JP2010209384A - Method for recovering manganese - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering manganese which can obtain a leachate in which manganese is sufficiently leached and also iron is hardly leached from a raw material such as manganese ore including a manganese compound and iron. <P>SOLUTION: A raw material comprising a manganese compound and iron is dissolved into a sulfuric acid aqueous solution, sulfuric acid is further added to the aqueous solution, while retaining its pH to <3, preferably to ≤2.5, leaching with sulfuric acid is performed, thereafter, hydrogen peroxide is added to the aqueous solution as a reducing agent, so as to adjust the pH of the aqueous solution to 3 to 7, and, hydrogen peroxide and sulfuric acid are further added to the aqueous solution, and while retaining its pH to 3 to 7, leaching is performed with hydrogen peroxide and sulfuric acid, thus iron is separated from the leachate, and manganese is recovered into the leachate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for recovering manganese, and more particularly to a method for recovering manganese from raw materials such as manganese ore containing manganese compounds such as manganese oxide and iron.

Manganese oxide includes manganese oxide (manganese monoxide, MnO), manganese oxide (manganese trioxide, Mn ₂ O ₃ ), manganese trioxide (Mn ₃ O ₄ , There are various manganese oxides such as MnO ₂ · 2MnO) and manganese dioxide (MnO ₂ ). Manganese ores mainly composed of manganese produced in nature have various forms of manganese oxides depending on the oxidation state of manganese. It is included in various proportions.

In order to recover manganese from such manganese ore, a method of leaching manganese ore with sulfuric acid is known. However, in this method, divalent manganese of manganese oxide (MnO) can be dissolved and dissolved in sulfuric acid. However, manganese oxide (Mn ₂ O ₃ ), trimanganese tetroxide (Mn ₃ O ₄ ) can be leached. , MnO ₂ .2MnO), manganese dioxide (MnO ₂ ) and other tetravalent manganese (Mn ⁴⁺ ) cannot be leached, and there is a problem that the leaching rate of manganese is low. Therefore, it is necessary to reduce the manganese ore to manganese oxide (MnO) before leaching the manganese ore with sulfuric acid.

As a method for recovering manganese by reducing such manganese ore containing tetravalent manganese, manganese ore of trimanganese tetroxide (Mn ₃ O ₄ ) is used in the presence of a reducing agent such as sulfur dioxide (SO ₂ ). After leaching with sulfuric acid at a pH of 3 or less, neutralization and oxidizing agents are added to the leachate to remove iron, and sulfur is added to the leachate to remove heavy metals as sulfides. In addition, a method for recovering manganese metal by electrolysis using a liquid from which heavy metals have been removed has been proposed (see, for example, Patent Document 1).

US Pat. No. 5,932,086 (columns 1-3)

  However, in the method of Patent Document 1, since leaching with sulfuric acid is performed at a pH of 3 or less in the presence of a reducing agent, iron is also leached at the same time, and a neutralizing agent and an oxidizing agent are added to the leaching solution to remove iron. Is required. Moreover, in this deironing process, it is necessary to add a sufficient amount of neutralizing agent until the pH of the leachate becomes 4 to 7, and the deironing residue increases.

  Therefore, in view of such conventional problems, the present invention can obtain a leachate in which manganese is sufficiently leached and iron is hardly leached from a raw material such as manganese ore containing a manganese compound and iron. It aims at providing the method of collect | recovering.

  As a result of diligent research to solve the above problems, the present inventors have dissolved a raw material containing a manganese compound and iron in an aqueous sulfuric acid solution, and added sulfuric acid to the aqueous solution to maintain a pH lower than pH 3 while using sulfuric acid. After leaching, hydrogen peroxide is added to the aqueous solution as a reducing agent to bring the pH of the aqueous solution to 3-7, and hydrogen peroxide and sulfuric acid are further added to the aqueous solution to maintain the pH of 3-7. By leaching with sulfuric acid, it was found that a leaching solution in which manganese is sufficiently leached and almost no iron is leached can be obtained from a raw material such as manganese ore containing a manganese compound and iron, and the present invention has been completed. It was.

  That is, in the method for recovering manganese according to the present invention, a raw material containing a manganese compound and iron is dissolved in a sulfuric acid aqueous solution, and sulfuric acid is further added to the aqueous solution to maintain a pH lower than pH 3, preferably pH 2.5 or lower. After leaching, hydrogen peroxide is added to the aqueous solution as a reducing agent to bring the pH of the aqueous solution to 3-7, and hydrogen peroxide and sulfuric acid are further added to the aqueous solution to maintain the pH of 3-7. By leaching with sulfuric acid, iron is separated from the leachate, and manganese is recovered in the leachate.

  In this manganese recovery method, it is preferable to separate iron from the leaching solution by filtration after leaching with hydrogen peroxide and sulfuric acid. Moreover, it is preferable to obtain metal manganese by electrolysis from the leachate. Further, the manganese compound is preferably a manganese compound or oxide having a valence of more than two, and is further at least one selected from the group consisting of manganese oxide, trimanganese tetroxide and manganese dioxide. preferable.

  According to the present invention, a leachate in which manganese is sufficiently leached and iron is hardly leached from a raw material such as a manganese ore containing a manganese compound and iron can be obtained.

It is process drawing which shows embodiment of the collection | recovery method of manganese by this invention. It is a graph which shows the density | concentration of Mn, Fe, and Si in a slurry with respect to the leaching time with a sulfuric acid, hydrogen peroxide, and a sulfuric acid in Example 1. FIG. 2 is a graph showing the oxidation-reduction potential and pH of a slurry with respect to leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid in Example 1. It is a graph which shows the density | concentration of Mn in a slurry with respect to the leaching time with a sulfuric acid, hydrogen peroxide, and a sulfuric acid in Example 2, and Fe. In Example 2, it is a graph which shows the oxidation reduction potential and pH of a slurry with respect to the leaching time with a sulfuric acid, hydrogen peroxide, and a sulfuric acid. It is a graph which shows the density | concentration of Mn in a slurry with respect to the leaching time with a sulfuric acid, hydrogen peroxide, and a sulfuric acid in Example 3, and Fe. In Example 3, it is a graph which shows the oxidation reduction potential and pH of a slurry with respect to the leaching time with a sulfuric acid, hydrogen peroxide, and a sulfuric acid. 4 is a graph showing the concentrations of Mn, Fe, and Si in a slurry with respect to leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid in Comparative Example 1. 4 is a graph showing the oxidation-reduction potential and pH of a slurry with respect to leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid in Comparative Example 1. 6 is a graph showing the concentrations of Mn, Fe and Si in a slurry with respect to leaching time with sulfuric acid and SO ₂ gas in Comparative Example 2. 6 is a graph showing the oxidation-reduction potential and pH of a slurry with respect to the leaching time with sulfuric acid and SO ₂ gas in Comparative Example 2. 6 is a graph showing the concentrations of Mn, Fe, and Si in a slurry with respect to leaching time with sulfuric acid and SO ₂ gas in Comparative Example 3. 6 is a graph showing the oxidation-reduction potential and pH of a slurry with respect to the leaching time with sulfuric acid and SO ₂ gas in Comparative Example 3.

As shown in FIG. 1, the embodiment of the method for recovering manganese according to the present invention comprises a sulfuric acid leaching process in which a raw material containing a manganese compound and iron is leached with sulfuric acid, and the leachate obtained in this sulfuric acid leaching process is peroxidized. Hydrogen peroxide leaching process in which hydrogen (H ₂ O ₂ ) and sulfuric acid are added to perform leaching with hydrogen peroxide and sulfuric acid, a liquid cleaning process for purifying the leachate obtained in this hydrogen peroxide leaching process, and this purification And an electrolysis step of obtaining metal manganese by electrolyzing the liquid obtained in the liquid step. Hereinafter, these steps will be described in detail.

(Sulfuric acid leaching process)
First, a raw material containing a manganese compound and iron is prepared. The manganese compound is preferably a manganese compound having a valence of more than two, such as manganese oxide (dimanganese trioxide, Mn ₂ O ₃ ), trimanganese tetraoxide (Mn ₃ O ₄ , MnO _2. More preferably, it is a manganese oxide containing tetravalent manganese (or manganese having a valence higher than ₂ ) such as 2MnO) or manganese dioxide (MnO ₂ ).

  The raw material containing the manganese compound and iron is dissolved in an aqueous sulfuric acid solution, and sulfuric acid is further added to the aqueous solution to perform leaching with sulfuric acid while maintaining a pH lower than pH 3, preferably 2.5 or lower, more preferably about pH 2.

In this leaching with sulfuric acid, divalent manganese (Mn ²⁺ ) in the raw material containing manganese oxide such as trimanganese tetroxide (Mn ₃ O ₄ , MnO ₂ .2MnO) is leached and dissolved in the leachate. Valent manganese (Mn ⁴⁺ ) is not leached. Further, since leaching is performed at a pH lower than pH 3, Fe is also dissolved in the leaching solution.

(Hydrogen peroxide leaching process)
Next, hydrogen peroxide is added as a reducing agent to the leachate obtained in the sulfuric acid leaching step to bring the pH of the leachate to 3-7, and hydrogen peroxide and sulfuric acid are further added to this aqueous solution to maintain pH 3-7. While leaching with hydrogen peroxide and sulfuric acid. When this leaching with hydrogen peroxide and sulfuric acid is carried out at a pH of 3 to 7, the reaction according to the following reaction formula proceeds at an equivalent amount, and tetravalent manganese (Mn ⁴⁺ ) is leached. In addition, since Fe also dissolves in the leachate at a pH lower than pH 3, a deironing step for removing iron from the leachate is necessary. However, at pH 3 or higher, Fe is hardly dissolved in the leachate. It becomes unnecessary. On the other hand, at a pH higher than pH 7, Mn is not leached.
MnO ₂ + H ₂ O ₂ + H ₂ SO ₄ → MnSO ₄ + 2H ₂ O + O ₂

In the leaching with hydrogen peroxide and sulfuric acid, by using hydrogen peroxide as a reducing agent, tetravalent manganese (Mn ⁴⁺ ) that has not been leached in the sulfuric acid leaching step and is left undissolved is leached and dissolved in the leachate. Further, since sulfur dioxide (SO ₂ ) is not used as the reducing agent, the sulfate ion concentration can be kept constant.

Moreover, since leaching is performed at pH 3 to 7, dissolution of Fe in the leaching solution is suppressed, and Fe dissolved in the sulfuric acid leaching step is also precipitated. Therefore, the deironing step required when sulfur dioxide (SO ₂ ) is used as the reducing agent becomes unnecessary, and generation of a deiron residue can be prevented. In addition, hydrogen peroxide and sulfuric acid are added to neutralize to pH 3-7 and leaching is performed, so when sulfur dioxide (SO ₂ ) is used as a reducing agent, a neutralizing agent necessary for removing Fe becomes unnecessary. . Furthermore, even if Si or Al is contained in the raw material, the amount of Si or Al dissolved in the leachate can be reduced. In the case of using sulfur dioxide (SO ₂₎ as the reducing agent, because the pH is lowered by blowing SO ₂ gas can not be to pH3 above.

(Purification process)
Next, the leachate obtained in the hydrogen peroxide leaching step is purified. In this cleaning step, when impurities such as heavy metals are contained in the leachate obtained in the hydrogen peroxide leaching step, a sulfiding agent such as sulfur is added to the leachate to sulfidize and remove heavy metals.

(Electrolysis process)
Next, the liquid obtained in the liquid purification step is electrolyzed to obtain metal manganese. The post-electrolysis solution obtained after this electrolysis step can be reused as it is in the sulfuric acid leaching step without adjusting the sulfate ion concentration. That is, when using SO ₂ as a reducing agent as in the prior art, since sulfate ions accumulate in the post-electrolysis solution obtained after the electrolysis step, unless the sulfate ion concentration is adjusted with a neutralizer, Although it cannot be reused in the sulfuric acid leaching step, the post-electrolysis solution obtained after the electrolytic step of the embodiment of the manganese recovery method according to the present invention can be reused as it is in the sulfuric acid leaching step.

  Examples of the method for recovering manganese according to the present invention will be described in detail below.

[Example 1]
First, as a raw material containing a manganese compound and iron, as shown in Table 1, 66.91 mass% Mn (28.10 g), 3.91 mass% Fe (1.64 g), and 0.96 mass 42 g of manganese ore of trimanganese tetroxide (Mn ₃ O ₄ ) with a grade of% Si (0.40 g) was prepared.

  42 g of this raw material and 72 g of ammonium sulfate were repulped with 600 mL of pure water, 500 g / L sulfuric acid was added to the resulting slurry to pH 2.0, and further leaching was carried out for 2 hours while maintaining pH 2 by adding sulfuric acid. It was. The amount of leachate obtained by filtering the slurry after leaching with sulfuric acid was 670 mL, and the concentrations (and weights) of Mn, Fe and Si in the leachate were 23790 mg / L (15.94 g) and 374 mg, respectively. / L (0.25 g) and 216 mg / L (0.14 g), and the leaching rates of Mn, Fe and Si were 56.7%, 15.3% and 35.9%, respectively. The amount of Mn and the like in this leachate was measured by ICP using a leachate obtained by filtering a part of the slurry.

  The slurry after leaching with sulfuric acid was added with 5 mL of hydrogen peroxide at a rate of 1 mL / min and then stirred for 10 minutes to neutralize to pH 5 and further added to the slurry after neutralization at a rate of 1 mL / min. After adding 5 mL of hydrogen peroxide, leaching was performed while stirring for 10 minutes and adding sulfuric acid to maintain pH of 5. The amount of leachate obtained by filtering the slurry after leaching with hydrogen peroxide and sulfuric acid was 720 mL, and the concentration (and weight) of Mn, Fe and Si in the leachate was 34275 mg / L (24. 68 g), 0.815 mg / L (0.00 g) and 115.8 mg / L (0.08 g), and the leaching rates of Mn, Fe and Si were 87.8%, 0.0% and 20. 7%. The weight of the leaching residue was 13.4 g (7.9 g after drying), and the grades (and weights) of Mn and Fe in the leaching residue were 43.37% by mass (3.43 g) and 20. It was 79 mass% (1.64 g).

  These results are shown in Table 1. The concentration of Mn, Fe and Si in the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide and sulfuric acid is shown in FIG. 2, and the oxidation-reduction potential and pH of the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide and sulfuric acid are shown in FIG. Shown in

  As shown in Table 1, FIG. 2 and FIG. 3, in this example, Fe dissolved in leaching with sulfuric acid (leaching at pH 2) was precipitated in subsequent leaching with hydrogen peroxide and sulfuric acid (leaching at pH 5). It can be seen that a leachate containing no Fe can be obtained. After this leachate is purified, it can be used as an electrolytic solution, and metal manganese can be recovered by electrolysis.

[Example 2]
First, as a raw material containing a manganese compound and iron, as shown in Table 2, 68.27 mass% Mn (28.68 g), 2.29 mass% Fe (0.96 g), 0.48 mass 42 g of manganese ore of trimanganese tetroxide (Mn ₃ O ₄ ) with a grade of% Si (0.20 g) was prepared.

  Using this raw material, the same treatment as in Example 1 was performed, except that leaching with hydrogen peroxide and sulfuric acid was performed at pH 4.

  As a result, the amount of leachate obtained by filtering the slurry after leaching with sulfuric acid was 680 mL, and the concentration (and weight) of Mn, Fe and Si in this leachate was 28800 mg / L (18.22 g), respectively. 210 mg / L (0.14 g) and 97 mg / L (0.07 g), and the leaching rates of Mn, Fe and Si were 63.6%, 14.8% and 32.7%, respectively.

  The amount of the leachate obtained by filtering the slurry after leaching with hydrogen peroxide and sulfuric acid was 700 mL, and the concentrations (and weights) of Mn, Fe, and Si in the leachate were 39500 mg / L (27 0.65 g), 35 mg / L (0.02 g) and 95 mg / L (0.07 g), and the leaching rates of Mn, Fe and Si were 96.4%, 2.6% and 32.8%, respectively. there were. The weight of the leaching residue was 6.4 g (3.2 g after drying), and the grades (and weight) of Mn and Fe in the leaching residue were 32.44% by mass (1.03 g) and 29. It was 64 mass% (0.94g).

  These results are shown in Table 2. FIG. 4 shows the concentrations of Mn, Fe, and Si in the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid, and FIG. 5 shows the oxidation-reduction potential and pH of the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid. Shown in

  As shown in Table 2, FIG. 4 and FIG. 5, in the present example, most of the dissolved Fe in the leaching with sulfuric acid (leaching at pH 2) is in the subsequent leaching with hydrogen peroxide and sulfuric acid (leaching at pH 4). It can be seen that a leachate containing almost no Fe can be obtained by precipitation.

[Example 3]
The same raw material as in Example 1 was used, and the same treatment as in Example 1 was performed, except that leaching with hydrogen peroxide and sulfuric acid was changed to pH 2-6.

  As a result, the amount of leachate obtained by filtering the slurry after leaching with sulfuric acid was 670 mL, and the concentrations (and weights) of Mn, Fe and Si in the leachate were 24300 mg / L (16.28 g), respectively. 276 mg / L (0.19 g) and 214 mg / L (0.14 g), and the leaching rates of Mn, Fe and Si were 57.9%, 11.3% and 35.5%, respectively.

  The amount of leachate obtained by filtering the slurry after leaching with hydrogen peroxide and sulfuric acid was 690 mL, and the concentrations (and weights) of Mn, Fe, and Si in the leachate were 30325 mg / L (20 .92 g), 1 mg / L (0.00 g) and 54 mg / L (0.04 g), and the leaching rates of Mn, Fe and Si were 74.5%, 0.0% and 9.3%, respectively. there were. The weight of the leaching residue was 20.7 g (13.3 g after drying).

  These results are shown in Table 3. Further, FIG. 6 shows the concentrations of Mn, Fe and Si in the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide and sulfuric acid, and FIG. Shown in

  As shown in Table 3, FIG. 6 and FIG. 7, in this example, Fe dissolved in the leaching with sulfuric acid (leaching at pH 2) precipitates in the subsequent leaching with hydrogen peroxide and sulfuric acid and does not contain Fe. It can be seen that a leachate can be obtained. It can also be seen that Si precipitates as the pH increases, and at pH 6, Si in the leachate is very low.

[Comparative Example 1]
First, as a raw material containing a manganese compound and iron, as shown in Table 4, 69.67 mass% Mn (29.26 g), 2.16 mass% Fe (0.91 g), and 0.48 mass 42 g of manganese ore of trimanganese tetroxide (Mn ₃ O ₄ ) with a grade of% Si (0.20 g) was prepared.

Using this raw material, the same treatment as in Example 1 was performed except that leaching with hydrogen peroxide and sulfuric acid was performed at pH 2. Note that Mn ⁴⁺ is leached by hydrogen peroxide.

  As a result, the amount of leachate obtained by filtering the slurry after leaching with sulfuric acid was 650 mL, and the concentration (and weight) of Mn, Fe and Si in this leachate was 28900 mg / L (18.79 g), respectively. 11 mg / L (0.01 g) and 106 mg / L (0.07 g), and the leaching rates of Mn, Fe and Si were 64.2%, 0.8% and 34.1%, respectively.

  The amount of leachate obtained by filtering the slurry after leaching with hydrogen peroxide and sulfuric acid was 700 mL, and the concentrations (and weights) of Mn, Fe, and Si in the leachate were 41300 mg / L (28 .91 g), 865 mg / L (0.61 g) and 110 mg / L (0.08 g), and the leaching rates of Mn, Fe and Si were 98.8%, 66.7% and 38.2%, respectively. there were. The weight of the leaching residue is 1.5 g (1.0 g after drying), and the grades (and weights) of Mn and Fe in the leaching residue are 34.57 mass% (0.35 g) and 29.29%, respectively. It was 64 mass% (0.30 g).

  These results are shown in Table 4. FIG. 8 shows the concentrations of Mn, Fe, and Si in the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid, and FIG. 9 shows the oxidation-reduction potential and pH of the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid. Shown in

  As shown in Table 4, FIG. 8, and FIG. 9, in this comparative example, Fe dissolved in the leaching with sulfuric acid (leaching at pH 2) does not precipitate because the pH is low in the subsequent leaching with hydrogen peroxide and sulfuric acid. It can be seen that it is contained in the leachate.

[Comparative Example 2]
First, as a raw material containing a manganese compound and iron, as shown in Table 5, 66.86 mass% Mn (28.08 g), 3.53 mass% Fe (1.48 g), and 0.96 mass 42 g of manganese ore of trimanganese tetroxide (Mn ₃ O ₄ ) with a grade of% Si (0.40 g) was prepared.

Using this raw material, instead of leaching with hydrogen peroxide and sulfuric acid, the same treatment as in Example 1 was performed except that leaching was performed at pH 2 while blowing SO ₂ gas into the slurry after leaching with sulfuric acid. . Incidentally, ^{Mn 4+} is leached with SO _2, the leaching SO _2, even pH is lowered without the addition of sulfuric acid.

  As a result, the amount of the leachate obtained by filtering the slurry after leaching with sulfuric acid was 670 mL, and the concentrations (and weights) of Mn, Fe and Si in the leachate were 24300 mg / L (16.31 g), respectively. 349 mg / L (0.23 g) and 222 mg / L (0.15 g), and the leaching rates of Mn, Fe and Si were 58.1%, 15.8% and 37.0%, respectively.

  The amount of leachate obtained by filtering the slurry after leaching with hydrogen peroxide and sulfuric acid was 690 mL, and the concentrations (and weights) of Mn, Fe, and Si in the leachate were 39925 mg / L (27 .55 g), 1322 mg / L (0.91 g) and 225 mg / L (0.16 g), and the leaching rates of Mn, Fe and Si were 98.1%, 61.5% and 38.5%, respectively. there were. The weight of the leaching residue was 2.5 g (1.8 g after drying), and the grades (and weights) of Mn and Fe in the leaching residue were 29.26% by mass (0.53 g) and 31. It was 31 mass% (0.57 g).

These results are shown in Table 5. Also shows Mn in the slurry for leaching time with sulfuric acid and SO ₂ gas, the concentration of Fe and Si in FIG 10, Figure 11 shows the oxidation-reduction potential and pH of the slurry for leaching time with sulfuric acid and SO ₂ gas.

As shown in Table 5, FIG. 10, and FIG. 11, in this comparative example, Fe dissolved in leaching with sulfuric acid (leaching at pH 2) did not precipitate because the pH was low even in leaching with SO ₂ gas thereafter, It can be seen that it is contained in the leachate.

[Comparative Example 3]
First, as shown in Table 6, 67.17% by mass of Mn (28.21 g), 2.17% by mass of Fe (0.91 g), and 0.48 mass as raw materials containing a manganese compound and iron. 42 g of manganese ore of trimanganese tetroxide (Mn ₃ O ₄ ) with a grade of% Si (0.20 g) was prepared.

  Using this raw material, the same treatment as in Example 1 was performed, except that leaching with sulfuric acid and leaching with hydrogen peroxide and sulfuric acid were both performed at pH 3.

  As a result, the amount of leachate obtained by filtering the slurry after leaching with sulfuric acid was 610 mL, and the concentration (and weight) of Mn, Fe and Si in this leachate was 10883 mg / L (6.64 g), respectively. 0 mg / L (0.00 g) and 69 mg / L (0.04 g), and the leaching rates of Mn, Fe and Si were 23.5%, 0.0% and 20.9%, respectively.

  The amount of leachate obtained by filtering the slurry after leaching with hydrogen peroxide and sulfuric acid was 650 mL, and the concentrations (and weights) of Mn, Fe and Si in this leachate were 26000 mg / L (16 .90 g), 13 mg / L (0.01 g) and 94 mg / L (0.06 g), and the leaching rates of Mn, Fe and Si were 59.9%, 0.9% and 30.3%, respectively. there were. The weight of the leaching residue was 21.6 g (16.9 g after drying), and the grades (and weights) of Mn and Fe in the leaching residue were 67.02% by mass (11.31 g) and 5. It was 34 mass% (0.90 g).

  These results are shown in Table 6. FIG. 12 shows the concentrations of Mn, Fe, and Si in the slurry with respect to the leaching time with sulfuric acid, hydrogen peroxide, and sulfuric acid, and FIG. Shown in

As shown in Table 6, FIG. 12 and FIG. 13, in this comparative example, Fe is not leached because the pH during leaching with hydrogen peroxide and sulfuric acid is high, but because the pH during leaching with sulfuric acid is high. Since Mn ²⁺ is not sufficiently leached, Fe is not contained in the leaching solution, but it can be seen that the leaching rate of Mn is low.

Claims (7)

A raw material containing a manganese compound and iron is dissolved in an aqueous sulfuric acid solution, and further sulfuric acid is added to the aqueous solution to perform leaching with sulfuric acid while maintaining a pH lower than pH 3. Thereafter, hydrogen peroxide is added to the aqueous solution as a reducing agent. The pH of the aqueous solution is adjusted to 3 to 7, and further, hydrogen peroxide and sulfuric acid are added to the aqueous solution to perform leaching with hydrogen peroxide and sulfuric acid while maintaining pH 3 to 7, thereby separating iron from the leachate and A method for recovering manganese, comprising recovering manganese. The method for recovering manganese according to claim 1, wherein the pH lower than pH 3 is pH 2.5 or less. The method for recovering manganese according to claim 1 or 2, wherein iron is separated from the leachate by performing filtration after the leaching with hydrogen peroxide and sulfuric acid. The method for recovering manganese according to any one of claims 1 to 3, wherein metal manganese is obtained from the leachate by electrolysis. The method for recovering manganese according to any one of claims 1 to 4, wherein the manganese compound is a compound of manganese having a valence greater than two. 5. The method for recovering manganese according to claim 1, wherein the manganese compound is an oxide of manganese having a valence greater than 2. 5. The method for recovering manganese according to claim 1, wherein the manganese compound is at least one selected from the group consisting of manganic oxide, trimanganese tetroxide, and manganese dioxide.

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