Method for preparing high-purity manganese sulfate by taking pyrolusite and pyrite as raw materials

Abstract

The invention provides a method for preparing high-purity manganese sulfate by taking pyrolusite and pyrite as raw materials, which comprises the following steps: carrying out reduction reaction on the pyrolusite and the pyrite by adopting acid leaching to obtain a manganese sulfate solution, and continuously feeding the pyrolusite until ferrous ions in the system are completely oxidized into iron ions; adding a pH regulator to remove iron, adding a vulcanizing agent to remove heavy metals, adding a pH regulator to remove silicon and aluminum, and carrying out solid-liquid separation to obtain a manganese sulfate solution containing calcium and magnesium; adding a fluorinating agent into the manganese sulfate solution containing calcium and magnesium to remove calcium and magnesium, and carrying out solid-liquid separation to obtain a fluorine-containing high-purity manganese sulfate solution; and extracting the fluorine-containing high-purity manganese sulfate solution to obtain a fluorine-containing organic phase and battery-grade high-purity manganese sulfate. According to the method, the medicament cost in the removal process is greatly reduced, namely, the raw material pyrolusite is used for replacing an external oxidant to oxidize Fe < 2 + > in a system, and a large amount of jarosite and sodium jarosite are generated in situ, so that complete removal of potassium, sodium and iron is realized.

Description

Technical Field

[0001] The invention relates to the technical field of mineral processing and hydrometallurgy, and in particular to a method for preparing high-purity manganese sulfate by using pyrolusite and pyrite as raw materials. Background Art

[0002] Manganese sulfate (MnSO4) is an alkaline manganese salt and a key industrial intermediate for the production of electrolytic manganese, manganese oxide and manganese carbonate. With the explosive growth of the global green new energy battery industry, manganese sulfate has been widely used as a precursor for the preparation of positive electrode materials for nickel-cobalt-manganese-oxide lithium batteries and as a basic raw material for the preparation of battery-grade high-purity manganese tetraoxide and high-purity manganese dioxide, and its demand is increasing rapidly. At the same time, with the depletion of high-grade and high-quality manganese ore resources around the world, it is forced to turn manganese sources to the development of low-grade pyrolusite to meet the growing demand for manganese resources.

[0003] At present, the mainstream technology in the relevant industry is to reduce pyrite (FeS2) and pyrolusite (MnO2) under acidic conditions to prepare manganese sulfate. The process (Formula 1 below) has significant economic cost advantages. However, the impurity elements carried by pyrolusite and pyrite themselves will also be dissolved in large quantities as the reduction reaction occurs, which will significantly increase the difficulty of purifying manganese sulfate solution. Therefore, the removal of impurity ions (potassium, sodium, iron, zinc, nickel, cobalt, cadmium, copper (heavy metals), silicon, aluminum, calcium, magnesium) in the above process has always been a technical difficulty and research direction for preparing high-purity manganese sulfate. Generally speaking, according to the ascending process of the precipitation pH value of the above-mentioned impurity ions, the corresponding removal agent and the impurity ions are separated from the manganese sulfate solution to form a hardly soluble compound precipitate, thereby obtaining a qualified high-purity manganese sulfate solution. Specifically, potassium and sodium impurities are removed by generating yellow potassium iron alum and yellow sodium iron alum (external oxidant oxidizes Fe 2+ ), with the increase of pH, the residual impurity iron (Fe 3+ ) will be further removed, but the addition of an oxidant will also increase the cost of the removal process. Adding a sulfiding agent and further increasing the pH in sequence to remove heavy metals and silicon and aluminum respectively can obtain relatively satisfactory technical indicators. However, the physical and chemical properties of calcium and magnesium ions are similar to those of manganese, and too high a pH will cause manganese (Mn 2+ ) precipitation, which is one of the key technical difficulties in the process of purifying manganese sulfate. At present, the most effective approach is to use manganese fluoride as a removing agent for calcium and magnesium. The reason is that the solubility of calcium fluoride and magnesium fluoride formed by calcium, magnesium ions and fluoride ions is low, while the solubility of manganese fluoride is large, which enables calcium and magnesium ions to be preferably removed. But this also leads to a large amount of fluoride ions remaining in manganese sulfate solution, which not only affects the technical indicators of manganese sulfate but also increases the process cost. In order to maximize the removal of fluoride ions, extraction is usually used to remove it, and the organic phase containing fluoride ions is separated from manganese sulfate solution, but the use of organic reagents also increases process costs.

[0004] In summary, in order to achieve low-cost and efficient industrial-scale production of high-purity manganese sulfate, the present invention is specially proposed to address the technical bottlenecks faced in the preparation process of high-purity manganese sulfate, such as the difficulty in removing calcium, magnesium and fluoride ions and the high cost of the entire removal process technology.

[0005] 2FeS2 +15MnO2 + 14H2SO4 = Fe2(SO4)3 + 15MnSO4 + 14H2O (1) Summary of the invention

[0006] The present invention provides a method for preparing high-purity manganese sulfate by using pyrolusite and pyrite as raw materials, and its purpose is to solve the above-mentioned problems existing in the background technology.

[0007] In order to achieve the above-mentioned purpose, the embodiment of the present invention provides a method for preparing high-purity manganese sulfate using pyrolusite and pyrite as raw materials. The method greatly reduces the use of removal agents, has significant economic cost advantages, and is easy to achieve large-scale industrial production of high-purity manganese sulfate, thereby meeting the growing demand for manganese resources. The method is specifically: pyrolusite and pyrite of a certain particle size are uniformly mixed in a sulfuric acid environment for reduction leaching to prepare a MnSO4 solution. This will result in a large amount of divalent iron (Fe 2+ ) dissolution will significantly increase the difficulty of iron removal. Therefore, under the premise of ensuring a good leaching rate of manganese, the present invention adds a certain amount of raw material pyrolusite again after a certain reaction time to reduce the Fe in the system. 2+ Directed oxidation to Fe 3+ (Formula (2) below). This is because the ferrous sulfate raw material (Fe 3+ -Fe2(SO4)3) in situ, and can induce the in situ generation of more jarosite and sodium jarosite (XFe3[SO4(OH)3]2, X = K / Na) in an acidic system, thereby promoting the complete removal of potassium, sodium and iron (the following formula (3) ~ (4)). Further, the pH adjuster and the sulfiding agent are added in sequence to respectively remove the residual iron (Fe 3+) and heavy metals are removed in situ. After a certain period of reaction, the pH is further increased to remove residual silicon and aluminum. After a certain period of reaction, a vacuum filter is used to separate the solid and liquid from the above, and the obtained manganese sulfate solution (containing calcium and magnesium) is further purified. Under certain conditions, manganese fluoride is added to remove calcium and magnesium in the system. Finally, the fluorine-containing manganese sulfate solution is subjected to organic extraction and fluorine removal. First, sulfuric acid is added to acidify it to release hydrogen ions that combine with free fluoride ions to form hydrofluoric acid; then a specific extractant is selected to separate the hydrofluoric acid molecules from the manganese sulfate solution. As the reaction occurs, the organic phase and the manganese sulfate solution are clearly stratified, thereby achieving fluorine removal. Specifically, the present invention will also conduct a stripping test on the fluorine in the above-mentioned organic phase; that is, a redox reaction is carried out between metallic manganese powder and the fluoride ions in the organic phase to generate a new manganese fluoride product. This part of the regenerated manganese fluoride can be used to remove calcium and magnesium in continuous production. At the same time, the organic phase regenerated after stripping and defluorination can also be recycled for extracting hydrofluoric acid molecules (such as Figure 1 As shown). In summary, the present invention greatly reduces the cost of reagents in the removal process, that is, the raw material pyrolusite is used to replace the external oxidant to remove Fe in the system. 2+ The oxidation of potassium ferrosite and sodium ferrosite (XFe3[SO4(OH)3]2, X = K / Na) is generated in situ, thereby achieving the complete removal of potassium, sodium and iron. In addition, the regeneration and recycling of calcium and magnesium removal agent manganese fluoride and extractant is achieved, which significantly reduces the discharge of fluorine-containing filter residues and organic waste liquid, has dual economic and environmental benefits, and also significantly reduces the process cost, which is easy for large-scale industrial production.

[0008] MnO2 + 2Fe 2+ + 4H + = 2Fe 3+ + Mn 2+ + 2H2O (2)

[0009] K2SO4+3Fe2(SO4)3+12H2O→2KFe3[SO4(OH)3]2↓+6H2SO4 (3)

[0010] Na2SO4+3Fe2(SO4)3+12H2O→2NaFe3[SO4(OH)3]2↓+6H2SO4 (4)

[0011] An embodiment of the present invention provides a method for preparing high-purity manganese sulfate using pyrolusite and pyrite as raw materials, comprising the following steps:

[0012] S1: Acid leaching is used to reduce pyrolusite and pyrite to obtain a manganese sulfate solution, and pyrolusite is continuously added until all ferrous ions in the system are oxidized to ferric ions;

[0013] S2: adding a pH adjuster to the oxidized iron ion system to perform an iron removal reaction;

[0014] S3: adding a sulfiding agent to the system after iron removal to perform a heavy metal removal reaction;

[0015] S4: adding a pH adjuster to the system after heavy metal removal to perform a silicon-aluminum removal reaction, and the product is subjected to solid-liquid separation to obtain a manganese sulfate solution containing calcium and magnesium and a silicon-aluminum solid residue;

[0016] S5: adding a fluorinating agent to the manganese sulfate solution containing calcium and magnesium to perform a calcium and magnesium removal reaction, and subjecting the product to solid-liquid separation to obtain a fluorine-containing high-purity manganese sulfate solution and a calcium and magnesium solid residue;

[0017] S6: extracting the fluorine-containing high-purity manganese sulfate solution to obtain a fluorine-containing organic phase and battery-grade high-purity manganese sulfate;

[0018] Among them, the organic phase used for extraction is tributyl orthosilicate TBO;

[0019] Alternatively, the organic phase used for extraction is a mixture of tributyl orthosilicate TBO and tributyl phosphate TBP.

[0020] Preferably, in step S6, the aqueous phase used for extraction is sulfuric acid, and the amount used is determined according to the concentration of free fluoride ions, which is 1.0 to 3.0 times the theoretical amount; the extraction phase ratio is 1:1 to 4:1, the extraction temperature is 25 to 60°C, the extraction time is 2 to 10 min, the number of extractions is 3 to 8 times, and the stirring intensity is 150 to 350 rpm; the volume ratio of tributyl phosphate to tributyl orthosilicate is 8:2 to 4:6.

[0021] Preferably, in step S1, the particle size of pyrolusite and pyrite is -100 μm, accounting for more than 85%, wherein the total manganese content in pyrolusite is 15.6% to 32.5%, and the total sulfur content in pyrite is 20.0% to 36.8%; the amount of pyrite is calculated according to a molar ratio of MnO2 to S of 1:0.5 to 1:1.75; the amount of sulfuric acid is calculated according to a mass ratio of manganese acid of 1:0.5 to 1:1.2, and the liquid-solid mass ratio is 0.5:1 to 5:1; and the amount of pyrolusite added is 5% to 25% of the initial amount.

[0022] Preferably, in step S1, the reduction reaction temperature is 80-100° C., and the reduction reaction time is 1-3 h; the oxidation reaction temperature is 80-100° C., and the oxidation reaction time is 2-8 h; and the stirring intensity is 150-350 r / min.

[0023] Preferably, the pH adjuster is at least one of calcium carbonate and calcium oxide; in step S2, the pH value is adjusted to 4.0-4.5, the reaction temperature is 80-100°C, the reaction time is 10-60min, and the stirring intensity is 150-350r / min; in step S4, the pH value is adjusted to 5.5-6.0, the reaction temperature is 80-100°C, the reaction time is 10-60min, and the stirring intensity is 150-350r / min.

[0024] Preferably, in step S3, the sulfiding agent is at least one of barium sulfide and manganese sulfide, the amount used is 1.0 to 3.0 times the theoretical amount, the reaction temperature is 80 to 100° C., the reaction time is 10 to 60 min, and the stirring intensity is 150 to 350 r / min.

[0025] Preferably, in step S5, the fluorinating agent is manganese fluoride, the amount used is 1.5 to 4.5 times the theoretical amount, and it is added in a slurry adjustment manner. The reaction temperature is 70 to 95° C., the reaction time is 3 to 6 hours, and the stirring intensity is 150 to 350 r / min.

[0026] Preferably, the method further comprises: stripping the fluorine-containing organic phase to obtain an organic phase and manganese fluoride solid slag.

[0027] More preferably, metal manganese powder is used for stripping; the stripping temperature is 25-60° C., the stripping time is 10-30 min, the stirring intensity is 150-350 rpm, and the amount of metal manganese is 5.0-10.0 g / L.

[0028] More preferably, the organic phase can be recycled to extract fluorine-containing high-purity sulfuric acid solution; and the manganese fluoride solid slag can be recycled as a fluorinating agent.

[0029] The above scheme of the present invention has the following beneficial effects:

[0030] (1) The new method for preparing high-purity manganese sulfate proposed in the present invention can significantly reduce the process cost and achieve efficient removal of impurity elements. Its advantage is that, without the need to add an additional oxidant, the Fe 2+ All oxidized to Fe 3+, realizing the in-situ removal of potassium, sodium and iron. On this basis, the in-situ removal of heavy metals and silicon and aluminum was realized, and the technical indicators were better than those of battery-grade manganese sulfate. The removal of calcium, magnesium and fluorine realized the recycling and reuse of the removal agent manganese fluoride and the organic extractant, reducing the cost of the reagents and having significant economic benefits. At the same time, whether it is the in-situ removal of the front-end impurity elements or the removal of calcium, magnesium and fluorine, the water in the system is recycled, thereby reducing the discharge of fluorine-containing waste residues and waste liquids, and significantly reducing the process energy consumption and technical costs. In summary, this set of technologies has dual economic and environmental benefits, is easy to be industrialized on a large scale, and has important guiding and practical significance.

[0031] (2) In the present invention, in the stage of removing potassium, sodium and iron, the raw material pyrolusite is used as the oxidant of divalent iron, and no external oxidant is needed to make Fe in the system 2+ All oxidized to Fe 3+ , inducing the in-situ generation of a large amount of jarosite and sodium ferrosite, which helps to completely remove potassium, sodium and iron, and significantly reduces the cost of reagents. At the same time, along with the sedimentation of jarosite, sodium ferrosite and goethite, other impurities will also be precipitated together, greatly reducing the difficulty of removal. Reducing the cost of the roasting process has important economic and environmental significance.

[0032] (3) The fluoride used in the stage of removing calcium and magnesium impurities in the present invention can be recycled and reused in the subsequent extraction and defluorination step. That is, by stripping the fluoride ions in the organic phase, the manganese fluoride filter residue can be used again for the removal of calcium and magnesium. At the same time, the organic phase after stripping is also regenerated and can be used to extract hydrofluoric acid molecules to remove fluorine. This realizes the recycling and reuse of the calcium and magnesium removal agent manganese fluoride and the organic extractant, significantly reduces the discharge of fluorine-containing filter residues and organic waste liquid, and has dual economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 The present invention is a schematic flow chart of a method for preparing high-purity manganese sulfate using pyrolusite and pyrite as raw materials. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0036] 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.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0038] The "mass ratio of manganese acid" in this article refers to the mass ratio of MnO2 and sulfuric acid in pyrolusite, i.e., m(MnO2:H2SO4). If the mass ratio of manganese acid is 1:0.5 or 1:1.2, the amount of sulfuric acid used is 50% or 120% of the mass of MnO2.

[0039] In view of the existing problems, the present invention provides a method for preparing high-purity manganese sulfate using pyrolusite and pyrite as raw materials. Figure 1 shown.

[0040] Example 1

[0041] The particle size of a certain pyrolusite is -100um, accounting for more than 90%, of which the total manganese content is 24.5%. The particle size of another raw material pyrite is -100um, accounting for more than 90%, of which the total sulfur content is 33.5%.

[0042] A method for preparing high-purity manganese sulfate using pyrolusite and pyrite as raw materials comprises the following steps:

[0043] Step 1: Evenly mix the pyrolusite and pyrite of the above-mentioned particle size and place them in a reaction container, add deionized water at a liquid-solid mass ratio of 2:1, and then add concentrated sulfuric acid at a manganese acid mass ratio of 1:0.8 and mix evenly; when the reaction container is heated to 90°C, reduction leaching is started to prepare manganese sulfate solution, the reaction time is 2.5h, and the stirring intensity is 300r / min. After the reduction reaction is completed, 10% of the raw material pyrolusite is directly added to the reactor as an oxidant, and Fe is generated in the system. 2+ Directed oxidation to Fe 3+ , so that yellow potassium iron ore and yellow sodium iron alum are generated in situ in the system, which is beneficial to the removal of potassium, sodium and iron; the reaction is carried out at a temperature of 90°C and a stirring intensity of 300r / min for 6h.

[0044] Step 2: When the oxidation reaction is terminated, calcium carbonate (pH adjuster) is first slowly added to adjust the pH of the slurry to 4.0-4.5 under the condition that the above temperature and stirring intensity remain unchanged to remove the residual iron (Fe 3+ ), reaction time 30min;

[0045] Step 3: Add barium sulfide (2.0 times the theoretical amount) to remove heavy metals (zinc, nickel, cobalt, cadmium, copper), and the reaction time is 10 minutes;

[0046] Step 4: adding calcium carbonate to adjust the pH of the slurry to 5.5-6.0 for removing aluminum and silicon elements. The reaction time is 30 minutes. The purified manganese sulfate solution (containing calcium and magnesium) is separated by solid-liquid separation.

[0047] Step 5: Take a certain volume of leachate and place it in a reaction container, then add manganese fluoride to the slurry, the amount of which is 2.5 times the theoretical amount, the reaction temperature is 80°C, the reaction time is 4h, the stirring intensity is 300r / min, and when the reaction is terminated, the above solution is separated into solid and liquid to obtain high-purity manganese sulfate (containing fluoride) and solid residue.

[0048] Step 6: The purified high-purity manganese sulfate solution (containing fluorine) is placed in a reaction container, and then sulfuric acid is added and mixed evenly, and the amount is 2.0 times the theoretical amount; secondly, according to the extraction phase ratio (O / A) of 2:1, a mixture of tributyl phosphate and tributyl orthosilicate (volume ratio of 7:3) is added, the extraction temperature is 25°C, the extraction time is 5min, the stirring intensity is 200rpm, the extraction number is 3 times, and when the extraction reaction is terminated, an organic phase (containing fluorine) and high-purity manganese sulfate are obtained.

[0049] Step 7: Take a certain volume of organic phase (containing fluorine) and add a certain amount of metallic manganese powder to strip the fluorine therein. The amount is 8.0 g / L, the stripping temperature is 25°C, the stripping time is 20 min, and the stirring intensity is 200 rpm. When the reaction is terminated, the regenerated organic phase can be used for extraction and defluorination, and the manganese fluoride solid slag can also be used for calcium and magnesium removal.

[0050] The technical indicators of the high-purity manganese sulfate obtained in this example are: manganese leaching rate 91.2%, potassium 4.8 mg / L, sodium 0.8 mg / L, iron 0.5 mg / L, zinc 2.4 mg / L, nickel 4.5 mg / L, cobalt 0.2 mg / L, cadmium 0.4 mg / L, copper 0.1 mg / L, calcium 7.6 mg / L, magnesium 22.5 mg / L, fluorine 5.0 mg / L.

[0051] Comparative Example 1

[0052] The "after the reduction reaction is completed, 10% of the raw material pyrolusite is directly added to the reactor as an oxidant" in Example 1 is replaced by "6% volume fraction of hydrogen peroxide (H2O2) is directly added to the reactor", and other parameters and operations are the same as in Example 1. In this comparative example, the oxidant of the divalent iron in the system is changed to external chemically pure hydrogen peroxide, which can oxidize all the divalent iron in the system into trivalent iron, which is conducive to the in-situ formation of jarosite and sodium jarosite, and can effectively remove the subsequent impurity ions. However, due to the strong oxidizing property of hydrogen peroxide, the generated manganese sulfate (Mn 2+ ) is reoxidized to high-valent manganese (Mn 4+ ), so in the process of removing impurity ions, manganese will be re-precipitated in the form of hydroxide, which leads to a low leaching rate of manganese. Finally, the technical indicators obtained in Comparative Example 1 are: manganese leaching rate is 75.4%, potassium 6.5mg / L, sodium 1.4mg / L, iron 1.7mg / L, zinc 2.1mg / L, nickel 3.7mg / L, cobalt 0.1mg / L, cadmium 0.6mg / L, copper 0.3mg / L, calcium 9.1mg / L, magnesium 21.8mg / L, fluorine 5.1mg / L.

[0053] Example 2

[0054] The particle size of a certain pyrolusite is -100um, accounting for more than 90%, and the total manganese content is 20.2%. The particle size of another raw material pyrite is -100um, accounting for more than 90%, and the total sulfur content is 28.4%.

[0055] The method of this embodiment is the same as that of embodiment 1, except that:

[0056] The reaction time for preparing manganese sulfate in the reduction stage is 2 hours, and the amount of pyrolusite added again as an oxidant is 8%; after the reduction reaction is completed, 15% of the raw material pyrolusite is directly added to the reactor again as an oxidant, and the reaction time for removing sodium and potassium is 8 hours; the amount of barium sulfide used to remove heavy metals (zinc, nickel, cobalt, cadmium, copper) is 1.5 times the theoretical amount; the amount of manganese fluoride is 2.0 times the theoretical amount, and the reaction time is 3 hours; the extractant used is a mixture of tributyl phosphate and tributyl orthosilicate (volume ratio is 6:4), and the extraction phase ratio (O / A) is 3:1; the amount of metal manganese powder is 6.0 g / L, and the stripping time is 30 minutes;

[0057] The technical indicators of the high-purity manganese sulfate obtained in this example are: manganese leaching rate 90.8%, potassium 4.5 mg / L, sodium 0.9 mg / L, iron 0.4 mg / L, zinc 2.2 mg / L, nickel 4.4 mg / L, cobalt 0.2 mg / L, cadmium 0.4 mg / L, copper 0.1 mg / L, calcium 7.9 mg / L, magnesium 23.4 mg / L, fluorine 5.6 mg / L.

[0058] Comparative Example 2

[0059] The "after the reduction reaction is completed, 8% of the raw material pyrolusite is directly added to the reactor as an oxidant" in Example 2 is replaced with "without adding an external oxidant, directly reacting continuously for 8 hours, and then removing the impurity elements in sequence according to the original process of Example 2", and the other parameters and operations are the same as Example 2. In this comparative example, the oxidant of the divalent iron in the system is changed to the excess concentrated sulfuric acid in the system (as shown in Reaction Formula 5). This part of the concentrated sulfuric acid will cause the divalent iron in the pyrite to be directly oxidized into trivalent iron, and is also conducive to the in-situ formation of jarosite and sodium ferrosite. However, excessive concentrated sulfuric acid will also cause excessive dissolution of impurity ions in the raw materials pyrolusite and pyrite, and the generated trivalent iron accounts for a relatively small proportion as a whole, and there is still a large amount of divalent iron in the system, which greatly increases the difficulty of removing impurity elements. According to the removal steps of Example 2, the technical indicators obtained in Comparative Example 2 are: manganese leaching rate 90.12%, potassium 24.4 mg / L, sodium 68.95 mg / L, iron 12.54 g / L, zinc 5.4 mg / L, nickel 4.8 mg / L, cobalt 3.5 mg / L, cadmium 2.8 mg / L, copper 1.4 mg / L, calcium 21.4 mg / L, magnesium 25.8 mg / L, fluorine 6.4 mg / L.

[0060] 2FeS2 + 3.25H2SO4 = Fe2(SO4)3 + 2.25H2S↑+S + H2O (5)

[0061] Example 3

[0062] The particle size of a certain pyrolusite is -100um, accounting for more than 90%, of which the total manganese content is 28.6%. The particle size of another raw material pyrite is -100um, accounting for more than 90%, of which the total sulfur content is 35.8%.

[0063] The method of this embodiment is the same as that of embodiment 1, except that:

[0064] The mass ratio of manganese acid is 1:1.25; after the reduction reaction is completed, 15% of the raw material pyrolusite is directly added to the reactor as an oxidant; the reaction time for adding calcium carbonate to remove residual iron is 35 minutes, and the reaction time for adding barium sulfide again to remove heavy metals is 15 minutes; the reaction time for adding calcium oxide again to remove aluminum and silicon elements is 35 minutes; the amount of manganese fluoride is 3.0 times the theoretical amount, and the reaction time is 4.5 hours; the extractant used is tributyl orthosilicate, the extraction ratio (O / A) is 3:1, the extraction temperature is 20°C, the extraction time is 6 minutes, and the number of extractions is 4 times; the stripping time is 35 minutes, and the stirring intensity is 250rpm;

[0065] The technical indicators of the high-purity manganese sulfate obtained in this example are: manganese leaching rate 92.3%, potassium 4.9 mg / L, sodium 1.0 mg / L, iron 0.5 mg / L, zinc 2.5 mg / L, nickel 4.6 mg / L, cobalt 0.3 mg / L, cadmium 0.4 mg / L, copper 0.2 mg / L, calcium 8.0 mg / L, magnesium 22.8 mg / L, fluorine 5.8 mg / L.

[0066] Comparative Example 3

[0067] After the reduction reaction of Example 3 was completed, the raw material pyrolusite of Example 1 was directly added to the reactor again as an oxidant to generate Fe 2+ Directed oxidation to Fe 3+ , so that jarosite and sodium ferroaluminate are generated in situ in the system, thereby promoting the removal of potassium, sodium and iron" is replaced by "the alum seed crystals generated in the potassium and sodium removal stage are added again as the source of jarosite and sodium ferroaluminate, thereby promoting the removal of potassium, sodium and iron, and after continuous reaction for 8 hours, the impurity elements are removed in sequence according to the original process of Example 3", and other parameters and operations are the same as those of Example 3. This comparative example 3 is to reflect that the present invention no longer adds additional seed crystals as a source of inducing alum generation, but uses self-generated raw material pyrolusite as an oxidant, which not only improves the purification effect but also reduces the production cost. More importantly, the new The added alum seeds come from the actual reaction system, and the surface also carries a large amount of impurity ions, so the re-addition to the reaction system also carries new impurity elements, making it more difficult to remove. Finally, the technical indicators obtained in Comparative Example 3 are: manganese leaching rate is 91.5%, potassium 15.2mg / L, sodium 42.5mg / L, iron 18.5g / L, zinc 8.5mg / L, nickel 6.8mg / L, cobalt 5.7mg / L, cadmium 4.1mg / L, copper 2.3mg / L, calcium 12.9mg / L, magnesium 24.1mg / L, fluorine 5.8mg / L.

[0068] Example 4

[0069] The particle size of a certain pyrolusite is -100um, accounting for more than 90%, and the total manganese content is 29.8%. The particle size of another raw material pyrite is -100um, accounting for more than 90%, and the total sulfur content is 34.2%.

[0070] The method of this embodiment is the same as that of embodiment 1, except that:

[0071] The mass ratio of manganese acid is 1:1.5, and the reaction time is 3h; after the reduction reaction is completed, 25% of the raw material pyrolusite is directly added to the reactor as an oxidant, and the reaction time for removing sodium and potassium is 8h; the reaction time for adding calcium carbonate to remove residual iron is 25min, and the reaction time for adding barium sulfide again to remove heavy metals is 8min; the reaction time for adding calcium oxide again to remove aluminum and silicon elements is 25min; the amount of manganese fluoride is 2.0 times the theoretical amount, the reaction temperature is 90°C, the reaction time is 3.0h, and the stirring intensity is 350r / min; the amount of the extractant used is 3.0 times the theoretical amount, the extraction temperature is 35°C, and the extraction time is 3min; the metal manganese powder is used to strip the fluorine therein, and its amount is 10.0g / L, the stripping time is 25min, and the stirring intensity is 250rpm;

[0072] The technical indicators of the high-purity manganese sulfate obtained in this example are: manganese leaching rate 92.4%, potassium 4.6 mg / L, sodium 0.7 mg / L, iron 0.4 mg / L, zinc 2.1 mg / L, nickel 4.2 mg / L, cobalt 0.2 mg / L, cadmium 0.3 mg / L, copper 0.1 mg / L, calcium 7.4 mg / L, magnesium 21.7 mg / L, fluorine 5.4 mg / L.

[0073] Comparative Example 4

[0074] The following is directly deleted from Example 4: "Take a certain volume of organic phase (containing fluorine), and add a certain amount of metal manganese powder to strip the fluorine therein, the amount is 10.0 g / L, the stripping temperature is 25°C, the stripping time is 25 min, and the stirring intensity is 250 rpm; when the reaction is terminated, the regenerated organic phase can be used for extraction and removal of fluorine, and the manganese fluoride solid slag can also be used for calcium and magnesium removal" to analyze Comparative Example 4. That is, this Comparative Example 4 does not have the regeneration of organic extractant and the regeneration of manganese fluoride, a calcium and magnesium removal agent, although a satisfactory removal effect can be obtained under the above conditions. The specific indicators are: manganese leaching rate is 92.8%, potassium 3.4 mg / L, sodium 1.2 mg / L, iron 0.2 mg / L, zinc 2.5 mg / L, nickel 3.9 mg / L, cobalt 0.3 mg / L, cadmium 0.5 mg / L, copper 0.1 mg / L, calcium 8.2 mg / L, magnesium 20.6 mg / L, fluorine 5.4 mg / L. However, in continuous industrial production, without the above-mentioned stripping and recycling process of the organic phase and manganese fluoride, the fluorine-containing waste residue will cause serious harm to the ecological environment, hinder the large-scale industrial production of high-purity manganese sulfate, and increase the process cost. Therefore, the present invention proposes a low-cost new method for recycling the organic phase and manganese fluoride, which has dual economic and environmental benefits and great practical significance.

[0075] Comparative Example 5

[0076] The "addition of a mixture of tributyl phosphate and tributyl orthosilicate (volume ratio of 7:3) and extraction times 3 times" in Example 4 is replaced by "addition of a mixture of tributyl phosphate and tributyl orthosilicate (volume ratio of 2:8) and extraction times 5 times", and other parameters and operations are the same as those in Example 4. This comparative example 5 is intended to demonstrate that within the extractant ratio range and extraction parameter range adopted by the present invention, the removal effect of impurity fluoride ions in the manganese sulfate solution meets the requirements, and the final index of the obtained high-purity manganese sulfate product is better. The technical indicators of the high-purity manganese sulfate obtained in this comparative example 5, such as manganese leaching rate and the impurity contents of potassium, sodium, iron, zinc, nickel, cobalt, cadmium, copper, calcium and magnesium, are consistent with those in Example 4, but the fluoride ion of the high-purity manganese sulfate in Example 4 is only 5.4 mg / L, and correspondingly, the manganese fluoride ion content in this comparative example 5 is as high as 43.55 mg / L.

[0077]

[0078] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing high-purity manganese sulfate using pyrolusite and pyrite as raw materials, characterized in that: The steps include: S1: Acid leaching is used to reduce pyrolusite and pyrite to obtain a manganese sulfate solution, and pyrolusite is continuously added until all ferrous ions in the system are oxidized to ferric ions; S2: adding a pH adjuster to the oxidized iron ion system to perform an iron removal reaction; S3: adding a sulfiding agent to the system after iron removal to perform a heavy metal removal reaction; S4: adding a pH adjuster to the system after heavy metal removal to perform a silicon-aluminum removal reaction, and the product is subjected to solid-liquid separation to obtain a manganese sulfate solution containing calcium and magnesium and a silicon-aluminum solid residue; S5: adding a fluorinating agent to the manganese sulfate solution containing calcium and magnesium to perform a calcium and magnesium removal reaction, and subjecting the product to solid-liquid separation to obtain a fluorine-containing high-purity manganese sulfate solution and a calcium and magnesium solid residue; S6: extracting the fluorine-containing high-purity manganese sulfate solution to obtain a fluorine-containing organic phase and battery-grade high-purity manganese sulfate; Wherein, the organic phase used for extraction is tributyl orthosilicate; Alternatively, the organic phase used for extraction is a mixture of tributyl orthosilicate and tributyl phosphate.

2. The method according to claim 1, characterized in that In step S6, the aqueous phase used for extraction is sulfuric acid, and the amount used is determined according to the concentration of free fluoride ions, which is 1.0 to 3.0 times the theoretical amount; the extraction phase ratio is 1:1 to 4:1, the extraction temperature is 25 to 60°C, the extraction time is 2 to 10 minutes, the number of extractions is 3 to 8 times, and the stirring intensity is 150 to 350 rpm; the volume ratio of tributyl phosphate to tributyl orthosilicate is 8:2 to 4:

6.

3. The method according to claim 1, characterized in that In step S1, the particle sizes of pyrolusite and pyrite are both -100 μm, accounting for more than 85%, wherein the total manganese content in the pyrolusite is 15.6% to 32.5%, and the total sulfur content in the pyrite is 20.0% to 36.8%; the amount of the pyrite is calculated according to a molar ratio of MnO2 to S of 1:0.5 to 1:1.75; the amount of sulfuric acid is calculated according to a mass ratio of manganese acid of 1:0.5 to 1:1.2, and the liquid-solid mass ratio is 0.5:1 to 5:1; and the amount of pyrolusite added is 5% to 25% of the initial amount.

4. The method according to claim 1, characterized in that: In step S1, the reduction reaction temperature is 80-100° C., and the reduction reaction time is 1-3 hours; the oxidation reaction temperature is 80-100° C., and the oxidation reaction time is 2-8 hours; and the stirring intensity is 150-350 r / min.

5. The method according to claim 1, characterized in that The pH adjuster is at least one of calcium carbonate and calcium oxide; in step S2, the pH value is adjusted to 4.0-4.5, the reaction temperature is 80-100°C, the reaction time is 10-60min, and the stirring intensity is 150-350r / min; in step S4, the pH value is adjusted to 5.5-6.0, the reaction temperature is 80-100°C, the reaction time is 10-60min, and the stirring intensity is 150-350r / min.

6. The method according to claim 1, characterized in that In step S3, the sulfiding agent is at least one of barium sulfide and manganese sulfide, the amount used is 1.0 to 3.0 times the theoretical amount, the reaction temperature is 80 to 100° C., the reaction time is 10 to 60 min, and the stirring intensity is 150 to 350 r / min.

7. The method according to claim 1, characterized in that In step S5, the fluorinating agent is manganese fluoride, the amount of which is 1.5 to 4.5 times the theoretical amount, and is added in a slurry mixing manner. The reaction temperature is 70 to 95° C., the reaction time is 3 to 6 hours, and the stirring intensity is 150 to 350 r / min.

8. The method according to claim 1, characterized in that The method further comprises: stripping the fluorine-containing organic phase to obtain an organic phase and manganese fluoride solid slag.

9. The method according to claim 8, characterized in that Metal manganese powder is used for stripping; the stripping temperature is 25-60° C., the stripping time is 10-30 min, the stirring intensity is 150-350 rpm, and the amount of metal manganese is 5.0-10.0 g / L.

10. The method according to claim 8, characterized in that The organic phase can be recycled to extract fluorine-containing high-purity sulfuric acid solution; the manganese fluoride solid slag can be recycled as a fluorinating agent.

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