A method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide.

Abstract

This invention discloses a method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide. The method uses SO2-containing flue gas from metal smelting or SO2 gas from sulfuric acid production as a reducing agent. After absorption, the exhaust gas concentration can be as low as 30 mg / m³. 3 Within this range, the manganese leaching rate can reach over 98%. This process technology easily achieves a comprehensive manganese recovery rate of over 95% and produces two high-value products: high-purity MnSO4 and battery-grade MnO2. A high-temperature oxidation process is used to decompose and remove S2O6 in the same reactor. 2‑ Manganese sulfate solution was obtained and high-quality MnO2 product suitable for batteries was produced. High-temperature crystallization was carried out using a rate-controlled crystallization method, which steadily increased the purification rate of impurity ions such as magnesium, calcium, potassium, and sodium from 70-80% to over 90% in the first crystallization separation, achieving the goal of obtaining battery-grade high-purity manganese sulfate product in just two recrystallizations.

Description

Technical Field

[0001] This invention relates to the field of manganese dioxide technology for batteries, specifically to a method for preparing high-purity manganese sulfate by reducing manganese oxide ore with sulfur dioxide and co-producing manganese dioxide for batteries. Background Technology

[0002] With the development of new energy power technology, the application of battery energy storage and power has been deeply integrated into our daily lives. The mainstream products on the market are mainly ternary lithium batteries, lithium manganese iron phosphate batteries, lithium manganese oxide batteries, zinc manganese batteries, etc. These batteries all require high-purity manganese products as raw materials.

[0003] Currently, the main raw material mineral for producing high-purity manganese-based products is manganese oxide ore (pyrolusite). Manganese oxide ore (pyrolusite) can be used to produce high-purity manganese sulfate monohydrate, manganese tetroxide, manganese carbonate, manganese dioxide and other battery-grade manganese-based products using two main types of processes: pyrometallurgical carbon reduction and wet reduction. Currently, over 95% of the market share for high-purity manganese sulfate monohydrate, battery-grade manganese tetroxide, electrolytic manganese dioxide, and high-purity manganese carbonate products is produced using pyrometallurgical carbon reduction, the two-ore acid leaching method, and the rhodochrosite acid leaching / electrolytic manganese flake method. The pyrometallurgical carbon reduction method requires large quantities of carbon-based raw materials such as coal, and the escape of fugitive dust during production is difficult to control effectively. The two-ore acid leaching method requires large quantities of pyrite and sulfuric acid, and the successful production of battery-grade manganese products depends heavily on the impurity content of the pyrite, requiring stringent impurity control of both manganese ore and pyrite powder. The rhodochrosite acid leaching / electrolytic manganese flake method suffers from a scarcity of high-quality raw materials, difficult resource sourcing, a long electrolytic process, high production costs, and large investment. The SO2 wet reduction process for manganese oxide ore is simplified, does not use carbon-based reducing agents, and is a truly low-carbon process. It boasts extremely high leaching rates, rapid reactions, short processes, low energy consumption, high production efficiency, and low capital and land investment, making it a highly promising process.

[0004] CN108165742A mentions a method for reducing the manganese dithionite content in pyrolusite leaching solutions. This method involves independently adjusting the pH in separate reaction tanks. In one tank with pH > 5, sulfur dioxide is absorbed for reductive leaching. Then, in another tank, the pH is adjusted to 2-3 to allow MnS₂O₆ to react with H₂SO₄ to form MnSO₄ and H₂S₂O₆. It is assumed that H₂S₂O₆ itself undergoes a disproportionation decomposition reaction to produce H₂SO₄ and SO₂. The introduction of oxygen or the addition of hydrogen peroxide is intended to oxidize SO₂ to sulfuric acid in the solution. According to this technical solution, the MnS₂O₆ content in the leaching solution can be reduced by 50%-65% from 0.03 mol / L. However, the treated solution still retains more than 1.68 g / L of MnS₂O₆, indicating a low impurity removal efficiency. This falls short of the process specifications required for the industrial-scale production of high-purity manganese products.

[0005] CN104477999B proposes a method for producing manganese sulfate by absorbing sulfur dioxide from flue gas using a composite slurry. The method involves mixing manganese oxide powder (a desulfurizing agent) and pyrite powder (an accelerator) to prepare a composite absorption slurry. The low-valence sulfur in the pyrite powder forms a more reducing compound with the sulfur dioxide and sulfites dissolved in the absorption reaction system, inhibiting the oxidation of sulfur dioxide and sulfites by oxygen to form sulfuric acid, thus suppressing the formation of manganese dithionite and stabilizing the pH of the absorption reaction system at an acidic level above 2.0. This technical solution can control the formation of manganese dithionite to between 3 and 5 g / L, but it still fails to completely and efficiently remove manganese dithionite. This remaining manganese dithionite impurity will adversely affect the service life of equipment and product quality in subsequent processes.

[0006] CN102634819B discloses a method for producing electrolytic manganese by leaching manganese oxide with sulfur dioxide. The method involves simultaneously feeding manganese oxide slurry, sulfur dioxide gas, and ozone into an absorption leaching reactor, allowing the gas-liquid-solid three-phase contact to carry out the absorption leaching reaction. Ozone is used to oxidize manganese disulfide to manganese sulfate and sulfuric acid. After the absorption leaching reaction is completed, the slurry is discharged into a purification reactor where ozone is continuously introduced and the pH is increased to between 5.0 and 5.5 for deoxidation, hydrolysis, precipitation, and removal of iron and aluminum. Ozone is then used to oxidize manganese (Mn). 2+ The method involves the adsorption and removal of heavy metals by fine and porous Mn3O4. However, ozone is introduced into the reduction leaching system, which is costly to purchase or prepare and will inevitably partially oxidize SO2 and sulfurous acid in the reduction leaching system, thus affecting the consumption of reducing agent.

[0007] CN107445209B discloses a method for removing manganese dithionite from pyrolusite slurry to prepare saturated manganese sulfate slurry and manganese sulfate. The method involves heating a mixture of manganese sulfate and manganese dithionite, evaporating and concentrating it to a saturated solution with crystal precipitation, then adding sulfuric acid to ensure the H2SO4 content in the evaporated solution is not less than 1 mol / L. Under high acid and high temperature (not less than 90°C), the manganese dithionite is decomposed into manganese sulfate and sulfur dioxide. The saturated manganese sulfate slurry, after removing the manganese dithionite, undergoes solid-liquid separation to obtain manganese sulfate crystals and a manganese sulfate solution with high acid content. This technical solution uses a high-concentration strong acid to decompose manganese dithionite at not less than 90°C. The evaporated vapor contains a large amount of SO2 gas, which condenses with the vapor to form sulfurous acid. The corrosiveness of both SO2 gas and sulfurous acid in the entire production unit presents a significant industrialization challenge.

[0008] In summary, manganese oxide ore (pyrolusite) can be processed into high-purity manganese products such as manganese sulfate monohydrate, manganese tetroxide, and manganese carbonate using two main types of processes: pyrometallurgical carbon reduction and wet reduction. While research on the SO2 wet reduction process for manganese oxide ore has been reported for decades, large-scale production applications are still lacking both domestically and internationally. Currently, over 95% of the market share for high-purity manganese sulfate monohydrate and battery-grade manganese tetroxide is produced using pyrometallurgical carbon reduction, the two-ore acid addition method, and the rhodochrosite acid leaching / electrolytic manganese flake method. As recognized by industry researchers, the core challenge for large-scale application of the SO2 wet reduction method for manganese oxide ore lies in efficiently and cost-effectively addressing the impact of dithionite generated during SO2 reduction leaching on subsequent processes and product quality. Furthermore, breakthroughs in impurity removal technology are needed for low-grade, high-impurity manganese ore raw materials. Summary of the Invention

[0009] To overcome the current challenges of efficient and low-cost solutions for the dithionite generated during SO2 reduction leaching in manganese oxide ore processes, which hinders the large-scale production and application of this technology, this invention provides a method for preparing high-purity manganese sulfate and co-producing battery-grade manganese dioxide from manganese oxide ore using sulfur dioxide reduction. This method boasts strong economic competitiveness and is low-carbon, environmentally friendly, and resource-saving. The technical solution of this invention uses SO2 wet reduction of pyrolusite ore to prepare high-purity manganese sulfate and co-produce battery-grade MnO2 without employing carbon-based reducing agents, making it a truly low-carbon process. This invention is forward-looking and developmental for the domestic manganese product industry's foothold and competitiveness within the sector.

[0010] The present invention discloses a method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide. The technical principle of the method is as follows:

[0011] A method for preparing high-purity MnSO4 from manganese oxide ore using SO2 and co-producing MnO2 for batteries, the principle of which is as follows:

[0012] (1) After grinding the oxidized manganese ore into fine powder of less than 100 mesh, it is mixed with a solvent in a certain proportion to form a slurry to obtain a mineral powder slurry. The solvent here can be tap water, pure water or manganese-containing process water produced in the workshop.

[0013] (2) The mineral powder slurry and SO2 gas are fed into the absorption reaction tower. The gas and manganese ore slurry come into countercurrent contact in the absorption reaction tower and undergo a redox reaction. The higher manganese oxides in the manganese oxide ore are reduced to Mn. 2+ When SO2 enters the solution, it is absorbed and oxidized to form SO4. 2- and some byproducts S2O6 2- ;

[0014] (3) After the reaction is complete, transfer the slurry to a hydrolysis sedimentation tank, and add acid-consuming agents to adjust the pH to 4.0–6.5 to make Fe... 3+ AL 3+ Hydrolysis and precipitation are performed, and then the slurry after the hydrolysis and precipitation reaction is completed is sent to a filter press for filtration to obtain filter residue and filtrate;

[0015] (4) Transfer the filtrate into a sealed container and introduce SO2 gas into the sealed container so that the filtrate absorbs SO2 to generate sulfurous acid. When the pH of the solution drops to 0.5-2.5, stop introducing SO2. Then add an appropriate amount of manganese powder to adjust the pH to 6.0-7.0 and maintain the pressure in the sealed container between 0.05-0.35 MPa. After reacting for a certain period of time, filter to obtain the impurity-free residue and the impurity-free filtrate.

[0016] (5) The purified filtrate is fed into a reaction vessel for preparing MnO2 for batteries. After adding an oxidant, the mixture is stirred and heated to 90℃~160℃ for a certain period of time. The filtrate is then discharged for solid-liquid separation. When the reaction temperature is below 100℃, S2O6-free solution is obtained. 2- The crude MnO2 powder was prepared by washing the crude MnO2 powder with pure water to remove trace amounts of soluble salts such as manganese sulfate, followed by solid-liquid separation to obtain refined MnO2 powder. When the reaction temperature was between 110℃ and 160℃, S2O6-free powder was obtained. 2- The crude powder of a mixture of MnO2 and MnSO4·H2O, containing impurities, was prepared by dissolving the MnSO4·H2O crystals and other soluble salts in pure water, followed by solid-liquid separation to obtain a product free of S2O6. 2- The impurities are manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder is washed with pure water to remove trace amounts of soluble salts such as manganese sulfate, and then solid-liquid separation is performed again to obtain refined MnO2 powder. The obtained refined MnO2 powder is dried to obtain a battery-grade MnO2 product with extremely high purity.

[0017] (6) No S2O6 2- The manganese sulfate solution containing impurities is used as the feed solution for recrystallization to obtain high-purity manganese sulfate. It is fed into a high-temperature crystallization kettle and heated to crystallize at 140℃~200℃ 2~3 times. After solid-liquid separation and drying, the manganese sulfate monohydrate product for batteries can be obtained.

[0018] The objective of this invention is achieved through the following technical solution:

[0019] A method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide includes the following steps:

[0020] S1. Grind oxidized manganese ore into fine manganese ore powder of 100-500 mesh, and mix the fine manganese ore powder with a solvent at a mass ratio of 1:2.5-10 to prepare a mineral powder slurry. The solvent is one or more of tap water, pure water or manganese-containing process water produced in the workshop.

[0021] S2. The mineral powder slurry and SO2 gas are uniformly and continuously fed into the absorption reaction tower at a Mn:SO2 molar ratio of 1:1.10 to 1.50. Within a reaction temperature range of 30℃ to 90℃, the SO2 gas and mineral powder slurry undergo countercurrent contact absorption and redox reaction in the absorption reaction tower, reducing higher-order manganese oxides in the manganese oxide ore to Mn. 2+ When SO2 enters the solution, it is absorbed and oxidized to form SO4. 2- and byproduct S2O6 2- After the reaction is complete, a reduced leachate is obtained and output uniformly and continuously.

[0022] S3. Place the reduced leaching slurry from the previous step into a hydrolysis sedimentation tank. Add an acid-consuming agent to the hydrolysis sedimentation tank to adjust the pH value to 4.0–6.5, so that the Fe in the reduced leaching slurry… 3+ AL 3+ Hydrolysis and precipitation are performed, and then the slurry after the hydrolysis and precipitation reaction is completed is sent to a filter press for filtration to obtain filter residue and liquid after iron and aluminum removal.

[0023] S4. Place the iron-aluminum-removed liquid in a sealed container for impurity removal. Introduce SO2 gas into the sealed container; the water in the solution absorbs the SO2 to form sulfurous acid, thus making the iron-aluminum-removed liquid contain SO3. - When the pH of the solution drops to 0.5-2.5, stop the flow of SO2. Then add 2.0-5.0 times the molar amount of manganese powder equivalent to the sum of the heavy metal ions in the solution to adjust the pH to 6.0-7.0. Maintain the pressure in the sealed container at 0.05MPa-0.35MPa. After reacting for 2-5 hours, calcium ions and various heavy metal impurities are precipitated and removed. Filter by pressure to obtain the impurity-removed residue and the impurity-removed filtrate.

[0024] S5. After removing impurities, the filtrate is sent into the oxidation synthesis reactor. After adding the oxidant, the mixture is stirred and heated to 90℃~160℃ for 2h~24h. The slurry is then discharged for solid-liquid separation.

[0025] When the reaction temperature is below 100℃, manganese sulfate fails to crystallize or crystallizes in very small amounts, resulting in a product without S2O6. 2- The impurities were a manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder was washed with pure water to remove trace amounts of manganese sulfate soluble salts, and then solid-liquid separation was performed again to obtain refined MnO2 powder.

[0026] When the reaction temperature is between 110℃ and 160℃, manganese sulfate crystals precipitate out, and the higher the temperature, the greater the amount of precipitation, resulting in the formation of S2O6-free products. 2- The mother liquor of the dilute manganese sulfate solution containing impurities, and the crude mixed powder of (MnO2 and MnSO4·H2O), were used to dissolve the soluble salts of MnSO4·H2O crystals in pure water. Solid-liquid separation was then performed again to obtain S2O6-free powder. 2- The impurities are manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder is washed with pure water to remove trace amounts of manganese sulfate soluble salts. Then, solid-liquid separation is performed again to obtain refined MnO2 powder. The obtained refined MnO2 powder is dried to obtain a battery-grade MnO2 product with extremely high purity.

[0027] S6. Obtain the S2O6-free solution from S5. 2- The manganese sulfate solution containing impurities is fed into a high-temperature crystallization reactor. If no S2O6 is present... 2- If the concentration of the impurity manganese sulfate solution is below 30 Baume degrees, it needs to be evaporated and concentrated to a concentration between 30 and 40 Baume degrees first. Then, it needs to be heated to 140°C to 200°C for high-temperature recrystallization twice. After solid-liquid separation and drying, the battery-grade manganese sulfate monohydrate product can be obtained, with a manganese leaching rate ≥98% and an exhaust gas concentration <30 mg / m³ after absorption. 3 .

[0028] The technical solution of this invention is achieved through the following process steps:

[0029] Furthermore, the SO2 gas mentioned in step S2 is a gas composed of SO2 volume fraction of 0.1% to 100% and other components volume fraction of 99.9% to 0%. The amount of SO2 volume fraction in the gas will not affect the target of 98% manganese leaching rate of manganese oxide ore in this technical solution. It is only necessary to configure a sufficient number of absorption reaction tower devices to ensure that SO2 is completely absorbed and that the Mn:SO2 molar ratio of the two reactants can react at a ratio of 1:1.10 to 1.50. The other components refer to one or more of the gases commonly found in the atmospheric environment, such as air, nitrogen, and carbon dioxide, which are not particularly toxic or flammable and explosive, in any proportion. However, it should be emphasized that if the oxygen volume content in the combined gas is too high, it will increase the proportion of SO2 oxidized to sulfuric acid in the absorption reaction tower, resulting in a gradual decrease in the pH value of the slurry.

[0030] Furthermore, in step S2, the SO2 gas and mineral powder slurry are absorbed in a countercurrent contact in the absorption reaction tower, undergoing a redox reaction. During the reaction, manganese monoxide powder is added to maintain the pH value of the slurry system. The amount of manganese monoxide powder added is sufficient to maintain the pH value of the slurry system between 2.5 and 4.0. A pH value between 2.5 and 4.0 is more conducive to the absorption reaction of SO2 and the production of a certain amount of MnS2O6 as a byproduct, thereby increasing the yield ratio of MnO2 obtained subsequently. The SO2 gas inlet flow rate is such that the gas phase velocity in the tower is between 0.1 and 5.0 m / s, and the SO2 content in the exhaust gas discharged from the tower is less than 30 mg / m³. 3 The method of control is used to ensure that the SO2 content in the exhaust gas is far below the limit of 400 mg / m³ in the "GB31573-2015 Emission Standard for Pollutants from Inorganic Chemical Industry". 3 The requirements; the main reaction principles involved are:

[0031] SO2 + H2O → H2SO3

[0032] MnO2 + H2SO3 → MnSO4 + H2O

[0033] MnO₂ + 2H₂SO₃ → MnS₂O₆ + 2H₂O

[0034] Furthermore, the temperature of the hydrolysis precipitation reaction in step S3 is 50℃~100℃, preferably 80℃~100℃; the acid-consuming agent can be one or more of calcium carbonate, metallic manganese powder, manganese carbonate, and manganese monoxide in any proportion, but considering the cost of raw materials, calcium carbonate is preferred as the acid-consuming agent, and the amount of acid-consuming agent added is based on the pH value of the reduced leaching slurry rising to 4.0~6.5.

[0035] Furthermore, the impurity removal reaction temperature in step S4 is between 30 and 100°C, preferably between 50 and 90°C. Using a sealed container as the reaction vessel can prevent oxygen from the outside air from entering the reaction vessel and affecting the SO3 generated after SO2 absorption. 2-Oxidation damage is carried out, thereby affecting the formation of sulfite-sulfate complex insoluble precipitates by reacting sulfite ions with CaSO4 and MnSO4 in the solution. These sulfite-sulfate complex insoluble precipitates are formed under near-neutral and weakly alkaline conditions. This technical solution uses 2.0–5.0 times the molar amount of manganese powder (based on the sum of the heavy metal ion contents in the solution) to adjust the pH to 6.0–7.0, promoting the formation and removal of the sulfite-sulfate complex insoluble precipitates while simultaneously displacing and removing various heavy metal impurities. The addition of manganese powder generates hydrogen gas, increasing the pressure inside the sealed container. The pressure is controlled at 0.05–0.35 MPa via a valve, increasing the total pressure inside the container and promoting the dissolution of SO2 in the upper gas phase into the slurry to participate in the formation of the sulfite-sulfate complex insoluble precipitate. We found that under a certain reaction pressure, the sulfite-sulfate complex insoluble precipitate formed has a larger crystal size and more stable properties, which can remove CaSO4 and MnSO4. 2+ The concentration of calcium ions was rapidly reduced to below 250 mg / L, effectively removing them and significantly reducing the pressure on calcium impurity separation and purification during subsequent high-temperature crystallization. Furthermore, the introduction of SO2 gas to generate a certain amount of sulfurous acid in the solution effectively removes the manganese oxide layer on the surface of the manganese powder, exposing the manganese elemental lattice. This greatly increases the probability of heavy metal impurities such as nickel, cobalt, zinc, copper, cadmium, and lead contacting and undergoing a displacement reaction with the manganese elemental lattice. Simultaneously, the oxidizing substances in the reaction solution are reduced, creating a low-potential reducing atmosphere, which facilitates the displacement reaction between heavy metal ions and manganese to generate stable heavy metal elemental particles. This technology overcomes the shortcomings of existing technologies, such as low efficiency, excessive consumption of equivalents, and incomplete removal of impurities by manganese powder. The main relevant reaction equations are as follows:

[0036]

[0037] 2H + +Mn→Mn 2+ +H2↑

[0038] M 2+ +Mn→Mn 2+ +M (where M represents heavy metal elements such as Ni, Co, Zn, Cu, Cd, and Pb)

[0039] Furthermore, the oxidant mentioned in step S5 is one or more of pure oxygen and compressed air, and the amount of oxidant added is based on the molar content of O2 in the gas and the amount of S2O6 in the liquid after weight removal. 2-The molar ratio is 1–10. Manganese dithionate is oxidized to MnO2 and H2SO4 under heating (90–160°C) using the oxidizing properties of oxygen. Because MnO2 is generated in an acidic solution environment, the resulting MnO2 crystals have extremely low impurity content and a high degree of oxygen vacancies, making them excellent as a battery cathode material. The relevant reaction principle is as follows:

[0040]

[0041] Furthermore, the high-temperature recrystallization described in step S6 employs rate-controlled crystallization technology. This technology is based on the fundamental relationship between the solubility of manganese sulfate and temperature, and through extensive experimental research, optimal crystallization process parameters have been obtained that facilitate the separation and purification of impurity ions and the acquisition of uniform crystal particle size. Extensive experimental verification has shown that controlling the heating rate of the manganese sulfate solution during crystallization maintains a supersaturation level conducive to the separation and purification of impurity ions and the acquisition of uniform crystal particle size. The operation method of the rate-controlled crystallization process is as follows:

[0042] Initial concentration of solution C before high-temperature crystallization begins (硫酸锰) When the temperature is <35 Baume, the heating rate is not controlled before the temperature reaches ≤80℃. When the temperature is between 80 and 100℃, the heating rate is 1.3 to 2.0℃ / min. When the temperature is between 100 and 140℃, the heating rate is 0.44 to 0.67℃ / min. When the temperature is between 140 and 200℃, the heating rate is 1.0 to 1.5℃ / min.

[0043] Initial concentration of solution C before high-temperature crystallization begins (硫酸锰) When the temperature is ≥35 Baume, the heating rate is not controlled before the temperature reaches ≤70℃. When the temperature is between 70 and 100℃, the heating rate is 1.2 to 1.6℃ / min. When the temperature is between 100 and 140℃, the heating rate is 0.38 to 0.60℃ / min. When the temperature is between 140 and 200℃, the heating rate is 1.0 to 1.5℃ / min.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The method for preparing high-purity manganese sulfate and co-producing battery-grade manganese dioxide by reducing manganese oxide ore with sulfur dioxide as described in this invention has wide applicability to manganese ore raw materials, and the manganese leaching rate can reach over 98%. This process technology can easily achieve a comprehensive manganese recovery rate of over 95% and produce two high-value products: high-purity MnSO4 and battery-grade MnO2.

[0046] 2. As is generally acknowledged by researchers in this field, the most critical technical challenge in the SO2 reduction of manganese ore method is how to efficiently remove the impurity component S2O6 generated by the side reaction. 2- This invention discloses a method for preparing high-purity manganese sulfate and co-producing battery-grade manganese dioxide by reducing manganese oxide ore with sulfur dioxide. In the MnS₂O₆ removal step, a high-temperature oxidation process is cleverly employed to decompose and remove MnS₂O₆ in the same reactor, yielding a manganese sulfate solution and co-producing high-quality MnO₂ suitable for batteries. This is a two-in-one technical approach with low process cost, a short process flow, and easy stable control. We have successfully transformed the harmful by-reaction impurity MnS₂O₆ present in existing technologies into a component beneficial to this technical solution, embodying the concept of turning harm into benefit.

[0047] 3. Unlike existing technologies that strive to minimize the amount of MnS2O6 generated during the reduction leaching process, this invention utilizes MnS2O6 as an intermediate product to produce high-value battery-grade products, allowing the generation of MnS2O6 during the reduction leaching process. Furthermore, unlike existing technologies that decompose MnS2O6 into manganese sulfate and corrosive SO2 gas, this invention directly prepares high-purity MnO2 from MnS2O6, without generating SO2 gas, making it friendly to production equipment and the environment.

[0048] 4. This invention uses SO2-containing flue gas from metal smelting or SO2 gas from sulfuric acid production as a reducing agent, which is widely available and cost-effective. After absorption, the exhaust gas concentration can be as low as 30 mg / m³. 3 Within this range, the concentration is far below the national environmental protection requirement of ≤400mg / m³. 3 The limit.

[0049] 5. In the impurity removal step, this invention removes calcium ions and heavy metal impurity ions in the same technical step, combining the existing calcium removal and heavy metal removal processes into one, greatly shortening the process flow. By introducing SO2 gas to generate a certain amount of sulfite ions in the solution, and then adding manganese powder to control the pH of the solution system, the sulfite ions react with CaSO4 and MnSO4 in the solution to form a sulfite-sulfate complex insoluble precipitate, which is then removed. 2+The content was quickly controlled to within 250 mg / L, achieving effective removal of calcium ions and greatly reducing the pressure on the separation and purification of calcium impurities during subsequent high-temperature crystallization. After SO2 gas was introduced to generate a certain amount of sulfurous acid in the solution, the manganese oxide layer on the surface of the manganese powder was reduced and dissolved, exposing the manganese elemental lattice. This greatly increased the probability of heavy metal impurity ions such as nickel, cobalt, zinc, copper, cadmium, and lead contacting the manganese elemental lattice and undergoing a displacement reaction. On the other hand, the oxidizing substances in the reaction solution system were reduced to form a reducing atmosphere with a very low potential, which is conducive to the displacement reaction of heavy metal ions with manganese to generate stable heavy metal elemental particles. This breakthrough overcomes the various drawbacks of existing technologies, such as low efficiency in removing heavy metal ions by manganese powder, excessive consumption of equivalents, and incomplete removal of impurities.

[0050] 6. This invention uses a controlled-rate crystallization method for high-temperature crystallization, which steadily increases the purification rate of impurity ions such as magnesium, calcium, potassium, and sodium from 70-80% to over 90% in a single crystallization process. This greatly improves the ability to crystallize and purify impurity ions, and achieves the goal of obtaining battery-grade high-purity manganese sulfate products after only two recrystallizations. Attached Figure Description

[0051] Figure 1 This is a process flow diagram of a method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide, as described in an embodiment of the present invention. Figure 1 (When the reaction temperature in step S5 is below 100℃);

[0052] Figure 2 This is a process flow diagram of a method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide, as described in an embodiment of the present invention. Figure 2 (When the reaction temperature in step S5 is 110–160°C). Detailed Implementation

[0053] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0054] Figure 1 This is the process flow of the method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide, as described in Example 1. Figure 1 (When the reaction temperature in step S5 is below 100℃);

[0055] Example 1:

[0056] A method for preparing high-purity MnSO4 from manganese oxide ore by SO2 reduction and co-producing MnO2 for batteries includes the following steps:

[0057] The main components of the raw material manganese oxide ore powder involved in this embodiment are detected as follows:

[0058]

[0059] Note: The total Mn component data in the raw material manganese oxide ore powder composition data refers to the manganese element content in the ore powder, which includes the manganese in the MnO2 component.

[0060] The main components of SO2 gas are shown below:

[0061]

[0062] S1. Oxidized manganese ore is ground into fine powder of 100-300 mesh and then mixed with tap water at a mass ratio of 1:2.5 to prepare a mineral powder slurry.

[0063] S2. The mineral powder slurry and SO2 gas are uniformly and continuously fed into the absorption reaction tower at a Mn:SO2 molar ratio of 1:1.10. Within a reaction temperature range of 50℃ to 70℃, the SO2 gas and mineral powder slurry undergo countercurrent contact absorption and redox reaction in the absorption reaction tower, reducing higher-order manganese oxides in the manganese oxide ore to Mn. 2+ When SO2 enters the solution, it is absorbed and oxidized to form SO4. 2- and some byproducts S2O6 2- After the reaction is complete, a uniform and continuous reduced leaching slurry is produced. Testing shows the reduced leaching slurry has a pH of 3.05 and contains S2O6. 2- 43.27 g / L;

[0064] S3. Transfer the reductive leaching slurry from the previous step to a hydrolysis sedimentation tank. Adjust the temperature of the reductive leaching slurry to between 50℃ and 70℃. Add calcium carbonate to the hydrolysis sedimentation tank to adjust the pH to 4.21, thereby reducing the Fe content in the reductive leaching slurry. 3+ AL 3+ Hydrolysis and precipitation are performed, and then the slurry after the hydrolysis and precipitation reaction is completed is sent to a filter press for filtration to obtain filter residue and iron and aluminum removed liquid. The iron and aluminum removed liquid is taken for testing and analysis. The main components that need quality control are as follows:

[0065]

[0066] S4. Transfer the iron-aluminum-removed liquid to a sealed container, controlling the reaction liquid temperature between 30 and 45°C. Introduce SO2 gas into the sealed container. Stop introducing SO2 when the solution pH drops to 1.55. Then add 5.0 times the chemical reaction equivalent of the total heavy metal impurities in the iron-aluminum-removed liquid as manganese powder. After reacting for 5 hours, the pH rises to 6.85, and the pressure in the sealed container is 0.27 MPa. Filter to obtain the removed residue and the removed filtrate. Sample the removed filtrate for testing. Ca... 2+ The residual amount was 207.50 mg / L, Ca 2+ The removal rate was 72.87%, and the removal rates of various heavy metals were all above 90%. The main components requiring quality control are as follows:

[0067]

[0068] S5. The purified filtrate is fed into the oxidation synthesis reactor, and the concentrations of O2 and S2O6 in the purified filtrate are adjusted according to the molar amounts. 2- After adding pure oxygen as an oxidant at a molar ratio of 10.0, stirring and heating to 90℃~100℃ for 24 hours, the liquid was discharged for solid-liquid separation to obtain manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder was washed with pure water to remove trace amounts of soluble salts such as manganese sulfate, and then solid-liquid separation was performed again to obtain high-purity refined MnO2 powder. The high-purity refined MnO2 powder was dried to obtain a battery-grade MnO2 product with extremely high purity. The S2O6 content of the manganese sulfate solution was tested. 2- The residual amount is 0.08 g / L, S2O6 2- The removal rate was 99.82%. The MnO2 product was tested for impurity content, and the impurity content data are as follows:

[0069]

[0070] S6. The manganese sulfate solution obtained in S5 has a detection concentration of 37 Baume degrees. The manganese sulfate solution is then placed in a high-temperature crystallization reactor. Crystallization is carried out at a rate of 1.2–1.6 °C / min when the temperature is between 70 and 100 °C, and at a rate of 0.40–0.60 °C / min when the temperature is between 100 and 140 °C. The material temperature is then raised to 140 °C. This high-temperature recrystallization process is repeated twice. After solid-liquid separation and drying, the manganese sulfate monohydrate product for battery use is obtained. The quality test data of the obtained manganese sulfate monohydrate product are as follows:

[0071]

[0072] In this embodiment, the reduction leaching rate of manganese oxide ore reaches 98.07%, and the total manganese recovery rate is about 95.33%, which is high. The produced MnO2 product has low impurity content and has a crystal structure with oxygen defects, making it an excellent battery material. The produced manganese sulfate monohydrate exceeds the performance requirements of battery-grade products.

[0073] Example 2:

[0074] Figure 2 This is the process flow of the method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide, as described in Example 2. Figure 2 (When the reaction temperature in step S5 is 110–160°C).

[0075] A method for preparing high-purity MnSO4 from manganese oxide ore by SO2 reduction and co-producing MnO2 for batteries differs from Example 1 in that:

[0076] The manganese oxide ore raw material remains unchanged, and the main components of the SO2 gas raw material are shown below:

[0077]

[0078] The fine manganese ore powder mentioned in step S1 has a mesh size of 300-500 mesh and is mixed with pure water at a mass ratio of 1:3.0 to form a slurry.

[0079] In step S2, the mineral powder slurry and SO2 gas are reacted at a Mn:SO2 molar ratio of 1:1.35. The reaction temperature is controlled within the range of 30℃ to 50℃. After the reaction is completed, the resulting reduction leaching slurry has a pH value of 2.84 and contains S2O6. 2- 54.38 g / L;

[0080] Step S3: Adjust the temperature of the reductive leaching slurry in the hydrolysis sedimentation tank to between 50℃ and 70℃. Add manganese carbonate to the hydrolysis sedimentation tank to adjust the pH to 3.93, then add metallic manganese powder to further adjust the pH to 6.51, thus reducing the Fe content in the reductive leaching slurry. 3+ AL 3+ After hydrolysis precipitation and removal of iron and aluminum, the main components requiring quality control in the post-precipitate analysis are as follows:

[0081]

[0082] Step S4: The temperature of the reaction solution is controlled between 40 and 60°C. SO2 gas is introduced into a sealed container until the pH of the solution drops to 2.42, at which point the SO2 introduction is stopped. Then, 4.0 times the chemical reaction equivalent of the total heavy metal impurities in the solution after iron and aluminum removal is added. After reacting for 3 hours, the pH rises to 6.41, and the pressure in the sealed container is 0.27 MPa. Filtration is performed to obtain the removed residue and the removed filtrate. The removed filtrate is sampled for testing. Ca... 2+ The residual amount was 193.61 mg / L, Ca 2+ The removal rate was 65.03%, and the removal rates of various heavy metals were all above 95%. The main components requiring quality control are as follows:

[0083]

[0084] Step S5: The purified filtrate is fed into the oxidation synthesis reactor, and the concentration of O2 and S2O6 in the purified filtrate is adjusted according to the molar amount of O2. 2- After adding pure oxygen as an oxidant at a molar ratio of 5.5, stirring and heating to 100℃~120℃ for 10 hours, the liquid was discharged for solid-liquid separation to obtain a dilute manganese sulfate solution and a crude mixed powder of (MnO2 and MnSO4·H2O). The crude mixed powder of (MnO2 and MnSO4·H2O) was dissolved in pure water to remove soluble salts such as MnSO4·H2O crystals, and then subjected to solid-liquid separation again to obtain a manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder was rinsed with pure water to remove trace amounts of soluble salts such as manganese sulfate, and then subjected to solid-liquid separation again to obtain a high-purity refined MnO2 powder. The high-purity MnO2 powder was dried to obtain a battery-grade MnO2 product with extremely high purity. The S2O6 content of the manganese sulfate solution was then tested. 2- The residual amount was not detected, S2O6 2- The removal rate was 100%. The MnO2 product was tested for impurity content, and the impurity content data are as follows:

[0085]

[0086] In step S6, the manganese sulfate solution obtained in S5 has a detection concentration of 34 Baume degrees and a temperature of 83.7°C. The manganese sulfate solution is then placed in a high-temperature crystallization reactor. Crystallization is carried out by heating at a rate of 1.3–2.0°C / min when the temperature is between 80 and 100°C, at a rate of 0.44–0.67°C / min when the temperature is between 100 and 140°C, and at a rate of 1.0–1.5°C / min when the temperature is between 140 and 200°C, until the material temperature reaches 200°C. After recrystallization at high temperature twice using this method, solid-liquid separation and drying are performed to obtain the manganese sulfate monohydrate product for battery use. The quality test data of the obtained manganese sulfate monohydrate product are as follows:

[0087]

[0088] In this embodiment, the reduction leaching rate of manganese oxide ore reaches 99.04%, and the total manganese recovery rate is about 97.22%, which is a high leaching rate. The produced MnO2 product has low impurity content and a crystal structure with oxygen defects, making it an excellent battery material. The produced manganese sulfate monohydrate exceeds the performance requirements of battery-grade products.

[0089] Example 3:

[0090] A method for preparing high-purity MnSO4 from manganese oxide ore by SO2 reduction and co-producing MnO2 for batteries differs from Example 1 in that:

[0091] The manganese oxide ore raw material remains unchanged, and the main components of the SO2 gas raw material are shown below:

[0092]

[0093] The fine manganese ore powder mentioned in step S1 has a mesh size of 200 to 400 mesh and is mixed with the manganese-containing process water in the workshop with a Mn content of 37.57 g / L at a mass ratio of 1:5.0.

[0094] In step S2, the mineral powder slurry and SO2 gas are reacted at a Mn:SO2 molar ratio of 1:1.25. The reaction temperature is controlled within the range of 70℃ to 90℃. During the reaction, if the pH value of the slurry drops below 2.50, small amounts of manganese monoxide powder are continuously added to maintain the pH value between 2.50 and 3.0. After the reaction is completed, the resulting reduction leaching slurry has a pH value of 2.66 and contains S2O6. 2- 38.59 g / L;

[0095] Step S3: Adjust the temperature of the reductive leaching slurry in the hydrolysis sedimentation tank to between 80℃ and 90℃. Add manganese monoxide powder to the hydrolysis sedimentation tank to adjust the pH to 4.07, then add metallic manganese powder to further adjust the pH to 6.94, thus reducing the Fe content in the reductive leaching slurry. 3+ AL 3+ After hydrolysis precipitation and removal of iron and aluminum, the main components requiring quality control in the post-precipitate analysis are as follows:

[0096]

[0097] Step S4: Control the temperature of the reaction solution between 60 and 80°C. Introduce SO2 gas into a sealed container until the pH of the solution drops to 1.07, then stop introducing SO2. Next, add manganese powder in amounts equivalent to 2.5 times the chemical reaction weight of the total heavy metal impurities in the solution after iron and aluminum removal. After reacting for 3 hours, the pH rises to 6.76, and the pressure in the sealed container is 0.33 MPa. Filter the solution to obtain the removed residue and the removed filtrate. Sample the removed filtrate for analysis. Ca... 2+ The residual amount was 217.34 mg / L, Ca 2+ The removal rate was 65.10%, and the removal rates of various heavy metals were all above 99%. The main components requiring quality control are as follows:

[0098]

[0099] Step S5: The purified filtrate is fed into the oxidation synthesis reactor, and the concentration of O2 and S2O6 in the purified filtrate is adjusted according to the molar amount of O2. 2- After adding pure oxygen as an oxidant at a molar ratio of 3.0, stirring and heating to 120℃~140℃ for 5 hours, the liquid was discharged for solid-liquid separation to obtain a dilute manganese sulfate solution and a crude mixed powder of (MnO2 and MnSO4·H2O). The crude mixed powder of (MnO2 and MnSO4·H2O) was dissolved in pure water to remove soluble salts such as MnSO4·H2O crystals, and then subjected to solid-liquid separation again to obtain a manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder was rinsed with pure water to remove trace amounts of soluble salts such as manganese sulfate, and then subjected to solid-liquid separation again to obtain a high-purity refined MnO2 powder. The high-purity MnO2 powder was dried to obtain a battery-grade MnO2 product with extremely high purity. The S2O6 content of the manganese sulfate solution was then tested. 2- The residual amount was not detected, S2O6 2- The removal rate was 100%. The MnO2 product was tested for impurity content, and the impurity content data are as follows:

[0100]

[0101]

[0102] In step S6, the manganese sulfate solution obtained in S5 is tested at a concentration of 31 Baume degrees and a temperature of 85.2°C. The manganese sulfate solution is then placed in a high-temperature crystallization reactor. Crystallization is carried out by heating at a rate of 1.3–2.0°C / min when the temperature is between 80 and 100°C, at a rate of 0.44–0.67°C / min when the temperature is between 100 and 140°C, and at a rate of 1.0–1.5°C / min when the temperature is between 140 and 200°C, until the material temperature reaches 160°C. After recrystallization at high temperature twice using this method, solid-liquid separation and drying are performed to obtain the manganese sulfate monohydrate product for battery use. The quality test data of the obtained manganese sulfate monohydrate product are as follows:

[0103]

[0104] In this embodiment, the reduction leaching rate of manganese oxide ore reached 98.84%, and the total manganese recovery rate was about 96.49%, indicating a high leaching rate. The produced MnO2 product has low impurity content and a crystal structure with oxygen defects, making it an excellent battery material. The produced manganese sulfate monohydrate meets the performance requirements of battery-grade products.

[0105] Example 4:

[0106] A method for preparing high-purity MnSO4 from manganese oxide ore by SO2 reduction and co-producing MnO2 for batteries differs from Example 1 in that:

[0107] The raw material of manganese oxide ore remains unchanged, and the SO2 gas is high-purity SO2 obtained by vaporizing liquefied sulfur dioxide.

[0108]

[0109] The fine manganese ore powder in step S1 has a mesh size of 100 to 200 mesh and is mixed with tap water at a mass ratio of 1:10.

[0110] In step S2, the mineral powder slurry and SO2 gas are reacted at a Mn:SO2 molar ratio of 1:1.50. The reaction temperature is controlled within the range of 60℃ to 80℃. After the reaction is completed, the resulting reduction leaching slurry has a pH value of 2.53 and contains S2O6. 2- 63.47 g / L;

[0111] Step S3: Adjust the temperature of the reductive leaching slurry in the hydrolysis sedimentation tank to between 90℃ and 100℃, and add calcium carbonate to the hydrolysis sedimentation tank to adjust the pH value to 5.62, so that the Fe in the reductive leaching slurry... 3+ AL 3+ After hydrolysis precipitation and removal of iron and aluminum, the main components requiring quality control in the post-precipitate analysis are as follows:

[0112]

[0113] Step S4: Control the temperature of the reaction solution between 80 and 100°C. Introduce SO2 gas into a sealed container until the pH of the solution drops to 0.49, then stop introducing SO2. Next, add manganese powder in amounts equal to 2.0 chemical reaction equivalents of the total heavy metal impurities in the solution after iron and aluminum removal. After reacting for 2 hours, the pH rises to 6.83, and the pressure in the sealed container is 0.35 MPa. Filter the solution to obtain the removed residue and the removed filtrate. Sample the removed filtrate for analysis. Ca... 2+ The residual amount was 207.56 mg / L, Ca 2+ The removal rate was 65.10%, and the removal rates of various heavy metals were all above 97%. The main components requiring quality control are as follows:

[0114]

[0115] Step S5: The purified filtrate is fed into the oxidation synthesis reactor, and the concentration of O2 and S2O6 in the purified filtrate is adjusted according to the molar amount of O2. 2- After adding oxidant and compressed air at a molar ratio of 1.2, stirring and heating to 140℃~160℃ for 2 hours, the liquid is discharged for solid-liquid separation to obtain a dilute manganese sulfate solution and a crude mixed powder of (MnO2 and MnSO4·H2O). The crude mixed powder of (MnO2 and MnSO4·H2O) is dissolved in pure water to remove soluble salts such as MnSO4·H2O crystals, and then subjected to solid-liquid separation again to obtain a manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder is rinsed with pure water to remove trace amounts of soluble salts such as manganese sulfate, and then subjected to solid-liquid separation again to obtain a high-purity refined MnO2 powder. The high-purity MnO2 powder is dried to obtain a battery-grade MnO2 product with extremely high purity. The manganese sulfate solution is then tested. The residual amount was 0.12 g / L. The removal rate was 99.81%. The MnO2 product was tested for impurity content, and the impurity content data are as follows:

[0116]

[0117] Step S6: The manganese sulfate solution obtained in S5 has a detection concentration of 25 Baume degrees and a temperature of 82.3℃. The manganese sulfate solution is concentrated to 40 Baume degrees by vacuum evaporation and then fed into a high-temperature crystallization reactor. Crystallization is carried out at a rate of 1.2–1.6℃ / min when the temperature is between 70 and 100℃, at a rate of 0.40–0.60℃ / min when the temperature is between 100 and 140℃, and at a rate of 1.0–1.5℃ / min when the temperature is between 140 and 200℃, until the material temperature reaches 160℃. After recrystallization at high temperature twice using this method, solid-liquid separation and drying are performed to obtain the manganese sulfate monohydrate product for battery use. The quality test data of the obtained manganese sulfate monohydrate product are as follows:

[0118]

[0119] In this embodiment, the reduction leaching rate of manganese oxide ore reaches 99.23%, and the total manganese recovery rate is about 97.57%, which is a high leaching rate. The produced MnO2 product has low impurity content and has a crystal structure with oxygen defects, making it an excellent battery material. The produced manganese sulfate monohydrate exceeds the performance requirements of battery-grade products.

[0120] Example 5:

[0121] A method for preparing high-purity MnSO4 from manganese oxide ore by SO2 reduction and co-producing MnO2 for batteries includes the following steps:

[0122] This embodiment uses manganese oxide slag, a byproduct of nickel and cobalt product production, as raw material, based on MHP (Note: MHP is an abbreviation for Mixed Hydroxide Precipitate). The main components of the manganese oxide slag are analyzed as follows:

[0123]

[0124] Note: The total Mn component data in the manganese oxide slag composition data refers to the manganese content in the mineral powder, which includes the manganese in the MnO2 component.

[0125] The main components of SO2 gas are shown below:

[0126]

[0127] S1. Manganese oxide slag is pulverized and sieved to obtain fine manganese slag powder with a mesh size of less than 100 mesh. It is then mixed with tap water at a mass ratio of 1:2.5 to prepare manganese oxide slag slurry.

[0128] S2. Manganese oxide slag slurry and SO2 gas are fed uniformly and continuously into the absorption reaction tower at a Mn:SO2 molar ratio of 1:1.20. The reaction temperature is controlled at 50℃~60℃. During the reaction, if the pH value of the slurry drops below 2.50, small amounts of manganese monoxide powder are continuously added to maintain the pH value between 2.50 and 3.0. After the reaction is completed, a reductive leaching slurry is uniformly and continuously output. The pH value of the reductive leaching slurry is tested to be 2.64, containing S2O6. 2- 38.68 g / L;

[0129] S3. Transfer the reductive leaching slurry from the previous step to a hydrolysis sedimentation tank. Adjust the temperature of the reductive leaching slurry to between 80℃ and 90℃. Add calcium carbonate to the hydrolysis sedimentation tank to adjust the pH to 5.35, thereby reducing the Fe content in the reductive leaching slurry. 3+ AL 3+ Hydrolysis and precipitation are performed, and then the slurry after the hydrolysis and precipitation reaction is completed is sent to a filter press for filtration to obtain filter residue and iron and aluminum removed liquid. The iron and aluminum removed liquid is taken for testing and analysis. The main components that need quality control are as follows:

[0130]

[0131] S4. Transfer the iron-aluminum-removed liquid to a sealed container, controlling the reaction liquid temperature between 70 and 85°C. Introduce SO2 gas into the sealed container. Stop introducing SO2 when the solution pH drops to 0.98. Then add 2.0 times the chemical reaction equivalent of the total heavy metal impurities in the iron-aluminum-removed liquid as manganese powder. After reacting for 2 hours, the pH rises to 6.97, and the pressure in the sealed container is 0.29 MPa. After reacting for 3.5 hours, filter to obtain the removed residue and the removed filtrate. Sample the removed filtrate for analysis. Ca... 2+ The residual amount was 203.47 mg / L, Ca 2+ The removal rate was 72.41%, and the removal rate of various heavy metals was over 99%. The main components requiring quality control are as follows:

[0132]

[0133] S5. The purified filtrate is fed into the oxidation synthesis reactor, and the concentrations of O2 and S2O6 in the purified filtrate are adjusted according to the molar amounts. 2-After adding pure oxygen as an oxidant at a molar ratio of 3.0, stirring and heating to 120℃~140℃ for 5 hours, the liquid was discharged for solid-liquid separation to obtain a dilute manganese sulfate solution and a crude mixed powder of (MnO2 and MnSO4·H2O). The crude mixed powder of (MnO2 and MnSO4·H2O) was dissolved in pure water to remove soluble salts such as MnSO4·H2O crystals, and then subjected to solid-liquid separation again to obtain a manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder was rinsed with pure water to remove trace amounts of soluble salts such as manganese sulfate, and then subjected to solid-liquid separation again to obtain a high-purity refined MnO2 powder. The high-purity MnO2 powder was dried to obtain a battery-grade MnO2 product with extremely high purity. The S2O6 content of the manganese sulfate solution was then tested. 2- The residual amount was not detected, S2O6 2- The removal rate was 100%. The MnO2 product was tested for impurity content, and the impurity content data are as follows:

[0134]

[0135]

[0136] S6. The manganese sulfate solution obtained in S5 has a detection concentration of 40 Baume degrees. The manganese sulfate solution is then placed in a high-temperature crystallization reactor. Crystallization is carried out at a rate of 1.2–1.6 °C / min when the temperature is between 70 and 100 °C, and at a rate of 0.40–0.60 °C / min when the temperature is between 100 and 140 °C. The material temperature is then increased to 160 °C. This high-temperature recrystallization process is repeated twice. After solid-liquid separation and drying, the manganese sulfate monohydrate product for battery use is obtained. The quality test data of the obtained manganese sulfate monohydrate product are as follows:

[0137]

[0138] In this embodiment, the reduction leaching rate of manganese oxide ore reaches 99.20%, and the total manganese recovery rate is about 97.76%, which is a high leaching rate. The produced MnO2 product has low impurity content and a crystal structure with oxygen defects, making it an excellent battery material. The produced manganese sulfate monohydrate exceeds the performance requirements of battery-grade products.

[0139] Comparative Example 1:

[0140] Following the same steps and material ratios as in Example 3, the reaction solution from step S4 was placed in an open reaction vessel. SO2 gas was introduced into the solution until the pH dropped to 1.07. Then, manganese powder was added, and the reaction vessel was kept under normal pressure while stirring. After the reaction was completed, the mixture was filtered to obtain a residue and a filtrate after impurity removal. The filtrate after impurity removal was sampled for testing. Ca 2+ The residual amount was 501.52 mg / L, Ca 2+The removal rate was only 19.48%, Cu 2+ The removal rate was 98.12%, while the removal rates of other heavy metals were all below 85%. The main components requiring quality control are as follows:

[0141]

[0142] Step S5 is based on the molar amount of O2 and the S2O6 content in the filtrate after impurity removal. 2- After adding pure oxygen as an oxidant at a molar ratio of 0.8, the mixture is stirred and heated to 120℃~140℃ for 5 hours. The liquid is then discharged for solid-liquid separation.

[0143] After the reaction, the discharged material had a distinct, pungent odor of SO2 gas. A manganese sulfate solution was used to test for S2O6. 2- The residual amount was 5.84 g / L, S2O6 2- The removal rate was only 84.84%.

[0144] By comparing Example 1 and the embodiment, it can be seen that in an open reaction vessel and under atmospheric pressure, the oxidation-reduction potential of the reaction system changes due to the direct contact between oxygen in the air and the reactants, thus affecting the Ca2+ reaction. 2+ Heavy metal impurity ions are difficult to remove efficiently; and the molar amount of O2 and the S2O6 contained in the filtrate after impurity removal are compared. 2- After the molar ratio decreased from 3.0 to 0.8, S2O6 2- If it is not completely removed, it will seriously affect the quality control of subsequent processes.

[0145] Comparative Example 2:

[0146] The S5 step was calculated based on the molar amount of O2 and the S2O6 contained in the filtrate after impurity removal. 2- The molar ratio is 3.0. After adding pure oxygen as an oxidant, the mixture is stirred and heated to 120℃~140℃ for 1.5h. The liquid is then discharged for solid-liquid separation. The remaining conditions are the same as in Example 3.

[0147] After the reaction is complete, the manganese sulfate solution is taken to detect S2O6. 2- The residual amount was 6.77 g / L, S2O6 2- The removal rate was only 82.43%.

[0148] By comparing Example 2 and the Example 1, it can be seen that the reaction time needs to be more than 2 hours to ensure the S2O6 reaction. 2- It is completely removed by oxidation and decomposition.

[0149] Comparative Example 3:

[0150] The S5 step was calculated based on the molar amount of O2 and the S2O6 contained in the filtrate after impurity removal. 2-The molar ratio is 3.0. After adding the oxidant pure oxygen, stir and heat to 70℃~80℃ for 24h.

[0151] Step S6: The manganese sulfate solution obtained in S5 is concentrated by conventional atmospheric pressure evaporation at 100℃~105℃. When the crystallization rate of manganese sulfate monohydrate reaches about 75%, solid-liquid separation is performed to obtain the manganese sulfate monohydrate product.

[0152] The remaining conditions are the same as in Example 3.

[0153] After the reaction in step S5 is completed, almost no MnO2 product is produced. The S2O6 content in the manganese sulfate solution is then analyzed. 2- The residual amount was 34.89 g / L, S2O6 2- The removal rate was only 9.45%;

[0154] The quality test data of the manganese sulfate monohydrate product obtained by concentration and crystallization in step S6 are as follows:

[0155]

[0156] By comparing Comparative Example 3 and the Examples, it can be seen that even when the reaction temperature is below 90°C and the reaction time is extended to 24 hours, the impurity component S2O6... 2- The proportion of oxidation and decomposition was still very low, and no MnO2 product was obtained. The monohydrate manganese sulfate produced by concentration and crystallization was grayish-white after drying. Among the test indicators, the three indicators of Mn, Ca and Mg failed to meet the requirements of downstream customers.

[0157] Summary and discussion:

[0158] This invention uses SO2-containing flue gas from metal smelting or SO2 gas from sulfuric acid production as a reducing agent, which is widely available and cost-effective. After absorption, the exhaust gas concentration can be as low as 30 mg / m³. 3 The concentration is within the range, far below the requirement of ≤400 mg / m³ in the "GB31573-2015 Emission Standard for Pollutants from Inorganic Chemical Industry". 3 The limits are not met; it has wide applicability to manganese ore raw materials, and the manganese leaching rate can reach over 98%. Using this process technology, a comprehensive manganese recovery rate of over 95% can be easily achieved, producing two high-value products: high-purity MnSO4 and battery-grade MnO2. The high-temperature oxidation process cleverly achieves the decomposition and removal of S2O6 in the same reactor. 2- A manganese sulfate solution was obtained, along with a high-quality MnO2 product suitable for battery use, effectively resolving the side reaction component S2O6. 2-This technology addresses the technical challenges hindering the industrialization of processes and products, offering a dual benefit: a streamlined process that is easy to control stably; and the use of a rate-controlled crystallization method for high-temperature crystallization, which steadily increases the purification rate of impurity ions such as magnesium, calcium, potassium, and sodium from 70-80% to over 90% in a single crystallization process. This significantly enhances the ability to purify impurity ions through crystallization, enabling the production of battery-grade high-purity manganese sulfate products with just two recrystallization cycles.

[0159] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, any non-essential improvements and changes made without departing from the inventive concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide, characterized in that: Includes the following steps: S1. Grind oxidized manganese ore into fine manganese ore powder of 100 mesh to 500 mesh, and mix the fine manganese ore powder with a solvent at a mass ratio of 1:2.5 to 10 to prepare a mineral powder slurry. The solvent is one or more of tap water, pure water or manganese-containing process water produced in the workshop. S2. The mineral powder slurry and SO2 gas are uniformly and continuously fed into the absorption reaction tower at a Mn:SO2 molar ratio of 1:1.10~1.

50. Within a reaction temperature range of 30℃~90℃, the SO2 gas and mineral powder slurry undergo countercurrent contact absorption and redox reaction in the absorption reaction tower, reducing higher-order manganese oxides in the manganese oxide ore to Mn. 2+ When SO2 enters the solution, it is absorbed and oxidized to form SO4. 2- and byproduct S2O6 2- After the reaction is complete, a reduced leachate is obtained and output uniformly and continuously. S3. Place the reduced leaching slurry from the previous step into a hydrolysis sedimentation tank. Add an acid-consuming agent to the hydrolysis sedimentation tank to adjust the pH value to 4.0~6.5, so that the Fe in the reduced leaching slurry... 3+ AL 3+ Hydrolysis and precipitation are performed, and then the slurry after the hydrolysis and precipitation reaction is completed is sent to a filter press for filtration to obtain filter residue and liquid after iron and aluminum removal. S4. Place the iron-aluminum-removed liquid in a sealed container for impurity removal. Introduce SO2 gas into the sealed container; the water in the solution absorbs the SO2 to form sulfurous acid, thus making the iron-aluminum-removed liquid contain SO3. - When the pH of the solution drops to 0.5-2.5, stop the flow of SO2. Then add 2.0-5.0 times the molar amount of manganese powder equivalent to the sum of the heavy metal ions in the solution to adjust the pH to 6.0-7.

0. Maintain the pressure in the sealed container at 0.05MPa-0.35MPa. After reacting for 2-5 hours, calcium ions and various heavy metal impurities are precipitated and removed. Filter by pressure to obtain the impurity-removed residue and the impurity-removed filtrate. S5. After removing impurities, the filtrate is sent into the oxidation synthesis reactor. After adding the oxidant, the mixture is stirred and heated to 90℃~160℃ for 2h~24h. The slurry is then discharged for solid-liquid separation. When the reaction temperature is below 100℃, manganese sulfate fails to crystallize or crystallizes in very small amounts, resulting in a product without S2O6. 2- The impurities were a manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder was washed with pure water to remove trace amounts of manganese sulfate soluble salts, and then solid-liquid separation was performed again to obtain refined MnO2 powder. When the reaction temperature is between 110℃ and 160℃, manganese sulfate crystals precipitate out, and the higher the temperature, the greater the amount of precipitation, resulting in the formation of S2O6-free products. 2- The mother liquor of the dilute manganese sulfate solution containing impurities, and the crude powder of the mixed MnO2 and MnSO4•H2O, were subjected to solid-liquid separation after dissolving the soluble salts of MnSO4•H2O crystals in pure water to obtain S2O6-free powder. 2- The impurities are manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder is washed with pure water to remove trace amounts of manganese sulfate soluble salts. Then, solid-liquid separation is performed again to obtain refined MnO2 powder. The obtained refined MnO2 powder is dried to obtain a battery-grade MnO2 product with extremely high purity. S6. Obtain the S2O6-free solution from S5. 2- The manganese sulfate solution containing impurities is fed into a high-temperature crystallization reactor. When no S2O6 is present... 2- If the concentration of the impurity manganese sulfate solution is below 30 Baume degrees, it is first evaporated and concentrated to a concentration of 30-40 Baume degrees. Then, it is heated to 140℃-200℃ for high-temperature recrystallization twice. After solid-liquid separation and drying, the battery-grade manganese sulfate monohydrate product is obtained, with a manganese leaching rate ≥98% and an exhaust gas concentration <30mg / m³ after absorption. 3 .

2. The method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The SO2 gas mentioned in step S2 is a gas composed of SO2 with a volume fraction of 0.1% to 100% and other components with a volume fraction of 99.9% to 0%; the other components refer to one or more of air, nitrogen, and carbon dioxide in any proportion.

3. The method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The SO2 gas inlet flow rate mentioned in step S2 is such that the gas phase velocity inside the tower is between 0.1 and 5.0 m / s and the SO2 content in the exhaust gas discharged from the tower is less than 30 mg / m³. 3 Control methods.

4. The method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The temperature of the hydrolysis precipitation reaction in step S3 is 50℃~100℃; the acid-consuming agent is one or more of calcium carbonate, metallic manganese powder, manganese carbonate, and manganese monoxide in any proportion, and the amount of acid-consuming agent added is based on the pH value of the reduced leaching slurry rising to 4.0~6.

5.

5. The method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The impurity removal reaction temperature in step S4 is 30~100℃.

6. The method for preparing high-purity manganese sulfate and co-producing manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The high-temperature recrystallization described in step S6 employs a rate-controlled crystallization process. The operation method of the rate-controlled crystallization process is as follows: Initial concentration of solution C before high-temperature crystallization begins （硫酸锰） When the temperature is <35 Baume, the heating rate is not controlled before the temperature reaches ≤80℃. When the temperature is between 80 and 100℃, the heating rate is 1.3 to 2.0℃ / min. When the temperature is between 100 and 140℃, the heating rate is 0.44 to 0.67℃ / min. When the temperature is between 140 and 200℃, the heating rate is 1.0 to 1.5℃ / min. Initial concentration of solution C before high-temperature crystallization begins （硫酸锰） When the temperature is ≥35 Baume, the heating rate is not controlled before the temperature reaches ≤70℃. When the temperature is between 70~100℃, the heating rate is 1.2~1.6℃ / min. When the temperature is between 100~140℃, the heating rate is 0.38~0.60℃ / min. When the temperature is between 140~200℃, the heating rate is 1.0~1.5℃ / min.

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