Preparation method of battery grade manganese sulfate

Abstract

The invention relates to a preparation method of battery grade manganese sulfate. The preparation method comprises the following steps: providing a manganese-containing material, firstly removing water-soluble impurities in the manganese-containing material, and then mixing and slurrying with water to obtain a slurried material; sulfur dioxide gas is introduced into the pulpified material for a reduction leaching reaction, meanwhile, the potential in the reaction process is monitored, when the potential begins to drop from the maximum value and the drop value reaches 150 mV to 270 mV, introduction of the sulfur dioxide gas is stopped, and a reduction leaching solution is obtained; the reduction leaching liquid is subjected to sulfuration impurity removal, and manganese sulfate clear liquid is obtained; carrying out deep oxidation on the manganese sulfate clear liquid to obtain a manganese sulfate purified liquid; and carrying out evaporative crystallization on the manganese sulfate purified liquid at least once to obtain the battery-grade manganese sulfate. According to the preparation method, the manganese-containing material is selectively leached, the technological process is shortened, the utilization rate of sulfur dioxide is increased, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for preparing battery-grade manganese sulfate. Background Art

[0002] Manganese sulfate is a typical representative of manganese compounds. It can be used to produce metallic manganese, other manganese salts and manganese oxides. It is widely used in energy, medicine, fertilizer, feed, food, papermaking, catalyst and other industries. Battery-grade manganese sulfate is mainly used as a precursor for the preparation of positive electrode materials for lithium batteries. The manganese element in the positive electrode material can improve the safety and stability of the battery material, and replace part of the cobalt content in the material to reduce costs. In the industrial field, manganese sulfate is mainly obtained through the smelting and processing of manganese ore.

[0003] The wet smelting process of manganese ore mainly includes two-ore one-step acid leaching method, ferrous sulfate reduction leaching method, direct reduction method and sulfur dioxide leaching method. Among them, the two-ore one-step acid leaching method has problems such as low reduction rate and leaching rate, large slag volume, etc., which affects the recovery rate of manganese, and the reaction temperature is required to be above 95°C, and the steam generation is large, which is not conducive to production operation; the ferrous sulfate reduction leaching method has a high iron content in the leachate, and the use of iron hydroxide neutralization precipitation method to remove iron will produce a large amount of colloidal precipitation, causing difficulty in filtration and loss of manganese adsorption; the direct reduction method not only consumes a large amount of acid, but also has high requirements for the corrosion resistance of the equipment.

[0004] The traditional sulfur dioxide leaching method uses a full reduction leaching method to make sulfur dioxide gas react with manganese ore powder slurry to generate manganese sulfate, and the reaction rate is fast. However, a large amount of iron is also reduced to the leachate, which needs to be oxidized first and then removed by neutralization precipitation. In addition, the leachate is acidic, which brings great difficulties to the neutralization and precipitation removal of iron, resulting in a complicated process flow. At the same time, full reduction leaching also has problems such as low sulfur dioxide utilization, which increases the cost of raw materials. Summary of the invention

[0005] Based on this, it is necessary to provide a method for preparing battery-grade manganese sulfate in order to solve the above problems; the preparation method can achieve selective leaching of manganese-containing materials, shorten the process flow, improve the utilization rate of sulfur dioxide, and reduce production costs.

[0006] A method for preparing battery-grade manganese sulfate comprises the following steps:

[0007] Providing a manganese-containing material, first removing water-soluble impurities in the manganese-containing material, and then mixing the manganese-containing material with water to obtain a slurry material;

[0008] Passing sulfur dioxide gas into the slurry material to perform a reduction leaching reaction, while monitoring the potential during the reaction, and when the potential starts to decrease from a maximum value and the decrease value reaches 150 mV-270 mV, stopping passing sulfur dioxide gas to obtain a reduction leaching solution;

[0009] The reduction leaching solution is subjected to sulfidation to remove impurities to obtain a manganese sulfate clear solution;

[0010] Deeply oxidizing the manganese sulfate clear solution to obtain a manganese sulfate purified solution;

[0011] The purified manganese sulfate solution is evaporated and crystallized at least once to obtain battery-grade manganese sulfate.

[0012] In one embodiment, when the drop value reaches 150mV-250mV, the introduction of sulfur dioxide gas is stopped.

[0013] In one embodiment, the manganese-containing material satisfies at least one of the following conditions:

[0014] (1) The mass fraction of manganese in the manganese-containing material is at least 45%;

[0015] (2) The chemical form of manganese in the manganese-containing material mainly includes manganese dioxide.

[0016] In one embodiment, the manganese-containing material includes at least one of manganese ore powder and manganese slag.

[0017] In one embodiment, the liquid-to-solid ratio of the slurry material is 3:1-5:1.

[0018] In one embodiment, the iron concentration in the reducing leaching solution is below 0.05 g / L.

[0019] In one embodiment, in the reduction leaching reaction step, at least one of the following conditions is met:

[0020] (1) The flow rate of the sulfur dioxide gas is 1L / min-2L / min;

[0021] (2) The temperature of the reduction leaching reaction is 50°C-65°C;

[0022] (3) The reduction leaching reaction time is 2h-5h.

[0023] In one embodiment, the sulfidation and impurity removal step comprises: mixing the reduction leaching solution with manganese sulfide to carry out a sulfidation reaction, and filtering after the reaction is completed to obtain a manganese sulfate clear solution and sulfidation and impurity removal slag.

[0024] In one embodiment, in the step of sulfurization and impurity removal, at least one of the following conditions is met:

[0025] (1) The pH value during the sulfurization and impurity removal process is 4.0-5.0;

[0026] (2) The reaction temperature of the sulfurization and impurity removal is 60°C-85°C.

[0027] In one embodiment, the deep oxidation step comprises: mixing the manganese sulfate clear solution with hydrogen peroxide to carry out an oxidation reaction, and after the reaction is completed, standing and filtering to obtain a manganese sulfate purified solution and oxidation slag.

[0028] In one embodiment, evaporation mother liquor is also produced during the evaporation crystallization process, and the evaporation mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled in the sulfidation and impurity removal step.

[0029] In one embodiment, the evaporation crystallization is performed for more than 2 times.

[0030] The preparation method of the present invention uses the potential value of the redox system to accurately judge the oxidizability and reducibility of the reaction system. As the amount of sulfur dioxide introduced increases, Mn 2+ During the leaching process from manganese-containing materials, the oxidizing property of the system is enhanced. At this time, the potential of the reaction system continues to rise and reaches the highest potential value. At the same time, as the reduction leaching reaction proceeds, a large amount of sulfur dioxide dissolves in water to produce bisulfite ions (HSO3 - ), sulfite ion (SO3 2- ) and other reducing substances, the reducing property of the system is enhanced, and the potential of the reaction system begins to decrease. Then, when the potential starts to decrease from the highest value and the decrease value reaches 150mV-270mV, due to the high potential value, it does not reach the Fe 2+ The reduction potential not only effectively inhibits iron leaching, but also ensures that most of the manganese in the manganese-containing material is fully leached, so that battery-grade manganese sulfate can be prepared through subsequent simple sulfidation removal, deep oxidation and evaporation crystallization.

[0031] Therefore, compared with the traditional sulfur dioxide leaching method, the preparation method described in the present invention not only reduces the pressure of subsequent iron removal, simplifies the process flow, saves energy consumption, equipment investment and site, but also can improve the utilization rate of sulfur dioxide and reduce the amount of oxidant required in the subsequent deep oxidation step, thereby significantly reducing the overall production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of a method for preparing battery-grade manganese sulfate in one embodiment of the present invention. DETAILED DESCRIPTION

[0033] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific implementation methods or embodiments and are not intended to limit the present invention.

[0035] Combination Figure 1 As shown, a method for preparing battery-grade manganese sulfate provided by the present invention comprises the following steps:

[0036] S1, providing a manganese-containing material, first removing water-soluble impurities in the manganese-containing material, and then mixing with water to slurry to obtain a slurry material;

[0037] S2, introducing sulfur dioxide gas into the slurry material to perform a reduction leaching reaction, while monitoring the potential during the reaction process, and when the potential starts to decrease from the highest value and the decrease value reaches 150mV-270mV, stopping the introduction of sulfur dioxide gas to obtain a reduction leaching solution;

[0038] S3, subjecting the reduction leaching solution to sulfidation and impurity removal to obtain a manganese sulfate clear solution;

[0039] S4, deeply oxidizing the manganese sulfate clear solution to obtain a manganese sulfate purified solution;

[0040] S5, evaporating and crystallizing the purified manganese sulfate solution at least once to obtain battery-grade manganese sulfate.

[0041] In step S1, the manganese-containing material satisfies at least one of the following conditions: (1) the mass fraction of manganese in the manganese-containing material is at least 45%; (2) the chemical existence form of manganese in the manganese-containing material mainly includes manganese dioxide.

[0042] Preferably, the manganese-containing material satisfies both of the above conditions, which is more conducive to the preparation of battery-grade manganese sulfate.

[0043] Specifically, the manganese-containing material includes at least one of manganese ore powder and manganese slag.

[0044] It should be noted that manganese slag is a valuable product produced during the production process of the production line. Generally, the main metal element composition and mass fraction of manganese slag include: Mn (45%-55%), Co (0.4%-0.6%), Ni (1%-2.5%), Fe (0.4%-1%), Al (0.2%-0.5%), and also contains a small amount of copper, zinc, and chromium. Using manganese slag to prepare battery-grade manganese sulfate can effectively utilize the manganese-rich slag produced during the production process of the production line and improve the utilization rate of the slag during the production process of the production line.

[0045] Most of the water-soluble impurities such as nickel-cobalt salts in the manganese-containing material can be removed by water washing. In one embodiment, the manganese-containing material is preferably washed with water twice, which is beneficial to fully remove the water-soluble impurities in the manganese-containing material.

[0046] Preferably, the liquid-to-solid ratio of the slurry material is 3:1-5:1, wherein the liquid-to-solid ratio is the mass ratio of liquid to solid in the liquid-solid mixture.

[0047] It should be noted that the potential can be used to reflect the macroscopic redox properties of all substances in the solution. The higher the potential, the stronger the oxidizing property; the lower the potential, the stronger the reducing property. Among them, a positive potential indicates that the solution shows a certain oxidizing property; a negative potential indicates that the solution shows a certain reducing property.

[0048] In step S2, the potential value of the redox system is used to accurately determine the oxidizability and reducibility of the reaction system. As the amount of sulfur dioxide introduced increases, Mn 2+ During the leaching process from manganese-containing materials, the oxidizing property of the system is enhanced. At this time, the potential of the reaction system continues to rise and reaches the highest potential value. At the same time, as the reduction leaching reaction proceeds, a large amount of sulfur dioxide dissolves in water to produce bisulfite ions (HSO3 - ), sulfite ion (SO3 2- ) and other reducing substances, the reducing property of the system is enhanced, causing the potential of the reaction system to begin to decrease.

[0049] Furthermore, when the potential starts to decrease from the highest value and the decrease value reaches 150mV-270mV, the potential value is too high to reach Fe 2+ The reduction potential not only effectively inhibits iron leaching, but also ensures that most of the manganese in the manganese-containing material is fully leached, so that battery-grade manganese sulfate can be prepared through subsequent simple sulfidation removal, deep oxidation and evaporation crystallization.

[0050] Further preferably, when the drop value reaches 150mV-250mV, the introduction of sulfur dioxide gas is stopped, which is more conducive to the preparation of battery-grade manganese sulfate.

[0051] It should be noted that the present invention does not limit the flow rate and time of sulfur dioxide gas, and those skilled in the art can adjust them according to actual preparation conditions. When the flow rate of sulfur dioxide gas is low, those skilled in the art can also achieve the same effect by extending the time of introduction.

[0052] Preferably, when the flow rate of the sulfur dioxide gas is 1L / min-2L / min, not only can the reduction leaching reaction efficiency be higher, but also the reaction safety is higher, avoiding excessive consumption of sulfur dioxide gas, making the utilization rate of sulfur dioxide gas higher, and thus reducing the preparation cost. Further preferably, the temperature of the reduction leaching reaction is 50°C-65°C, which can make the dissolution and consumption of sulfur dioxide more balanced, and is more conducive to improving Mn 2+ The leaching efficiency and the utilization rate of sulfur dioxide gas are improved. More preferably, the reduction leaching reaction time is 2h-5h.

[0053] In one embodiment, after the reduction leaching reaction of the slurry material, the reduction leaching solution and the reduction leaching residue are obtained by filtration, wherein the iron concentration in the reduction leaching solution is below 0.05 g / L, which greatly alleviates the pressure of iron removal in the subsequent steps; the reduction leaching residue can be used as a low manganese content raw material.

[0054] In step S3, the reducing leaching solution is subjected to sulfidation to remove impurities, so as to remove metal elements such as cobalt, nickel, copper, zinc, and chromium in the reducing leaching solution, and the manganese sulfate crystals can reach the standard of battery-grade manganese sulfate.

[0055] In one embodiment, the sulfidation and impurity removal step comprises: mixing the reduction leaching solution with manganese sulfide to carry out a sulfidation reaction, and filtering after the reaction to obtain a manganese sulfate clear solution and sulfidation and impurity removal slag, wherein the sulfidation and impurity removal slag can be used as a sulfur source.

[0056] Preferably, the pH value during the sulfurization and impurity removal process is 4.0-5.0, which can remove most of the heavy metal ions.

[0057] Further preferably, in the step of sulfurization and impurity removal, the reaction temperature is 60°C-85°C, which is conducive to increasing the rate of sulfurization and impurity removal.

[0058] In step S4, the manganese sulfate clear solution is deeply oxidized to remove divalent sulfur and a very small amount of remaining iron, so that the manganese sulfate crystals reach the standard of battery-grade manganese sulfate.

[0059] In one embodiment, the deep oxidation step comprises: mixing the manganese sulfate clear solution with hydrogen peroxide to carry out an oxidation reaction, and after the reaction is completed, standing and filtering to obtain manganese sulfate purified solution and oxidation slag, wherein the oxidation slag can be returned to the sulfidation and impurity removal section for use.

[0060] In step S5, by at least one evaporation and crystallization, elements such as calcium, magnesium, potassium, and sodium in the manganese sulfate purification solution can be removed, so that the manganese sulfate crystals reach the standard of battery-grade manganese sulfate.

[0061] In one embodiment, an evaporation mother liquor is also generated during the evaporation and crystallization process, and the evaporation mother liquor is used to prepare manganese sulfide. The manganese sulfide is recycled in the sulfidation and impurity removal step, which is beneficial to improving the utilization rate of the preparation by-products and reducing the preparation cost.

[0062] In one embodiment, the manganese sulfate purification liquid is preferably evaporated and crystallized by vacuum evaporation and crystallization. After one evaporation and crystallization, the solution is filtered while hot. The obtained crystals are dissolved in water and evaporated and crystallized again. After repeated crystallization, purer manganese sulfate crystals can be obtained.

[0063] Preferably, the number of evaporation crystallization is 2 or more times, which is more conducive to making the manganese sulfate crystals reach the standard of battery-grade manganese sulfate. More preferably, the number of evaporation crystallization is 2 times.

[0064] Therefore, compared with the traditional sulfur dioxide leaching method, the preparation method described in the present invention not only reduces the pressure of subsequent iron removal, simplifies the process flow, saves energy consumption, equipment investment and site, but also can improve the utilization rate of sulfur dioxide and reduce the amount of oxidant required in the subsequent deep oxidation step, thereby significantly reducing the overall production cost.

[0065] Hereinafter, the preparation method of the battery-grade manganese sulfate will be further described through the following specific examples.

[0066] Example 1

[0067] Weigh 2000g of manganese slag, add pure water to wash twice at 85°C, and control the liquid-solid ratio during washing to be 4:1, and filter to obtain manganese slag after removing water-soluble impurities. Then add 4 times the mass of water to the manganese slag after removing water-soluble impurities, start stirring for slurrying, the speed is 1000rpm, and start heating to obtain slurry material.

[0068] When the slurry material reaches 65°C, sulfur dioxide gas is introduced, and the flow rate is controlled at 2L / min. At the same time, a potentiometer is inserted to synchronously display the change of potential. When the potential starts to drop from the highest value and the drop value reaches 200mV, the introduction of sulfur dioxide gas is stopped, and samples are taken for filtration to obtain reduction leaching solution and reduction leaching residue.

[0069] The reduction leaching solution was heated to 85°C, manganese sulfide was added to adjust the pH to 5.0 for sulfidation removal, and after reacting for two hours, it was filtered to obtain manganese sulfate clear solution and sulfidation removal slag.

[0070] Add hydrogen peroxide to the manganese sulfate clear solution, react for one hour, let stand, and filter to obtain manganese sulfate purified solution and oxidation slag.

[0071] The purified manganese sulfate solution is evaporated and crystallized at 110°C, filtered while hot, the obtained crystals are dissolved in water and then vacuum evaporated and crystallized again, the generated evaporated mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled in the sulfidation and impurity removal step, and manganese sulfate crystals are obtained after two vacuum evaporation and crystallizations.

[0072] Example 2

[0073] Weigh 2000g of manganese slag, add pure water to wash twice at 85°C, and control the liquid-solid ratio during washing to be 4:1, and filter to obtain manganese slag after removing water-soluble impurities. Then add 4 times the mass of water to the manganese slag after removing water-soluble impurities, start stirring for slurrying, the speed is 1000rpm, and start heating to obtain slurry material.

[0074] When the slurry material reaches 65°C, sulfur dioxide gas is introduced, and the flow rate is controlled at 2L / min. At the same time, a potentiometer is inserted to synchronously display the change of potential. When the potential starts to drop from the highest value and the drop value reaches 250mV, the introduction of sulfur dioxide is stopped, and samples are taken for filtration to obtain reduction leaching solution and reduction leaching residue.

[0075] The reduction leaching solution was heated to 85°C, manganese sulfide was added to adjust the pH to 5.0 for sulfidation removal, and after reacting for two hours, it was filtered to obtain manganese sulfate clear solution and sulfidation removal slag.

[0076] Add hydrogen peroxide to the manganese sulfate clear solution, react for one hour, let stand, and filter to obtain manganese sulfate purified solution and oxidation slag.

[0077] The purified manganese sulfate solution is evaporated and crystallized at 110°C, filtered while hot, the obtained crystals are dissolved in water and then vacuum evaporated and crystallized again, the generated evaporated mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled in the sulfidation and impurity removal step, and manganese sulfate crystals are obtained after two vacuum evaporation and crystallizations.

[0078] Example 3

[0079] Weigh 1350g of manganese slag, add pure water to wash twice at 85°C, and control the liquid-to-solid ratio during washing to be 4:1, and filter to obtain manganese slag after removing water-soluble impurities. Then add 4 times the mass of water to the manganese slag after removing water-soluble impurities, start stirring for slurrying, the speed is 1000rpm, and start heating to obtain slurry material.

[0080] When the slurry material reaches 65°C, sulfur dioxide gas is introduced, and the flow rate is controlled at 2L / min. At the same time, a potentiometer is inserted to synchronously display the change of potential. When the potential starts to drop from the highest value and the drop value reaches 200mV, the introduction of sulfur dioxide is stopped, and samples are taken for filtration to obtain reduction leaching solution and reduction leaching residue.

[0081] The reduction leaching solution was heated to 85°C, manganese sulfide was added to adjust the pH to 5.0 for sulfidation removal, and after reacting for two hours, it was filtered to obtain manganese sulfate clear solution and sulfidation removal slag.

[0082] Add hydrogen peroxide to the manganese sulfate clear solution, react for one hour, let stand, and filter to obtain manganese sulfate purified solution and oxidation slag.

[0083] The purified manganese sulfate solution is evaporated and crystallized at 110°C, filtered while hot, the obtained crystals are dissolved in water and then vacuum evaporated and crystallized again, the generated evaporated mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled in the sulfidation and impurity removal step, and manganese sulfate crystals are obtained after two vacuum evaporation and crystallizations.

[0084] Example 4

[0085] Weigh 1350g of manganese slag, add pure water to wash twice at 85°C, and control the liquid-to-solid ratio during washing to be 4:1, and filter to obtain manganese slag after removing water-soluble impurities. Then add 4 times the mass of water to the manganese slag after removing water-soluble impurities, start stirring for slurrying, the speed is 1000rpm, and start heating to obtain slurry material.

[0086] When the slurry material reaches 65°C, sulfur dioxide gas is introduced, and the flow rate is controlled at 1L / min. At the same time, a potentiometer is inserted to synchronously display the change in potential. When the potential starts to drop from the highest value and the drop value reaches 200mV, the introduction of sulfur dioxide is stopped, and samples are taken for filtration to obtain reduction leaching solution and reduction leaching residue.

[0087] The reduction leaching solution was heated to 85°C, manganese sulfide was added to adjust the pH to 5.0 for sulfidation removal, and after reacting for two hours, it was filtered to obtain manganese sulfate clear solution and sulfidation removal slag.

[0088] Add hydrogen peroxide to the manganese sulfate clear solution, react for one hour, let stand, and filter to obtain manganese sulfate purified solution and oxidation slag.

[0089] The purified manganese sulfate solution is evaporated and crystallized at 110°C, filtered while hot, the obtained crystals are dissolved in water and then vacuum evaporated and crystallized again, the generated evaporated mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled in the sulfidation and impurity removal step, and manganese sulfate crystals are obtained after two vacuum evaporation and crystallizations.

[0090] Example 5

[0091] Weigh 1350g of manganese slag, add pure water to wash twice at 85°C, and control the liquid-to-solid ratio during washing to be 4:1, and filter to obtain manganese ore after removing water-soluble impurities. Add 5 times the mass of water to the manganese ore after removing water-soluble impurities, start stirring for slurrying, the speed is 1000rpm, and start heating to obtain slurry material.

[0092] When the slurry material reaches 60°C, sulfur dioxide gas is introduced, and the flow rate is controlled at 2L / min. At the same time, a potentiometer is inserted to synchronously display the change of potential. When the potential starts to drop from the highest value and the drop value reaches 270mV, the introduction of sulfur dioxide is stopped, and samples are taken for filtration to obtain reduction leaching solution and reduction leaching residue.

[0093] The reduction leaching solution was heated to 75°C, manganese sulfide was added to adjust the pH to 4.0 for sulfidation removal, and after reacting for two hours, it was filtered to obtain manganese sulfate clear solution and sulfidation removal slag.

[0094] Add hydrogen peroxide to the manganese sulfate clear solution, react for one hour, let stand, and filter to obtain manganese sulfate purified solution and oxidation slag.

[0095] The purified manganese sulfate solution is evaporated and crystallized at 110°C, filtered while hot, the obtained crystals are dissolved in water and then vacuum evaporated and crystallized again, the generated evaporated mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled in the sulfidation and impurity removal step, and manganese sulfate crystals are obtained after two vacuum evaporation and crystallizations.

[0096] Example 6

[0097] The difference between Example 6 and Example 5 is that when the potential starts to decrease from the highest value and the decrease value reaches 150 mV, the introduction of sulfur dioxide is stopped.

[0098] Comparative Example 1

[0099] The difference between Comparative Example 1 and Example 3 is that when the potential starts to decrease from the highest value and the decrease value reaches 100 mV, the introduction of sulfur dioxide is stopped.

[0100] Comparative Example 2

[0101] The difference between Comparative Example 2 and Example 3 is that when the potential starts to decrease from the highest value and the decrease value reaches 300 mV, the introduction of sulfur dioxide is stopped.

[0102] Comparative Example 3

[0103] The difference between Comparative Example 3 and Example 3 is that the potential is not monitored until the slurry material reacts and turns grayish white, reaching the reaction end point, and then the introduction of sulfur dioxide is stopped.

[0104] The components of the reduction leaching solutions obtained in the preparation process of Examples 1-6 and Comparative Examples 1-3 were analyzed, and the results are shown in Table 1.

[0105] Table 1

[0106]

[0107] According to Table 1, when the redox potential is controlled to decrease after reaching the highest value and the decrease value reaches 150mV-270mV, the iron concentration in the reduction leaching solution is relatively low, all below 0.05g / L, which greatly alleviates the pressure of iron removal.

[0108] The components of the purified manganese sulfate solution obtained in the preparation process of Examples 1-6 and Comparative Examples 1-3 were analyzed and compared with T / ATCRR11-2020 battery-grade manganese sulfate first-class product. The results are shown in Table 2.

[0109] Table 2

[0110]

[0111]

[0112] According to Table 2, all indicators of the purified manganese sulfate solutions prepared in Examples 1-6 meet the requirements of battery-grade manganese sulfate solutions, while the iron concentration and aluminum concentration of the purified manganese sulfate solutions prepared in Comparative Examples 1-3 fail to meet the standards.

[0113] The components of the manganese sulfate crystals prepared in Examples 1-6 were analyzed and compared with the requirements of the HG / T4823-2015 "Manganese Sulfate for Batteries" standard. The results are shown in Table 3.

[0114] Table 3

[0115]

[0116] According to Table 3, the mass fraction of manganese in the manganese sulfate crystals obtained in Examples 1-6 is greater than 32%, which meets the mass fraction requirement of manganese in HG / T4823-2015 "Manganese sulfate for batteries", and the content of impurity ions such as iron, copper, and lead, pH and other indicators also meet the standard requirements of HG / T4823-2015. Therefore, battery-grade manganese sulfate can be prepared by the preparation method provided by the present invention.

[0117] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing battery-grade manganese sulfate, characterized in that: The preparation method comprises the following steps: Providing a manganese-containing material, first removing water-soluble impurities in the manganese-containing material, and then mixing the manganese-containing material with water to obtain a slurry material; Passing sulfur dioxide gas into the slurry material to perform a reduction leaching reaction, while monitoring the potential during the reaction, and when the potential starts to decrease from a maximum value and the decrease value reaches 150 mV-270 mV, stopping passing sulfur dioxide gas to obtain a reduction leaching solution; The reduction leaching solution is subjected to sulfidation to remove impurities to obtain a manganese sulfate clear solution; Deeply oxidizing the manganese sulfate clear solution to obtain a manganese sulfate purified solution; The purified manganese sulfate solution is evaporated and crystallized at least once to obtain battery-grade manganese sulfate.

2. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: When the drop value reaches 150mV-250mV, the introduction of sulfur dioxide gas is stopped.

3. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The manganese-containing material meets at least one of the following conditions: (1) The mass fraction of manganese in the manganese-containing material is at least 45%; (2) The chemical form of manganese in the manganese-containing material mainly includes manganese dioxide.

4. The method for preparing battery-grade manganese sulfate according to claim 1 or 3, characterized in that: The manganese-containing material includes at least one of manganese ore powder and manganese slag.

5. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The liquid-to-solid ratio of the slurry material is 3:1-5:

1.

6. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The iron concentration in the reduction leaching solution is below 0.05 g / L.

7. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: In the step of reduction leaching reaction, at least one of the following conditions is met: (1) The flow rate of the sulfur dioxide gas is 1L / min-2L / min; (2) The temperature of the reduction leaching reaction is 50°C-65°C; (3) The reduction leaching reaction time is 2h-5h.

8. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The sulfidation impurity removal step comprises: mixing the reduction leaching solution with manganese sulfide to carry out a sulfidation reaction, and filtering after the reaction is completed to obtain a manganese sulfate clear solution and sulfidation impurity removal slag.

9. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: In the step of sulfurization and impurity removal, at least one of the following conditions is met: (1) The pH value during the sulfurization and impurity removal process is 4.0-5.0; (2) The reaction temperature of the sulfurization and impurity removal is 60°C-85°C.

10. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The deep oxidation step comprises: mixing the manganese sulfate clear liquid with hydrogen peroxide to carry out oxidation reaction, and after the reaction is completed, standing and filtering to obtain manganese sulfate purified liquid and oxidation slag.

11. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The evaporation mother liquor is also generated during the evaporation crystallization process. The evaporation mother liquor is used to prepare manganese sulfide, and the manganese sulfide is recycled and used in the sulfidation and impurity removal step.

12. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that: The evaporation crystallization is performed at least twice.

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