Preparation method of manganese sulfate solution, positive electrode material and lithium battery

Abstract

The invention belongs to the technical field of lithium batteries, and particularly relates to a preparation method of a manganese sulfate solution, a positive electrode material and a lithium battery, and the method comprises the following steps: heating manganese ore and sulfuric acid to react to obtain a mixed solution of manganese sulfate; and removing potassium from the mixed solution until the potassium content is less than or equal to a potassium content threshold value to obtain a tail acid solution. And filtering the tail acid solution to obtain acidic filter residues and a primary filtered manganese sulfate solution. And carrying out washing and filter pressing on the acid filter residues, and returning washing filtrate to obtain acid washing filter residues. And neutralizing the acid washing filter residue to a first preset pH value by using a neutralizing agent greater than the total amount of sulfuric acid. And neutralizing the primary filtered manganese sulfate solution to a second preset pH value to obtain a neutralized manganese sulfate solution. And removing iron from the neutralized manganese sulfate solution until the iron content is less than or equal to an iron content threshold value to obtain an iron-removed manganese sulfate solution. And the iron-removed manganese sulfate solution is filtered to obtain the manganese sulfate solution, so that the production cost is reduced, and the yield of manganese is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of lithium batteries, and in particular relates to a method for preparing a manganese sulfate solution, a positive electrode material and a lithium battery. Background Art

[0002] At present, when manganese sulfate is prepared by reacting manganese ore with sulfuric acid, the prior art is to directly add a neutralizing agent to the chemical reaction tank to neutralize the tail acid after the manganese ore and sulfuric acid react in the chemical reaction tank, which will cause a lot of neutralizing agents to be consumed, and the neutralization cost is high. At the same time, the neutralization reaction directly in the chemical reaction tank also causes the sulfuric acid in the tail acid to be consumed by the neutralizing agent, which increases the consumption cost of sulfuric acid. In addition, the filtrate washed by the neutral filter residue after the reaction of manganese ore and sulfuric acid in the prior art is then put into the chemical reaction tank to recover soluble manganese, and the soluble manganese yield of a single feeding reaction is not high enough.

[0003] The existing technology for preparing manganese sulfate has the problems of large consumption of neutralizing sulfuric acid by neutralizing the neutralizer and low yield of soluble manganese. Summary of the invention

[0004] The present application provides a method for preparing a manganese sulfate solution, a positive electrode material and a lithium battery, which aim to solve the problems of large consumption of neutralizing sulfuric acid and low yield of soluble manganese in the preparation of manganese sulfate solution to a certain extent.

[0005] In a first aspect, the present application provides a method for preparing a manganese sulfate solution, comprising: placing the manganese ore and concentrated sulfuric acid in a chemical reaction tank containing the last washing filtrate, heating to a preset reaction temperature, and reacting for a preset time to obtain a mixed solution, wherein the mixed solution includes manganese sulfate; The mixed solution is subjected to aeration by using a Roots blower to remove potassium until the potassium content in the mixed solution is less than or equal to a potassium content threshold value, thereby obtaining a tail acid solution; The tail acid solution is subjected to an acidic primary plate-and-frame filtration to obtain an acidic filter residue and a primary filtered manganese sulfate solution; Washing and filtering the acidic filter residue, returning the washing filtrate to the chemical reaction tank to obtain an acidic washed filter residue; If the moisture content of the acidic filter residue and the sulfuric acid content in the filtrate after filter pressing meet the preset requirements, determine the total amount of sulfuric acid in the acidic washing filter residue; A neutralizing agent in an amount greater than the total amount of the sulfuric acid is mixed with the acidic washing filter residue to neutralize the acidic washing filter residue to a first preset pH value; Neutralizing the filtered manganese sulfate solution once to a second preset pH value in a neutralization and iron removal reaction tank to obtain a neutralized manganese sulfate solution; The neutralized manganese sulfate solution is subjected to aeration by using a Roots blower to remove iron until the iron content in the neutralized manganese sulfate solution is less than or equal to the iron content threshold value, thereby obtaining an iron-removed manganese sulfate solution; The deironing manganese sulfate solution is subjected to secondary plate-and-frame filtration to obtain a manganese sulfate solution; The iron removal residue from the secondary plate and frame filtration is returned to the chemical reaction tank.

[0006] In one embodiment, the preset reaction temperature is 80°C to 90°C; the preset reaction time is 8 h to 12 h.

[0007] In one embodiment, the molar ratio of manganese element to sulfuric acid in the manganese ore is 1:1.01~1.1; the concentration of sulfuric acid in the tail acid solution is 3 g / L~8 g / L.

[0008] In one embodiment, the mixed solution is aerated with a Roots blower to remove potassium to obtain a tail acid solution, which is replaced by: Manganese dioxide is added to the mixed solution to remove potassium, thereby obtaining a tail acid solution.

[0009] In one of the embodiments, the preset requirement is that the moisture content of the acidic filter residue is ≤30%, and the sulfuric acid content in the filtrate after the acidic filter residue is filtered is ≤0.225‰.

[0010] In one embodiment, the neutralized manganese sulfate solution is aerated with a Roots blower to remove iron, and the following can also be performed: An oxidant is added to the neutralized manganese sulfate solution to remove iron, and the oxidant includes hydrogen peroxide and manganese dioxide.

[0011] In one embodiment, the potassium content threshold is 30 ppm, and the iron content threshold is 0.5 ppm.

[0012] In one embodiment, the first preset pH value is greater than or equal to 4.5, and the second preset pH value is 3.5-4.5.

[0013] In a second aspect, the present application provides a positive electrode material, wherein the raw material of the positive electrode material includes manganese sulfate obtained by the preparation method described in any one of the first aspects.

[0014] In a third aspect, the present application provides a lithium battery, wherein the positive electrode of the lithium battery is made of the positive electrode material described in the second aspect.

[0015] It can be understood that the beneficial effects of the second to third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0016] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The present application provides a method for preparing a manganese sulfate solution. Compared with the prior art, since a neutralizing agent is not directly used to neutralize a mixed solution after the reaction of manganese ore and sulfuric acid, but the acidic filter residue is neutralized after potassium removal and plate-frame filtration, the amount of the neutralizing agent is reduced, and the amount of sulfuric acid consumed by the neutralizing agent is also reduced; in addition, since the mixed solution after the reaction of manganese ore and sulfuric acid is firstly subjected to plate-frame filtration, the acidic filter residue after filtration is washed to recover soluble manganese, and the iron-removing filter residue after filtration of the iron-removing manganese sulfate solution is returned to a chemical reaction tank to continue to recover soluble manganese, thereby improving the overall yield of soluble manganese, reducing the production cost and improving the yield of manganese, and obtaining a manganese sulfate solution after potassium removal, iron removal and filtration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a schematic flow chart of a method for preparing a manganese sulfate solution provided in one embodiment of the present application; Figure 2 It is a schematic flow chart of the preparation process of the manganese sulfate solution provided in Example 1 of the present application. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0020] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0021] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, where a, b, c can be single or multiple, respectively.

[0022] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. For example, without departing from the scope of the implementation regulations of this application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0023] The terms used in the embodiments of the present application are only for the purpose of describing specific implementation rules, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the implementation rules of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0024] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0025] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0026] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0027] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0028] At present, when manganese sulfate is prepared by reacting manganese ore with sulfuric acid, the prior art is to directly add a neutralizing agent (such as calcium hydroxide or calcium carbonate) to the chemical reaction tank to neutralize the tail acid after the manganese ore reacts with concentrated sulfuric acid (98% concentration) in the chemical reaction tank, which consumes too much neutralizing agent and increases the neutralization cost. At the same time, the neutralization reaction directly in the chemical reaction tank also causes the sulfuric acid in the tail acid to be consumed by the neutralizing agent, which increases the consumption cost of sulfuric acid. In addition, the prior art washes the filtrate of the neutral filter residue after the reaction of manganese ore with sulfuric acid and then puts it into the chemical reaction tank to recover the soluble manganese, and the soluble manganese yield of a single feeding reaction is not high enough.

[0029] In response to the above problems, Figure 1 As shown, the first aspect of the present application provides a method for preparing a manganese sulfate solution, comprising: S10, placing the manganese ore and concentrated sulfuric acid in a chemical reaction tank including the last washing filtrate, heating to a preset reaction temperature, and reacting for a preset time to obtain a mixed solution, wherein the mixed solution includes manganese sulfate.

[0030] S20, removing potassium from the mixed solution by aeration using a Roots blower until the potassium content in the mixed solution is less than or equal to a potassium content threshold value, thereby obtaining a tail acid solution.

[0031] S30, performing acidic primary plate-and-frame filtration on the tail acid solution to obtain an acidic filter residue and a primary filtered manganese sulfate solution.

[0032] S40, washing and filtering the acidic filter residue, returning the washing filtrate to the chemical reaction tank to obtain an acidic washed filter residue.

[0033] S50, if the water content of the acidic filter residue and the sulfuric acid content in the filtrate after filter pressing meet the preset requirements, determine the total amount of sulfuric acid in the acidic washing filter residue.

[0034] S60, mixing the acidic washing filter residue with a neutralizing agent in an amount greater than the total amount of sulfuric acid to neutralize the acidic washing filter residue to a first preset pH value.

[0035] S70, neutralizing the once filtered manganese sulfate solution to a second preset pH value in a neutralization and iron removal reaction tank to obtain a neutralized manganese sulfate solution.

[0036] S80, removing iron from the neutralized manganese sulfate solution by aeration using a Roots blower until the iron content in the neutralized manganese sulfate solution is less than or equal to the iron content threshold, thereby obtaining an iron-removed manganese sulfate solution.

[0037] S90, performing secondary plate and frame filtration on the de-ironized manganese sulfate solution to obtain a manganese sulfate solution.

[0038] S100, returning the iron removal residue from the secondary plate and frame filtration to the chemical reaction tank.

[0039] In this embodiment, in step S10, concentrated sulfuric acid is diluted by the washing filtrate to become dilute sulfuric acid with a concentration less than or equal to 70%. The dilute sulfuric acid reacts with the iron element in the manganese ore to generate ferrous sulfate, and the dilute sulfuric acid and the manganese ore to generate manganese sulfate. In step S20, Fe 2+ The oxygen in the air blown in by the Roots blower is oxidized to Fe 3+ , then with K + 、Na + The precipitates of potassium iron alum and sodium iron alum are formed. When the potassium content in the mixed solution is less than or equal to the potassium content threshold, the purpose of removing potassium, sodium and primary iron removal is achieved, and a tail acid solution is obtained. The acidic filter residue after the plate-and-frame filtration in step S30 includes potassium pyrite alum, sodium pyrite alum, manganese sulfate solution generated by part of the residual tail acid and manganese ore, and unreacted manganese ore; compared with the prior art, in step 60, since the mixed solution in the chemical reaction tank after the reaction of manganese ore and sulfuric acid is not directly neutralized by a neutralizer, but the acidic filter residue is neutralized after potassium removal and plate-and-frame filtration, the amount of the neutralizer is reduced, and the amount of sulfuric acid consumed by the neutralizer is also reduced; in addition, since the manganese ion content in the filtrate after the acidic filter residue is washed is greater than the manganese ion content in the filtrate after the neutral filter residue is washed in the prior art, in step 40, the mixed solution after the reaction of manganese ore and sulfuric acid is first plate-and-frame filtered, the filtered acidic filter residue is washed to recover soluble manganese, and the iron-removing filter residue after filtering the iron-removing manganese sulfate solution is returned to the chemical reaction tank to continue to recover soluble manganese, thereby improving the overall yield of soluble manganese, and in step S80, a Roots blower is used for aeration, that is, oxygen in the air is used to remove Fe in the solution 2+ Oxidized to Fe 3+ , forming iron sulfate (Fe 2 (SO 4 ) 3 ), and because the iron sulfate in manganese sulfate will hydrolyze to form iron hydroxide (Fe(OH) 3 ) precipitate, thus reducing the content of iron ions again. While reducing the cost and increasing the yield of manganese, a manganese sulfate solution was obtained after potassium and iron removal and filtration.

[0040] In one embodiment, manganese carbonate ore (MnCO 3 ) is 8%~18%, and the mass ratio of manganese ore to concentrated sulfuric acid (mass concentration is 98%) is 1:0.3~0.5. Since the manganese content in manganese ore is not evenly distributed, in order to dissolve the manganese in the manganese ore as much as possible, the minimum amount of sulfuric acid generally corresponds to the maximum manganese content. Therefore, after the manganese ore and sulfuric acid react in the chemical reaction tank, there will be excess sulfuric acid, resulting in the mixed solution after the reaction being acidic and having a relatively low pH value. The mixed solution is also called tail acid.

[0041] In one embodiment, the preset reaction temperature is 80°C to 90°C; the preset reaction time is 8 h to 12 h; the reaction temperature and reaction time of this embodiment can maximize the leaching of manganese in the manganese ore, thereby increasing the leaching rate of manganese.

[0042] In one embodiment, the molar ratio of manganese element to sulfuric acid in the manganese ore is 1:1.01~1.1; the concentration of sulfuric acid in the tail acid solution is 3 g / L~8 g / L. The molar ratio of manganese element to sulfuric acid in this embodiment is used to further improve the manganese leaching rate.

[0043] It should be noted that the sulfuric acid content test method in this application is the acid-base neutralization titration method, and the chemical formula of the acid-base neutralization principle is H 2 SO 4 +2NaOH → Na 2 SO 4 +2H 2 O; drop methyl orange indicator into a fixed volume of sample to form a test solution, then drop a sodium hydroxide standard solution of a specified molar concentration into the test solution, and the titration endpoint is when the test solution changes from red to orange. The sulfuric acid content is measured in mass volume concentration, and the value is expressed in g / L. The sulfuric acid content calculation formula is:

[0044] in, represents the mass volume concentration of sulfuric acid, is the molar concentration of sodium hydroxide (mol / L), is the volume of sodium hydroxide standard solution consumed in titration (mL), is the sample volume (mL), 98 is sulfuric acid (H 2 SO 4 )'s molar mass.

[0045] In one embodiment, the mixed solution is aerated with a Roots blower to remove potassium to obtain a tail acid solution, which is replaced by adding manganese dioxide to the mixed solution to remove potassium to obtain a tail acid solution; in this embodiment, Fe 2+ Oxidized to Fe by MnO2 3+ , then with K + 、Na + The precipitates of potassium iron alum and sodium iron alum are formed. When the potassium content in the mixed solution is less than or equal to the potassium content threshold, the purpose of removing potassium, sodium and primary iron removal is achieved, and the content of manganese ions is increased.

[0046] In one embodiment, the preset requirements are that the moisture content of the acidic filter residue is ≤30%, and the sulfuric acid content in the filtrate after the acidic filter residue is filtered is ≤0.225‰. If the moisture content of the acidic filter residue and the sulfuric acid content in the filtrate after the filtration are not within the range of this embodiment, the consumption of the neutralizer will increase, and the neutralization cost will be increased. Within the scope of this embodiment, the consumption of the neutralizer is greatly reduced, and the production cost is reduced.

[0047] In one embodiment, the use of Roots blower aeration to remove iron from the neutralized manganese sulfate solution is replaced by adding an oxidant to the neutralized manganese sulfate solution to remove iron, and the oxidant includes at least one of hydrogen peroxide or manganese dioxide. In this embodiment, Fe 2+ Oxidized to Fe by MnO2 3+ , and then generate iron sulfate (Fe 2 (SO 4 ) 3 ), because the iron sulfate in manganese sulfate will hydrolyze to form iron hydroxide (Fe(OH) 3 ) precipitate, thus reducing the iron ion content again.

[0048] In one embodiment, the potassium content threshold is 30 ppm. When the mass ratio of potassium ions to the mass ratio of the mixed solution is less than or equal to 30 ppm (3 parts per hundred thousand), the Roots blower aeration is stopped to remove potassium, thereby reducing the potassium ion content; the iron content threshold is 0.5 ppm. When the mass ratio of iron ions to the mass ratio of the neutralized manganese sulfate solution is less than or equal to 0.5 ppm (0.5 parts per million), the Roots blower aeration is stopped to remove iron, thereby reducing the iron ion content.

[0049] In one embodiment, the first preset pH value is greater than or equal to 4.5, and a neutralizer greater than the total amount of sulfuric acid is used to neutralize the acidic washing residue to a pH value greater than or equal to 4.5, that is, the residual sulfuric acid in the acidic washing residue is neutralized to weak acidity or neutrality, and the neutralizer includes calcium hydroxide or calcium carbonate; the second preset pH value is 3.5-4.5, and manganese carbonate or manganese monoxide is added to the neutralization and iron removal reaction tank to neutralize the once filtered manganese sulfate solution to a pH value of 3.5-4.5, that is, the once filtered manganese sulfate after potassium removal is neutralized to weak acidity, which is beneficial to the hydrolysis of iron sulfate into iron hydroxide for further iron removal, and at the same time protects low-valent manganese ions from being oxidized to high-valent manganese ions insoluble in water. It should be noted that the mass volume concentration of sulfuric acid in tail acid is 3 g / L~8 g / L. If a neutralizer is used directly in a chemical reaction tank to neutralize the mixed solution after the reaction of manganese ore and sulfuric acid or the tail acid solution after potassium removal, since the mixed solution and the tail acid solution include all the remaining sulfuric acid, the pH value is relatively low, about 0.5~1.5, and more neutralizers are needed to increase the pH value to 3.5~4.5.

[0050] A second aspect of the present application provides a positive electrode material, wherein the raw material of the positive electrode material includes a manganese sulfate solution obtained by the method for preparing a manganese sulfate solution as described in any one of the first aspect.

[0051] A third aspect of the present application provides a lithium battery, wherein the positive electrode of the lithium battery is made of the positive electrode material as described in the second aspect.

[0052] The technical solution of the present application is illustrated below through specific embodiments and comparative examples.

[0053] Example 1 like Figure 2 As shown, the preparation method of manganese sulfate solution is: Step 1, placing manganese ore (manganese content of 18% by mass) and concentrated sulfuric acid (mass concentration of 98%) in a chemical reaction tank including the last washing filtrate, heating to 80°C, and reacting for 8 hours to obtain a mixed solution, the mixed solution includes manganese sulfate, and the molar ratio of manganese element in the manganese ore to sulfuric acid is 1:1.01.

[0054] Step 2, the mixed solution is aerated by Roots blower to remove potassium in the potassium removal tank, and when the potassium content in the mixed solution is greater than 30 ppm, the tail acid solution after potassium removal is still subjected to acidic primary plate and frame filtration using a plate and frame filter, and potassium and sodium removal and initial iron removal are performed in this step, and the filtered manganese sulfate solution is returned to the potassium removal tank until the potassium content in the mixed solution after the plate and frame filtration is less than or equal to 30 ppm, to obtain a tail acid solution, the tail acid solution is sampled, and the sulfuric acid concentration in the tail acid is determined to be 3.11 g / L by acid-base neutralization titration, wherein the acidic filter residue after the primary plate and frame filtration includes pyrite potassium alum, pyrite sodium alum, a manganese sulfate solution generated by a portion of residual tail acid and manganese ore, and unreacted manganese ore.

[0055] Step 3, subjecting the tail acid solution to an acidic primary plate-and-frame filtration to obtain an acidic filter residue and a primary filtered manganese sulfate solution.

[0056] Step 4, washing the acidic filter residue and performing filter pressing, returning the washing filtrate to the chemical reaction tank, and the washed filter residue is the acidic washing filter residue.

[0057] Step 5, drying the sample of the acidic filter residue to obtain the water content of the acidic filter residue, measuring the sulfuric acid content of the filtrate after the acidic filter residue is filtered to obtain the sulfuric acid content of the acidic filter residue, if the water content of the acidic filter residue is 30% and the sulfuric acid content of the filtrate after the filter press is 0.225‰, the total amount of sulfuric acid in the acidic washing filter residue after this washing can be determined, that is, the weight of the sulfuric acid solution is obtained by the water content and the total weight of the acidic filter residue, and then the total amount of sulfuric acid is obtained according to the sulfuric acid content.

[0058] Step 6, using a neutralizing agent calcium carbonate greater than the total amount of sulfuric acid to mix with the acidic washing filter residue, stirring and neutralizing the calcium carbonate and the acidic washing filter residue before the pH value reaches 4.5, and obtaining the filtrate through the plate and frame filter for pH measurement, neutralizing the acidic washing filter residue until the first preset pH value is 4.5, and the neutralized neutral filter residue is subjected to other recovery treatments.

[0059] Step 7, adding manganese carbonate to the neutralization and iron removal reaction tank to neutralize the once filtered manganese sulfate solution, stirring and neutralizing the manganese carbonate and the once filtered manganese sulfate solution before the pH value reaches 3.5, and measuring the pH value by sampling until the second preset pH value is 3.5, to obtain a neutralized manganese sulfate solution.

[0060] Step 8: Using Roots blower to aerate the neutralized manganese sulfate solution to remove iron in the neutralization and iron removal reaction tank, that is, using oxygen in the air to neutralize Fe 2+ Oxidized again to ferrous sulfate (Fe 2 (SO 4 ) 3 ), and because the iron sulfate in manganese sulfate will hydrolyze to form iron hydroxide (Fe(OH) 3 ) precipitate, thereby reducing the iron ion content again, and the iron removal filter residue is circulated back to the chemical reaction tank, and the cycle is continued until the iron content in the neutralized manganese sulfate solution filtered through the plate and frame filter for the second time is less than or equal to 0.5 ppm, thereby obtaining an iron removal manganese sulfate solution.

[0061] Step 9, performing secondary plate and frame filtration on the deironing manganese sulfate solution to obtain a manganese sulfate solution.

[0062] Step 10, the iron removal residue from the secondary plate and frame filtration after the iron content test is qualified is returned to the chemical reaction tank.

[0063] Embodiment 2 is different from Embodiment 1 in that: Step 1, placing manganese ore and concentrated sulfuric acid in a chemical reaction tank including the last washing filtrate, heating to 90°C, and reacting for 12 hours to obtain a mixed solution, the mixed solution includes manganese sulfate, and the molar ratio of manganese element in the manganese ore to sulfuric acid is 1:1.11.

[0064] Step 2: Remove potassium from the mixed solution by aeration using a Roots blower until the potassium content in the mixed solution is less than or equal to 30 ppm, thereby obtaining a tail acid solution having a sulfuric acid concentration of 7.5 g / L.

[0065] And step 7, neutralizing the filtered manganese sulfate solution once in a neutralization and iron removal reaction tank to a pH value of 4.5 to obtain a neutralized manganese sulfate solution.

[0066] Comparative Example 1 S1, placing manganese ore and concentrated sulfuric acid in a chemical reaction tank including the last washing filtrate, heating to 80°C, and reacting for 8 hours to obtain a mixed solution, the mixed solution includes manganese sulfate, and the mass ratio of manganese ore (mass content of manganese is 18%) to sulfuric acid is 1:0.4.

[0067] S2, removing potassium from the mixed solution by aeration with a Roots blower until the potassium content in the mixed solution is less than or equal to 30 ppm, thereby obtaining a tail acid solution, in which the sulfuric acid concentration is 3.21 g / L.

[0068] S3, in a chemical reaction tank, using calcium carbonate in an amount greater than the total amount of sulfuric acid in the tail acid solution to neutralize the tail acid solution to a pH value of 4.5, to obtain a neutralized manganese sulfate solution.

[0069] S4, removing iron from the neutralized manganese sulfate solution by aeration using a Roots blower until the iron content in the neutralized manganese sulfate solution is less than or equal to 0.5 ppm, thereby obtaining a deironed manganese sulfate solution.

[0070] S5, performing secondary plate and frame filtration on the deironed manganese sulfate solution to obtain a manganese sulfate solution.

[0071] The data of tail acid sulfuric acid content, potassium content before and after potassium removal, and manganese content before and after filter residue washing in Examples 1, 2 and Comparative Example 1 are shown in Table 1.

[0072]

[0073] The production cost was calculated for Examples 1, 2 and Comparative Example 1: The soluble manganese content of the filter residue after neutralization of the tail acid solution of Comparative Example 1 is about 4%, wherein the manganese content of the unleached filter residue is 1.0%, and the manganese recovered by washing the filter residue is 1.0%, then the yield of soluble manganese is 2%, and 2% of the soluble manganese cannot be recovered, while the soluble manganese content of the acidic filter residue after neutralization of the tail acid solution of Examples 1 and 2 is about 3.5%, because the tail acid solution is subjected to acidic primary plate and frame filtration to obtain an acidic filter residue, and then the acidic filter residue is washed and filtered, and the washing filtrate is returned to the chemical reaction tank, wherein the manganese content of the unleached filter residue is 0.75%, and the soluble manganese recovered by washing is 0.7%, then the yield of soluble manganese is 2.05%, and only 1.45% of the soluble manganese cannot be recovered, compared with the manganese content of 4% in the traditional filter residue, the yield of soluble manganese is 2.55%.

[0074] Compared with the comparative example, based on the manganese content of 18% in the manganese ore, the raw material of manganese carbonate can increase the comprehensive yield of manganese by about 2.78% (0.5% / 18%=2.78%), that is, the yield of total manganese per ton of manganese carbonate raw material increases by 0.55% (2.55%-2.0%=0.55%). Based on the price of 1% manganese carbonate at 35-40 yuan / ton, the cost of manganese carbonate per ton is saved by about 17.5-20 yuan, and the cost of electrolytic manganese dioxide (EMD) product (the unit consumption of manganese carbonate is 3.8 tons / ton) is saved by 66.5-76 yuan / ton. Among them, the raw material of electrolytic manganese dioxide includes manganese sulfate solution.

[0075] In addition, theoretically, for manganese sulfate solution containing tail acid, 3 kg of sulfuric acid per cubic solution corresponds to 3.06 kg of calcium carbonate consumption. In actual production, 3 to 3.5 times the amount of calcium carbonate is required, that is, 9.18 to 10.71 kg is needed to neutralize sulfuric acid; if the unit consumption of manganese carbonate is 3.8 tons / ton, 3.8 tons of acidic filter residue contains about 0.855 kg of sulfuric acid, while the acidic filter residue only needs to consume 2.565 kg of calcium carbonate, saving 6.615 to 8.145 kg. According to the market price of calcium carbonate of 288 yuan / ton and 98% mass concentration of sulfuric acid of 400 yuan / ton, the corresponding saving of calcium carbonate cost in electrolytic manganese dioxide product (manganese sulfate solution unit consumption of 35 cubic meters / ton) is 91.53 to 107.21 yuan / ton, and sulfuric acid cost is 41.65 yuan / ton.

[0076] Since the acidic chemical solution is directly filtered by pressure without neutralizing the tail acid in the chemical reaction tank, the process operation of neutralizing and removing iron from the dispersed acidic filtrate is increased. Compared with the traditional production process operation, the corresponding increase in labor costs increases the cost of electrolytic manganese dioxide products by 25~30 yuan / ton.

[0077] Taking the above factors into consideration, the technical solution of the present application saves the comprehensive cost of electrolytic manganese dioxide products by 174.68 to 194.86 yuan per ton, that is, 66.5+91.53+41.65-25=174.68, 76+107.21+41.65-30=194.86.

[0078] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0079] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0080] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for preparing a manganese sulfate solution, characterized in that: include: placing the manganese ore and concentrated sulfuric acid in a chemical reaction tank containing the last washing filtrate, heating to a preset reaction temperature, and reacting for a preset time to obtain a mixed solution, wherein the mixed solution includes manganese sulfate; The mixed solution is subjected to aeration by using a Roots blower to remove potassium until the potassium content in the mixed solution is less than or equal to a potassium content threshold value, thereby obtaining a tail acid solution; The tail acid solution is subjected to an acidic primary plate-and-frame filtration to obtain an acidic filter residue and a primary filtered manganese sulfate solution; Washing and filtering the acidic filter residue, returning the washing filtrate to the chemical reaction tank to obtain an acidic washed filter residue; If the moisture content of the acidic filter residue and the sulfuric acid content in the filtrate after filter pressing meet the preset requirements, determine the total amount of sulfuric acid in the acidic washing filter residue; A neutralizing agent in an amount greater than the total amount of the sulfuric acid is mixed with the acidic washing filter residue to neutralize the acidic washing filter residue to a first preset pH value; Neutralizing the filtered manganese sulfate solution once to a second preset pH value in a neutralization and iron removal reaction tank to obtain a neutralized manganese sulfate solution; The neutralized manganese sulfate solution is subjected to aeration by using a Roots blower to remove iron until the iron content in the neutralized manganese sulfate solution is less than or equal to the iron content threshold value, thereby obtaining an iron-removed manganese sulfate solution; The deironing manganese sulfate solution is subjected to secondary plate-and-frame filtration to obtain a manganese sulfate solution; The iron removal residue from the secondary plate and frame filtration is returned to the chemical reaction tank.

2. The preparation method according to claim 1, characterized in that The preset reaction temperature is 80°C to 90°C; the preset reaction time is 8 h to 12 h.

3. The preparation method according to claim 1, characterized in that The molar ratio of manganese element to sulfuric acid in the manganese ore is 1:1.01-1.1; the concentration of sulfuric acid in the tail acid solution is 3 g / L-8 g / L.

4. The preparation method according to claim 1, characterized in that: The mixed solution is aerated with a Roots blower to remove potassium, and the tail acid solution is obtained, which is replaced by: Manganese dioxide is added to the mixed solution to remove potassium, thereby obtaining a tail acid solution.

5. The preparation method according to claim 1, characterized in that: The preset requirements are that the moisture content of the acidic filter residue is ≤30%, and the sulfuric acid content in the filtrate after the acidic filter residue is filtered is ≤0.225‰.

6. The preparation method according to claim 1, characterized in that: The neutralized manganese sulfate solution is aerated with a Roots blower to remove iron, which is replaced by: An oxidant is added to the neutralized manganese sulfate solution to remove iron, and the oxidant includes hydrogen peroxide and manganese dioxide.

7. The preparation method according to claim 1, characterized in that The potassium content threshold is 30 ppm, and the iron content threshold is 0.5 ppm.

8. The preparation method according to claim 1, characterized in that: The first preset pH value is greater than or equal to 4.5, and the second preset pH value is 3.5-4.

5.

9. A positive electrode material, characterized in that: The raw material of the positive electrode material includes the manganese sulfate solution obtained by the method for preparing the manganese sulfate solution according to any one of claims 1 to 8.

10. A lithium battery, characterized in that: The positive electrode of the lithium battery is made of the positive electrode material as claimed in claim 9.

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