Method for preparing high-purity manganese sulfate and co-producing manganese dioxide for battery by reducing manganese oxide ore with sulfur dioxide

Abstract

The invention discloses a method for preparing high-purity manganese sulfate and co-producing manganese dioxide for a battery by reducing manganese oxide ore with sulfur dioxide, metal smelting SO2-containing flue gas or sulfur acid-making industry SO2 gas is used as a reducing agent, discharged tail gas after absorption can be as low as 30 mg / m < 3 > or below, and the leaching rate of manganese element can reach 98% or above. By adopting the technical scheme of the process, the comprehensive recovery rate of manganese is easy to achieve more than 95%, and two high-value products of high-purity MnSO4 and MnO2 for batteries are produced; s2O6 < 2-> is decomposed and removed in the same reaction kettle by adopting a high-temperature oxidation process to obtain a manganese sulfate solution and co-produce a high-quality MnO2 product suitable for batteries; a speed-controlled crystallization method is adopted for high-temperature crystallization, the one-time crystallization separation and purification rate of impurity ions such as magnesium, calcium, potassium and sodium is stably increased from 70-80% to 90% or above, and the purpose of obtaining a battery-grade high-purity manganese sulfate product through two times of recrystallization is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of manganese dioxide for batteries, and in particular to a method for reducing manganese oxide ore with sulfur dioxide to prepare high-purity manganese sulfate co-production manganese dioxide for batteries. Background Art

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

[0003] Currently, the main raw material mineral for producing high-purity manganese products is manganese oxide ore (pyrolusite). Manganese oxide ore (pyrolusite) can be used in two major processes: pyrocarbon reduction and wet reduction to produce high-purity manganese sulfate monohydrate, manganese trimanganese tetroxide, manganese carbonate, manganese dioxide and other battery-grade manganese products. Currently, over 95% of the high-purity manganese sulfate monohydrate, battery-grade manganese oxide, electrolytic manganese dioxide, and high-purity manganese carbonate products on the market are produced using pyrometallurgical carbon reduction, the two-ore acidification process, and the rhodochrosite acid leaching / electrolytic manganese flake method. Pyrometallurgical carbon reduction requires large quantities of carbon-based raw materials, such as coal, and fugitive dust emission during production is difficult to effectively control. The two-ore acidification process requires large quantities of pyrite and sulfuric acid, and the successful production of manganese-based battery products depends on the impurity content of the pyrite, placing stringent requirements on the impurity content of the manganese ore and pyrite raw material powders. The rhodochrosite acid leaching / electrolytic manganese flake method faces challenges such as a shortage of high-quality raw materials and difficulty sourcing them. The electrolytic method also suffers from long process steps, high production costs, and high investment. The SO2 wet reduction of manganese oxide ore is a simplified process that does not use carbon-based reducing agents, making it a truly low-carbon process with extremely high leaching rates, rapid reactions, a short process flow, low energy consumption, high production efficiency, and minimal capital and land investment, making it a highly promising process.

[0004] CN108165742A mentions a method for reducing the content of manganese dithionate in a pyrolusite leachate. By adjusting the pH independently in different zones, sulfur dioxide is absorbed in a reaction tank with a pH>5 for reduction leaching. Then, in another reaction tank, the pH is adjusted to 2-3 to cause MnS2O6 to react with H2SO4 to produce MnSO4 and H2S2O6. It is then believed that H2S2O6 itself undergoes a disproportionate decomposition reaction to produce H2SO4 and SO2. Oxygen or hydrogen peroxide is introduced to oxidize SO2 to sulfuric acid in the solution. According to the technical solution, the 0.03 mol / L MnS2O6 content in the leachate can be reduced by 50% to 65%. However, more than 1.68 g / L of MnS2O6 still remains in the treated solution, resulting in a low impurity removal efficiency. This still falls far short of the process indicator requirements for the industrial preparation of high-purity manganese products.

[0005] CN104477999B proposes a method for producing manganese sulfate by absorbing sulfur dioxide in flue gas using a composite slurry. The composite absorption slurry is prepared by mixing manganese oxide ore powder as a desulfurizer and pyrite powder as a promoter. The low-valent sulfur in the pyrite powder forms a more reducible combination with sulfur dioxide and sulfite dissolved in the absorption reaction system, thereby inhibiting the oxidation of sulfur dioxide and sulfurous acid by oxygen in the absorption reaction system to form sulfuric acid, suppressing the production of manganese dithionate, and stabilizing the pH value of the absorption reaction system at an acidic level above 2.0. This technical solution can control the production of manganese dithionate to between 3 and 5 g / L, but still fails to completely and efficiently remove the manganese dithionate. This impurity component of manganese dithionate will adversely affect the service life of equipment in subsequent processes and product quality.

[0006] CN102634819B discloses a method for preparing electrolytic manganese dioxide by leaching manganese oxide with sulfur dioxide. The method includes simultaneously feeding manganese oxide slurry, sulfur dioxide gas, and ozone into an absorption leaching reactor, causing gas-liquid-solid three-phase contact to perform an absorption leaching reaction, utilizing ozone to oxidize manganese dithionate into manganese sulfate and sulfuric acid, and discharging the slurry into a purification and impurity removal reactor after the absorption leaching reaction is completed. Ozone is continuously introduced into the slurry and the pH is raised to between 5.0 and 5.5 to perform deoxidation, hydrolysis, precipitation, and removal of iron and aluminum. Ozone is also utilized to oxidize Mn. 2+ The heavy metals are adsorbed and removed by the small and porous Mn3O4. This solution introduces ozone into the reduction leaching system, but the purchase or preparation cost of ozone is high, and it is bound to partially oxidize the SO2 and sulfurous acid in the reduction leaching system, thereby affecting the consumption of the reducing agent.

[0007] CN107445209B discloses a method for removing manganese dithionate from a pyrolusite pulp leachate to prepare a saturated manganese sulfate slurry and manganese sulfate. The method comprises heating a mixed solution of manganese sulfate and manganese dithionate, evaporating and concentrating the solution to a saturated solution with crystal precipitation, then adding sulfuric acid to adjust the H2SO4 content in the evaporated solution to not less than 1 mol / L, decomposing the manganese dithionate into manganese sulfate and sulfur dioxide under high acid and high temperature (not less than 90°C), and then subjecting the saturated manganese sulfate slurry from which the manganese dithionate has been removed to solid-liquid separation to obtain manganese sulfate crystals and a manganese sulfate solution with a high acid content. This technical solution uses a high-concentration strong acid to decompose the manganese dithionate at a temperature not less than 90°C. The evaporated steam contains a large amount of SO2 gas, which condenses with the steam to form sulfurous acid. The corrosion problem faced by both the SO2 gas and the sulfurous acid in the entire production device is a major industrial problem.

[0008] In summary, manganese oxide ore (pyrolusite) can be produced using two major processes: pyrocarbon reduction and wet reduction to produce high-purity manganese sulfate monohydrate, manganese trimanganese tetroxide, manganese carbonate, and other battery-grade manganese products. Research on the wet reduction of manganese oxide ore with SO2 dates back decades, but to date, large-scale production and application have yet to be achieved. Currently, over 95% of high-purity manganese sulfate monohydrate and battery-grade manganese trimanganese tetroxide on the market are produced using pyrocarbon reduction, the two-ore acidification process, and the rhodochrosite acid leaching / electrolytic manganese flake process. As recognized by industry researchers, the core technical challenge of successfully translating the wet reduction of manganese oxide ore with SO2 into large-scale production is how to efficiently and cost-effectively address the impact of dithionate generated as a side reaction during SO2 reduction and leaching on subsequent processes and product quality. Furthermore, breakthroughs in impurity removal technologies are needed for low-grade, high-impurity manganese ore raw materials. Summary of the Invention

[0009] In order to overcome the problem that the current SO2 wet reduction process of manganese oxide ore cannot efficiently and cost-effectively solve the impact of dithionate generated by the side reaction during the SO2 reduction leaching process on subsequent processes and product quality, resulting in the inability to achieve large-scale production and application, the present invention provides a method for reducing manganese oxide ore with sulfur dioxide to prepare high-purity manganese sulfate and co-produce manganese dioxide for batteries. The method is a SO2 wet reduction process for manganese oxide ore with strong economic competitiveness and low carbon, environmental protection and resource conservation. The technical solution of the present invention uses the SO2 wet reduction process for pyrolusite to prepare high-purity manganese sulfate and co-produce battery-grade MnO2 products without using a carbon-based reducing agent. It is a truly low-carbon process and is forward-looking and developmental for the domestic manganese product industry to gain a foothold and compete in the industry.

[0010] The method of reducing manganese oxide ore with sulfur dioxide to prepare high-purity manganese dioxide for manganese sulfate co-production batteries according to the present invention has the following technical principles:

[0011] A method for preparing high-purity MnSO4 co-production battery MnO2 by reducing manganese oxide ore with SO2, the principle is as follows:

[0012] (1) Grinding the oxidized manganese ore into a fine powder of less than 100 mesh and then mixing it with a solvent in a certain proportion to obtain a slurry of ore powder, wherein the solvent can be tap water, pure water or manganese-containing process water produced in the workshop;

[0013] (2) The ore powder slurry and SO2 gas are sent to the absorption reaction tower. The gas and manganese ore slurry are in countercurrent contact in the absorption reaction tower and undergo redox reaction. The high-order manganese oxides in the manganese oxide ore are reduced to Mn 2+ When it enters the solution, SO2 is absorbed and oxidized to form SO4 2- and some by-products S2O6 2- ;

[0014] (3) After the reaction is completed, the slurry liquid is transferred to the hydrolysis sedimentation tank, and an acid-consuming agent is added to the hydrolysis sedimentation tank to adjust the pH to 4.0-6.5 to make Fe 3+ , AL 3+ Hydrolysis precipitation, and then sending the slurry after the hydrolysis precipitation reaction is completed into a filter press for filtration to obtain filter residue and filtrate;

[0015] (4) The filtrate is transferred to a sealed container, and SO2 gas is introduced into the sealed container to allow the filtrate to absorb SO2 to generate sulfurous acid. When the pH of the solution drops to 0.5-2.5, the introduction of SO2 is stopped, and then an appropriate amount of metallic manganese powder is added to adjust the pH to 6.0-7.0. The pressure in the sealed container is maintained between 0.05 and 0.35 MPa. After a certain reaction time, the filter is filtered to obtain the impurity-removed residue and the impurity-removed filtrate;

[0016] (5) The filtrate after impurity removal is sent to the MnO2 preparation reactor for battery, and after adding the oxidant, it is stirred and heated to 90℃~160℃ for a certain reaction time. After that, the feed liquid is discharged for solid-liquid separation. When the reaction temperature is below 100℃, S2O6-free is obtained. 2- The impurity manganese sulfate solution and MnO2 powder crude product are rinsed with pure water to remove the trace amount of manganese sulfate and other soluble salts, and then solid-liquid separation is performed again to obtain MnO2 powder fine product. When the reaction temperature is between 110℃ and 160℃, S2O6-free 2- The impurity-free dilute manganese sulfate solution and the (MnO2 and MnSO4·H2O) mixed powder crude product are dissolved in pure water to remove the MnSO4·H2O crystals and other soluble salts, and then the solid-liquid separation is performed again to obtain S2O6-free 2- The impurities in the manganese sulfate solution and the crude MnO2 powder are rinsed with pure water to remove the trace amount of manganese sulfate and other soluble salts, and then the solid-liquid separation is performed again to obtain the fine MnO2 powder. The obtained fine MnO2 powder is dried to obtain a highly pure MnO2 product for battery use;

[0017] (6) No S2O6 2- The impure manganese sulfate solution is used as a recrystallization solution to obtain high-purity manganese sulfate. The solution is sent to a high-temperature crystallization kettle for heating and crystallization at 140°C to 200°C for 2 to 3 times. After solid-liquid separation and drying, the monohydrate manganese sulfate product for battery use can be obtained.

[0018] The purpose of the present invention is achieved through the following technical solutions:

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

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

[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 1:1.10-1.50. At a reaction temperature of 30℃-90℃, the SO2 gas and mineral powder slurry are countercurrently contacted and absorbed in the absorption reaction tower and a redox reaction occurs. The high-order manganese oxides in the manganese oxide ore are reduced to Mn 2+ When it enters the solution, SO2 is absorbed and oxidized to form SO4 2- and by-product S2O6 2- After the reaction is completed, the reduction leaching slurry is obtained and output evenly and continuously;

[0022] S3, the reduction leaching slurry described in the above step is placed in a hydrolysis precipitation tank, and an acid-consuming agent is added to the hydrolysis precipitation tank to adjust the pH value to 4.0-6.5, so that the Fe in the reduction leaching slurry 3+ , AL 3+ Hydrolysis precipitation, then the slurry after the hydrolysis precipitation reaction is completed is sent to the filter press for filtration to obtain filter residue and iron and aluminum removed liquid;

[0023] S4. Place the iron and aluminum removed solution in a sealed container for impurity removal reaction. Pass SO2 gas into the sealed container. The water in the solution absorbs SO2 to generate sulfurous acid, so that the iron and aluminum removed solution contains SO3 - When the pH of the solution drops to 0.5-2.5, stop introducing SO2, then add 2.0-5.0 times the molar amount of manganese powder equivalent to the sum of the heavy metal ion contents in the solution to adjust the pH to 6.0-7.0, maintain the pressure in the sealed container at 0.05MPa-0.35MPa, react for 2-5 hours, and simultaneously precipitate and remove calcium ions and various heavy metal impurities, and filter press to obtain the impurity-removed residue and impurity-removed filtrate;

[0024] S5, the filtrate after impurity removal is sent to an oxidation synthesis reactor, after adding an oxidant, stirring and heating to 90°C to 160°C for reaction for 2h to 24h, and then the slurry liquid is discharged for solid-liquid separation;

[0025] When the reaction temperature is below 100℃, manganese sulfate fails to crystallize or the amount of crystallization is very small, and S2O6-free 2- The impurity manganese sulfate solution and MnO2 crude powder are rinsed with pure water to remove the trace amount of soluble manganese sulfate salts carried by the crude MnO2 powder, and then solid-liquid separation is performed again to obtain the fine MnO2 powder;

[0026] When the reaction temperature is 110℃~160℃, manganese sulfate crystals are precipitated, and the higher the temperature, the greater the precipitation amount, and S2O6-free 2- The mother liquor of dilute manganese sulfate solution with impurities and the crude mixed powder of (MnO2 and MnSO4·H2O) are used to dissolve the soluble salt of MnSO4·H2O crystals in the crude mixed powder of (MnO2 and MnSO4·H2O) with pure water, and then solid-liquid separation is performed again to obtain S2O6-free 2- The impurity-free manganese sulfate solution and MnO2 crude powder are rinsed with pure water to remove the trace amount of soluble manganese sulfate salts carried by the crude MnO2 powder, and then solid-liquid separation is performed again to obtain MnO2 fine powder. The obtained MnO2 fine powder is dried to obtain a highly pure MnO2 product for battery use;

[0027] S6, the S2O6-free 2- The impurity manganese sulfate solution is sent to the high temperature crystallization kettle. If there is no S2O6 2- If the concentration of impurity manganese sulfate solution is lower than 30 degrees Baume, it needs to be evaporated and concentrated to a concentration between 30 and 40 degrees Baume, and then heated to 140℃~200℃ for high temperature recrystallization twice. After solid-liquid separation and drying, monohydrate manganese sulfate product for battery can be obtained. The manganese element leaching rate is ≥98%, and the exhaust gas after absorption is <30mg / m 3 .

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

[0029] Furthermore, the SO2 gas described in step S2 is a gas composed of a SO2 volume fraction of 0.1 to 100% and a volume fraction of the remaining components of 99.9% to 0%. The volume fraction of SO2 in the gas does not affect the manganese leaching rate of the manganese oxide ore to achieve the goal of 98% for this technical solution. It is only necessary to configure a sufficient number of absorption reaction tower devices to ensure that SO2 can be completely absorbed so that the Mn:SO2 molar ratio of the two reaction materials can react at a ratio of 1:1.10 to 1.50; the remaining components refer to one or more combinations of any proportions of common non-toxic and flammable and explosive gases in the atmospheric environment, such as air, nitrogen, and carbon dioxide, but it should be emphasized that too high a volume content of oxygen in the combined gas will increase the proportion of SO2 oxidized to sulfuric acid in the absorption reaction tower, and then the pH value of the slurry liquid will gradually decrease.

[0030] Furthermore, the SO2 gas and the mineral powder slurry described in step S2 are countercurrently contacted and absorbed in the absorption reaction tower and undergo 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 based on the pH value of the slurry system being maintained 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 by-production of a certain amount of MnS2O6 to increase the subsequent production ratio of MnO2. The size of the SO2 gas inlet flow rate is such that the gas phase flow rate in the tower is between 0.1 and 5.0 m / s and the exhaust gas discharged from the tower contains less than 30 mg / m 3 The method is used to control the SO2 content in the exhaust gas to ensure that it is far lower than the limit of 400mg / m3 in the "GB31573-2015 Inorganic Chemical Industry Pollutant Emission Standard" 3 The reaction principles involved are mainly:

[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°C to 100°C, preferably 80°C to 100°C; the acid-consuming agent can be composed of one or more of calcium carbonate, metallic manganese powder, manganese carbonate, and manganese monoxide in any proportion, but calcium carbonate is preferably used as the acid-consuming agent in consideration of the price and cost of raw and auxiliary materials. The amount of the acid-consuming agent added is based on the pH value of the reduction leaching slurry rising to 4.0 to 6.5.

[0035] Furthermore, the impurity removal reaction temperature in step S4 is between 30 and 100°C, preferably 50 to 90°C. Using a sealed container as the reactor can prevent oxygen from the outside air from entering the reactor to absorb SO2 and generate SO3. 2-Oxidative destruction is carried out, thereby affecting the sulfite ion and CaSO4, MnSO4 in the solution to form a sulfite-sulfate complex insoluble precipitation and removal. The sulfite-sulfate complex insoluble is formed under conditions close to neutral and weak alkaline. The technical solution promotes the formation of sulfite-sulfate complex insoluble precipitation by adjusting the pH to 6.0-7.0 according to the molar amount of 2.0-5.0 times the sum of the heavy metal ion contents in the solution using metal manganese powder, and simultaneously replaces and removes various heavy metal impurity ions; after adding metal manganese powder, hydrogen will be generated to increase the pressure in the closed container, and the pressure in the container is controlled to be 0.05-0.35MPa through valve discharge, increasing the total pressure in the container to promote the dissolution of SO2 in the upper gas phase in the container into the slurry to participate in the formation of sulfite-sulfate complex insoluble precipitation. We found that the sulfite-sulfate complex insoluble crystals generated under a certain reaction pressure have larger particle size and more stable properties, which can remove Ca 2+ The content is quickly removed to less than 250 mg / L, achieving effective removal of calcium ions, thereby greatly reducing the pressure of subsequent high-temperature crystallization on the separation and purification of calcium impurities; and after the introduction of SO2 gas to generate a certain amount of sulfurous acid in the solution, on the one hand, the manganese oxide layer on the surface of the metal manganese powder can be reduced and dissolved to expose the manganese metal lattice, greatly increasing the probability of heavy metal impurity ions such as nickel, cobalt, zinc, copper, cadmium, and lead contacting with the manganese metal lattice and undergoing a replacement reaction. On the other hand, the oxidizing substances in the reaction liquid system can be reduced to form a reducing atmosphere with a very low potential, which is conducive to the replacement reaction between heavy metal ions and metal manganese to generate stable heavy metal elemental particles, breaking through the various shortcomings of the existing technology of low efficiency of metal manganese powder in the replacement of heavy metal ions, excessive consumption of equivalents, and unclean replacement and impurity removal. This technical solution can be used in heavy metal ions. The main related 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, Pb, etc.)

[0039] Furthermore, the oxidant in step S5 is one or more of pure oxygen and compressed air, and the amount of the oxidant added is determined by the molar content of O2 in the gas and the S2O6 in the liquid after weight removal. 2-The molar content ratio is 1 to 10. Manganese dithionate is oxidized to MnO2 and H2SO4 under heating (90 to 160°C) using the oxidizing property 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 deficiency. As a battery positive electrode material, they have excellent performance. The relevant reaction principle is as follows:

[0040]

[0041] Furthermore, the high-temperature recrystallization described in step S6 uses a controlled-rate crystallization technique. The controlled-rate crystallization technique is based on the basic physical property correspondence between the solubility of manganese sulfate and temperature, and through a large number of exploratory experiments, optimal crystallization process parameters are obtained that are conducive to crystallization separation and purification of impurity ions and to obtaining uniform crystal particle size. We have conducted a large number of experiments to demonstrate that by controlling the heating rate of the manganese sulfate solution during the crystallization process, it is found that the supersaturation is maintained, which is conducive to crystallization separation and purification of impurity ions and to obtaining uniform crystal particle size. The operating method of the controlled-rate crystallization process is as follows:

[0042] The initial concentration of the solution before high temperature crystallization begins C (硫酸锰) When the temperature is less than 35 degrees Baume, the heating rate is not controlled before the temperature is raised to ≤80°C. When the temperature is between 80 and 100°C, the crystallization is carried out at a rate of 1.3 to 2.0°C / min. When the temperature is between 100 and 140°C, the crystallization is carried out at a rate of 0.44 to 0.67°C / min. When the temperature is between 140 and 200°C, the crystallization is carried out at a rate of 1.0 to 1.5°C / min.

[0043] The initial concentration of the solution before high temperature crystallization begins C (硫酸锰) When the temperature is ≥35 degrees Baume, the heating rate is not controlled before the temperature is raised to ≤70°C. When the temperature is between 70 and 100°C, the crystallization is carried out at a rate of 1.2 to 1.6°C / min. When the temperature is between 100 and 140°C, the crystallization is carried out at a rate of 0.38 to 0.60°C / min. When the temperature is between 140 and 200°C, the crystallization is carried out at a rate of 1.0 to 1.5°C / min.

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

[0045] 1. The method of preparing high-purity manganese sulfate co-production manganese dioxide for batteries by reducing manganese oxide ore with sulfur dioxide according to the present invention has wide applicability to manganese ore raw materials, and the manganese leaching rate can reach more than 98%. The use of this process technology scheme can easily achieve a comprehensive manganese recovery rate of more than 95% and produce two high-value products, high-purity MnSO4 and MnO2 for batteries.

[0046] 2. As recognized by researchers in this field: The core technical difficulty of SO2 reduction of manganese ore is how to efficiently remove the impurity component S2O6 generated by the side reaction. 2- The present invention discloses a method for reducing manganese oxide ore with sulfur dioxide to produce high-purity manganese sulfate co-produced manganese dioxide for batteries. In the MnS2O6 removal process, a high-temperature oxidation process is employed to cleverly decompose and remove MnS2O6 in the same reactor to produce a manganese sulfate solution and co-produce a high-quality MnO2 product suitable for battery use. This achieves two goals at once, with low process costs, a concise process flow, and ease of stable control. We have successfully converted the harmful side-reaction impurity MnS2O6 present in the prior art into a component beneficial to this technical solution, embodying the concept of transforming harm into benefit.

[0047] 3. Unlike the existing technology that tries every possible means to minimize the amount of MnS2O6 generated during the reduction leaching process, the present invention uses MnS2O6 as an intermediate product to produce high-value battery-grade products, and allows the generation of MnS2O6 during the reduction leaching process; unlike the existing technology that decomposes MnS2O6 into manganese sulfate and corrosive pollutant SO2 gas, the technical solution of the present invention directly prepares MnS2O6 into high-purity MnO2, does not generate SO2 gas, and is friendly to production process equipment and the environment.

[0048] 4. The present invention uses SO2-containing flue gas from metal smelting or SO2 gas from sulfuric acid industry as reducing agent, which has a wide source and is economical. After absorption, the exhaust gas can be as low as 30mg / m 3 Within, far below the national environmental protection requirement ≤400mg / m 3 limit.

[0049] 5. In the impurity removal step, the present invention removes calcium ions and heavy metal impurity ions in the same technical step, combines the calcium removal and heavy metal removal steps in the prior art into one, and greatly shortens the process flow. By introducing SO2 gas to generate a certain amount of sulfite in the solution, and then adding metal manganese powder to control the pH value of the solution system, the sulfite forms a sulfite-sulfate complex insoluble product with CaSO4 and MnSO4 in the solution, and the Ca 2+The content is quickly controlled within 250 mg / L, achieving effective removal of calcium ions, thereby greatly reducing the pressure of subsequent high-temperature crystallization on the separation and purification of calcium impurities; and after the introduction of SO2 gas to generate a certain amount of sulfurous acid in the solution, on the one hand, the manganese oxide layer on the surface of the metallic manganese powder can be reduced and dissolved to expose the manganese metal lattice, greatly improving the probability of heavy metal impurity ions such as nickel, cobalt, zinc, copper, cadmium, and lead contacting with the manganese metal lattice and undergoing a replacement reaction; on the other hand, the oxidizing substances in the reaction liquid system can be reduced to form a reducing atmosphere with a very low potential, which is conducive to the replacement reaction between heavy metal ions and metallic manganese to generate stable heavy metal elemental particles, breaking through various disadvantages of the existing technology of low efficiency of heavy metal ion replacement by metallic manganese powder, excessive consumption of equivalents, and unclean replacement and impurity removal.

[0050] 6. The present invention adopts a controlled rate crystallization method for high-temperature crystallization, which steadily increases the primary crystallization separation and purification rate of impurity ions such as magnesium, calcium, potassium, and sodium from 70-80% to over 90%, greatly improving the ability of crystallization to separate and purify impurity ions, and achieving the goal of obtaining battery-grade high-purity manganese sulfate products after only two recrystallizations. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a process flow of a method for reducing manganese oxide ore with sulfur dioxide to prepare high-purity manganese sulfate co-production battery manganese dioxide according to an embodiment of the present invention. Figure 1 (When the reaction temperature in step S5 is below 100°C);

[0052] Figure 2 This is a process flow of a method for reducing manganese oxide ore with sulfur dioxide to prepare high-purity manganese sulfate co-production battery manganese dioxide according to an embodiment of the present invention. Figure 2 (When the reaction temperature in step S5 is 110-160°C). DETAILED DESCRIPTION

[0053] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0054] Figure 1 This is the process flow of the method for preparing high-purity manganese dioxide for co-production of manganese sulfate 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°C);

[0055] Example 1:

[0056] A method for preparing high-purity MnSO4 co-production MnO2 for batteries by reducing manganese oxide ore with SO2 comprises 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 content in the ore powder, including the manganese in the MnO2 component.

[0060] The main components of SO2 gas are as follows:

[0061]

[0062] S1. Grind the oxidized manganese ore into 100-300 mesh manganese ore fine powder and mix it 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. At a reaction temperature of 50℃~70℃, the SO2 gas and mineral powder slurry are countercurrently contacted and absorbed in the absorption reaction tower and a redox reaction occurs. The high-order manganese oxides in the manganese oxide ore are reduced to Mn 2+ When it enters the solution, SO2 is absorbed and oxidized to form SO4 2- and some by-products S2O6 2- After the reaction is completed, the reduction leaching slurry is uniformly and continuously output. The pH value of the reduction leaching slurry is 3.05, and it contains S2O6 2- 43.27g / L;

[0064] S3, the reduction leaching slurry described in the above step is transferred to the hydrolysis precipitation tank, the reduction leaching slurry temperature is adjusted to between 50 ° C and 70 ° C, calcium carbonate is added to the hydrolysis precipitation tank to adjust the pH value to 4.21 so that the Fe in the reduction leaching slurry is reduced. 3+ , AL 3+ After hydrolysis and precipitation, the slurry after the hydrolysis and precipitation reaction is completed is sent to the filter press for filtration to obtain the filter residue and the iron and aluminum removal liquid. The iron and aluminum removal liquid is taken for testing and analysis. The main components that need to be controlled are as follows:

[0065]

[0066] S4. Transfer the liquid after iron and aluminum removal into a sealed container, control the temperature of the reaction liquid between 30 and 45 ° C, and introduce SO2 gas into the sealed container. When the pH of the solution drops to 1.55, stop introducing SO2, and then add metal manganese powder in an amount of 5.0 times the chemical reaction equivalent of the total molar content of heavy metal impurities contained in the liquid after iron and aluminum removal. After reacting for 5 hours, the pH rises to 6.85. The pressure in the sealed container is 0.27 MPa, and filter press to obtain the impurity-removed residue and impurity-removed filtrate. The impurity-removed filtrate is sampled for detection. Ca 2+ The residual amount is 207.50 mg / L, Ca 2+ The removal rate is 72.87%, and the removal rates of various heavy metals are all above 90%. The main components that require quality control are as follows:

[0067]

[0068] S5, send the filtrate after impurity removal into the oxidation synthesis reactor, and add the O2 molar amount and S2O6 contained in the filtrate after impurity removal. 2- The molar ratio is 10.0, pure oxygen as an oxidant is added, stirred, and the temperature is raised to 90°C to 100°C for reaction for 24 hours, and then the liquid is discharged for solid-liquid separation to obtain manganese sulfate solution and crude MnO2 powder. The crude MnO2 powder is rinsed with pure water to remove trace amounts of manganese sulfate and other soluble salts, and then solid-liquid separation is performed again to obtain high-purity MnO2 powder. The high-purity MnO2 powder is dried to obtain extremely pure MnO2 products for batteries. The manganese sulfate solution is taken to detect S2O6 2- The residual amount is 0.08g / L, S2O6 2- The removal rate is 99.82%. The MnO2 product was tested for impurity content. The impurity content data are as follows:

[0069]

[0070] S6. The manganese sulfate solution obtained in S5 is subjected to a detection concentration of 37 degrees Baume. The manganese sulfate solution is fed into a high-temperature crystallization kettle and heated to 140°C by heating the material at a rate of 1.2 to 1.6°C / min for crystallization in the temperature range of 70 to 100°C and at a rate of 0.40 to 0.60°C / min for crystallization in the temperature range of 100 to 140°C. This method is used for high-temperature recrystallization twice. After solid-liquid separation and drying, a manganese sulfate monohydrate product for battery use can be 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 the manganese oxide ore reached 98.07%, and the total manganese recovery rate was approximately 95.33%, indicating a high leaching rate. The produced MnO2 product had a low impurity content and an oxygen-deficient crystal structure, and had excellent performance as a battery material. The produced manganese sulfate monohydrate exceeded 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 dioxide for co-production of manganese sulfate 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 co-production MnO2 for battery by reducing manganese oxide ore with SO2, which differs from Example 1 in that:

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

[0077]

[0078] The manganese ore fine powder 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;

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

[0080] Step S3: Adjust the temperature of the reduction leaching slurry in the hydrolysis precipitation tank to between 50°C and 70°C, add manganese carbonate to the hydrolysis precipitation tank to adjust the pH value to 3.93, then add metal manganese powder and continue to adjust the pH value to 6.51 to reduce the Fe in the reduction leaching slurry. 3+ , AL 3+ After hydrolysis and precipitation, the liquid was taken out for iron and aluminum removal and tested and analyzed. The main components that require quality control are as follows:

[0081]

[0082] Step S4 controls the temperature of the reaction liquid to be between 40 and 60° C., introduces SO2 gas into the sealed container until the pH of the solution drops to 2.42, stops introducing SO2, and then adds metal manganese powder in an amount of 4.0 times the chemical reaction equivalent of the total molar content of heavy metal impurities contained in the liquid after iron and aluminum removal. After reacting for 3 hours, the pH rises to 6.41, the pressure in the sealed container is 0.27 MPa, and filter presses to obtain the impurity-removed residue and the impurity-removed filtrate, and samples the impurity-removed filtrate for detection. Ca 2+ The residual amount is 193.61 mg / L, Ca 2+ The removal rate is 65.03%, and the removal rates of various heavy metals are all above 95%. The main components that require quality control are as follows:

[0083]

[0084] Step S5: The filtrate after impurity removal is sent to the oxidation synthesis reactor, and the O2 molar amount and the S2O6 contained in the filtrate after impurity removal are mixed. 2- The molar ratio is 5.5, and then pure oxygen as an oxidant is added, stirred, and heated to 100°C to 120°C for reaction for 10 hours. After that, the material 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 dissolve MnSO4·H2O crystals and other soluble salts, and then solid-liquid separation is performed again to obtain a manganese sulfate solution and a crude MnO2 powder. The crude MnO2 powder is rinsed with pure water to remove trace amounts of soluble salts such as manganese sulfate entrained, and then solid-liquid separation is performed again to obtain a high-purity MnO2 powder product. The high-purity MnO2 powder product is dried to obtain a highly pure MnO2 product for battery use. The manganese sulfate solution is taken to detect S2O6 2- The residual amount was not detected, S2O6 2- The removal rate is 100%. The MnO2 product was taken for impurity content testing. The impurity content data are as follows:

[0085]

[0086] In step S6, the manganese sulfate solution obtained in step S5 is subjected to a detection concentration of 34 degrees Baume and a temperature of 83.7°C. The manganese sulfate solution is fed into a high-temperature crystallization kettle and heated to 200°C for crystallization at a rate of 1.3-2.0°C / min in the temperature range of 80-100°C, 0.44-0.67°C / min in the temperature range of 100-140°C, and 1.0-1.5°C / min in the temperature range of 140-200°C. Following this method, high-temperature recrystallization is performed twice, followed by solid-liquid separation and drying to obtain a 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 the manganese oxide ore reached 99.04%, and the total manganese recovery rate was approximately 97.22%, indicating a high leaching rate. The produced MnO2 product had a low impurity content and an oxygen-deficient crystal structure, and had excellent performance as a battery material. The produced manganese sulfate monohydrate exceeded the performance requirements of battery-grade products.

[0089] Example 3:

[0090] A method for preparing high-purity MnSO4 co-production MnO2 for battery by reducing manganese oxide ore with SO2, which differs from Example 1 in that:

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

[0092]

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

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

[0095] Step S3: Adjust the temperature of the reduction leaching slurry in the hydrolysis precipitation tank to between 80°C and 90°C, add manganese monoxide powder into the hydrolysis precipitation tank to adjust the pH value to 4.07, then add metal manganese powder and continue to adjust the pH value to 6.94 to reduce the Fe in the reduction leaching slurry. 3+ , AL 3+ After hydrolysis and precipitation, the liquid was taken out for iron and aluminum removal and tested and analyzed. The main components that require quality control are as follows:

[0096]

[0097] Step S4 controls the temperature of the reaction liquid to be between 60 and 80°C, introduces SO2 gas into the sealed container until the pH of the solution drops to 1.07, stops introducing SO2, then adds metal manganese powder in an amount of 2.5 times the chemical reaction equivalent of the total molar content of heavy metal impurities contained in the liquid after iron and aluminum removal, and after reacting for 3 hours, the pH rises to 6.76, the pressure in the sealed container is 0.33 MPa, and filter presses to obtain the impurity-removed residue and the impurity-removed filtrate, and samples the impurity-removed filtrate for detection, Ca 2+ The residual amount is 217.34 mg / L, Ca 2+ The removal rate is 65.10%, and the removal rates of various heavy metals are all above 99%. The main components that require quality control are as follows:

[0098]

[0099] Step S5: The filtrate after impurity removal is sent to the oxidation synthesis reactor, and the O2 molar amount and the S2O6 contained in the filtrate after impurity removal are mixed. 2- The molar ratio is 3.0, and then pure oxygen as an oxidant is added, stirred, and heated to 120°C to 140°C for reaction for 5 hours. After that, the feed 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 dissolve MnSO4·H2O crystals and other soluble salts, and then solid-liquid separation is performed again to obtain a manganese sulfate solution and a 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 solid-liquid separation is performed again to obtain a high-purity MnO2 powder. The high-purity MnO2 powder is dried to obtain a highly pure MnO2 product for battery use. The manganese sulfate solution is taken to detect S2O6 2- The residual amount was not detected, S2O6 2- The removal rate is 100%. The MnO2 product was taken for impurity content testing. The impurity content data are as follows:

[0100]

[0101]

[0102] In step S6, the manganese sulfate solution obtained in step S5 has a detected concentration of 31 degrees Baume and a temperature of 85.2°C. The manganese sulfate solution is fed into a high-temperature crystallization kettle and heated to 160°C for crystallization at a rate of 1.3°C / min to 2.0°C / min in the temperature range of 80°C to 100°C, at a rate of 0.44°C / min to 0.67°C / min in the temperature range of 100°C to 140°C, and at a rate of 1.0°C / min to 1.5°C / min in the temperature range of 140°C to 200°C. Following this method, high-temperature recrystallization is performed twice, followed by solid-liquid separation and drying to obtain a 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 the manganese oxide ore reached 98.84%, and the total manganese recovery rate was approximately 96.49%, indicating a high leaching rate. The produced MnO2 product had a low impurity content and a crystal structure with oxygen defects, and had excellent performance as a battery material. The produced manganese sulfate monohydrate exceeded the performance requirements of battery-grade products.

[0105] Example 4:

[0106] A method for preparing high-purity MnSO4 co-production MnO2 for battery by reducing manganese oxide ore with SO2, which differs from Example 1 in that:

[0107] The manganese oxide ore used is the same as the raw material, and the SO2 gas is high-purity SO2 vaporized from liquefied sulfur dioxide:

[0108]

[0109] The manganese ore fine powder in step S1 has a mesh size of 100-200 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 mixed and reacted at a molar ratio of Mn:SO2 of 1:1.50. The reaction temperature is controlled within the range of 60°C to 80°C during the reaction. After the reaction, the pH value of the reduction leaching slurry obtained is 2.53, and the content of S2O6 is 2.53. 2- 63.47g / L;

[0111] Step S3: Adjust the temperature of the reduction leaching slurry in the hydrolysis precipitation tank to between 90℃ and 100℃, add calcium carbonate into the hydrolysis precipitation tank to adjust the pH value to 5.62 to reduce the Fe in the reduction leaching slurry. 3+ , AL 3+ After hydrolysis and precipitation, the liquid was taken out for iron and aluminum removal and tested and analyzed. The main components that require quality control are as follows:

[0112]

[0113] Step S4: Control the temperature of the reaction liquid between 80 and 100°C, introduce SO2 gas into the sealed container until the pH of the solution drops to 0.49, stop introducing SO2, then add metal manganese powder in an amount of 2.0 times the chemical reaction equivalent of the total molar content of heavy metal impurities contained in the liquid after iron and aluminum removal, and after reacting for 2 hours, the pH rises to 6.83, the pressure in the sealed container is 0.35 MPa, and filter press to obtain the impurity-removed residue and the impurity-removed filtrate, and sample the impurity-removed filtrate for detection, Ca 2+ The residual amount is 207.56 mg / L, Ca 2+ The removal rate is 65.10%, and the removal rates of various heavy metals are all above 97%. The main components that require quality control are as follows:

[0114]

[0115] Step S5: The filtrate after impurity removal is sent to the oxidation synthesis reactor, and the O2 molar amount and the S2O6 contained in the filtrate after impurity removal are mixed. 2- The molar ratio is 1.2, and then compressed air is added as an oxidant, stirred, and heated to 140°C to 160°C for reaction for 2 hours. The material 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 dissolve MnSO4·H2O crystals and other soluble salts, and then solid-liquid separation is performed again to obtain a manganese sulfate solution and a crude MnO2 powder. The crude MnO2 powder is rinsed with pure water to remove trace amounts of soluble salts such as manganese sulfate entrained, and then solid-liquid separation is performed again to obtain a high-purity MnO2 powder product. The high-purity MnO2 powder product is dried to obtain a highly pure MnO2 product for battery use. The manganese sulfate solution is taken for detection. The residual amount is 0.12g / L, The removal rate is 99.81%. The MnO2 product was tested for impurity content. The impurity content data are as follows:

[0116]

[0117] In step S6, the manganese sulfate solution obtained in step S5 is concentrated to a concentration of 25 degrees Baume and a temperature of 82.3°C. The manganese sulfate solution is concentrated to 40 degrees Baume by vacuum evaporation and then fed into a high-temperature crystallization kettle. The material is heated to 160°C by heating and crystallizing at a rate of 1.2 to 1.6°C / min when the temperature is between 70 and 100°C, at a rate of 0.40 to 0.60°C / min when the temperature is between 100 and 140°C, and at a rate of 1.0 to 1.5°C / min when the temperature is between 140 and 200°C. Following this method, high-temperature recrystallization is performed twice, followed by solid-liquid separation and drying to obtain a 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 the manganese oxide ore reached 99.23%, and the total manganese recovery rate was approximately 97.57%, indicating a high leaching rate. The produced MnO2 product had a low impurity content and an oxygen-deficient crystal structure, and had excellent performance as a battery material. The produced manganese sulfate monohydrate exceeded the performance requirements of battery-grade products.

[0120] Example 5:

[0121] A method for preparing high-purity MnSO4 co-production MnO2 for batteries by reducing manganese oxide ore with SO2 comprises the following steps:

[0122] In this example, MHP (Note: MHP is the abbreviation of Mixed Hydroxide Precipitate, which refers to nickel cobalt hydroxide) is used as a raw material to produce nickel and cobalt products. The manganese oxide slag, which is a by-product, is used as a raw material. The main components of the manganese oxide slag are detected as follows:

[0123]

[0124] Note: The total Mn component data in the composition data of manganese oxide slag refers to the manganese content in the ore powder, including the manganese in the MnO2 component.

[0125] The main components of SO2 gas are as follows:

[0126]

[0127] S1. Grind and sieve the manganese oxide slag to obtain fine manganese slag powder below 100 mesh, and mix it with tap water in a mass ratio of 1:2.5 to prepare a manganese oxide slag slurry;

[0128] S2. Manganese oxide slag slurry and SO2 gas are uniformly and continuously fed 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, the pH value of the slurry liquid drops below 2.50. A small amount of manganese monoxide powder is continuously added to maintain the pH value of the slurry liquid between 2.50 and 3.0. After the reaction is completed, the reduction leaching slurry is uniformly and continuously output. The pH value of the reduction leaching slurry is tested to be 2.64, containing S2O6 2- 38.68g / L;

[0129] S3, the reduction leaching slurry described in the above step is transferred to the hydrolysis precipitation tank, the reduction leaching slurry temperature is adjusted to between 80 ° C and 90 ° C, calcium carbonate is added to the hydrolysis precipitation tank to adjust the pH value to 5.35 so that the Fe in the reduction leaching slurry is reduced. 3+ , AL 3+ After hydrolysis and precipitation, the slurry after the hydrolysis and precipitation reaction is completed is sent to the filter press for filtration to obtain the filter residue and the iron and aluminum removal liquid. The iron and aluminum removal liquid is taken for testing and analysis. The main components that need to be controlled are as follows:

[0130]

[0131] S4. Transfer the de-ironized and de-aluminized liquid into a sealed container, control 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 metal manganese powder in an amount of 2.0 times the chemical reaction equivalent of the total molar content of heavy metal impurities contained in the de-ironized and de-aluminized liquid. After reacting for 2 hours, the pH rises to 6.97. The pressure in the sealed container is 0.29 MPa. After reacting for 3.5 hours, filter press to obtain the de-impurity residue and de-impurity filtrate. Sampling the de-impurity filtrate for detection, Ca 2+ The residual amount is 203.47 mg / L, Ca 2+ The removal rate is 72.41%, and the removal rate of various heavy metals is above 99%. The main components that require quality control are as follows:

[0132]

[0133] S5, send the filtrate after impurity removal into the oxidation synthesis reactor, and add the O2 molar amount and S2O6 contained in the filtrate after impurity removal. 2-The molar ratio is 3.0, and then pure oxygen as an oxidant is added, stirred, and heated to 120°C to 140°C for reaction for 5 hours. After that, the feed 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 dissolve MnSO4·H2O crystals and other soluble salts, and then solid-liquid separation is performed again to obtain a manganese sulfate solution and a 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 solid-liquid separation is performed again to obtain a high-purity MnO2 powder. The high-purity MnO2 powder is dried to obtain a highly pure MnO2 product for battery use. The manganese sulfate solution is taken to detect S2O6 2- The residual amount was not detected, S2O6 2- The removal rate is 100%. The MnO2 product was taken for impurity content testing. The impurity content data are as follows:

[0134]

[0135]

[0136] S6. The manganese sulfate solution obtained in S5 is subjected to a detection concentration of 40 degrees Baume. The manganese sulfate solution is fed into a high-temperature crystallization kettle and heated to 160°C by heating the material at a rate of 1.2 to 1.6°C / min for crystallization in the temperature range of 70 to 100°C and at a rate of 0.40 to 0.60°C / min for crystallization in the temperature range of 100 to 140°C. This method is used for high-temperature recrystallization twice. After solid-liquid separation and drying, a manganese sulfate monohydrate product for battery use can be 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 the manganese oxide ore reached 99.20%, and the total manganese recovery rate was approximately 97.76%, indicating a high leaching rate. The produced MnO2 product had a low impurity content and an oxygen-deficient crystal structure, and had excellent performance as a battery material. The produced manganese sulfate monohydrate exceeded the performance requirements of battery-grade products.

[0139] Comparative Example 1:

[0140] According to the same steps and material ratios as in Example 3, the reaction liquid in step S4 was placed in an open reaction vessel, and SO2 gas was introduced into the liquid until the pH of the solution dropped to 1.07; then, metallic manganese powder was added and the reaction vessel was kept under normal pressure and stirred for reaction. After the reaction, filter press was performed to obtain impurity-removed residue and impurity-removed filtrate, and the impurity-removed filtrate was sampled for detection. Ca 2+ The residual amount is 501.52 mg / L, Ca 2+The removal rate was only 19.48%, Cu 2+ The removal rate is 98.12%, and the removal rates of other heavy metals are all below 85%. The main components that require quality control are as follows:

[0141]

[0142] In step S5, the molar amount of O2 is equal to the S2O6 contained in the filtrate after impurity removal. 2- The molar ratio is 0.8, pure oxygen as an oxidant is added, stirred, and heated to 120°C to 140°C for reaction for 5 hours, after which the liquid is discharged for solid-liquid separation;

[0143] After the reaction is completed, the discharged material has a distinct pungent and unpleasant smell of SO2 gas. Take manganese sulfate solution to detect S2O6 2- The residual amount is 5.84g / L, S2O6 2- The removal rate is only 84.84%.

[0144] By comparing Example 1 with the embodiment, it can be seen that in an open reaction vessel and under normal pressure reaction conditions, the oxygen in the air can directly contact the reaction materials, causing the redox potential of the reaction system to change and cause Ca 2+ It is difficult to remove heavy metal impurity ions efficiently; and the molar amount of O2 and the S2O6 contained in the filtrate after impurity removal 2- When the molar ratio is reduced from 3.0 to 0.8, S2O6 2- Failure to completely remove it will have a serious impact on the quality control of subsequent processes.

[0145] Comparative Example 2:

[0146] In step S5, add O2 in molar amount and S2O6 in the filtrate after impurity removal. 2- The molar ratio was 3.0, pure oxygen as an oxidant was added, stirred, and heated to 120° C. to 140° C. for 1.5 hours, after which the feed liquid was discharged for solid-liquid separation. The other conditions were the same as those in Example 3.

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

[0148] By comparing Example 2 with the embodiment, it can be seen that the reaction time needs to be more than 2h to ensure the S2O6 2- Completely removed by oxidative decomposition.

[0149] Comparative Example 3:

[0150] In step S5, add O2 in molar amount and S2O6 in the filtrate after impurity removal. 2-The molar ratio was 3.0, and pure oxygen as an oxidant was added, stirred, and heated to 70°C to 80°C for 24 hours;

[0151] Step S6: The manganese sulfate solution obtained in step S5 is subjected to conventional evaporation and concentration at 100° C. to 105° C. under normal pressure. When the crystallization rate of manganese sulfate monohydrate reaches about 75%, solid-liquid separation is performed to obtain a manganese sulfate monohydrate product.

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

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

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

[0155]

[0156] By comparing Example 3 with the embodiment, it can be seen that the reaction temperature is lower than 90°C, even if the reaction time is extended to 24h, the impurity component S2O6 2- The proportion of oxidative decomposition is still very low, and MnO2 products cannot be obtained. The monohydrate manganese sulfate produced by concentrated crystallization has a grayish white appearance after drying, and the three indicators of Mn, Ca and Mg in the test indicators fail to meet the requirements of downstream customers.

[0157] Summary and discussion:

[0158] The present invention uses SO2-containing flue gas from metal smelting or SO2 gas from sulfuric acid industry as reducing agent, which has a wide source and is economical. After absorption, the exhaust gas can be reduced to 30mg / m 3 It is far lower than the requirement of ≤400mg / m3 in GB31573-2015 Inorganic Chemical Industry Pollutant Emission Standard. 3 The process is widely applicable to manganese ore raw materials, and the manganese leaching rate can reach more than 98%. The process technology solution can easily achieve a comprehensive manganese recovery rate of more than 95% and produce two high-value products: high-purity MnSO4 and battery-grade MnO2. The high-temperature oxidation process is cleverly used to decompose and remove S2O6 in the same reactor. 2- Obtain manganese sulfate solution and co-produce high-quality MnO2 products suitable for battery use, efficiently solving the problem of side reaction component S2O6 2-This is a technical means to kill two birds with one stone by overcoming the technical difficulties that hinder the industrialization of processes and products. The process flow is short and the process is easy to stably control. The high-temperature crystallization is carried out by the controlled rate crystallization method, which steadily increases the single crystallization separation and purification rate of impurity ions such as magnesium, calcium, potassium, and sodium from 70-80% to more than 90%, greatly improving the ability of crystallization to separate and purify impurity ions, and achieving the goal of obtaining battery-grade high-purity manganese sulfate products after two recrystallizations.

[0159] The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, without departing from the creative concept of the present invention, they can make non-essential improvements and changes, which all fall within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity manganese dioxide for manganese sulfate co-production batteries by reducing manganese oxide ore with sulfur dioxide, characterized in that: The steps include: S1. Grind the oxidized manganese ore into a 100-500 mesh manganese ore fine powder, and mix the manganese ore fine powder with a solvent in a mass ratio of 1:2.5-10 to prepare a slurry, wherein the solvent is tap water, pure water, or manganese-containing process water produced in the workshop, or any combination thereof; 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. At a reaction temperature of 30℃-90℃, the SO2 gas and mineral powder slurry are countercurrently contacted and absorbed in the absorption reaction tower and a redox reaction occurs. The high-order manganese oxides in the manganese oxide ore are reduced to Mn 2+ When it enters the solution, SO2 is absorbed and oxidized to form SO4 2- and by-product S2O6 2- After the reaction is completed, the reduction leaching slurry is obtained and output evenly and continuously; S3, the reduction leaching slurry described in the above step is placed in a hydrolysis precipitation tank, and an acid-consuming agent is added to the hydrolysis precipitation tank to adjust the pH value to 4.0-6.5, so that the Fe in the reduction leaching slurry 3+ , AL 3+ Hydrolysis precipitation, then the slurry after the hydrolysis precipitation reaction is completed is sent to the filter press for filtration to obtain filter residue and iron and aluminum removed liquid; S4. Place the iron and aluminum removed solution in a sealed container for impurity removal reaction. Pass SO2 gas into the sealed container. The water in the solution absorbs SO2 to generate sulfurous acid, so that the iron and aluminum removed solution contains SO3 - When the pH of the solution drops to 0.5-2.5, stop introducing SO2, then add 2.0-5.0 times the molar amount of manganese powder equivalent to the sum of the heavy metal ion contents in the solution to adjust the pH to 6.0-7.0, maintain the pressure in the sealed container at 0.05MPa-0.35MPa, react for 2-5 hours, and simultaneously precipitate and remove calcium ions and various heavy metal impurities, and filter press to obtain the impurity-removed residue and impurity-removed filtrate; S5, the filtrate after impurity removal is sent to an oxidation synthesis reactor, after adding an oxidant, stirring and heating to 90°C to 160°C for reaction for 2h to 24h, and then the slurry liquid is discharged for solid-liquid separation; When the reaction temperature is below 100℃, manganese sulfate fails to crystallize or the amount of crystallization is very small, and S2O6-free 2- The impurity manganese sulfate solution and MnO2 crude powder are rinsed with pure water to remove the trace amount of soluble manganese sulfate salts carried by the crude MnO2 powder, and then solid-liquid separation is performed again to obtain the fine MnO2 powder; When the reaction temperature is 110℃~160℃, manganese sulfate crystals are precipitated, and the higher the temperature, the greater the precipitation amount, and S2O6-free 2- The mother liquor of dilute manganese sulfate solution with impurities and the crude mixed powder of MnO2 and MnSO4·H2O are used to dissolve the soluble salt of MnSO4·H2O crystals in the crude mixed powder of MnO2 and MnSO4·H2O with pure water, and then solid-liquid separation is performed again to obtain S2O6-free 2- The impurity-free manganese sulfate solution and MnO2 crude powder are rinsed with pure water to remove the trace amount of soluble manganese sulfate salts carried by the crude MnO2 powder, and then solid-liquid separation is performed again to obtain MnO2 fine powder. The obtained MnO2 fine powder is dried to obtain a highly pure MnO2 product for battery use; S6, the S2O6-free 2- The impurity manganese sulfate solution is sent to the high temperature crystallization kettle. 2- If the concentration of the impurity manganese sulfate solution is lower than 30 degrees Baume, it is first evaporated and concentrated to a concentration of 30-40 degrees Baume, and then heated to 140℃-200℃ for high-temperature recrystallization twice. After solid-liquid separation and drying, the monohydrate manganese sulfate product for battery can be obtained. The manganese element leaching rate is ≥98%, and the exhaust gas after absorption is <30mg / m 3 .

2. The method for preparing high-purity manganese dioxide for manganese sulfate co-production batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The SO2 gas described in step S2 is a gas composed of a SO2 volume fraction of 0.1 to 100% and a volume fraction of the remaining components of 99.9% to 0%; the remaining components refer to one or more gases commonly found in the atmospheric environment of air, nitrogen, and carbon dioxide that are non-toxic, flammable, and explosive, in any proportion.

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

4. The method for preparing high-purity manganese dioxide for manganese sulfate co-production 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°C to 100°C; the acid-consuming agent is composed of 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 reduction leaching slurry rising to 4.0 to 6.

5.

5. The method for preparing high-purity manganese dioxide for manganese sulfate co-production 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°C.

6. The method for preparing high-purity manganese dioxide for manganese sulfate co-production batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The oxidant in step S5 is one or more of pure oxygen and compressed air. The amount of oxidant added is determined by the molar ratio of O2 in the gas to the S2O6 in the liquid after weight removal. 2- The molar content ratio is 1 to 10.

7. The method for preparing high-purity manganese dioxide for manganese sulfate co-production batteries by reducing manganese oxide ore with sulfur dioxide according to claim 1, characterized in that: The high temperature recrystallization in step S6 adopts a rate-controlled crystallization process, and the operation method of the rate-controlled crystallization process is as follows: The initial concentration of the solution before high temperature crystallization begins C (硫酸锰) When the temperature is less than 35 degrees Baume, the heating rate is not controlled before the temperature is raised to ≤80°C. When the temperature is between 80 and 100°C, the crystallization is carried out at a rate of 1.3 to 2.0°C / min. When the temperature is between 100 and 140°C, the crystallization is carried out at a rate of 0.44 to 0.67°C / min. When the temperature is between 140 and 200°C, the crystallization is carried out at a rate of 1.0 to 1.5°C / min. The initial concentration of the solution before high temperature crystallization begins C (硫酸锰) When the temperature is ≥35 degrees Baume, the heating rate is not controlled before the temperature is raised to ≤70°C. When the temperature is between 70 and 100°C, the crystallization is carried out at a rate of 1.2 to 1.6°C / min. When the temperature is between 100 and 140°C, the crystallization is carried out at a rate of 0.38 to 0.60°C / min. When the temperature is between 140 and 200°C, the crystallization is carried out at a rate of 1.0 to 1.5°C / min.

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