阅读说明：本技术 基于蔗渣造纸白泥的电解二氧化锰生产方法 (Electrolytic manganese dioxide production method based on bagasse papermaking white mud ) 是由 万维华 苏广源 陈奇志 韦国柱 韦革斌 方皓 王绍立 陆宾 容长厚 史磊 于 2019-11-26 设计创作，主要内容包括：本发明公开了一种基于蔗渣造纸白泥的电解二氧化锰生产方法,包括：S1)将氧化锰矿粉、硫铁矿粉与硫酸加入到浸出化合槽中进行化合反应,经固液分离得粗制硫酸锰溶液；S2)加入蔗渣造纸白泥进行中和除杂；S3)调整硫酸锰化合液的pH值,控制化合液中铁离子浓度、保温时间及温度,生成黄钠铁矾晶体,通过沉降工艺去除化合液中的钠离子；S4)在硫酸锰溶液中添加絮凝剂净化去除纤维素；S5)液固分离去除沉淀后的纤维素及硫酸鈣渣；S6)在净化后的硫酸锰溶液中加入制备好的悬浮剂和发泡剂,电解后得到电解二氧化锰。本发明能够大大节约成本,有效解决蔗渣造纸企业白泥固废堆积,并保证避免影响硫酸锰溶液的净化和EMD品质。(The invention discloses a method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, which comprises the following steps: s1) adding manganese oxide ore powder, pyrite ore powder and sulfuric acid into a leaching chemical combination tank for chemical combination reaction, and performing solid-liquid separation to obtain a crude manganese sulfate solution; s2) adding bagasse papermaking white mud for neutralization and impurity removal; s3) adjusting the pH value of the manganese sulfate compound solution, controlling the concentration of iron ions in the compound solution, the heat preservation time and the temperature to generate jarosite crystals, and removing sodium ions in the compound solution through a settling process; s4) adding a flocculating agent into the manganese sulfate solution to purify and remove cellulose; s5) carrying out liquid-solid separation to remove precipitated cellulose and calcium sulfate slag; s6) adding the prepared suspending agent and foaming agent into the purified manganese sulfate solution, and electrolyzing to obtain electrolytic manganese dioxide. The method can greatly save cost, effectively solve the problem of solid waste accumulation of white mud of bagasse papermaking enterprises, and ensure that the purification and EMD quality of the manganese sulfate solution are not influenced.)

1. A production method of electrolytic manganese dioxide based on bagasse papermaking white mud is characterized by comprising the following steps:

s1) adding manganese oxide ore powder, pyrite ore powder and sulfuric acid into a leaching combination tank for leaching combination reaction, and performing solid-liquid separation to obtain a crude manganese sulfate solution;

s2) adding bagasse papermaking white mud to neutralize and remove impurities from the crude manganese sulfate solution;

s3) adjusting the pH value of the manganese sulfate compound solution, controlling the concentration of iron ions in the compound solution, the heat preservation time and the temperature to generate jarosite crystals, and removing sodium ions in the compound solution through a settling process;

s4) adding a flocculating agent into the manganese sulfate solution to purify and remove cellulose;

s5) removing precipitated cellulose and calcium sulfate slag through liquid-solid separation and purification;

s6) adding the prepared suspending agent and foaming agent into the purified manganese sulfate solution, and electrolyzing to obtain electrolytic manganese dioxide.

2. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 1, wherein the manganese oxide ore powder in the step S1 is pyrolusite powder or reduced low-grade manganese oxide ore powder, and the low-grade manganese oxide ore powder contains 16-22% by weight of manganese.

3. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 2, wherein the manganese content of the low-grade manganese oxide ore powder is 16-22% by weight, and the moisture content of the manganese oxide ore powder after being mixed with coal and dried is 0-10% by weight.

4. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, according to claim 1, wherein in step S1, manganese oxide ore powder, pyrite ore powder and sulfuric acid are added into a leaching chemical combination tank at the same time, and are heated to 90-95 ℃ for leaching chemical combination reaction for 4-6 hours, and a crude manganese sulfate solution is obtained through solid-liquid separation.

5. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 1, wherein the step S3) is to adjust the pH of the manganese sulfate compound liquid to be 1.6-2.4, control the temperature of the compound liquid to be 90-100 ℃, and control the holding time to be 40-80 minutes.

6. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 1, wherein the step S6 is to heat the purified manganese sulfate solution to 90-100 ℃ by a plate heat exchanger, then to enter an elevated tank, and at the same time to add the prepared suspending agent and foaming agent, and to supply the solution to each electrolytic tank through a pipeline, wherein the electrolysis conditions are as follows: the temperature of the electrolyte is 100-103 ℃, and the current density of the anode is 80-85A/m²The cell voltage is 2.2-3.5V, the electrolysis period is 12-20 days, and electrolytic manganese dioxide is obtained after electrolysis.

7. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 1, wherein in the step S6, the crude manganese sulfate solution is purified for the second time, and in the first purification process, sodium dimethyldithiocarbamate (SDD) or barium sulfide (BaS) is added under stirring to remove impurities, and then aluminum sulfate is added to purify; firstly adding 10-30% of deep impurity removal agent for secondary purification, then adding ammonium sulfide for zinc removal, reacting for 1-2 hours, checking and adjusting the pH value to 6.0-8.0, and transferring to a standing tank for standing after filter pressing; and adding the residual deep impurity removal agent into the standing tank.

8. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 7, wherein activated carbon is dropped into a chute during the secondary purified liquid filter pressing process, and the rest of deep impurity removal agent is added into a standing tank.

9. The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud according to claim 7, wherein the deep impurity removal agent is a mixture of an organic agent and an inorganic agent, so that the content of heavy metal impurities in the solution is reduced to 0-1 mg/l; the organic medicament is one or more of sodium citrate, tricalcium citrate, sodium oxalate, potassium oxalate and hydroxyethylidene diphosphonate; the inorganic medicament is two or more than two of sodium sulfide, magnesium sulfide, ferrous sulfate and aluminum sulfate.

Technical Field

The invention relates to a production method of electrolytic manganese dioxide, in particular to a production method of electrolytic manganese dioxide based on bagasse papermaking white mud.

Background

The bagasse papermaking white mud is a byproduct obtained after clarifying and causticizing bagasse pulping green liquor, 0.8-1 ton of white mud waste can be generated on average when pulping and papermaking enterprises produce 1 ton of pulp paper, and the chemical components mainly comprise CaCO₃(>80.0％)，SiO₂(about 10%), residual base NaOH and other inorganic sodium salts, and also small amounts of organic impurities. Due to the reasons of purity, fineness, alkalinity and the like, the alkali recovered white mud cannot meet the use requirement of commercial light calcium carbonate (PCC), and can only be transported out and buried for disposal at present, thereby not only causing secondary pollution to the environment, but also wasting calcium carbonate resources. And because the bagasse papermaking white mud has high silicon content which is 2-3 times that of the wood papermaking white mud, CaSiO in the white mud is obtained in the high-temperature calcination process₃Can be dissolved into a glassy substance to be coated on CaCO₃Surface, resulting in CaCO₃Can not be completely decomposed, and the product quality is poor. Thus, bagasse lime mud, as a non-wood pulp lime mud, cannot be as good as other wood pulp lime mudThe lime kiln calcining method is adopted to regenerate lime from lime mud, so that the aim of recycling resources in causticization is fulfilled. Therefore, the bagasse pulping and paper making industry brings great economic benefits, and the byproduct white mud also brings pressure to environmental management.

Reports on the utilization of bagasse white mud solid waste resources mainly focus on the aspects of papermaking fillers, building materials, environment-friendly desulfurizing agents and the like at present, but the problems which are difficult to solve exist. If white mud is used as a papermaking filler, under the current technical level, the whiteness is low, and the highest whiteness is only about 85% ISO; the impurity content is high, and obvious negative effects on AKD sizing exist; the white mud particles have poor uniformity and cause the problem of sticking and pasting during filling. The wet rotary kiln is used for producing ordinary portland cement by using white mud as a building material, so that the energy consumption is high, the high alkali content of the white mud seriously damages a refractory material of a furnace lining, and the cement quality is seriously influenced. In the application of the environment-friendly desulfurizer, the white mud can corrode desulfurization equipment after being used for a long time at a high pH value. In addition, when the white slime is used as a coal combustion desulfurizer and a briquette adhesive, a small amount of sulfur dioxide can be generated at a certain temperature, so that the environment is polluted, and the expected effect cannot be achieved.

Therefore, the existing bagasse papermaking white mud resource utilization technology has the problems of maturity and reliability of the technology, and the insufficient proportion and total amount of white mud resource utilization; the trouble of massive accumulation of white mud solid waste of bagasse papermaking enterprises can not be effectively solved.

On the other hand, Electrolytic Manganese Dioxide (EMD) is an important raw material necessary for high-quality alkaline batteries or lithium ion storage batteries, and China is the largest producing country of the electrolytic manganese dioxide industry in the world. The mainstream production process adopted by the current domestic EMD enterprises is a high-temperature manganese sulfate solution electrolysis method, and lime (CaO is a main component) is required to be used as a neutralizer of a manganese ore liquefaction working section (0.26 ton of lime is consumed for producing 1 ton of EMD) so as to adjust the pH value of electrolyte and remove other metal impurities in manganese ore.

Therefore, if the bagasse papermaking white mud is used in the production of electrolytic manganese dioxide, the production cost of EMD can be saved, the market competitiveness of EMD products is improved, the white mud treatment pressure of bagasse papermaking enterprises can be relieved, and the method has positive significance for realizing the resource application of solid wastes and environmental protection. However, when the bagasse papermaking white mud is used for replacing lime, a small amount of residual impurities such as NaOH, other inorganic sodium salts, cellulose and hemicellulose existing in the bagasse white mud also enter the manganese sulfate solution and are recycled to the combination process along with the circulation of the electrolysis tail liquid, so the impurities are continuously accumulated in the continuous production process, and the purification of the manganese sulfate solution, the normal operation of a production line and the performance of a product are seriously influenced.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, which can greatly save cost, effectively solve the problem of massive accumulation of solid waste of the bagasse papermaking white mud, and ensure that the purification of manganese sulfate solution and the quality of EMD products are not influenced.

The invention adopts the technical scheme that the method for producing the electrolytic manganese dioxide based on the bagasse papermaking white mud comprises the following steps: s1) adding manganese oxide ore powder, pyrite ore powder and sulfuric acid into a leaching combination tank for leaching combination reaction, and performing solid-liquid separation to obtain a crude manganese sulfate solution; s2) adding bagasse papermaking white mud to neutralize and remove impurities from the crude manganese sulfate solution; s3) adjusting the pH value of the manganese sulfate compound solution, controlling the concentration of iron ions in the compound solution, the heat preservation time and the temperature to generate jarosite crystals, and removing sodium ions in the compound solution through a settling process; s4) adding a flocculating agent into the manganese sulfate solution to purify and remove cellulose; s5) removing precipitated cellulose and calcium sulfate slag through liquid-solid separation and purification; s6) adding the prepared suspending agent and foaming agent into the purified manganese sulfate solution, and electrolyzing to obtain electrolytic manganese dioxide.

In the above method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, the manganese oxide ore powder in step S1 is pyrolusite powder or reduced low-grade manganese oxide ore powder, and the manganese content of the low-grade manganese oxide ore powder is 16-22% by weight.

The electrolytic manganese dioxide production method based on the bagasse papermaking white mud comprises the following steps of mixing the low-grade manganese oxide ore powder with coal, wherein the manganese content of the low-grade manganese oxide ore powder is 16-22 wt%, and the water content of the manganese oxide ore powder after the manganese oxide ore powder and the coal are uniformly mixed and dried is 0-10 wt%.

The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud comprises the step S1 of simultaneously adding manganese oxide ore powder, pyrite ore powder and sulfuric acid into a leaching combination tank, heating to 90-95 ℃ for leaching combination reaction for 4-6 hours, and carrying out solid-liquid separation to obtain a rough manganese sulfate solution.

The method for producing electrolytic manganese dioxide based on bagasse papermaking white mud comprises the step S3) of adjusting the pH value of the manganese sulfate compound liquid to be 1.6-2.4, controlling the temperature of the compound liquid to be 90-100 ℃, and controlling the heat preservation time to be 40-80 minutes.

The electrolytic manganese dioxide production method based on bagasse papermaking white mud comprises the following steps of S6, heating the purified manganese sulfate solution to 90-100 ℃ through a plate heat exchanger, feeding the heated manganese sulfate solution into a head tank, adding the prepared suspending agent and the prepared foaming agent, and feeding the mixture to each electrolytic tank through a pipeline, wherein the electrolysis conditions are as follows: the temperature of the electrolyte is 100-103 ℃, and the current density of the anode is 80-85A/m²The cell voltage is 2.2-3.5V, the electrolysis period is 12-20 days, and electrolytic manganese dioxide is obtained after electrolysis.

In the step S6, performing secondary purification and impurity removal on the crude manganese sulfate solution, in the first purification process, under a stirring state, adding sodium dimethyldithiocarbamate (SDD) or barium sulfide (BaS) to remove impurities, and then adding aluminum sulfate to purify; firstly adding 10-30% of deep impurity removal agent for secondary purification, then adding ammonium sulfide for zinc removal, reacting for 1-2 hours, checking and adjusting the pH value to 6.0-8.0, and transferring to a standing tank for standing after filter pressing; and adding the residual deep impurity removal agent into the standing tank.

In the method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, activated carbon is dripped into the chute in the secondary purified liquid filter pressing process, and the rest deep impurity removal agent is added into the standing tank.

In the method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, the deep impurity removal agent is a mixture of an organic agent and an inorganic agent, so that the content of heavy metal impurities in the solution is reduced to 0-1 mg/l; the organic medicament is one or more of sodium citrate, tricalcium citrate, sodium oxalate, potassium oxalate and hydroxyethylidene diphosphonate; the inorganic medicament is two or more than two of sodium sulfide, magnesium sulfide, ferrous sulfate and aluminum sulfate.

Compared with the prior art, the invention has the following beneficial effects: according to the electrolytic manganese dioxide production method based on the bagasse papermaking white mud, the bagasse papermaking white mud is used for replacing lime, and impurities introduced into the bagasse papermaking white mud are removed in a targeted manner, so that the influence on the purification of a manganese sulfate solution and the quality of an EMD product is avoided, the cost is greatly saved, and the trouble of massive accumulation of white mud solid waste of bagasse papermaking enterprises is effectively solved.

Drawings

FIG. 1 is a flow chart of a process for producing electrolytic manganese dioxide in an example of the present invention.

Detailed Description

The invention is further described below with reference to the figures and examples.

The bagasse papermaking white mud is used in the production of electrolytic manganese dioxide, so that the production cost of EMD can be saved, the market competitiveness of EMD products is improved, the white mud treatment pressure of bagasse papermaking enterprises can be relieved, and the method has positive significance for realizing the resource application of solid wastes and environmental protection. However, the direct application of the bagasse papermaking white mud in the EMD production also faces the following technical problems.

The bagasse papermaking white mud is mainly used for a chemical combination procedure in the EMD production process, and the procedure is mainly used for preparing a manganese sulfate solution for electrolytic production of manganese dioxide. The common combination procedure in the current manganese industry EMD production line adopts a one-step method of dissolving pyrolusite and pyrite by adding sulfuric acid, then adjusting the pH value by using lime as a neutralizer, and electrolyzing to produce EMD after purification. When the bagasse papermaking white mud is used for replacing lime, a small amount of residual impurities such as NaOH, other inorganic sodium salts, cellulose and hemicellulose existing in the bagasse white mud also enter the manganese sulfate solution and are recycled to the combination process along with the circulation of the electrolysis tail liquid, so the impurities are continuously accumulated in the continuous production process, and the purification of the manganese sulfate solution, the normal operation of a production line and the performance of a product are seriously influenced. The purification of the manganese sulfate solution is the core of the quality control of the EMD product, and impurities brought by the white slime mainly affect the purification of the manganese sulfate solution and the quality of the EMD product through the following two ways:

(1) influence of Na ion.

The basic unit of manganese dioxide structure is [ MnO ] composed of one manganese atom and six oxygen atoms₆]Octahedron, manganese atom in the middle of six oxygen atoms, high quality EMD product is typical gamma-MnO₂The crystal phase has a one-dimensional chain or tunnel structure, and the crystal lattice has a large number of defects (such as stacking faults, dislocation and chain defects), non-ideal proportion, irregular holes and the like, H⁺Easy diffusion in the electrolyte, small overpotential, high reaction activity and excellent discharge performance. If MnSO₄Na in electrolyte⁺When the concentration exceeds a certain range, the manganese oxide may enter MnO₂With octahedral structure, a new phase NaxMnO is generated₂The valence state of manganese and the apparent specific gravity of an EMD product are reduced, and the discharge capacity of the battery is reduced. In addition, due to Na⁺At MnO level₂In the tunnel structure, the migration of protons is prevented during the discharge process, which affects the discharge.

Therefore, the bagasse papermaking white mud is used as a neutralization and impurity removal agent, and the introduced sodium ions are in MnSO₄The EMD solid phase structure and activity are influenced by accumulation in the solution to a certain degree, the quality of the high-sodium EMD product or the low-sodium EMD product is influenced by the accumulation, and a process for removing sodium ions must be added in the production flow to ensure the performance of the EMD product.

(2) Influence of organic substances

Organic matters brought by the white mud can be enriched in the electrolytic process of the manganese sulfate solutionOn the working electrode anode, the oxidation reaction Mn is influenced²⁺->Mn⁴⁺Is not favorable for MnO₂Depositing on the surface of the working electrode. However, in the original production process, no relevant process for removing organic matters is provided. Therefore, in order to replace lime with the bagasse papermaking white mud as a neutralization and impurity removal agent in the manganese ore liquefaction working section, the purification process of a manganese sulfate solution needs to be improved, and MnSO caused by bagasse white mud impurities is solved₄Solution purification and EMD product performance.

In order to solve the problem of enrichment of organic matters such as sodium element, cellulose and the like in the white bagasse mud in the EMD continuous production, the invention researches the original MnSO through elaborately₄After the liquid preparation stage is finished, the MnSO is adjusted₄The pH value of the compound liquid is between 1.6 and 2.4, the concentration of iron ions in the compound liquid, the heat preservation time and the temperature are controlled, and the generation and sedimentation process stages of jarosite crystals are newly added in the MnSO stage₄When the combination procedure is completed, most of sodium ions introduced by the white mud are removed in the form of sodium jarosite, so that the problem that the performance of an EMD product is influenced due to accumulation of sodium elements caused by circulation of an electrolysis tail liquid is solved; and for organic matters such as cellulose in the white bagasse mud, a flocculating agent is added in the concentration process of the manganese sulfate solution and is removed through the purification process, so that the influence of the organic matters on the manganese sulfate electrolysis process is avoided.

The method is mainly used for solving the technical problem of impurity circulation accumulation caused by replacement of lime by the bagasse white mud, the optimal sodium removal process and the organic matter flocculation process are researched to ensure the quality of the EMD product, the product meeting the industrial standard is obtained, and the method can play a demonstration role in resource utilization of the bagasse white mud in the EMD industry. Compared with lime as a neutralizer, the bagasse white mud has obvious economic cost advantages and environmental benefit advantages. Corresponding pilot experiments are carried out at present, and the neutralization and impurity removal effects of the bagasse papermaking white mud can completely meet the requirements of the conventional MnSO₄The liquid preparation process and the purification process are required, the problem of accumulation of white mud impurities (sodium, organic matters and the like) caused by recycling of the electrolysis tail liquid is solved, and pilot-scale experiments prove that the product quality is higher than the existing industrial standard. Compared with the old production process, the new equipment investment is less, and the new process is only changedThe process flow can not greatly change the existing production line.

According to the method for producing electrolytic manganese dioxide based on bagasse papermaking white mud, manganese oxide ore powder can be pyrolusite powder or reduced low-grade manganese oxide ore powder, such as low-grade manganese oxide ore powder with the manganese content of 16-22% by weight. For the reduction treatment of the low-grade manganese oxide ore powder, refer to the prior patent document CN103205772A of the applicant, and no further description is given.

And carrying out solid-liquid separation on the ore pulp after leaching and combination to obtain a rough manganese sulfate solution.

And purifying the crude manganese sulfate solution to remove impurities to obtain a qualified manganese sulfate solution. The crude manganese sulfate solution contains heavy metals such as copper, lead, nickel and zinc and impurities such as calcium and magnesium, so the purification and impurity removal are required. In the first purification step, certain amount of SDD and barium sulfide (BaS) are added at proper temperature, the reaction time, pH and other conditions are controlled, so that heavy metal ions such as nickel and the like form sulfide precipitate, and the sulfide precipitate is separated from the solution after filter pressing and is removed. And (3) performing secondary purification after the purified liquid of the first-stage filter pressing comes out, adding a deep purification medicament, removing heavy metal impurities such as zinc and the like, and further improving the quality of the manganese sulfate solution. The deeply purified manganese sulfate solution flows through a long-distance chute to dynamically remove calcium and magnesium, then is conveyed to a standing tank to be stood, so that the solution is aged to remove impurities such as calcium, magnesium and the like through precipitation, and the stood solution is pumped into a box type filter press to be filtered, so that the qualified manganese sulfate solution is obtained.

And after the qualified manganese sulfate solution is electrolyzed in an electrolytic cell, stripping, washing, drying and packaging to obtain an electrolytic manganese dioxide product. The following description will be made with respect to specific embodiments:

1. liquid preparation

(1) Leaching chemical combination

Adding manganese monoxide ore powder into a leaching chemical combination tank, adding water into sulfuric acid with the concentration of 98% to prepare a dilute sulfuric acid solution with the concentration of 100g/L, simultaneously adding sulfuric acid according to the molar ratio of the ore powder to the sulfuric acid of 1:1, carrying out redox reaction for 4-6 hours at the temperature of 90 ℃, and directly heating by using a steam pipe in the tank to ensure the temperature of the leaching chemical combination reaction.

And adding a proper amount of ammonium sulfate in the heating leaching process to ensure that the concentration of the ammonium sulfate reaches the index requirement of the solution, namely 100-120 g/l.

And after the leaching reaction is finished, qualitatively detecting whether ferrous iron in the solution is qualified or not, wherein the color is blue green when the ferrous iron is unqualified, and the color is earthy yellow when the ferrous iron is qualified. And if the ferrous iron is unqualified, adjusting the pH value of the solution to 5.5-6.5, and adding a proper amount of manganese oxide or hydrogen peroxide to remove the ferrous iron until the ferrous iron is qualified in qualitative detection.

And after ferrous iron is removed, adding ammonia water into the combination tank, adjusting the pH value of the leachate to be 6.6-7.0, then qualitatively detecting whether ferric iron of the solution is qualified or not, if the ferric iron is not qualified, the extraction layer is iron red, if the ferric iron is qualified, the extraction layer is transparent white, and if the ferric iron is not qualified, adding a proper amount of hydrogen peroxide and adjusting the ammonia water to remove the ferric iron until the ferric iron is qualified.

(2) One-time purification

And transferring the leached qualified solution to a purification tank for primary purification through filter pressing, adding SDD and BaS for conventional impurity removal, adding aluminum sulfate for purification, precipitating metal impurities such as nickel in the form of sulfides and the like, and converting the solution after filter pressing into a secondary purification tank for secondary purification.

Adding SDD into a first-stage purification tank under a stirring state, reacting for a certain time, qualitatively detecting that nickel in the solution is qualified, adding aluminum sulfate, reacting fully, performing filter pressing, performing second-stage purification, and conveying filter residues to a residue field.

Before SDD is added, the pH value of the solution in the tank must be adjusted to reach an index, so that the pH value is 6.0-7.0, otherwise, the impurity removal effect is poor and SDD waste is caused. In addition, the stirring cannot be stopped during the filter pressing process, and the solution in the tank should be discharged completely as much as possible.

(3) Second purification

And (3) firstly adding a part of deep impurity removal agent, such as 10-30% of the preset amount of deep impurity removal agent, adding a specified amount of ammonium sulfide for zinc removal, reacting for 1 hour, checking and adjusting the pH value to 6.0-8.0, and transferring to a standing tank for standing after filter pressing. The deep impurity removal agent reasonably matches and uses an organic agent and an inorganic agent, so that the content of heavy metal impurities which are difficult to remove in the solution is reduced to below 1 mg/l; the organic medicament is one or more of sodium citrate, tricalcium citrate, sodium oxalate, potassium oxalate and hydroxyethylidene diphosphonate; the inorganic medicament is two or more than two of sodium sulfide, magnesium sulfide, ferrous sulfate and aluminum sulfate. In this embodiment, the deep impurity removal medicament comprises the following components in parts by weight: 15-30 parts of tricalcium citrate, 10-20 parts of potassium oxalate, 5-10 parts of hydroxyethylidene diphosphonate, 5-15 parts of magnesium sulfide and 5-15 parts of ferrous sulfate.

By utilizing the characteristic that the organic medicament and heavy metal ions form a chelate, the trace amount of heavy metal impurities such as zinc in the manganese sulfate solution is controlled on the premise of not seriously damaging the concentration of the divalent manganese.

And (3) dripping active carbon into the chute in the secondary purified liquid filter pressing process, and adding the residual deep impurity removal agent into the standing tank.

And (3) allowing the pressure filtrate to enter a standing tank, detecting whether the contents of manganese sulfate and ammonium sulfate, the PH value and the heavy metal impurity in the solution in the standing tank are qualified, and if the solution in the standing tank is found to be unqualified, returning to the second-stage purification for corresponding treatment until the solution is qualified.

The solution is kept stand and settled for 24 hours, and then is subjected to filter pressing by a filter press and electrolytic production.

2. Electrolysis

And (3) carrying out superfine filtration on the refined qualified manganese sulfate solution, heating the manganese sulfate solution to 90 ℃ by a plate heat exchanger, and then entering an elevated tank for suspension electrolysis. Simultaneously adding the prepared suspending agent and the foaming agent, wherein the temperature of the electrolyte is 100-103 ℃, and the current density of the anode is 80-85A/m²The cell voltage is 2.2-3.5V, the electrolysis period is 12-20 days, the manganese dioxide crude product is stripped from the anode, the manganese dioxide crude product is crushed to 6-8 mm particles by a crusher and then enters the rinsing cells, and the effective volume of each rinsing cell is 1m³The method adopts a three-stage rinsing process of water washing, alkali washing and water washing, wherein the temperature of a first rinsing solution and a second rinsing solution is 60 ℃, the temperature of the last rinsing water is 80 ℃, the rinsing cycle is 40 hours, and the rinsing solutions are directly heated by steam. Sending the rinsed electrolytic manganese dioxide to a pendulum type pulverizer to pulverize and collect product powder (the particle size is 325 meshes)) In order to eliminate the quality difference of products and ensure the uniformity of the products, the products are conveyed to a gravity type blending bin in a dense phase conveying mode for homogenization and blending for about 16 hours to prepare qualified mercury-free alkali manganese type manganese dioxide products.

Obtaining the main index MnO of manganese dioxide product₂≥91.0％、Fe≤60ppm、Cu≤5ppm、Pb≤5ppm、Ni≤5ppm、Co≤5ppm、Mo≤0.5ppm、As≤0.5ppm、Sb≤0.5ppm、K≤200ppm。

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.