WO2013002416A1

WO2013002416A1 - Manganese recovery method

Info

Publication number: WO2013002416A1
Application number: PCT/JP2012/067137
Authority: WO
Inventors: 山口　東洋司; 八尾　泰子
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2011-06-29
Filing date: 2012-06-28
Publication date: 2013-01-03
Also published as: CN103620069B; CN103620069A; JP2014005496A; JP5229416B1

Abstract

Provided is a method of economically recovering manganese from low-grade minerals and manganese-containing waste. Iron-reducing bacteria and a manganese-containing substance to be treated are mixed in a treatment solution containing trivalent iron ions, the trivalent iron ions are reduced to divalent iron ions by means of the iron-reducing bacteria, manganese ions are leached from the treated substance into the aforementioned treatment solution with the divalent iron ions as reducing agent, the obtained leachate is solid-liquid separated, the manganese ions contained in the separated liquid are insolubilized (solidified) mainly as oxides, and the obtained manganese oxides are precipitated, separated, and recovered.

Description

Manganese recovery method

The present invention relates to a technology for recovering manganese, which is a valuable metal, from ironworks by-products containing manganese components, low-grade minerals, used batteries, and the like.

It has been difficult to recover specific valuable metals from low-grade ore or concentrate or steelworks by-products for cost reasons. However, in recent years, it has become necessary to recover valuable metals from such materials due to depletion of metal resources and an increase in transaction prices. For example, manganese, which is one of valuable metals, is regarded as an essential metal in various fields of industry, but there is concern that the demand will exceed the reserves in the future.

In particular, since ironworks consume a large amount of manganese as a raw material for steelmaking, the problem of securing a manganese source is extremely serious in the steelmaking field. On the other hand, many manganese is contained in steelworks by-products such as dust, sludge, and slag generated in large quantities at steelworks. Therefore, it is expected that the above problems will be greatly resolved by establishing a technique for recovering manganese from steelworks by-products and reusing it as a steelmaking raw material.

Here, as a method for recovering valuable metals from minerals, an acid or alkali treatment liquid is brought into contact with the mineral, and the valuable metals contained in the mineral are dissolved and leached into the treatment liquid. A method of recovering by selectively neutralizing a metal is known. Moreover, when recovering valuable metals from low-grade minerals, generally, from a cost standpoint, a method of leaching and recovering valuable metals from target minerals using an acid such as sulfuric acid is employed.

However, the method of recovering valuable metals from target minerals using an acid such as sulfuric acid as a treatment liquid is still expensive, and in some cases, the input cost and the cost of recovered valuable metals are often not balanced. Cases are limited. In addition, in the recovery with an acid, there is a problem that some forms of manganese are difficult to leach out and the recovery rate decreases.

On the other hand, a method of recovering valuable metals by leaching valuable metal ions from minerals into the processing liquid using microorganisms is also known. According to this method, the valuable metal can be leached from the mineral into the treatment liquid without using a large amount of sulfuric acid or the like, so that the valuable metal can be recovered from the mineral without causing the above-described problems.

In addition, the method of leaching metal from minerals using microorganisms as described above is called a bioleaching method (bioleaching), and is characterized by lower energy consumption and lower risk to the environment. Thus, bioleaching is considered to be capable of improving the metal leaching rate and reducing the cost, and has attracted attention as an effective means for leaching valuable metals from low-grade minerals.

For example, in Patent Document 1, an iron-reducing bacterium is allowed to act to reduce trivalent iron to divalent iron, and using the divalent iron, a metal contained in the group consisting of a metal oxide and a metal hydroxide ( Cobalt, nickel, manganese, etc.) are leached to produce a leachate and a residue, and the leachate and residue are separated to recover a desired metal. Specifically, a leaching treatment medium, an iron-reducing bacterium, and a metal oxide or metal hydroxide are placed in a reactor to perform leaching treatment. More specifically, a batch-type agitation type Using a reactor, while stirring the medium so that metal oxides and the like do not settle, adjust the maximum pH during the leaching process to 8.5 or less, preferably neutral (for example, pH 7.5 or less), Techniques have been proposed for leaching metals with the entire preferred pH range being preferred. According to this technology, it is said that valuable metals (cobalt, nickel) contained in the leachate can be recovered by a known method and used for a desired application.

JP 2007-113116 A

However, Patent Document 1 does not specifically describe a method for recovering valuable metals contained in the leachate. Therefore, there is a concern that depending on the recovery method, the high-concentration iron-containing solution becomes disposable and uneconomical.
That is, when manganese contained in a workpiece (metal oxide or the like) is leached according to the technique proposed in Patent Document 1, manganese ions and iron ions (obtained by oxidation of divalent iron during the leaching treatment). In addition, it is necessary to recover manganese from the leachate containing trivalent iron or divalent iron remaining without being oxidized.

As a known method for separating a desired metal from a leachate containing a plurality of types of metal ions, there is a method in which a metal species is selectively precipitated and separated by adding a chemical or the like to the leachate. When this method is applied to treat leachate containing manganese ions and iron ions, in many cases, iron ions that easily form insoluble salts are precipitated and separated, so that manganese ions remain in the leachate. After separation from iron, it is necessary to separate manganese from the leachate. In such a method, there is a problem that two separation steps are required for the recovery of manganese, and the steps become complicated. Moreover, if iron ions are precipitated and separated from the leachate, it becomes difficult to reuse the iron-containing solution (leachate).

On the other hand, when recovering valuable metals from the leachate, it is also conceivable to apply an electrolytic method or an adsorption method using an ion exchange resin, a chelate resin or the like as an adsorbent. However, in a normal electrolysis method, a substance that forms a complex with iron or the like is added in the previous stage to make iron soluble in an organic solvent. A separation process is required to extract and separate the target manganese in the water tank, and a large amount of organic solvent must be used. In addition, the number of processing steps is increased and a large amount of power is consumed. Furthermore, the adsorbent used in the adsorption method is generally expensive and requires desorption and recovery steps after adsorption separation. For this reason, when manganese is to be recovered from a large amount of material to be processed such as a steelworks by-product, the recovery cost becomes enormous if an electrolytic method or an adsorption method is applied.

In addition, high purity manganese is required for manganese used as a steelmaking raw material in steelworks in order to prevent impurities such as carbon (C) and phosphorus (P) from being mixed into the steel. Therefore, depending on the concentration of impurities such as C and P of the recovered manganese, it cannot be used as a steelmaking raw material.

As described above, depending on the use of the recovered manganese, it is also important to sufficiently reduce the impurity content, but the prior art has not studied reducing impurities contained in the recovered manganese. .

The present invention has been made in view of the above problems, and after leaching manganese contained in an object containing manganese into the leachate, the leached manganese is concentrated and recovered, and the leachate can be used repeatedly. It is an object of the present invention to provide a method for recovering manganese from low-grade minerals and manganese-containing wastes and by-products at low cost.

The present inventors mix a treatment object containing manganese and iron-reducing bacteria in a treatment solution containing trivalent iron, act iron-reducing bacteria, and reduce trivalent iron to divalent iron. Manganese ions are leached into the treatment liquid from the treatment object containing manganese by utilizing the action of valence iron being oxidized to trivalent iron, and the leachate from which manganese ions are leached is separated into solid and liquid. When recovering manganese from the separated liquid, the inventors studied diligently about means for precipitating and separating the target manganese while leaving the soluble iron remaining in the separated liquid. As a result, it was found that the precipitate can be separated by subjecting the separation liquid to a predetermined oxidation treatment and insolubilizing manganese ions contained in the separation liquid mainly as manganese oxide.

FIG. 1 is a state diagram (Eh-pH diagram) of oxidation-reduction potential (ORP) and pH of manganese and iron in an aqueous solution at 25 ° C. As shown in FIG. 1, in the Eh-pH diagram, the region where manganese precipitates and the region where iron precipitates are substantially the same except for the region surrounded by circles in FIG. 1, and the region where iron precipitates is wider. Yes. Therefore, when the state of redox potential (ORP) and pH is changed from the region where both manganese and iron are dissolved (ionized), iron is first converted into an oxide or hydroxide in most regions. Solidified and precipitated. However, only the low pH / high ORP region (the region surrounded by a circle in FIG. 1) has a region where manganese is mainly solidified and precipitated as an oxide.

Therefore, the inventors of the present invention have described the pH and redox potential (ORP) of the above-mentioned separation liquid containing manganese ions and trivalent iron ions in the region where manganese is solidified and precipitated mainly as oxides in the Eh-pH diagram. By adjusting the pH and the oxidation-reduction potential (ORP) of the region (circled in FIG. 1), iron ions that are substrates of iron-reducing bacteria are left in the solution in a dissolved state. It was conceived that it can be insolubilized and precipitated as an oxide.

As a result of further investigations, the present inventors have reduced the pH of the separation liquid using acid and raised the ORP of the separation liquid by acting ozone, so that the manganese ions can be easily and inexpensively produced. It has been found that manganese can be mainly solidified as an oxide from the above-mentioned separation liquid containing trivalent iron ions.

In addition, the above separation liquid contains abundant trivalent iron ions or further divalent iron ions. Therefore, the iron ions contained in the separation liquid are not separated by precipitation, and the iron ions remain in the separation liquid, so that the separation liquid is reused as a treatment liquid used for leaching manganese ions from the object to be treated. It can be used.

Furthermore, it was discovered that low-grade manganese contained in the workpiece can be leached at high speed and efficiency by reducing trivalent iron in the treatment liquid to divalent iron using specific iron-reducing bacteria.

In addition, the present inventors examined means for reducing the content of impurities (carbon, phosphorus, etc.) of manganese finally recovered.
In the case of a bioleaching method (bioleaching) using a treatment liquid containing bacteria, the treatment liquid usually contains a plurality of kinds of components for promoting the metal leaching reaction by iron-reducing bacteria. In the case of a treatment solution containing iron-reducing bacteria, it contains components such as a trivalent iron ion, an electron donor, a pH adjuster, and a pH buffer. Naturally, it also contains carbon and phosphorus, which are essential elements for the growth of iron-reducing bacteria, which are microorganisms. If these components are deficient, iron-reducing bacteria cannot grow, and as a result, it is difficult to leach metals. Therefore, the treatment liquid generally contains components (C, P, etc.) that can become impurities depending on the intended use of the recovered metal.

The inventors of the present invention have found that there is a problem that a component that can be an impurity in the treatment liquid is mixed into the recovered material depending on the ratio of the existing component. As a result of further investigation, by limiting the impurity concentration in the treatment liquid, the amount of impurities transferred from the treatment liquid into the recovered manganese is reduced while promoting the leaching of manganese ions from the object to be treated. As a result, it has been found that the impurity concentration of recovered manganese can be reduced.

The experiment that led to the above findings will be described.
First, an iron (III) citrate medium-compliant solution was prepared as a treatment liquid containing trivalent iron. Common components of this iron (III) citrate medium compliant solution are iron (III) citrate, sodium citrate, sodium formate, carbon, sodium dihydrogen phosphate, phosphorus, and peptone. Contains carbon and phosphorus as elements. All of these elements are essential components for the metal leaching reaction by iron-reducing bacteria, and the concentrations (or contents) of various components are as follows.

Iron (III) citrate trihydrate: 16.7 g / L (56 mM)
Sodium citrate dihydrate (complexing agent): 10.3 g / L (35 mM)
Sodium dihydrogen phosphate: 0.6 g / L

Peptone: 0.5g
KCl: 0.1g
NH ₄ Cl: 1.5 g
Wolfe Mineral Solution: 10cm ³
Wolfe's vitamin solution: 10 cm ³
Sodium formate (electron donor): 2.0 g / L (30 mM)

The values of the concentrations (or contents) of the various components described above are all values per 1 L of iron (III) citrate medium-compliant solution. In addition, mM shows mmol / L.

Here, the present inventors have determined that the carbon concentration and phosphorus concentration in the iron (III) citrate medium-based solution (treatment liquid containing trivalent iron) are the carbon concentration and phosphorus in the manganese finally recovered. Presumed to affect the concentration. The treatment liquid having the concentrations (or contents) of the various components described above is used as a reference treatment liquid, and the carbon concentration or phosphorus concentration is changed in total as shown in (A) to (C) below with respect to this reference treatment liquid. An iron (III) citrate medium-based solution was prepared as a treatment solution, and the effects of carbon concentration and phosphorus concentration on the manganese leaching rate were investigated.

(A) Treatment liquid (concentration: 0.6 g / L, 0.3 g / L) in which the concentration of sodium dihydrogen phosphate, which is a phosphorus component, is reduced stepwise from 0.6 g / L of the standard treatment liquid to 0 g / L. L, 0.1 g / L, 0 g / L in total 4 types). In addition, the density | concentration (or content) of components other than sodium dihydrogen phosphate was made the same with a reference | standard process liquid. Moreover, when the density | concentration of the processing liquid in case the density | concentration of sodium dihydrogen phosphate was 0 g / L was measured, it was 5 mg / L (0.16 mM). This is considered to be derived from components other than sodium dihydrogen phosphate.

(B) A treatment liquid in which the concentration of iron (III) citrate trihydrate as a carbon component is reduced stepwise from 16.7 g / L (56 mM) of the standard treatment liquid to 1.5 g / L. (Concentration: 16.7 g / L, 7.5 g / L, 3.0 g / L, 1.5 g / L in total 4 types). The concentration (or content) of components other than iron (III) citrate trihydrate was the same as that of the standard treatment solution, with no addition of sodium dihydrogen phosphate.

(C) A treatment liquid in which the concentration of sodium citrate dihydrate, which is a carbon component, is gradually reduced from 10.3 g / L (35 mM) to 0 g / L of the standard treatment liquid. (Concentration: 10.3 g / L, 2.9 g / L, 1.03 g / L, 0 g / L in total 4 types). In addition, the concentration (or content) of components other than sodium citrate dihydrate is 1.5 g / L of iron (III) citrate trihydrate, no sodium dihydrogen phosphate is added, The other components were the same as the standard treatment solution.

In the above (A) to (C), peptone containing a carbon component or phosphorus component and sodium formate containing a carbon component are added in small amounts, so that their respective concentrations (or contents) are the same as the standard treatment liquid. .

In a batch type stirring vessel, various iron (III) citrate medium-compliant solutions (treatment liquids containing trivalent iron) of the above (A) to (C): 150 cm ³ , containing metal generated in the refining process of the ironworks Dust (Mn: 69% by mass, Fe: 3% by mass): 0.75 g, and iron-reducing bacterium Shewanella algae (NBRC 103173 strain): 1 × 10 ⁷ pieces / cm ³ are added, and the temperature of the mixed solution is about 30 ° C. The leaching treatment was performed in which nitrogen gas was bubbled and stirred for 24 to 144 hours. Thereafter, the leachate was collected by solid-liquid separation, and the Mn leach rate was calculated by measuring the Mn concentration in the leachate. These results are shown in Tables 1 to 3.

Table 1 shows the results of performing the leaching process for 24 hours using the processing liquid (A). As shown in Table 1, the leaching treatment time: manganese at 24 hours between when the sodium dihydrogen phosphate (NaH ₂ PO ₄ ), which is a phosphorus component, is added as in the standard treatment solution and when it is not added There was no significant difference in the leaching rate.

Table 2 shows the results of leaching treatment using the treatment liquid (B). As shown in Table 2, when the concentration of iron (III) citrate containing a carbon component was reduced, the initial manganese leaching rate was lowered. However, in the leaching treatment time: 144 hours, even when the concentration of the iron (III) citrate trihydrate containing the carbon component is reduced to 1.5 g / L, the manganese leaching rate equivalent to that in the case of the standard treatment liquid was gotten.

Table 3 shows the results of the leaching process using the above processing liquid (C). Reducing the concentration of sodium citrate containing carbon components significantly reduced the manganese leaching rate, and the leaching rate remained low even if the leaching time was extended. That is, from the viewpoint of manganese leaching rate, it is preferable to maintain the sodium citrate dihydrate concentration in the treatment liquid at the same concentration (10.3 g / L) as in the case of the standard treatment liquid without reducing it. It can be said.
Treatment liquid when the iron (III) citrate trihydrate concentration in the treatment liquid is 1.5 g / L (5 mM) and the sodium citrate dihydrate concentration is 10.3 g / L (35 mM) The carbon concentration inside was 270 mM.

Furthermore, the present inventors repeated the same experiment as described above, and finally measured the impurity concentration (carbon concentration and phosphorus concentration) of manganese recovered. As a result, if the carbon concentration in the treatment solution is limited to 300 mM or less and the phosphorus concentration to 0.5 mM or less, the impurity concentration of manganese finally recovered is greatly reduced, and recovery applicable to steelmaking raw materials and the like. It was found that manganese can be obtained.

The present invention has been completed based on the above findings, and the gist thereof is as follows.
[1] A treatment solution containing trivalent iron ions is mixed with a treatment object containing manganese and iron-reducing bacteria, and the iron-reducing bacteria reduce the trivalent iron ions to divalent iron ions. A leaching step of leaching manganese ions from the object to be treated into the treatment liquid using iron ions as a reducing agent; a solid-liquid separation step of solid-liquid separation of the leachate obtained in the leaching step; and a step after the solid-liquid separation step A manganese recovery method comprising: an insolubilization step of oxidizing and insolubilizing manganese ions contained in a separation liquid; and a recovery step of separating and recovering a manganese component obtained in the insolubilization step.

[2] A method for recovering manganese according to [1], wherein the post-recovery separation liquid containing trivalent iron ions from which the manganese component has been recovered from the separation liquid is reused as a treatment liquid in the leaching step.

[3] In the above [1] or [2], the insolubilization step is a step in which manganese ions are oxidized and insolubilized by applying ozone to the separated liquid after the solid-liquid separation step under acidic conditions. A method for recovering manganese.

[4] In any one of the above [1] to [3], the workpiece is an ironworks by-product and / or low-grade ore, and / or used battery, and / or manganese-containing dust, and / or A method for recovering manganese, which is / or manganese-containing sludge and / or manganese-containing slurry.

[5] In any one of the above [1] to [4], in the insolubilization step, the liquid during the insolubilization treatment is taken out periodically or continuously, and the change in the color of the solution portion of the taken out liquid is observed. And a manganese recovery method characterized by determining an end point of oxidation reaction of manganese ions.

[6] The manganese recovery method according to any one of [1] to [5], wherein the treatment liquid in the leaching step is a treatment liquid in which a carbon concentration and a phosphorus concentration are limited.

[7] The method for recovering manganese according to [6], wherein the carbon concentration is 300 mM or less and the phosphorus concentration is 0.5 mM or less.

According to the manganese recovery method of the present invention, manganese contained in manganese minerals can be concentrated and recovered at a high concentration rate under relatively mild conditions such as room temperature and atmospheric pressure. By allowing the liquid to be used repeatedly, it becomes possible to reduce the cost related to manganese recovery, and there is a remarkable industrial effect. In addition, the manganese recovery method of the present invention can recover manganese from a large amount of material to be processed at low cost and easily, so that it is extremely useful as a method for recovering manganese from a steelworks by-product generated in large quantities at a steelworks. It is valid.

FIG. 1 is a state diagram (Eh-pH diagram) of redox potential (ORP) and pH of manganese and iron in an aqueous solution. Fig.2 (a) is a flowchart explaining one form of the manganese recovery method of this invention. FIG.2 (b) is a flowchart explaining the other form of the manganese recovery method of this invention. FIG. 3 is a graph showing the manganese leaching rate of an example in which waste dry cell crushed waste was tested. FIG. 4 is a view showing a composition in a solid substance when ozone diffusion is performed on the manganese leachate of the example under acidic conditions. FIG. 5 is a diagram showing the manganese recovery rate when ozone diffusing was performed on the manganese leachate of the example under acidic conditions. FIG. 6 is a graph showing changes in manganese recovery rate and filtrate color when the manganese leachate of the present invention is treated with ozone aeration under acidic conditions.

Hereinafter, the present invention will be described in detail.
In the method for recovering manganese according to the present invention, a treatment liquid containing trivalent iron ions is mixed with a treatment object containing manganese and iron-reducing bacteria, and the iron-reducing bacteria reduce the trivalent iron ions to divalent iron ions. A leaching step of leaching manganese ions from the object to be treated into the treatment liquid using the divalent iron ions as a reducing agent; a solid-liquid separation step of separating the leachate obtained in the leaching step; It comprises an insolubilization step for oxidizing and insolubilizing manganese ions contained in the separation liquid after the liquid separation step, and a recovery step for precipitation separation and recovery of the manganese component obtained in the insolubilization step. Further, the post-recovery separation liquid containing trivalent iron ions from which the manganese component is recovered from the separation liquid may be reused in the leaching step.

FIG. 2A is a flowchart showing an embodiment of the present invention. As shown to Fig.2 (a), in this invention, first, the to-be-processed object 1 containing manganese is grind | pulverized by the crushing process 2 as needed. Next, in the leaching step 3, the treatment object 1, the treatment liquid 4 containing trivalent iron ions, and iron-reducing bacteria are mixed to obtain a leaching slurry (leaching liquid) 5. In the leaching step 3, trivalent iron ions are reduced to divalent iron ions by iron-reducing bacteria, and the divalent iron ions are allowed to act on the manganese component in the object 1 to be processed. The manganese component in 1 is dissolved.

The object to be treated 1 contains manganese. For example, ironworks by-products such as manganese-containing dust and / or manganese-containing sludge, low-grade ore, and used batteries can be used. Moreover, as a shape of the to-be-processed object 1, a manganese containing dust and / or manganese containing sludge and / or a manganese containing slurry other than the solid substance containing manganese can be illustrated.

When a used battery is used as the object 1 to be processed, it is desirable to separate a metal such as iron used in the casing by crushing, sieving, or the like in advance to obtain a mixture of a positive electrode material and a negative electrode material. .
As the manganese component contained in the object to be processed _1, it may be exemplified _{_{MnO 2, Mn 2 O 3,}} Mn 3 O 4 and the like.

The object to be processed 1 is mixed with the treatment liquid 4 and subjected to a leaching step 3 in which manganese ions are leached into the treatment liquid 4. However, if the particle size of the object 1 to be processed at the stage of shifting to the leaching process 3 is large, the specific surface area becomes small and the solid-liquid contact area (contact area between the object 1 and the process liquid 4) decreases. Leaching rate is reduced. Further, when the leaching step 3 is performed using a batch-type reaction vessel, if the particle size of the workpiece 1 is large, the workpiece 1 is settled during the leaching treatment, and the leaching treatment cannot be sufficiently performed. Is also a concern.

For the reasons described above, in the present invention, when the workpiece 1 is solid, it is preferable to provide the crushing step 2 for the purpose of improving the reaction efficiency in the leaching step 3 by reducing the particle diameter. The smaller the particle size, the better the reaction efficiency and the reaction time in the leaching step 3 can be shortened. Therefore, in this invention, it is preferable that the particle diameter of the to-be-processed object 1 in the stage which transfers to the leaching process 3 shall be 100 mm or less, and it is more preferable to set it as 100 micrometers or less. However, from the viewpoint of ease of solid-liquid separation, it is preferable that the particle diameter of the workpiece 1 be 1 μm or more.
As a crushing method, a known crushing method such as a jaw crusher or a rolling mill can be used. In addition, when the particle diameter of the workpiece 1 is sufficiently small, the crushing step 2 may be omitted.

The workpiece 1 obtained as described above is transferred to the leaching step 3. In the leaching step 3, the treatment liquid 4 and the workpiece 1 are mixed, and manganese ions are leached into the treatment liquid 4 from the workpiece 1 using an action in which divalent iron ions are oxidized to trivalent iron ions. . That is, in the leaching step 3, divalent iron is oxidized to trivalent iron and the workpiece 1 is reduced by the reaction (i) below, and manganese ions are leached into the treatment liquid 4.
Fe ²⁺ + Mn oxide or hydroxide (eg MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ )
→ Fe ³⁺ + Mn ²⁺ (soluble) ... (i)

Here, as the treatment liquid 4, a treatment liquid to which divalent iron ions are added can also be used. However, in the present invention, a treatment liquid containing trivalent iron ions is used, the treatment object and iron-reducing bacteria are mixed in the treatment liquid, and the trivalent iron ions are reduced to divalent iron ions. It is preferable that manganese ions are leached into the treatment liquid 4 from the workpiece 1 using valent iron ions as a reducing agent.
An iron-reducing bacterium is a bacterium that grows by respiration of iron that receives and transfers electrons from an electron donor (such as an organic substance) and supplies it to trivalent iron ions that are electron acceptors, and is trivalent by the following reaction (ii). Has the effect of reducing iron to divalent iron.
Fe ³⁺ + e ⁻ → Fe ²⁺ (ii)

Therefore, when the treatment object 1 and iron-reducing bacteria are mixed in a treatment solution containing trivalent iron ions, the iron-reducing bacteria use the electrons (e ⁻ ) from the electron donor to convert trivalent iron ions (Fe ³⁺ ). Direct reduction produces divalent iron ions (Fe ²⁺ ), resulting in a treatment liquid containing divalent iron and iron-reducing bacteria. The divalent iron generated by the reaction (ii) contributes to the reaction (i), so that manganese ions can be leached into the treatment liquid 4 in the leaching step 3.

Examples of the trivalent iron and iron-reducing bacteria used in the present invention include the following types. An electron donor is added to the treatment solution containing trivalent iron ions together with an electron acceptor (trivalent iron ions) necessary for iron respiration of iron-reducing bacteria. Furthermore, it is preferable to adjust the pH of the treatment liquid to a predetermined pH described later by adding at least one of the following acids, alkalis, and pH adjusting agents, and a pH buffering agent. It goes without saying that it is necessary to coexist elements essential for the growth of iron-reducing bacteria.

<Iron-reducing bacteria>
Examples of the iron-reducing bacteria used in the leaching step 3 of the present invention include, for example, Geobacter metalliducens Lovely et al. (ATCC 53774, DSM 7210), Desulfomonas palmitatis Coates et al. (ATCC 51701, DSM 12931), Desulfuromusakisii Liesack & Finster (DSM 7343), Pelobacter venetianus Schin & Stieb (DSM 2395), Shewanella algae . 1990 (NBRC 103173, IAM 14159, ATCC 51181), Ferrimonas balearica Rossello-Mora et al. (DSM 9799), Aeromonas hydrophila subsp. hydrophila (Chester) Stanier (DSM 30014), Sulfurospirillum barnesii Stolz et al. (ATCC 700032, DSM 10660), Wolinella succinogenes (Wolin et al.) Tanner et al. (DSM 1740, ATCC 29543), Desulfovibrio desulfuricans subsp. desulfuricans (Beijerink) Kluyver & van Niel (DSM 642, ATCC 29777), Geotrix fermentans Coates et al. (ATCC 7000066), Deferibacter thermophilus Greene et al. (DSM 14813), Thermotoga maritime Stetter & Huber (DSM 3109).

In the present invention, iron-reducing archaea can also be used. Examples of iron-reducing archaea include Archaeoglobus fulgidus Stetter (ATCC 49558, DSM 4304), Pyrococcus furiosus Finala & Setter (ATCC 49587, DSM 36, 38). Pyrodictium abyssi Pley and Stetter (ATCC 49828 , DSM 6158), Methanothermococcus thermolithotrophicus (Huber et al.) Whitman (DSM 2095, JCM 10549, ATCC 35097) , and the like can be given.

Here, for the iron-reducing bacteria and iron-reducing archaea described above, the strain number is described in parentheses, but the present invention is not limited to this.
Moreover, the synonyms of the above bacterial species are equivalent to the above bacterial species, and the bacterial species to which the above strain belongs are also equivalent to the above bacterial species.
In the present specification, the bacterial species may be specified by a genus name (including acronym) and a species name.

In the above, the names of strain storage institutions and facilities respectively represent the following.
ATCC: American Type Culture Collection, Manassas, VA, USA
DSM: Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ), Braunschweig, Germany
NBRC: NITE Biological Resource Center, Chiba, Japan
[National Biological Resource Center (NITE Biological Resource Center)]
JCM, IAM: Japan Collection of Microorganisms, RIKEN, Saitama, Japan
[RIKEN BioResource Center, Microbial Materials Development Office (JCM)]

The iron-reducing bacteria are preferably facultative anaerobic bacteria from the viewpoint of ease of handling outdoors. For example, among the above bacterial species, those described as iron-reducing bacteria can be mentioned.
Moreover, as iron-reducing bacteria, those that grow in a normal temperature range are preferable from the viewpoint of easy handling outdoors. For example, among the above bacterial species, those described as iron-reducing bacteria (excluding Gethorix fermentans and Thermotoga maritime ) can be mentioned.
Furthermore, as an iron-reducing bacterium, Geobacter metallyreducens or Shewanella algae is preferable, and Shewanella algae is more preferable.

The number of iron-reducing bacteria is not particularly limited. However, from the viewpoint of a higher leaching rate-leach efficiency, during the leaching step, as an initial value, preferably contains 1.0 × ^{10 13} atoms / ^{m 3} or more in the treatment solution, 1.0 × ^{10 13} ~ 1 0.0 × 10 ¹⁵ pieces / m ³ is more preferable, and 5.0 × 10 ¹³ to 2.0 × 10 ¹⁴ pieces / m ³ is further more preferable.

<Trivalent iron ion>
The trivalent iron ion used in the leaching step 3 of the present invention is not particularly limited. However, the trivalent iron ion is preferably added to the treatment liquid as a water-soluble trivalent iron salt. The water-soluble trivalent iron salt is preferably an inorganic acid salt or an organic acid salt.
As said inorganic acid salt, iron chloride (III), iron nitrate (III), iron sulfate (III), etc. can be mentioned, for example. On the other hand, examples of the organic acid salt include iron (III) citrate, iron (III) formate, and iron (III) acetate.

The concentration of trivalent iron ions is not particularly limited, but from the viewpoint of further increasing the leaching rate and leaching efficiency, it is preferable that the treatment liquid contains 10 mol / m ³ or more as an initial value during the leaching step. More preferably, m ^{3 is} contained, and even more preferably 25 to 100 mol / m ^{3 is} contained.

<Electron donor>
The electron donor can be appropriately selected according to the iron-reducing bacteria. For example, when the iron-reducing bacterium is Geobacter metalreducens or Shewanella algae , an organic substance can be used as an electron donor.

Examples of the organic substance include organic substances having 1 to 7 carbon atoms [carboxylate (fatty carboxylate (fatty acid salt): formate, acetate, etc., aromatic carboxylate: benzoate, etc., oxocarboxylic acid, etc. Salt: pyruvate, etc., other carboxylates: lactate, etc.), alcohol (ethanol, etc.), unsaturated aromatic (toluenephenol, etc.)] and the like. Needless to say, the organic substance may contain, for example, nitrogen, sulfur and other elements in addition to carbon, hydrogen and oxygen. The organic material is not limited to water-soluble or water-dispersible materials, and may be contained as organic fine particles that are neither water-soluble nor water-dispersible.

The concentration of the electron donor is not particularly limited. However, it is preferable to contain 100 mol / m ³ or more as an initial value in the leaching step.

<Acid, alkali, pH adjuster>
One or more selected from the group consisting of acids, alkalis, and pH adjusters can be added to the treatment liquid 4 to adjust the pH of the treatment liquid 4 to a predetermined pH described later.
The acid is not particularly limited, and for example, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as formic acid, acetic acid, lactic acid, citric acid, succinic acid, and malic acid can be used. The alkali is not particularly limited, and for example, sodium hydroxide, potassium hydroxide, an aqueous solution thereof or the like can be used. Moreover, the said pH adjuster is also not specifically limited, For example, potassium carbonate, sodium hydrogencarbonate, etc. can be used.

<PH buffering agent>
In the leaching step 3, the pH may change as the reaction proceeds. Therefore, the pH adjusting agent and / or pH buffering agent may be added to adjust the pH appropriately and suppress fluctuations.

The pH buffer added to the treatment liquid 4 is not particularly limited as long as it has a buffering ability in a neutral pH range. For example, acetic acid / sodium acetate, citric acid / sodium citrate, lactic acid / sodium lactate, Phosphoric acid / sodium phosphate, tartaric acid / sodium tartrate, N- (2-acetamino) -2-aminoethanesulfonic acid, N- (2-acetamino) iminodiacetic acid, N, N-bis (2-hydroxyethyl)- 2-aminoethanesulfonic acid, N, N-bis (2-hydroxyethyl) glycine, 2- [4- (2-hydroxyethyl) -1-piperazinyl] ethanesulfonic acid, 2- [4- (2-hydroxyethyl) ) -1-piperazinyl] ethanesulfonic acid sodium, 2-morpholinoethanesulfonic acid, 2-hydroxy-3-morpholinopropanesulfonic acid Piperazine-1,4-bis (2-ethanesulfonic acid), can be mentioned piperazine-1,4-bis (2-hydroxy-3-propanesulfonic acid) and the like.

The pH buffering agent to be added to the treatment solution 4, can also be used for the can also function as the electron donor. For example, when the iron-reducing bacterium is Shewanella algae , lactic acid / sodium lactate and the like can function as a pH buffer and at the same time as an electron donor. Moreover, as a pH buffer agent added to the said process liquid 4, what can form a complex with the manganese ion leached from the to-be-processed object 1 can be used. For example, citric acid / sodium citrate or the like can form a complex with Mn ²⁺ .

In addition, the said pH buffering agent should be used by arbitrary content in the range which does not impair the objective of this invention, and does not impair pH buffering effect individually or in combination of 2 or more types. Can do.

<PH>
Although iron-reducing bacteria used in the present invention have some differences depending on the species or strain, the optimum growth pH is in the neutral pH range. However, in the leaching step 3, the pH of the treatment liquid 4 may vary as the reaction proceeds.
Therefore, the pH of the treatment liquid 4 is not particularly limited as long as it is around 7.0. However, when the pH of the treatment liquid 4 varies, it is controlled to 5.0 or more and 9.0 or less, preferably 6.0 or more and 8.0 or less, and more preferably 6.5 or more and 7.5 or less. Efficient leaching can be achieved.

Also, depending on the use of recovered manganese, it is required to reduce impurities in the manganese as much as possible. For example, when using recovered manganese as a steelmaking raw material, high purity recovered manganese is required to prevent carbon and phosphorus from being mixed into the steel.

In the manganese recovery method of the present invention, in order to reduce the carbon concentration and phosphorus concentration in the finally recovered manganese, it is preferable that the treatment liquid 4 is a treatment liquid in which the carbon concentration and the phosphorus concentration are limited. That is, it is preferable that the composition of the treatment solution before adding the iron-reducing bacteria is such that the carbon concentration and phosphorus concentration are below certain values.
In order to obtain high-purity manganese oxide, it is preferable that the carbon concentration before adding the iron-reducing bacteria in the treatment solution 4 is 300 mM or less and the phosphorus concentration is 0.5 mM or less. More preferably, the carbon concentration is 270 mM or less and the phosphorus concentration is 0.16 mM or less.

However, if the carbon concentration and phosphorus concentration are extremely reduced, the growth of iron-reducing bacteria is inhibited and the manganese leaching rate is adversely affected. Therefore, it is preferable that the carbon concentration is 100 mM or more and the phosphorus concentration is 0.05 mM or more.

When the leaching process 3 is performed using the treatment liquid 4 as described above, the workpiece 1 and the treatment liquid 4 are contacted and mixed in a state where oxygen is blocked. This is because when oxygen is present, there is a concern that the iron-reducing bacteria will not perform a reduction reaction from trivalent iron to divalent iron. The temperature of the treatment liquid 4 is preferably maintained at 10 to 35 ° C. The leaching time varies depending on the leaching conditions, but is usually 24 to 72 hours.

As described above, when the treatment object 1, the iron-reducing bacteria, and the treatment liquid 4 containing trivalent iron ions are mixed, the trivalent iron ions in the treatment liquid 4 are reduced by the iron-reducing bacteria to become divalent iron ions. . The divalent iron ions act as a reducing agent to the object to be processed 1, divalent iron is 3 is oxidized to ferric in Rutotomoni treatment object in one manganese leach into the processing solution 4, and manganese ions A leaching slurry (leaching solution) 5 containing trivalent iron ions or unreacted divalent iron ions is obtained. The leaching slurry (leaching solution) 5 obtained in the leaching step 3 is sent to the solid-liquid separation step 6.

In the solid-liquid separation step 6, the leaching slurry (leaching liquid) 5 is subjected to solid-liquid separation.
When the leaching slurry (leaching liquid) 5 is subjected to solid-liquid separation in the solid-liquid separation step 6, a manganese component-containing leachate (separation liquid) 10 and a residue (solid matter) 7 which are supernatant components are obtained.
The solid-liquid separation means used in the solid-liquid separation step 6 is any means selected from gravity sedimentation separation, filtration, centrifugation, filter press, membrane separation and the like. Moreover, when the solid substance concentration of the leaching slurry 5 is high, it is preferable to use a filter press.

The manganese component-containing leachate (separation liquid) 10 mainly contains manganese ions and iron ions (trivalent iron ions or further divalent iron ions). Further, the residue (solid matter) 7 mainly contains iron-reducing bacteria and solid components other than manganese of the object 1 to be processed.
Next, the manganese component-containing leachate (separation liquid) 10 is transferred to the insolubilization step 11. On the other hand, since the residue (solid matter) 7 contains many iron-reducing bacteria, a part thereof is returned to the leaching step 3 as a return residue 9 and a part is recovered as an unreacted residue 8 (FIG. 2 (a)).

In the insolubilization step 11, the manganese component-containing leachate (separation solution) 10 obtained in the solid-liquid separation step 6 is subjected to a predetermined insolubilization process, and the pH and oxidation-reduction potential (ORP) of the manganese component-containing leachate (separation solution) 10 are set. Manganese is insolubilized (solidified) and precipitated as an oxide, but iron is not precipitated, that is, adjusted to pH and redox potential (ORP) in the region surrounded by circles in the Eh-pH diagram (Fig. 1). To do. Thereby, the manganese dissolved in the manganese component-containing leachate 10 is preferentially insolubilized and becomes a solid. This insolubilization step 11 is preferably a step in which ozone is allowed to act on the manganese component-containing leachate (separation solution) 10 under acidic conditions. For example, after adding the acid 12 to the manganese component-containing leachate (separation solution) 10, It is preferable that ozone is diffused by the ozone generator 13. That is, by adjusting the pH of the manganese component-containing leachate (separate) 10 by adding acid 12, and adjusting the oxidation-reduction potential (ORP) of the manganese component-containing leachate (separate) 10 by ozone aeration, region pH and redox potential of the ingredient-containing leachate 10 (ORP), manganese solids as oxides Monoka, although precipitation region iron does not precipitate, i.e., the Eh-pH diagram (Figure 1), enclosed in ○ The pH and the redox potential (ORP) are preferably adjusted.

As an Eh-pH diagram, for example,
Pourbaix, M .; Atlas of electrochemical equilibria in aquatic solutions. National Association of Corrosion Engineers. (1974) 644 p. Can be used.

As is apparent from FIG. 1, the region where both Fe and Mn are solidified varies depending on the concentration of each component in the solution. For example, when the Fe concentration in the solution is 0.05 M and the Mn concentration in the solution of the eluted Mn is 0.1 M, in FIG. 1, Fe is between the lines of 10 ⁰ M and 10 ⁻² M. Based on the boundary near 10 ⁻² M (line * 1 in FIG. 1), Mn may be considered as the boundary (line * 2 in FIG. 1) between the lines of 10 ⁰ M and 10 ⁻² M.
In this case, in FIG. 1, the pH and oxidation-reduction potential (ORP) of the region where manganese solidifies and precipitates as an oxide (the region surrounded by circles in FIG. 1) are approximately “pH: 0” as shown in FIG. 0.1 to less than 2.2 "and" Oxidation-reduction potential (ORP): about +0.9 V or more and +1.2 V or less ".

Further, FIG. 1 shows a case where the water temperature is 25 ° C., but if the water temperature is different, temperature correction may be performed. As a correction method, a known method (for example, correction of an equilibrium multiplier by the Van't Hoff equation) may be performed.
Therefore, in the case where the manganese component-containing leachate (separation liquid) 10 obtained in the solid-liquid separation step 6 has the above Fe and Mn concentrations, acid 12 is added to this solution to lower the pH to less than 2.2, Next, ozone is diffused to raise the oxidation-reduction potential (ORP) to +0.9 V or more, whereby manganese becomes a solid as an oxide and can be precipitated.

The acid 12 may be a general acid, and sulfuric acid, nitric acid, hydrochloric acid, and other acids can be used. As the amount of ozone diffused, ozone was diffused while observing the oxidation-reduction potential (ORP), and the oxidation-reduction potential (ORP) was a predetermined value (for example, the temperature of the manganese-containing leachate was 25 ° C., It is preferable to adjust so that the Fe and Mn concentrations in the leachate are +1 V or more when Fe: 0.05M and Mn: 0.1M, respectively. In addition, since the required amount of ozone varies depending on the shape of the apparatus and the bubble diameter at the time of air diffusion, the most efficient method may be selected by comparing costs and the like.

In the insolubilization step 11, the manganese component-containing leachate (separated liquid) 10 during the insolubilization process (that is, during the ozone aeration process) becomes black due to the manganese oxide generated by the oxidation of manganese, and the progress of the manganese oxidation reaction progresses. It becomes difficult to distinguish visually. When the manganese oxidation reaction in the insolubilization process 11 is inadequate, manganese ion does not precipitate as a solid substance and causes a deterioration in manganese recovery rate.

On the other hand, if the manganese oxidation reaction becomes excessive, the manganese oxide once generated becomes peroxide ions and redissolves, resulting in a deterioration in manganese recovery rate as in the case of insufficient oxidation. As a result of the study by the present inventors on the reason, when the manganese oxidation reaction is excessive, the solid oxide of manganese is further oxidized and becomes manganese peroxide ions and redissolved in the solution. Because of that.

In FIG. 1, the ORP in which manganese peroxide (the uppermost part in FIG. 1, the substance called MnO ₄ ⁻ ) is mainly present is around +1.6 V even at pH 2. Usually, such an increase in ORP is observed. Not. However, it was found that when the manganese oxidation reaction becomes excessive, some manganese oxides become peroxides due to the action of ozone. It was also found that peroxide was formed after almost all manganese was solidified as an oxide.

From these facts, it is necessary to determine the end point of the manganese oxidation reaction. However, even if the end point of the manganese oxidation reaction is controlled by the reaction time, in the case of a manganese component-containing leachate (separation liquid) 10 obtained by bioleaching or the like, the composition of the solution may differ for each leachate. However, the same recovery rate is not always obtained in the same reaction time. In addition, when the control by the oxidation-reduction potential (ORP) is considered, the same problem occurs, and it is difficult to confirm a clear reaction end point.

On the other hand, the solution containing manganese peroxide ions is reddish purple. Therefore, the formation of manganese peroxide in the solution can be easily determined by observing the color of the solution. However, as described above, during the insolubilization treatment, in the presence of manganese oxide (solid matter) fine particles such as the manganese component-containing leachate (separation liquid) 10, the entire solution becomes black, which is the color of manganese oxide. The discoloration of the solution cannot be determined. However, if manganese oxide is separated from the manganese component-containing leachate (separation liquid) 10 during the insolubilization treatment, it is possible to observe the color change of the leachate, and thus determine the formation of manganese peroxide. It becomes possible.

Therefore, in actual operation, in the insolubilization step 11 with ozone, the manganese component-containing leachate (separation liquid) 10 during the insolubilization treatment is taken out periodically or continuously, manganese oxide is separated from the taken-out liquid, and the solution itself It is preferable to determine the end point of the oxidation reaction of manganese ions by observing the color. Specifically, the manganese component-containing leachate (separation liquid) 10 during the insolubilization process is taken out and separated from the taken-out liquid by filtering or standing still to settle the manganese oxide, By observing the color of the filtrate or the supernatant and changing the color of the filtrate to light red as the end point of the manganese oxidation reaction and ending the insolubilization step 11, the manganese recovery rate can be maximized.
Further, if it is allowed in relation to cost, installation space, etc., more objective evaluation can be performed by measuring the supernatant with an absorptiometer. Since manganese peroxide ions have a maximum absorption wavelength near 525-545 nm, the absorbance at wavelengths near 525-545 nm increases rapidly due to the generation of manganese peroxide ions. Thereby, the coloring of the supernatant and the reaction end point can be objectively determined.
In actual operation, the absorbance near 525-545 nm is measured in advance for the solution before the ozone oxidation reaction, and the coloration of the supernatant and the end point of the reaction are determined from the increase in absorbance when this absorbance is 1. Just decide.

In the case of determining the end point of the oxidation reaction of manganese ions as described above, in the insolubilization step 11, for example, a separation / observation tank 19 can be provided as shown in FIG. In such a case, for example, a small amount of the manganese component-containing leachate (separation liquid) 10 during the insolubilization process is taken out from the reaction tank (not shown) in the insolubilization step 11 to the separation / observation tank 19 periodically or continuously. The liquid is allowed to stand to precipitate and separate the manganese oxide, and the color of the supernatant (that is, the color of the solution itself) is observed. After the observation, the supernatant and the precipitated manganese oxide may be returned to the reaction tank of the insolubilization step 11 in order to increase the manganese recovery rate. However, the operation of returning the supernatant and / or manganese oxide to the reaction vessel is not essential. Such an operation may be repeated until the end point of the oxidation reaction of manganese ions is confirmed (that is, until the supernatant turns light red).

In the above description, the method for precipitating and separating manganese oxide by removing a small amount of the manganese component-containing leachate (separation solution) 10 during the insolubilization treatment and leaving it in the separation / observation tank 19 has been described. However, in this invention, you may isolate | separate the manganese component containing leaching liquid (separation liquid) 10 and manganese oxide in the insolubilization process not only by the method by the precipitation separation mentioned above but by other methods. For example, in the separation / observation tank 19, the extracted liquid may be filtered, and the color of the filtrate may be observed to determine the manganese ion oxidation reaction end point. In such a case, the manganese oxide separated by filtration and / or filtration may be returned to the reaction tank of the insolubilization step 11 in order to increase the manganese recovery rate after observation. However, the operation of returning the filtrate and / or manganese oxide to the reaction vessel is not essential.

Further, when the manganese component-containing leachate (separation solution) 10 being insolubilized is taken out and the color thereof is observed, it is not always necessary to completely separate the taken-out solution and the manganese oxide. That is, the separation state of both may be such that the color of the taken out solution itself can be observed.

Through the above steps, manganese dissolved in the manganese component-containing leachate (separation liquid) 10 is preferentially insolubilized to become a solid, and most of the iron ions (trivalent iron ions or even divalent iron ions) are manganese components. It will be in the state melt | dissolved in the containing leachate (separation liquid) 10. FIG. In the subsequent recovery step 14, the concentrated high concentration manganese oxide 15 is recovered by solid-liquid separation of the separation liquid 10 after the insolubilization step 11. The solid-liquid separation means used for the solid-liquid separation can be any means selected from gravity sedimentation separation, filtration, centrifugation, filter press, membrane separation, and the like.

On the other hand, the post-recovery separation liquid 10a from which the manganese oxide 15 has been recovered is rich in iron ions (trivalent iron ions or even divalent iron ions). Therefore, in the present invention, the post-recovery separation liquid 10a can be neutralized in the neutralization step 16 and reused as the treatment liquid 4 used in the leaching step 3.
The post-recovery separation liquid 10 a sent to the neutralization step 16 is neutralized by the alkali 18. Examples of the alkali 18 used for neutralization include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, and sodium bicarbonate. However, it is not limited to these. Moreover, in the neutralization process 16, it is preferable to draw a part out of the system as blow water 17 for the purpose of preventing the concentration of salts and the like.

The post-recovery separation liquid 10a that has passed through the neutralization step 16 is then mixed with the treatment liquid 4 in the leaching step 3. Then, the trivalent iron ions in the separation liquid 10a after recovery are reduced to divalent iron ions by the iron reducing bacteria contained in the treatment liquid 4, and the divalent iron ions act as a reducing agent for the object 1 to be processed. Will do. According to the present invention in which the treatment object 4 and iron-reducing bacteria are mixed with the treatment liquid 4 containing trivalent iron ions, a neutralization step 16 is provided as a subsequent step of the recovery step 14, and the neutralized post-recovery separation liquid 10a is leached. The processing liquid can be reused by a simple process of mixing with the processing liquid 4 in step 3. In addition, when mixing the separation liquid 10a after recovery after the neutralization step 16 with the treatment liquid 4 of the leaching step 3, medium components other than iron are consumed and reduced by microorganisms, so that a new treatment is performed as necessary. Liquid can be added.

As described above, when iron-reducing bacteria are allowed to act to reduce trivalent iron to divalent iron and reduce the object to be treated containing manganese using the divalent iron, the manganese contained in the object to be treated is reduced. It can be leached in time and at low cost. In addition, the residue is separated from the leachate from which manganese has been leached, and the separated leachate is treated with ozone under acidic conditions, so that manganese is preferentially insolubilized and precipitated as manganese oxide to recover manganese. In addition, the leachate remaining after separating the precipitate (eg, as a supernatant) can be used repeatedly.

That is, when the treatment liquid 4 used in the leaching step 3 is a treatment liquid containing trivalent iron ions, and an object to be treated and iron-reducing bacteria are mixed therewith, first, the iron-reducing bacteria reduce the trivalent iron ions in the treatment liquid. Then, divalent iron is generated by the reaction (Fe ³⁺ + e ⁻ → Fe ²⁺ ) of (ii). Next, in the leaching step 3, the reaction (i) (Fe ²⁺ + (“Mn oxide, hydroxide, etc.” or “MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ ”)) → Fe ³⁺ + Mn ²⁺ ) Produces manganese ions and trivalent iron ions, and a leaching solution (leaching slurry) 5 containing manganese ions and trivalent iron ions is obtained. Further, the leachate (leaching slurry) 5 is solid-liquid separated, manganese is recovered from the separated liquid 10 after solid-liquid separation, and after the separation, the separated liquid 10a is neutralized and mixed with the treatment liquid 4 used in the leaching step 3. Then, iron-reducing bacteria in the treatment liquid 4 reduce trivalent iron ions in the manganese recovery / separation liquid 10a, and divalent iron ions are generated by the reaction (Fe ³⁺ + e ⁻ → Fe ²⁺ ). By repeating the reactions (i) and (ii) above, manganese can be recovered and the leachate can be reused.

As described above, the treatment liquid 4 used in the leaching step 3 is a treatment liquid containing trivalent iron ions, and the treatment object containing manganese and iron-reducing bacteria are mixed with the treatment liquid 4 so that manganese ions are leached from the treatment object. When the method is employed, the leachate 10a after the manganese recovery step 14 can be neutralized in the neutralization step 16, and then mixed with the treatment liquid 4 in the leach step 3 without taking any special measures.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this Example.
1) Manganese leaching by iron-reducing bacteria This was carried out using the following iron-reducing bacteria, treatment liquid, and workpiece containing manganese.
<Iron-reducing bacteria>
Shewanella algae NBRC 103173 (NITE Biological Resource Center)
<Processing liquid>
The processing liquid which added the said iron reduction bacteria to the solution which has a mixing | blending component of Table 4.
The amount of solution and the concentration of iron-reducing bacteria are as follows.
Amount of solution: 3000 cm ³
Initial iron-reducing bacteria concentration: 5 × 10 ¹³ cells / m ³ (5 × 10 ⁷ cells / cm ³ )
“Mineral solution” in Table 4 is Wolfe's Mineral Solution having the ingredients in Table 5, and “Vitamin solution” in Table 4 is Wolfe's having ingredients in Table 6. Vitamin solution (Wolfe's Vitamin Solution).
In Tables 4, 5, and 6, “total amount of 1000 cm ³ ” of ion-exchanged water means that the total amount of the solution is adjusted to be 1000 cm ³ .
<Processed object>
Alkaline battery waste (manganese content: 32% by mass)

The treatment liquid and the object to be treated were mixed in a reaction vessel, and leaching treatment was performed under the following conditions.
Sample (g) -treatment liquid (cm ³ ) mixing ratio: 22 g / 1000 cm ³
Treatment liquid temperature: 25 ° C
PH of treatment solution: 7
Processing time: 24 hr
Atmosphere: Anaerobic conditions

During the leaching process, the obtained manganese leachate was sampled and immediately filtered through a 0.45 μm membrane filter. The manganese concentration of the filtered sample (filtrate) was quantified by ICP emission spectrometry. FIG. 3 shows the result of calculating the ratio of leached manganese (leaching rate) to manganese in the workpiece based on the quantitative value.
The manganese concentration in the filtrate after the 24-hour leaching treatment was 0.1 mol / 1000 cm ³ , and according to the present invention, a high manganese leaching rate of about 80% was obtained as shown in FIG. 3 ((0.1 mol / 1000 cm ³ ) ÷ (22 g / 1000 cm ³ × 32 mass% ÷ Mn molecular weight 55 g / mol) ≈80%).

2) Recovery of Manganese by Acid Ozone Diffusing Treatment In order to test the concentration and purification / recovery of manganese from the leachate, experiments were conducted using the filtered manganese leachate obtained in 1). The leachate obtained in 1) was transferred to a reaction vessel, and ozone was diffused under sulfuric acid acidity under the following conditions, and an experiment was conducted to solidify manganese as an oxide.
Liquid volume of leachate (after filtration): 500mL
Ozone generator: EZ-OG-R4 (Ecodesign)
Stirrer rotation speed of reaction tank: 800rpm
Ozone generator current: Current 3.8A
Ozone diffuseness: 1 L / min
Acid used: Sulfuric acid Concentration: Change from 0.1N to 3N Ozone diffusion time: 150 minutes

After the experiment, it was filtered through a 0.22 μm membrane filter, and the solid was dried at 50 ° C. for 3 days and then weighed.
Both the filtrate and the solid were quantified for manganese and iron concentrations by ICP emission spectrometry. Moreover, about the solid substance, the sulfur concentration was also quantified by the combustion ion chromatography method. The results are shown in FIG. 4 and FIG.
Table 7 shows the results of measurement of the pH of the leachate at each sulfuric acid concentration (leachate before ozone diffusion treatment). When the sulfuric acid concentration was high, the pH value became zero or less. In this example, since the pH was measured with a normal glass electrode type pH meter, it was not an accurate value when the measurement result was negative, but it was described as a measured value in the table.

As shown in FIG. 4, the higher the concentration of sulfuric acid added to make the leachate acidic, the lower the content of iron precipitated with manganese, and the better the separation of manganese and iron. I understand.
In addition, other components are considered to be manganese dioxide, so oxygen is bound to manganese, and it is dried for a long time at low temperature to avoid changes in morphology, so water remains. It is done.
It was also confirmed that the sulfur content derived from sulfuric acid added to make the leachate acidic was hardly contained in the solid matter.

In the region where the sulfuric acid concentration is 0.3 N or more, the iron content in the precipitate is less than 10%, and it can be said that manganese and iron are well separated. Under conditions where the sulfuric acid concentration was 0.1 N, iron was mixed in the precipitate by 10% or more, exceeding the target value of less than 10% initially set by the present inventors.

Furthermore, as shown in FIG. 5, manganese has moved to a solid matter of 80% or more with respect to the amount of manganese in the leachate. On the other hand, only less than 1% of manganese on the filtrate side is detected with respect to the amount of manganese in the leachate. The remaining manganese is almost a recovery loss. Actually, it is considered that almost 100% of the manganese in the leachate is solidified and transferred to the solid. In addition, as a factor of recovery loss, when manganese is oxidized with ozone and becomes a solid substance, it is considered that the reaction vessel is stuck in a thin film.

On the other hand, paying attention to iron, the lower the sulfuric acid concentration, the higher the ratio of transfer of iron to precipitates, and the tendency for separation between manganese and iron became insufficient. In particular, under the condition of a sulfuric acid concentration of 0.1 N, 50% or more of the iron in the leachate was transferred to the precipitate, and it was a result that the separation of iron was not sufficient.

3) Determine the end point of manganese oxidation reaction in acidic ozone aeration treatment (1)
Transfer the leachate obtained in 1) to the reaction vessel and perform 2) above except that the ozone is diffused while sampling the leachate, the acid concentration is 1N, and the ozone aeration time is 190 minutes. The experiment was conducted under the same conditions as in Example 1, with ozone diffused under sulfuric acid, and solidified manganese as an oxide.

The leachate was sampled immediately before ozone diffusion and during ozone diffusion treatment. The sampling during the ozone aeration treatment was performed several times with the passage of the ozone aeration time. When sampling the leachate, it was confirmed that the leachate was sufficiently stirred and in a uniform state, and was sampled by 50 cm ³ each. The sampled leachate was filtered through a 0.22 μm membrane filter to separate manganese oxide, and the color of the filtrate (solution part) was observed.
Further, each manganese recovery rate was measured from the sampled leachate by the same method as in 2) above. The total amount of manganese (mass) contained in the leachate sampled immediately before ozone diffusion was set to 100%.

There was no precipitation (solid matter) in the leachate sampled immediately before ozone diffusion. In addition, solid manganese sticks to the reaction vessel in the form of a thin film as described above, causing an error in quantitativeness. Therefore, the manganese concentration in the filtrate of the sample immediately before the ozone aeration treatment and the filtrate of the sample in the ozone aeration treatment The manganese recovery rate (mass basis) was calculated based on the manganese concentration on the side. The manganese concentration in the filtrate was quantified by ICP emission spectrometry.
The experimental results are shown in FIG.

FIG. 6 shows changes in the color of the filtrate and the manganese recovery rate with the passage of ozone aeration time. As shown in FIG. 6, for a while after ozone was applied, it was considered that organic matter in the leachate that was thought to be due to the medium components was consuming ozone, and no manganese oxide was produced. After about 100 minutes, manganese oxide began to form, and the leachate suddenly turned black. However, at this time, when the manganese oxide was removed by filtration, the color of the filtrate from which the manganese oxide was removed (solution portion) was a pale yellow color that was thought to be due to the medium components. In addition, when manganese oxide begins to form, the manganese recovery rate rises rapidly in a short time as the ozone aeration time elapses, and a manganese recovery rate of 99% or more is achieved in the vicinity of the ozone aeration time: 150 minutes. It was.

However, when the ozone aeration time: 150 minutes passed and the ozone aeration was continued as it was, the manganese recovery rate decreased. At this time, the color of the filtrate changed from red to magenta, which is the color of manganese peroxide. From these results, ozone dispersion time: Manganese peroxide is generated after 150 minutes, and manganese peroxide becomes ions and redissolves in the reaction solution. You can conclude.

4) Identifying the end point of manganese oxidation reaction in acidic ozone aeration treatment (2)
As shown in the experimental results of 3) above, in the acidic ozone aeration treatment, there is an optimum ozone aeration time for obtaining a high manganese recovery rate. However, the optimum ozone aeration time is easily affected by the composition of the reaction solution, the reactor shape, the bubble diameter, the stirring speed, and the like. Therefore, to determine the optimal ozone aeration time in advance based on the type of iron-reducing bacteria, the manganese content of the object to be treated, and other acidic ozone aeration treatment conditions (ozone aeration amount, acid concentration, etc.) It is extremely difficult.

Table 8 shows that the ozone aeration time is 150 minutes, that is, the ozone aeration time optimal for the high manganese recovery obtained in 3) above is the same as in 3) above under sulfuric acid acidity. The experiment of aeration and solidification with manganese as an oxide was conducted four times, and the results (batch Nos. 1A to 4A) were shown.
At the same time, the absorbance at a wavelength of 525.5 nm was measured, and the ratio with the absorbance of the solution at the start of the reaction was determined.

As shown in Table 8, even when the ozone aeration time and other conditions were the same, the manganese recovery rate varied, and the recovery rate exceeding 99% was obtained because the color of the filtrate was light red. It was only once of “Batch No. 1A” presented. “Batch No. 2A, 3A” is presumed that the oxidation reaction of manganese was insufficient because the color of the filtrate was light yellow. On the other hand, in the case of “Batch No. 4A”, the color of the filtrate is reddish purple, and it is assumed that the oxidation reaction of manganese has progressed too much. At this time, when the absorbance at a wavelength of 525.5 nm is measured and a ratio with the absorbance before ozone diffusion (0 minutes) is taken, the solution is colored due to the production of manganese peroxide ions, and the absorbance depends on the amount of production. It can be confirmed that it has increased. In the case of “Batch No. 1A”, the production rate of manganese peroxide ions was very small, so the recovery rate was kept high. However, in “Batch No. 4A”, the production of manganese peroxide ions was excessive and the loss was large. It was thought that it became. As described above, it is difficult to stably maximize the manganese recovery rate in the ozone aeration time management.

On the other hand, Table 9 shows the same conditions as the above 3) except that the time when the color of the filtrate changed from light yellow to light red was determined as the “manganese oxidation reaction end point” and the “ozone diffusion time” was determined. The experiment was conducted four times in which ozone was diffused in the presence of sulfuric acid and solidified with manganese as an oxide, and the results (batch Nos. 1B to 4B) were shown. That is, in this experiment, the acidic ozone aeration process is completed when the color of the filtrate changes from light yellow to light red.

As shown in Table 9, it was possible to always obtain a recovery rate exceeding 99% by observing the color of the filtrate of the leachate and determining the end point of the manganese oxidation reaction (ozone aeration time). At this time, the absorbance measurement results confirmed that in all cases, the production of manganese peroxide ions was kept low and the reaction was carried out without excess or deficiency, so that the recovery rate was maximized. It was.

As described above, since the manganese oxidation reaction by ozone is affected by the composition of the reaction solution, the reactor shape, the bubble diameter, the stirring speed, etc., the same manganese recovery rate is not necessarily obtained in the same reaction time (ozone aeration time). It is not necessarily obtained. In particular, when using a manganese leachate using microorganisms, the composition of the leachate may vary greatly depending on the activity of the microorganism, the number of bacteria, etc., so management by reaction time is difficult and realistic. I can't say that. On the other hand, for example, even when the composition of the leachate varies greatly depending on the activity of microorganisms, the number of bacteria, etc., by extracting a small amount of leachate and observing the color of the filtrate or supernatant, it is stably high. It becomes possible to obtain a manganese recovery rate.

5) Limitation of treatment liquid components First, manganese was leached by iron-reducing bacteria using the following iron-reducing bacteria, treatment liquid, and the object to be treated containing manganese.
<Iron-reducing bacteria>
Shewanella algae NBRC 103173 (NITE Biological Resource Center)
<Processing liquid>
Treatment liquid A: A treatment liquid obtained by adding the iron-reducing bacteria to a solution having the blending components shown in Table 4.
Treatment liquid B: A treatment liquid obtained by adding the iron-reducing bacteria to a solution having the blending components shown in Table 10. In addition, “1000 cm ^{3 in the} total amount” of ion-exchanged water in Table 10 means that the total amount of the solution is adjusted to be 1000 cm ³ .
The amount of the solution and the concentration of iron-reducing bacteria are as follows for both of the treatment liquids A and B.
Amount of solution: 500 cm ³
Initial iron-reducing bacteria concentration: 5 × 10 ¹³ cells / m ³ (5 × 10 ⁷ cells / cm ³ )
“Mineral solutions” in Tables 4 and 10 are Wolfe's Mineral Solution having the ingredients shown in Table 5, and “Vitamin solutions” in Tables 4 and 10 are ingredients in Table 6. Wolfe's Vitamin Solution with
The carbon concentration and phosphorus concentration in the treatment liquids A and B before adding the iron-reducing bacteria are quantified by a total organic carbon meter and a high-frequency inductively coupled plasma emission spectrometry (ICP emission spectrometry). Concentration. The quantitative results are shown in Table 11.
<Processed object>
Metal-containing dust generated in the refining process of steelworks (Mn: 69% by mass, Fe: 3% by mass)

The treatment liquid and the object to be treated were mixed in a reaction vessel, and leaching treatment was performed under the following conditions.
Sample (g) -treatment liquid (cm ³ ) mixing ratio: 5 g / 1000 cm ³
Treatment liquid temperature: 25 ° C
PH of treatment solution: 7
Processing time: 24 hr
Atmosphere: Anaerobic conditions

After the above leaching treatment, the obtained manganese leaching solution was filtered with a 0.45 μm membrane filter. The concentration of manganese contained in the filtered sample (filtrate) was quantified by high frequency inductively coupled plasma emission analysis (ICP emission analysis). The quantitative results are shown in Table 11.

Next, manganese was recovered by ozone aeration treatment using the obtained manganese leachate after filtration. The ozone diffusion treatment conditions were the same as the above 2) except that the acid concentration was 1N, and a treatment for solidifying manganese as an oxide by ozone diffusion was performed.
After the treatment, it was filtered through a 0.22 μm membrane filter, and the solid was dried at 50 ° C. for 3 days and then weighed.
Next, the solid matter was dissolved in an acid, and manganese, carbon, and phosphorus were quantified by ICP emission analysis and a carbon sulfur analyzer, whereby the manganese concentration, carbon concentration, and phosphorus concentration of the solid matter were quantified. The quantitative results are shown in Table 11.

As shown in Table 11, the carbon concentration and phosphorus concentration in the treatment liquids A and B before adding the iron-reducing bacteria are 600 mM and 5.2 mM in the treatment liquid A, whereas in the treatment liquid B, 270 mM and 0 16 mM.
When manganese was leached using the treatment liquid B, the manganese concentration of the leaching liquid after the 24-hour leaching treatment was 42 mM, and a high manganese leaching rate of 75% or more was obtained. Further, as shown in Table 11, the manganese leaching rate when manganese was leached using the treatment liquid B was the same as the case where manganese was leached using the treatment liquid A.

Furthermore, the content of manganese, carbon and phosphorus in the solid matter containing manganese recovered by the ozone aeration treatment, when the treatment liquid A is used, manganese: 45 mass%, carbon: 0.14 mass%, Phosphorus: 0.8% by mass, but when treatment solution B is used, manganese: 45% by mass, carbon: 0.07% by mass, phosphorus: 0.03% by mass, based on the manganese content The carbon and phosphorus content is greatly reduced.

DESCRIPTION OF SYMBOLS 1 ... To-be-processed object 2 ... Crushing process 3 ... Leaching process 4 ... Treatment liquid 5 ... Leaching slurry (leaching liquid)
6 ... Solid-liquid separation step 7 ... Residue 8 ... Unreacted residue 9 ... Return residue 10 ... Manganese component-containing leachate (separate)
10a ... Separation liquid after recovery 11 ... Insolubilization step 12 ... Acid 13 ... Ozone generator 14 ... Recovery step 15 ... Manganese oxide 16 ... Neutralization step 17 ... Blow water 18 ... Alkali 19 ... Separation / observation tank

Claims

A treatment solution containing trivalent iron ions is mixed with an object to be treated containing manganese and iron-reducing bacteria, and the iron-reducing bacteria reduce the trivalent iron ions to divalent iron ions. In the separation liquid after the solid-liquid separation step, a leaching step of leaching manganese ions from the material to be treated as a reducing agent into the treatment liquid, a solid-liquid separation step of separating the leachate obtained in the leaching step into a solid-liquid separation, and A method for recovering manganese, comprising: an insolubilization step for oxidizing and insolubilizing manganese ions contained in the solution; and a recovery step for separating and recovering the manganese component obtained in the insolubilization step.
The method for recovering manganese according to claim 1, wherein a post-recovery separation liquid containing trivalent iron ions obtained by recovering a manganese component from the separation liquid is reused as a treatment liquid in the leaching step.
The said insolubilization process is a process of oxidizing and insolubilizing manganese ion by making ozone act on the separated liquid after the said solid-liquid separation process on acidic conditions, The Claim 1 or 2 characterized by the above-mentioned. Manganese recovery method.
The workpiece is a steelworks by-product and / or low-grade ore, and / or used battery, and / or manganese-containing dust, and / or manganese-containing sludge and / or manganese-containing slurry. The manganese recovery method according to any one of claims 1 to 3.
In the insolubilization step, the liquid during insolubilization treatment is taken out periodically or continuously, and the end point of the oxidation reaction of manganese ions is determined by observing a change in the color of the solution portion of the liquid taken out. 5. The manganese recovery method according to any one of 1 to 4.
The manganese recovery method according to any one of claims 1 to 5, wherein the treatment liquid in the leaching step is a treatment liquid in which a carbon concentration and a phosphorus concentration are limited.
The method for recovering manganese according to claim 6, wherein the carbon concentration is 300 mM or less and the phosphorus concentration is 0.5 mM or less.