, manganese tetroxide precipitate is obtained by solid-liquid separation. The mother liquor obtained by separation is used for evaporation and crystallization to prepare agricultural grade ammonium sulfate. S6. Stir the manganese tetroxide precipitate obtained in step S5 with dilute acid solution. After the reaction is complete, wash with pure water until neutral to remove impurities in manganese tetroxide. After solid-liquid separation, pure manganese tetroxide is obtained. S7. The pure manganese tetroxide obtained in step S6 is stirred and reacted with dilute sulfuric acid to obtain a mixed solution of sulfates containing divalent and trivalent manganese. S8. Stir the battery-grade manganese sulfate solution and γ-MnO2 seed crystals evenly, introduce ozone to react, and after the reaction is completed, separate the solid and liquid to obtain low-density γ-crystalline chemical manganese dioxide. S9. The mixed solution of sulfate containing divalent and trivalent manganese obtained in step S7 is stirred and reacted with the low-density γ-crystalline chemical manganese dioxide obtained in step S8. During the reaction, the mixture is continuously heated to cause the trivalent manganese ions to undergo a disproportionation reaction. After the reaction is completed, solid-liquid separation is performed to obtain high-density γ-crystalline chemical manganese dioxide and battery-grade manganese sulfate solution. S10. The high-density γ-crystalline chemical manganese dioxide obtained in step S9 is washed with pure water by vacuum filtration until the conductivity is 90~110us / cm, and then dried and ground until the particle size is <45um to obtain the battery-grade chemical manganese dioxide. S11. 50% to 75% of the battery-grade manganese sulfate solution obtained in step S9 is recycled back to step S8 to prepare low-density γ-crystalline chemical manganese dioxide (CMD), and the remaining 50% to 25% of the battery-grade manganese sulfate solution is used for evaporation and crystallization to prepare battery-grade manganese sulfate. S12. The sulfuric acid-containing mother liquor obtained after evaporation and crystallization in step S11 is recycled back to step S3 for the preparation of crude manganese sulfate solution.

2. The method for preparing battery-grade chemical manganese dioxide from manganese ore according to claim 1, characterized in that, In step S1, the mineral powder has a mesh size of 200-300 mesh; in step S2, the mass ratio of pure water to mineral powder is 1.4-1.6:1; in step S3, the concentrated sulfuric acid has a mass fraction of 98 wt%, the mass ratio of concentrated sulfuric acid to mineral powder is 0.95-1.05:1, the mass ratio of the replenishing pure water to mineral powder is 0.9-1.1:1, the critical pressure of the pressure relief valve is 1.5-2.5 bar, and the reaction time is 30-40 min.

3. The method for preparing battery-grade chemical manganese dioxide from manganese ore according to claim 1, characterized in that, In step S4, the mass ratio of hydrogen peroxide to iron in the crude manganese sulfate solution is 1.02~1.11:1, the concentration of hydrogen peroxide is 27.5wt%~30wt%, the stirring reaction time is 4-10 min, and the pH for the precipitation of iron, aluminum, and silicon is 5.0~5.2; in step S5, the mass ratio of ammonia to manganese in the purified manganese sulfate solution is 1.3~1.4:1, the heating temperature is controlled at 75~80℃, and the reaction time is 6.5~8.5 h.

4. The method for preparing battery-grade chemical manganese dioxide from manganese ore according to claim 1, characterized in that, In step S6, the dilute acid solution is a hydrochloric acid or nitric acid solution with a pH of 1.9-2.1, the mass ratio of the dilute acid solution to the manganese tetroxide precipitate is 4-5:1, the reaction time is 70-90 min, and the washing method includes vacuum filtration washing; in step S7, the molar ratio of the pure manganese tetroxide to dilute sulfuric acid is 1:4.15-4.25, the concentration of the dilute sulfuric acid is 2.3-2.5 mol / L, and the reaction time is 20-30 min.

5. The method for preparing battery-grade chemical manganese dioxide from manganese ore according to claim 1, characterized in that, In step S8, the concentration of the battery-grade manganese sulfate solution is 2.3~2.5 mol / L, the amount of γ-MnO2 seed crystals added is 3%~5% of the mass of the added manganese sulfate, the reaction time is 2~2.5 h, the mass of ozone introduced is 0.37~0.43 times the mass of the added manganese sulfate, and the concentration of the introduced ozone is 100~150 mg / L.

6. The method for preparing battery-grade chemical manganese dioxide from manganese ore according to claim 1, characterized in that, In step S9, the amount of the mixed solution of divalent and trivalent manganese sulfate and the low-density γ-crystalline chemical manganese dioxide fed together are calculated based on the total number of moles of manganese contained therein, and the molar ratio is (2~3):

1. The heating temperature is 65~70℃ and the reaction time is 40~50min.

7. The method for preparing battery-grade chemical manganese dioxide from manganese ore according to claim 1, characterized in that, The battery-grade chemical manganese dioxide obtained in step S10 can be used as γ-MnO2 seed crystals in step S8.

8. A method for preparing battery-grade chemical manganese dioxide from manganese ore according to any one of claims 1 to 7, characterized in that, Its loose bulk density is 1.9~2.2 g / cm³. 3 .

9. The application of battery-grade chemical manganese dioxide prepared by the method for preparing battery-grade chemical manganese dioxide from manganese ore according to any one of claims 1 to 7 in the field of zinc-manganese battery preparation.

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