Method for producing manganese sulfate aqueous solution using sulfur dioxide reduction leaching method

Abstract

One embodiment of the present invention is a method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method, comprising: a raw material preparation step of preparing a manganese-containing by-product containing manganese and impurities; a pulverization step and a washing step of pulverizing and washing the manganese-containing by-product; a reduction leaching step of leaching the manganese-containing by-product pulverized by the pulverization step and the washing step; a neutralization step of neutralizing the post-leaching solution generated by the reduction leaching step; a first purification step of purifying the post-neutralization solution generated by the neutralization step; and a second purification step of additionally purifying the solution after the first purification generated by the first purification step, wherein the reduction leaching step is carried out using an inorganic acid and sulfur dioxide gas, and discloses a method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method.

Description

Technical Field

[0001] The present invention relates to a method for producing an aqueous manganese sulfate solution from a manganese-containing by-product generated during the wet smelting process of zinc. In particular, it relates to a method for producing an aqueous manganese sulfate solution of high purity used as a raw material for a precursor among the cathode active materials of lithium-ion secondary batteries.

Background Art

[0002] Manganese sulfate is mainly produced through processes such as leaching, precipitation, and crystallization from low-purity manganese ores or manganese-containing substances. On the other hand, for the production of manganese sulfate used as a raw material for a precursor among the cathode active materials of lithium-ion secondary batteries, a wet reaction is required. Among them, leaching using an acid from solid manganese-containing substances must be carried out.

[0003] The use of a reducing agent for the composition of the reducing atmosphere is required in this process. However, there is a problem that the process operation cost increases due to excessive use of the reducing agent for complete leaching of manganese.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to produce manganese sulfate, particularly an aqueous manganese sulfate solution of high purity, from a by-product containing manganese. In particular, in order to replace the reducing agent used in the reduction leaching process, a reduction gas containing sulfur dioxide gas is used as a leaching aid to propose a process with high recovery rate and economic efficiency.

[0005] Furthermore, a high-purity aqueous manganese sulfate solution is produced through neutralization and purification of the post-leaching solution secured in the reduction leaching process of manganese.

Means for Solving the Problems

[0006] One embodiment of the present invention is a method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method, comprising a raw material preparation step of preparing a manganese-containing by-product containing manganese and impurities; a pulverization step and a washing step of pulverizing and washing the manganese-containing by-product; a reduction leaching step of leaching the manganese-containing by-product pulverized by the pulverization step and the washing step; a neutralization step of neutralizing the post-leaching solution generated by the reduction leaching step; a first purification step of purifying the post-neutralization solution generated by the neutralization step; and a second purification step of additionally purifying the solution after the first purification generated by the first purification step. The reduction leaching step is performed using an inorganic acid and sulfur dioxide gas, and discloses a method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method.

[0007] In one embodiment, the average particle size of the pulverized manganese-containing by-product may be 1 μm to 25 μm.

[0008] In one embodiment, the pulverization step and the washing step may be performed in the same reactor.

[0009] In one embodiment, in the pulverization step and the washing step, the manganese-containing by-product is washed with a dilute acid and water. The dilute acid is at least one of sulfuric acid, hydrochloric acid, and nitric acid, and the concentration of the dilute acid may be 10 g / L to 100 g / L.

[0010] In one embodiment, the amount of water introduced for the washing step may be 1.5 times to 3 times the manganese-containing by-product by weight ratio.

[0011] In one embodiment, the neutralization step may be performed using a manganese-containing by-product as a neutralizing agent.

[0012] In one embodiment, sulfur dioxide gas may be additionally injected in the neutralization step.

[0013] In one embodiment, the first purification step includes a step of removing the impurities using a precipitation method, and the second purification step may include a step of removing the impurities using a solvent extraction method.

[0014] In one embodiment, the first purification step may be carried out through a precipitation reaction of the impurities by adding at least one of sodium sulfide, sodium hydrosulfide, ammonium hydrogen sulfide, and hydrogen sulfide as a precipitating agent.

[0015] In one embodiment, the second purification step may include a loading step of extracting manganese contained in the liquid after the first purification into an organic phase; a scrubbing step of washing the organic phase from which manganese has been extracted with water; and a stripping step of adding sulfuric acid to the organic phase after the scrubbing step to recover manganese in the form of an aqueous manganese sulfate solution.

Advantages of the Invention

[0016] According to the present invention, manganese sulfate, particularly an aqueous solution of high-purity manganese sulfate, can be produced from manganese-containing by-products.

[0017] In the case of the reduction leaching step included in the present invention, different from leaching using a normal reducing agent, by using a reducing gas, relatively high recovery rate and high economic efficiency can be achieved.

[0018] The manganese sulfate according to the present invention can be suitably used as a raw material for a precursor among the positive electrode active materials of lithium secondary batteries.

Brief Description of the Drawings

[0019]

Figure 1

[0020]

Figure 2

Modes for Carrying Out the Invention

[0021] Examples of the present invention are illustrated for the purpose of explaining the technical idea of the present invention. The scope of rights according to the present invention is not limited to the examples presented below or the specific descriptions of these examples.

[0022] Among the positive electrode active materials of lithium ion secondary batteries, a wet reaction is required for the production of manganese sulfate used as a raw material for the precursor. Among them, leaching using an acid from a solid manganese-containing material must be performed.

[0023] In this process, different from the examples of the present invention, a reducing agent such as hydrogen peroxide (H2O2) for the composition of the reducing atmosphere can be used. In this case, there is a problem that the operating cost of the process increases due to excessive use of the reducing agent for complete leaching of manganese.

[0024] The method for producing an aqueous manganese sulfate solution according to an example of the present invention can use a reducing gas containing sulfur dioxide (SO2 gas) as a leaching aid, and can have a high recovery rate and economy.

[0025] Hereinafter, the present invention will be described with reference to the drawings.

[0026] FIG. 1 is a flowchart showing a method for producing an aqueous manganese sulfate solution using a sulfur dioxide gas reduction leaching method according to an example of the present invention. FIG. 2 is a flowchart showing a second purification step according to an example of the present invention.

[0027] Referring to FIGS. 1 and 2, a method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method according to an embodiment of the present invention includes a raw material preparation step (S100) of preparing a manganese-containing by-product containing manganese and impurities, a pulverization step and a washing step (S200) of pulverizing and washing the manganese-containing by-product, a reduction leaching step (S300) of leaching the manganese-containing by-product pulverized by the pulverization step and the washing step, a neutralization step (S400) of neutralizing the post-leaching solution generated by the reduction leaching step, a first purification step (S500) of purifying the post-neutralization solution generated by the neutralization step, and a second purification step (S600) of additionally purifying the solution after the first purification generated by the first purification step.

[0028] Raw material preparation step (S100) In the raw material preparation step (S100), a manganese-containing by-product containing manganese and impurities can be prepared. In one embodiment, the manganese-containing by-product can be generated in a zinc hydrometallurgy process. In this case, in the raw material preparation step (S100), the manganese-containing by-product can be prepared together with the zinc process solution.

[0029] As a raw material containing manganese for producing an aqueous manganese sulfate solution, the manganese-containing by-product can contain at least one of an oxide, a hydroxide, a sulfide, and a sulfur oxide. Among the manganese-containing by-products, manganese can be contained in the state of manganese dioxide (MnO2).

[0030] In one embodiment, the manganese-containing by-product can contain at least one of calcium (Ca), potassium (K), lead (Pb), zinc (Zn), magnesium (Mg), sodium (Na), and silicon (Si) as impurities other than manganese (Mn). In one embodiment, the composition of the manganese-containing by-product is as shown in Table 1 below. The unit is wt%.

[0031]

Table 1

[0032] In one embodiment, the manganese-containing by-product may contain oxygen (O). For example, the portion not shown in Table 1 may mostly be oxygen (O).

[0033] Crushing and washing step (S200) In the grinding step and the washing step (S200), the manganese-containing by-product can be ground and washed. The grinding step and the washing step (S200) correspond to the pretreatment step of the manganese-containing by-product. In the grinding step and the washing step (S200), a grinding step for reducing the particle size of the manganese-containing by-product can be performed. Also, a washing step for removing at least a part of the impurities contained in the manganese-containing by-product can be performed. In the raw material preparation step (S100), the manganese-containing by-product can be prepared together with the zinc process solution. In the washing step, the zinc process solution can be washed with water.

[0034] The average particle size of the ground manganese-containing by-product can be about 1 μm to 25 μm. Before the grinding step is performed, the average particle size of the manganese-containing by-product may be about 500 μm to 900 μm. The average particle size of the manganese-containing by-product may be reduced to about 1 μm to 25 μm by the grinding step. Therefore, by reducing the average particle size of the manganese-containing by-product through the grinding step before performing the reduction leaching step (S300), the leaching efficiency in the reduction leaching step (S300) can be increased. When the average particle size of the manganese-containing by-product is large, the reactivity is low, so in the subsequent reduction leaching step (S300), leaching may be substantially difficult. That is, when the average particle size of the manganese-containing by-product is larger than 25 μm, the leaching efficiency may decrease. For example, the grinding step can be performed using a milling machine such as a ball mill or a rod mill.

[0035] In the crushing process and the washing process (S200), at least a part of the impurities in the manganese-containing by-product can be removed. In one embodiment, in the crushing process and the washing process (S200), the manganese-containing by-product can be washed with dilute acid and water to remove at least a part of the impurities. In one embodiment, the dilute acid may be at least one of sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). In one embodiment, the concentration of the dilute acid may be 10 g / L to 100 g / L.

[0036] The amount of water input for the washing process may be 1.5 to 3 times the manganese-containing by-product by weight ratio. When the amount of water input for the washing process is less than 1.5 times that of the manganese-containing by-product, the impurity removal rate may be less than 50%. When the amount of water input for the washing process is more than 3 times, the impurity removal rate may increase, but the water consumption of the process increases, and the economy may decline.

[0037] In one embodiment, the crushing process and the washing process can be carried out simultaneously. The crushing process and the washing process can be carried out in the same reactor. For example, the crushing process and the washing process can be carried out simultaneously using a wet pulverizer. Then, by solid-liquid separation, a part of the impurities (such as calcium, potassium, magnesium, sodium, etc.) contained in the manganese-containing by-product can be removed. When the crushing process and the washing process are carried out simultaneously, the process of manufacturing an aqueous manganese sulfate solution can be simplified. This may be because during the process of manufacturing an aqueous manganese sulfate solution, the subsequent process after the crushing process and the washing process reacts with water. Also, when the crushing process and the washing process are carried out in the same reactor, the number of reactors can be reduced. In other embodiments, the crushing process and the washing process can be carried out individually.

[0038] Reductive leaching step (S300) In the reduction leaching step (S300), the manganese-containing by-product pulverized in the pulverization step and the washing step (S200) is leached. The reduction leaching step (S300) can be performed after the pulverization step and the washing step (S200). In the reduction leaching step (S300), the manganese-containing by-product pulverized using an inorganic acid and a reducing gas can be leached. The reducing gas may be sulfurous acid gas (SO2 gas). In one embodiment, the reduction leaching step (S300) can be performed using an inorganic acid and sulfurous acid gas. For example, the inorganic acid may be at least one of sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). The inorganic acid may be an inorganic acid diluted with water.

[0039] In one embodiment, the concentration of sulfurous acid gas may be 10% or more, and in this case, the dissolution rate of manganese may be 99.6% or more. Among the supplied sulfurous acid gas, the sulfurous acid gas that has not participated in the reaction is reused in the reduction leaching step (S300) through recycling. When the concentration of sulfurous acid gas is less than 10%, the circulation amount of gas other than sulfurous acid gas may increase and cause a decrease in the dissolution rate. Therefore, the concentration of sulfurous acid gas is preferably 10% or more. However, the present invention is not limited thereto, and in other embodiments of the present invention, sulfurous acid gas having a concentration of less than 10% may be used. The gas other than sulfurous acid gas may be an inert gas, oxygen, or air.

[0040] The sulfurous acid gas can be injected through an injection pipe. For example, the process liquid may be located in the reaction tank, and the sulfurous acid gas can be injected into the reaction tank through an injection pipe provided at the lower part of the reaction tank. Therefore, the sulfurous acid gas can react with manganese inside the process liquid.

[0041] Sulfuric acid and sulfurous acid gas can be used in the reduction leaching step. In this case, through the following [Reaction Formula 1] and [Reaction Formula 2], the sulfurous acid gas reacts with water to generate sulfurous acid, and from the manganese-containing by-product, manganese can be leached in the form of manganese sulfate (MnSO4) in a reducing atmosphere to obtain a leachate after leaching.

[0042] [Reaction Formula 1] SO2(g) → SO2(aq)

[0043] [Reaction formula 2] MnO2 + SO2(aq) → MnSO4

[0044] Manganese in the manganese-containing by-product mainly exists in the form of manganese dioxide (MnO2). However, since the manganese in manganese dioxide is tetravalent, the leaching of manganese may not be easy. In contrast, the leaching of divalent manganese can be easily carried out. Therefore, for manganese leaching, it is necessary to reduce the manganese in manganese dioxide in the manganese-containing by-product to divalent manganese. In connection with this, in the examples of the present invention, sulfurous acid gas as a reducing agent can be used to reduce tetravalent manganese to divalent manganese, whereby a leachate in the form of manganese sulfate can be generated from the manganese-containing by-product (see the above [Reaction formula 1] and [Reaction formula 2]).

[0045] The reduction leaching step (S300) can be carried out at about 20°C to 60°C. The reduction leaching step (S300) starts from room temperature, and during the leaching reaction, the internal temperature can rise to 60°C due to the exothermic reaction. This may mean that no additional heat source is required. Therefore, the reduction leaching step (S300) can be an economical process. The sulfuric acid concentration of the leachate may be 25 g / L to 100 g / L. The pH of the leachate may be 1 or less. In one embodiment, in the reduction leaching step (S300), not only manganese but also other impurities can be leached. For example, impurities such as calcium (Ca), potassium (K), lead (Pb), and zinc (Zn) can be leached together with manganese and may be contained in the leachate after leaching.

[0046] The manganese concentration of the leachate obtained in the reduction leaching step (S300) may be about 60 g / L to 100 g / L. As an example, the manganese concentration of the leachate may be 61 g / L to 64 g / L. Therefore, about 1.5 to 3 times as much water as the manganese-containing by-product pulverized by weight ratio can be used for the dilution of the inorganic acid.

[0047] Sulfurous acid generated from sulfur dioxide can replace the role of the leaching solution, reducing the amount of inorganic acid used for general acid leaching. Specifically, sulfurous acid can be generated from sulfur dioxide according to the following [Reaction Formula 3], and sulfuric acid can be generated from sulfurous acid according to [Reaction Formula 4]. Therefore, it is not necessary to maintain a one-to-one equivalent between the inorganic acid and manganese. That is, the amount of inorganic acid used can be reduced.

[0048] [Reaction Formula 3] SO2 + H2O → H2SO3

[0049] [Reaction Formula 4] 2H2SO3 + O2 → 2H2SO4

[0050] Neutralization step (S400) In the neutralization step (S400), the post-leaching solution generated in the reduction leaching step (S300) can be neutralized. The neutralization step (S400) can be performed after the reduction leaching step (S300). When obtaining the post-leaching solution, if the post-leaching solution is generated in an atmosphere with a high pH, the amount of the post-leaching solution generated can be small. In the examples of the present invention, after performing the reduction leaching step (S300) in an acidic atmosphere with a low pH to ensure a sufficient post-leaching solution, the neutralization step (S400) can be performed.

[0051] In the neutralization step (S400), a neutralizing agent is added to increase the pH of the post-leaching solution generated in the reduction leaching step (S300). The addition of the neutralizing agent can be for the subsequent purification step. The neutralizing agent is at least one of a manganese-containing by-product, sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), and magnesium oxide (MgO). Desirably, in the neutralization step (S400), as the neutralizing agent, the manganese-containing by-product can be used in the form of a pulverized manganese-containing by-product. There is no problem even if the amount of impurities increases due to the addition of the manganese-containing by-product. This is because the first purification step (S500) and the second purification step (S600) are performed after the neutralization step (S400).

[0052] When the neutralization process (S400) is carried out using a manganese-containing by-product, the amount of neutralizing agent separately introduced can be reduced, and the cost can be cut. Also, the inflow of additional other impurities can be prevented, and the manganese concentration in the post-neutralization liquid can be increased. When a manganese-containing by-product is used as the neutralizing agent, a reducing gas (e.g., sulfurous acid gas) may be additionally injected in the neutralization process (S400) for the dissolution of valuable metals contained in the additionally introduced manganese-containing by-product. In this case, the leaching reactor and the neutralization reactor can be continuously configured.

[0053] After the neutralization process (S400) is carried out, the pH of the post-neutralization liquid may be about 3 to 5. Desirably, the pH of the post-neutralization liquid may be about 4 to 5.

[0054] First purification step (S500) In the first purification process (S500), the post-neutralization liquid generated by the neutralization process (S400) can be purified. The post-neutralization liquid may be the neutralized post-leaching liquid. The first purification process (S500) is a process for removing impurities in the post-neutralization liquid after the neutralization process (S400).

[0055] The first purification process (S500) may be a process for removing impurities using the precipitation method. In the first purification process (S500), at least one of sodium sulfide (Na2S), sodium hydrosulfide (NaSH), ammonium hydrosulfide (NH4HS), and hydrogen sulfide (H2S) can be used as the precipitating agent to remove heavy metal impurities. Also, in the first purification process (S500), at least one of sodium fluoride (NaF), oxalic acid (C2H2O4), and sodium oxalate (Na2C2O4) can be used as the precipitating agent to remove light metal impurities. Through this, impurities such as zinc, lead, cadmium, cobalt, nickel, calcium, and magnesium can be removed. In one embodiment, when sodium hydrosulfide (NaSH) is used as the precipitating agent, the reaction formula is as shown in the following [Reaction Formula 5]. In one embodiment, when sodium fluoride (NaF) is used as the precipitating agent, the reaction formula is as shown in the following [Reaction Formula 6].

[0056] [Reaction Formula 5] 2M H SO4 + 2NaSH → Na2SO4 + H2SO4 + 2M H S↓(M H is heavy metals such as Zn, Pb, Cd, Co, Ni, Cu, etc.)

[0057] [Reaction formula 6] M L SO4 + 2NaF → Na2SO4 + M L F2↓(M L is light metals such as Ca, Mg, etc.)

[0058] The first purification step (S500) can be carried out at about 20°C to 60°C.

[0059] The precipitant for removing heavy metal impurities can be added at an equivalent ratio of about 0.8 to 1.4 with respect to the heavy metals contained in the post-neutralization solution. When the precipitant for removing heavy metal impurities is added at an equivalent ratio less than 0.8 of the heavy metal ratio, the heavy metal removal rate will be 85% or less, and a complete reaction may not occur. When the precipitant for removing heavy metal impurities is added at an equivalent ratio exceeding 1.4 of the heavy metal ratio, impurities caused by the precipitant will flow in excessively, which will have a negative impact on the process and at the same time the economy may decline.

[0060] The precipitant for removing light metal impurities can be added at an equivalent ratio of about 1.0 to 2.5 with respect to the light metals contained in the post-neutralization solution. When the precipitant for removing light metal impurities is added at an equivalent ratio less than 1.0 of the light metal ratio, the light metal removal rate may be 90% or less, and a complete reaction may not occur. If the precipitant for removing light metal impurities is added at an equivalent ratio exceeding 2.5 of the light metal ratio, impurities caused by the precipitant will flow in excessively, which will have a negative impact on the process and at the same time the economy may decline.

[0061] After the first purification step (S500), the contents of zinc, lead, cadmium, nickel, copper, and cobalt contained in the liquid after the first purification can each drop to 5 mg / L or less. After the first purification step (S500), the contents of calcium and magnesium contained in the liquid after the first purification can each drop to 50 mg / L or less.

[0062] Second purification step (S600) In the second purification step (S600), the liquid after the first purification generated by the first purification step (S500) can be further purified. The second purification step (S600) can be performed after the first purification step (S500). The second purification step (S600) may be a step of removing impurities using a solvent extraction method. An organic extractant can be used to remove impurities such as sodium (Na) and potassium (K) in the second purification step (S600). In one embodiment, the second purification step (S600) may include a loading step (S610), a scrubbing step (S620), and a stripping step (S630). At least one of phosphoric acid (di-2-ethylhexyl phosphoric acid), mono-2-ethylhexyl (2-ethylhexyl) phosphonate, and bis(2,4,4-trimethylpentyl) phosphinic acid can be used as the organic extractant.

[0063] The loading step (S610) may be a step of extracting manganese contained in the liquid after the first purification into the organic phase. The loading step (S610) may be a step of extracting manganese contained in the liquid after the first purification into the organic phase using an organic extractant after the first purification step (S500). The reaction temperature of the loading step (S610) may be about 30°C to 50°C. When the reaction temperature of the loading step (S610) is about 30°C to 50°C, the reaction of the organic extractant can be the most active. When the reaction temperature of the loading step (S610) is 30°C or lower, the viscosity of the organic extractant may increase and the reactivity may decrease. When the reaction temperature of the loading step (S610) exceeds 50°C, the amount of volatile components is large, so the efficiency of the process may decrease. The input amount of the organic phase with respect to the aqueous phase in the loading step (S610) may be about 3 to 6 in terms of volume ratio. When the input amount of the organic phase with respect to the aqueous phase in the loading step (S610) is less than 3 in terms of volume ratio, the binding of the target metal and the organic extractant is not complete, so the extraction rate may be 90% or less. When the input amount of the organic phase with respect to the aqueous phase in the loading step (S610) exceeds 6 in terms of volume ratio, the process cost may increase due to excessive use of the organic extractant. The pH range of the loading step (S610) may be about 4 to 5. In order to adjust the pH range of the loading step (S610) to 4 to 5, at least one of sodium hydroxide (NaOH), sodium carbonate (Na2CO3), and sodium sulfate (Na2SO4) may be used.

[0064] When the extraction of manganese into the organic phase is completed by mixing the aqueous phase and the organic phase, phase separation is possible due to the specific gravity difference between the organic phase and the aqueous phase. The organic phase containing manganese can be subjected to a scrubbing step (S620).

[0065] The scrubbing step (S620) can be a step of washing the organic phase from which manganese has been extracted with water. The scrubbing step (S620) may be a step for removing impurities in the loaded organic phase using water. The reaction temperature of the scrubbing step (620) may be about 30°C to 50°C. When the reaction temperature of the scrubbing step (620) is about 30°C to 50°C, the reaction of the organic extractant can be most active. When the reaction temperature of the scrubbing step (620) is 30°C or lower, the viscosity of the organic extractant may increase and the reactivity may decrease. When the reaction temperature of the scrubbing step (620) exceeds 50°C, the amount of volatile components is large, so the process efficiency may decrease. The input amount of the organic phase with respect to the aqueous phase in the scrubbing step (620) may be about 5 to 10 in terms of volume ratio. The scrubbing step (620) is a step of washing other impurities in addition to the target metal. When the input amount of the organic phase with respect to the aqueous phase in the scrubbing step (620) is less than 5 in terms of volume ratio, the impurity removal rate may be 85% or less. When the input amount of the organic phase with respect to the aqueous phase in the scrubbing step (620) exceeds 10 in terms of volume ratio, the impurities can be completely removed, but the process cost may increase as the amount of unnecessary water used increases. The organic phase containing manganese can be washed with water (Washing) to remove impurities such as sodium and potassium contained in the organic phase. The organic phase containing manganese with reduced impurities and increased purity can undergo the stripping step (S630).

[0066] In the stripping step (S630), sulfuric acid may be added to the organic phase after the scrubbing step (S620) to produce a solution after the second purification. The solution after the second purification may be an aqueous manganese sulfate solution. That is, in the stripping step (S630), after the scrubbing step (S620), sulfuric acid is added to the organic phase so that manganese can be recovered in the form of an aqueous manganese sulfate solution. The stripping step (S630) may be a step of back-extracting manganese contained in the organic phase into the aqueous phase. The reaction temperature of the stripping step (S630) may be about 30°C to 50°C. When the reaction temperature of the stripping step (S630) is about 30°C to 50°C, the reaction of the organic extractant can be most active. When the reaction temperature of the stripping step (S630) is 30°C or lower, the viscosity of the organic extractant may increase and the reactivity may decrease. When the reaction temperature of the stripping step (S630) exceeds 50°C, the amount of volatile components may be large and the process efficiency may decrease. The input amount of the organic phase relative to the aqueous phase in the stripping step (S630) may be about 5 to 10 in terms of volume ratio. When the input amount of the organic phase relative to the aqueous phase in the stripping step (S630) is less than 5 in terms of volume ratio, complete extraction of manganese is possible, but the amount of water used may increase. Therefore, the manganese content of the aqueous manganese sulfate solution may decrease. When the input amount of the organic phase relative to the aqueous phase in the stripping step (S630) exceeds 10 in terms of volume ratio, the efficiency of back-extracting manganese may decrease. The pH range of the stripping step (S630) may be about 0.5 to 1.5. Sulfuric acid (H2SO4) is used to adjust the pH range of the stripping step (S630) to about 0.5 to 1.5.

[0067] Through this, manganese sulfate (MnSO4) with impurities removed can be recovered in the form of an aqueous solution. The aqueous manganese sulfate solution according to an embodiment of the present invention may have a manganese content of about 115 g / L to 135 g / L. The composition of the aqueous manganese sulfate solution is as shown in Table 2 below.

[0068]

Table 2

[0069] Accordingly, according to the embodiments of the present invention, manganese sulfate, particularly an aqueous solution of high-purity manganese sulfate, can be produced from manganese-containing by-products.

[0070] In the case of the reduction leaching step included in the embodiments of the present invention, different from leaching using a normal reducing agent, by using a reducing gas, relatively high recovery rate and high economic efficiency can be achieved.

[0071] The manganese sulfate according to the embodiments of the present invention can be suitably used as a raw material for a precursor among the positive electrode active materials of lithium secondary batteries.

[0072] Example 1 (Raw material preparation step) A manganese-containing by-product containing the elements shown in Table 3 below was prepared.

[0073]

Table 3

[0074] (Grinding step and washing step) In order to increase the leaching efficiency, the manganese-containing by-product was ground and washed at the same time. As a result, impurities such as magnesium, sodium, and potassium, which are water-soluble impurities, were partially removed. The removal rates were 55% for magnesium, 55% for sodium, and 62% for potassium. The average particle size of the manganese-containing by-product before grinding was about 800 μm. After grinding for 30 minutes, the average particle size of the ground manganese-containing by-product was about 5 μm.

[0075] (Reduction leaching step) Next, 0.4 kg of the ground manganese-containing by-product, sulfuric acid with a concentration of 30 g / L, a solid-liquid ratio of 215 g / L, and 10% sulfurous acid gas at 10 NL / hr were dissolved at room temperature for 1 hour to obtain a leached solution with a manganese concentration of 61 g / L to 64 g / L. The solid-liquid ratio is the ratio of the by-product to sulfuric acid.

[0076] (Neutralization step) Next, 0.1 kg of crushed manganese-containing by-products and 2 NL / hr of 10% sulfurous acid gas were added to the post-leaching solution, and the mixture was neutralized at 50°C for 1 hour to obtain a post-neutralization solution with a manganese concentration of 80 g / L. In the case of manganese and zinc, a dissolution rate of 99.6% or more was shown.

[0077] (First purification step) Next, a precipitation step was performed to remove impurities present in the post-neutralization solution. First, 1.2 equivalents of sodium hydrosulfide (NaSH) were added to the post-neutralization solution to remove heavy metal impurities, and the mixture was reacted at 60°C for 2 hours. Through sulfide precipitation, lead and zinc could be removed by 99% or more.

[0078] Next, 2.0 equivalents of sodium fluoride (NaF) were added to remove light metal impurities, and the mixture was reacted at 70°C for 2 hours. Through fluoride precipitation, calcium and magnesium could be removed to 30 mg / L.

[0079] (Second purification step) Next, a solvent extraction step was performed to recover manganese from the first purified solution after the first purification step through precipitation purification. At this time, a 30% di-2-ethylhexyl phosphoric acid extractant was used. The pH was 4.5, the volume ratio of the organic phase to the aqueous phase was 5, and the reaction was carried out at 35°C. The volume ratio of the organic phase to the aqueous phase can be expressed as O / A (Organic / Aqueous). As a result, manganese was loaded from the aqueous phase to the organic phase, and the content of manganese remaining in the aqueous phase was recovered at 0.1 g / L or less.

[0080] Next, using the organic phase containing manganese and water, O / A was set to 10, and the reaction was carried out at 35°C. As a result, potassium, magnesium, sodium, etc. were scrubbed. At this time, the contents of the main impurities removed were 30 mg / L for potassium, 1 mg / L for magnesium, and 350 mg / L for sodium.

[0081] Next, in order to recover the manganese contained in the washed organic phase with the aqueous phase, sulfuric acid and the organic phase were reacted at 35 °C with an O / A of 10. As a result, it was recovered in the form of an aqueous manganese sulfate solution. The dissolution rate of manganese was at the 99.6% level.

[0082] Example 2 In the pulverization process and the washing process, when the reaction time was 10 minutes, the average particle size of the manganese-containing by-product pulverized was 130 μm. Other conditions, for example, the reaction conditions of the leaching process were the same as in Example 1. The reaction conditions of the leaching process are, for example, the solid-liquid ratio, sulfuric acid concentration, sulfurous acid gas concentration, reaction time, reaction temperature, and the like. In this case, the dissolution rate of manganese in the reduction leaching process was 82%.

[0083] Example 3 In the reduction leaching process of Example 1, the concentration of sulfurous acid gas was made different from 99.9%. Other conditions were the same as in Example 1. As a result of leaching, the dissolution rate of manganese was 99.6% or more as in the existing case, and a manganese leaching solution with a manganese concentration of 61 g / L to 64 g / L could be secured. That is, a leaching solution could be secured regardless of the concentration of sulfurous acid gas. When the concentration of sulfurous acid gas was 10% (low concentration) and when the concentration of sulfurous acid gas was 99.9% (high concentration), in both cases, the dissolution rate of manganese was at the 99% level, and a high dissolution effect could be obtained regardless of the concentration of sulfurous acid gas.

[0084] Comparative example Hereinafter, comparative examples for comparison with the examples will be described. In Comparative Examples 1 to 4, other conditions other than the process conditions described below were the same as in Example 1.

[0085] Comparative example 1 In the leaching process, after adding 300 g / L of sulfuric acid without adding a reducing agent, it was calcined at 600 °C for 5 hours to produce manganese sulfate. This manganese sulfate was dissolved in water to obtain a leaching solution. The dissolution rate of manganese was 75%.

[0086] Comparative example 2 In the leaching process, sodium oxalate was added as a reducing agent in an amount of 1 to 3 times the molar mass of manganese. At this time, the dissolution rate of manganese was 95% or more, but impurities such as sodium were additionally generated. These impurities may increase the cost of auxiliary raw materials in subsequent processes.

[0087] Comparative example 3 In the first purification process, 0.75 equivalents of sodium hydrosulfide were added to remove heavy metal impurities. The removal rates of the main impurities were 98.7% for lead and 65.2% for zinc.

[0088] Comparative example 4 In the first purification process, 0.5 times the equivalent ratio of sodium unsaturated was added to remove light metal impurities. 52% of the main impurity calcium was removed.

[0089] Although the technical idea of the present invention has been described by the above partial embodiments and the examples shown in the attached drawings, it will be understood that various substitutions, modifications, and changes can be made without departing from the technical idea and scope of the present invention that can be understood by those having ordinary knowledge in the technical field to which the present invention belongs. Also, such substitutions, modifications, and changes must be considered to fall within the scope of the attached claims.

Claims

1. A method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method, a raw material preparation step of preparing a manganese-containing by-product containing manganese and impurities; a grinding step and a washing step of grinding and washing the manganese-containing by-product; a reduction leaching step of leaching the manganese-containing by-product ground by the grinding step and the washing step; a neutralization step of neutralizing the post-leaching solution produced by the reduction leaching step; a first purification step of purifying the post-neutralization solution produced by the neutralization step; and a second purification step of additionally purifying the solution after the first purification produced by the first purification step; comprising The reduction leaching step is carried out using an inorganic acid and sulfur dioxide gas, and a method for producing an aqueous manganese sulfate solution using a sulfur dioxide reduction leaching method.

2. The average particle size of the ground manganese-containing by-product is 1 μm to 25 μm, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 1.

3. The grinding step and the washing step are carried out in the same reactor, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 1 or 2.

4. In the grinding step and the washing step, the manganese-containing by-product is washed with a dilute acid and water, The dilute acid is at least one of sulfuric acid, hydrochloric acid, and nitric acid, The concentration of the dilute acid is 10 g / L to 100 g / L, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 1 or 2.

5. The amount of water introduced for the washing step is 1.5 to 3 times the manganese-containing by-product by weight ratio, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 4.

6. The neutralization step is carried out using a manganese-containing by-product as a neutralizing agent, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 1 or 2.

7. Sulfur dioxide gas is additionally injected in the neutralization step, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 6.

8. The first purification step includes a step of removing the impurities using a precipitation method, The second purification step includes a step of removing the impurities using a solvent extraction method, and the method for producing an aqueous manganese sulfate solution using the sulfur dioxide reduction leaching method according to Claim 1 or 2.

9. The manufacturing method of an aqueous manganese sulfate solution using the sulfurous acid gas reduction leaching method according to claim 8, wherein the first purification step is performed through a precipitation reaction of the impurities by adding at least one of sodium sulfide, sodium hydrosulfide, ammonium hydrogen sulfide, and hydrogen sulfide as a precipitating agent.

10. The second purification step is a loading step of extracting manganese contained in the liquid after the first purification into an organic phase; a scrubbing step of washing the organic phase from which manganese has been extracted with water; and a stripping step of adding sulfuric acid to the organic phase after the scrubbing step to recover manganese in the form of an aqueous manganese sulfate solution, the manufacturing method of an aqueous manganese sulfate solution using the sulfurous acid gas reduction leaching method according to claim 8.

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