KR101641074B1 - Biological decomposition of monazite by using phosphate solubilizing bacteria - Google Patents

Abstract

The present invention relates to a technique for biologically decomposing monazite using a phosphate-dissolving microorganism to recover a rare earth metal.
(B) adding monazite to the culture medium; (c) feeding microorganisms into the medium of step (b); and (d) ) Culturing the microorganism in step (c); and (e) leaching the rare earth metal from monazite using the cultured microorganism in step (d). . ≪ / RTI >
According to the present invention, rare earth metals can be economically recovered, and the process is simplified compared to conventional processes, while environmental pollution is not caused.

Description

[0002] Biological decomposition of monazite by using phosphate-solubilizing bacteria [

The present invention relates to a technique for biologically decomposing monazite using a phosphate-dissolving microorganism to recover a rare earth metal.

Rare earth metals are a group of 17 elements including lanthanides from atomic number 57, lanthanum from lanthanum (La) to lanthanum (71), scandium (Sc), and yttrium (Y) do. Because of its unique physical and chemical properties, rare earth metals are used in a wide variety of applications such as optical glass, abrasives, fluorescent materials, pigments, magnetic materials, metal additives, and ceramics in all industrial fields such as metals, chemicals and materials. .

Monazite is a rare earth metal with a large amount of cerium (Ce) rare earth metals and thorium (Th) in the phosphate form and widely distributed in many parts of the world. In general, the rare earth oxide (REO) ratio in monazite is composed of 20-30% Ce ₂ O ₃ , 10-40% La ₂ O ₃ , ~ 5% Y ₂ O ₃ , 4-12% Th and the like. Because monazite is chemically stable, decomposition techniques must be preceded for rare earth recovery, but existing monazite decomposition techniques have had little new approach besides acid / alkali decomposition.

Korean Patent Publication No. 10-2013-0076261 discloses a method for efficiently separating and extracting a desired rare earth element from monazite by alkali decomposition or acid decomposition of monazite concentrate to prepare a rare earth element solution ; Extracting a rare earth element to be extracted in the rare earth element solution with an acid solvent; Separating the organic phase containing the rare earth element and the water phase by extraction with an acid solvent; Removing an acid in the ion exchange resin to which the rare earth element is adsorbed by using an anion exchange resin adsorbing an acid and a rare earth element to be extracted by using an anion exchange resin adsorbing an acid in the organic phase and a rare earth element to be extracted; And recovering the rare earth element to be extracted in the anion exchange resin from which the acid has been removed by using a rare earth recovery solvent, in which the rare earth element is extracted from the monazite.

Also, Korean Patent No. 10-1058567 discloses a method of mixing a mixture of monazite and sodium hydroxide containing phosphoric acid and a rare earth element into a mill containing a plurality of balls, A step of pulverizing and transforming the mixture into a rare earth hydroxide and sodium phosphate through a mechano-chemical effect which occurs in a repetitive collision process, and a pulverization conversion step of pulverizing and transforming the rare earth element (Using known extraction techniques), which are well known to those skilled in the art.

However, the acid decomposition method using acid has a merit of using a low-cost acid, but it has a drawback in that corrosion of equipment is large and releases a large amount of corrosive gas to cause environmental pollution. In addition, the alkali decomposition method has advantages in terms of economical efficiency and decomposition rate because it has low decomposition temperature and low energy consumption. However, it has a disadvantage of causing environmental pollution (Gupta and Krishnamurthy, 2005).

In addition, since rare earths are usually present as ionic compounds, they need to be subjected to a separate purification process. Therefore, it is necessary to use a large amount of strong chemicals for the disadvantages and drawbacks, Toxic wastewater is generated, and since it has the characteristic of being poured together with the radioactive element, a large amount of radioactive contamination also occurs. In other words, serious environmental pollution occurs in the extraction and extraction process, and the reprocessing and purification process is costly. Therefore, there is a need for a new rare earth metal refining technology capable of securing rare earth metals and reducing environmental pollution.

Recently, biotechnology has attracted attention because it can recover metal with low cost and relatively simple technology and has the advantage of not polluting the environment. One example of biotechnology is the use of microorganisms in the production of metals from ore, using microbes, bacteria, yeast, and food waste from algae. Biosorption, bioleaching, and biomineralization have been studied by technology using microorganisms. Up to now, bioabsorption has been mainly studied for the recovery of rare earth metals (Japanese Patent Laid-Open No. 2013-1964 However, bio-adsorption technology is a method of recovering dissolved metals from leached leachate using existing chemical and physical methods. On the other hand, the technology of directly leaching rare-earth metals from the target ore using microorganisms has been studied I can say no.

The present invention relates to rare earth leaching technology using phosphate solubilizing bacteria (PSB) that convert immobilized phosphorus to water-soluble phosphorus, which is important in terms of securing an environmentally friendly and economical fusion-based technology.

An object of the present invention is to provide a biological leaching method using a phosphate-dissolving microorganism in recovering rare earth metals from monazite.

(B) adding monazite to the culture medium; (c) feeding microorganisms into the medium of step (b); and (d) ) Culturing the microorganism in step (c), and (e) leaching the rare earth metal from the monazite using the cultured microorganism in step (d), extracting the rare earth metal using the microorganism in the monazite . ≪ / RTI >

According to the present invention, rare earth metals can be economically recovered, and the process is simplified compared with the existing acid / alkali decomposition method, but the advantage of not causing environmental pollution is provided.

1 is a schematic diagram of a rare earth extraction method in a monazite according to the present invention.
FIG. 2 is a graph showing the degree of formation of zona pellucida according to a carbon source in a Reyes minimal medium to which bromocresol green is added.
FIG. 3 is a graph showing the phosphate solubility and total phosphorus and total calcium solubility of each microorganism in a Reyes minimal medium supplemented with calcium phosphate (Ca ₃ (PO ₄ ) ₂ ).
FIG. 4 is a graph showing the phosphate solubility and total phosphorus and total aluminum solubility of each microorganism in a Reyes minimal medium containing aluminum phosphate (AlPO ₄ ). FIG.
FIG. 5 is a graph showing the phosphate solubility and total phosphorus and total iron solubility of each microorganism in a minimum medium of Reyes minimal medium containing iron phosphate (FePO ₄ ). FIG.
6 is a graph showing the degree of rare earth dissolution in monazite by the phosphate-dissolving microorganism.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

The present invention relates to a rare earth leaching technique using phosphate solubilizing bacteria (PSB) that converts immobilized phosphorus to water-soluble phosphorus. The object of the present invention is to provide a biological leaching method using a phosphate-dissolving microorganism from monazite will be.

In order to achieve the above object, the present invention provides a method for producing a culture medium, comprising the steps of: (a) preparing a medium; (b) introducing monazite into the medium; and (c) (D) introducing the microorganism in step (c), and (e) leaching the rare earth metal from the monazite using the cultured microorganism in step (d). A method for extracting rare earth metals using microorganisms in monazite is provided.

In the present invention, the rare earth metal generally refers to scandium, yttrium, and 17 elements of lanthanum series having atomic numbers of 57 to 71. The monazite ore includes cerium (Ce), lanthanum (La), neodymium (Nd), praseodymium (Pr), yttrium (Y), gadolinium (Gd), samarium (Sm) and the like.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings.

1 is a schematic diagram of a rare earth extraction method in a monazite according to the present invention.

The present invention relates to a method for producing microorganisms which comprises the steps of (a) preparing a medium, (b) introducing monazite into the medium, (c) introducing microorganisms into the medium of step (b), and (d) Culturing the microorganism; and (e) leaching the rare earth metal from the monazite using the cultured microorganism of the step (d).

In the present invention, a medium suitable for culturing phosphate solubilizing bacteria (PSB) may be used as the medium of step (a). As a specific example, a Reyes minimal medium may be used, and the composition contained in 1 L of the Reyes minimal medium is 0.4 g of NH ₄ Cl; 0.78 g of KNO ₃ ; 0.1 g of NaCl; MgSO ₄ .7H ₂ O 0.5 g; 0.1 g CaCl ₂ .2H ₂ O; FeSO ₄ .7H ₂ O 0.5 mg; MnSO ₄ .H ₂ O 1.56 mg; ZnSO ₄ .7H ₂ O, 1.40 mg, but is not limited thereto.

In the present invention, the medium of step (a) is characterized by being a Reyes minimal medium having a carbon source content of 25 g / L to 35 g / L.

In the present invention, sucrose or glucose may be used as a carbon source, and glucose is preferably used, but not limited thereto.

In the present invention, in the step (b) The metal containing material containing the rare earth element in the present invention may be an ore (monazite, bastesite, genome time, etc.) or a product containing a rare earth element (hydrogen absorbing alloy, secondary battery raw material, optical glass, strong rare earth magnet, , An abrasive, an optical disk, a magneto-optical disk, a petroleum refining catalyst, an exhaust purification catalyst for an automobile, etc.), a waste containing a rare earth element, and the like. The metal-containing material including the rare-earth element may contain a component other than the metal (for example, an inorganic or organic substance other than the metal). The metal-containing material containing the rare earth element may contain one or more rare earth elements.

Among the metal inclusions containing the rare earth element, monazite can be preferably used.

In the present invention, the metal-containing material containing a rare earth element can be pulverized. The pulverization method is not particularly limited and may be pulverized using a known method. As a specific example, a roller mill, a vibration mill, a ball mill, a pot mill, or the like can be used, but the present invention can be applied without any separate grinding.

In the present invention, the microorganism in step (b) is a phosphate-decomposing microorganism.

Phosphorus solubilizing bacteria (PSB) have been reported to solubilize insoluble inorganic phosphate compounds such as tricalcium phosphate, dicalcium phosphate, hydroxyapatite, rock phosphate, iron and aluminum phosphates as microorganisms that convert immobilized phosphorus to water soluble phosphorus (Chen et al., 2006; Jeong et al., 2012; Rodriguez and Fraga, 1999). The main mechanism by which phosphorus is solubilized is by organic acids produced by PSBs (Goldstein et al., 1993; Reyes et al., 2002). Such organic acids include glutamic, 2-ketogluconic, lactic, isovaleric, isobutyric, acetic, glycolic, oxalic, malonic and succinic acids. The pH of the soil is changed by the organic acid, and the heavy metals forming the phosphorus and chelate compounds are dissolved, resulting in the solubilization of the immobilized phosphorus. In particular, Pseudomonas , Bacillus, Rhizobium PSBs belonging to the genus are known to be highly soluble in phosphoric acid (Rodriguez and Fraga, 1999).

Therefore, the phosphate was dissolved in the microorganism of the present invention (phosphate solubilizing bacteria; PSB) include Pseudomonas, Bacillus, Rhizobium, Paenibacillus, Ensifer, Azospirillum, Mesorhizobium, Acetobacter Bacteria belonging to the genus Pseudomonas can be used, more particularly, rhizosphaerae DSM 16299, Pseudomonas putida DSM 291, Pseudomonas fluorescens DSM 50090, Bacillus megaterium DSM 32, Paenibacillus polymyxa DSM 36, Ensifer meliloti DSM 30135, Azospirillum brasilense DSM 1690, Azospirillum lipoferum DSM 1842, Mesorhizobium cicero , Acetobacter aceti DSM 2002, and the like may be used, but the present invention is not limited thereto. Preferably Acetobacter Bacteria, most preferably Acetobacter < RTI ID = 0.0 > aceti DSM 2002 can be used.

In the present invention, the bacteria of step (c) are pre-grown bacteria.

In the present invention, the step (d) is characterized by culturing for 8 to 10 days after the inoculation with the phosphate-dissolving microorganism. Preferably, the phosphate-dissolving microorganism is inoculated and then cultured in an incubator at a rate of 30 rpm and 180 rpm for 9 days.

(e) leaching the rare earth metal from the monazite using the cultured microorganism in step (d) comprises converting phosphorus immobilized with phosphate solubilizing bacteria (PSB) into water soluble phosphorus to form tricalcium phosphate, dicalcium It is made possible by solubilizing insoluble inorganic phosphate compounds such as phosphate, hydroxyapatite, rock phosphate, iron and aluminum phosphates. At this time, it is the organic acid produced by PSB that can be solubilized, such as glutamic, 2-ketogluconic, lactic, isovaleric, isobutyric, acetic, glycolic, oxalic, malonic and succinic acids. The pH is changed by the organic acid, and the heavy metal forming the phosphorus and chelate compound is dissolved, thereby solubilising the immobilized phosphorus.

Hereinafter, the present invention will be described in more detail by way of examples.

[Experimental Example 1]

Phosphate dissolution microorganism application and screening experiment for rare earth degradation

Clear zone assay was performed by adding bromo cresol green (BCG) to Reyes minimal medium. The microorganism usedPseudomonas rhizosphaerae DSM 16299,Pseudomonas putida DSM 291,Pseudomonas fluorescens DSM 50090,Bacillus megaterium DSM 32,Paenibacillus polymyxa DSM 36,Ensifer meliloti DSM 30135,Azospirillum brasilense DSM 1690,Azospirillum lipoferum DSM 1842,Mesorhizobium ciceri , Acetobacter aceti DSM 2002 totaled ten. The composition contained in 1 L of Reyes minimal medium is NH₄Cl 0.4 g; KNO₃ 0.78 g; 0.1 g of NaCl; MgSO4₄.7H₂0.5 g; CaCl₂.2H₂0.1 g; FeSO₄.7H₂O 0.5 mg; MnSO₄.H₂O 1.56 mg; ZnSO₄.7H₂O 1.40 mg. When the zona pellucida is formed, insoluble phosphate (PO₄) Is decomposed to form soluble phosphate (PO₄). In addition, bromo cresol green (BCG) is a pH indicator, which changes from blue to green and yellow when microorganisms form an organic acid. FIG. 2 is a graph showing the degree of formation of zona pellucida according to a carbon source in a Reyes minimal medium to which bromocresol green is added. As shown in Fig. 2, among the total 10 microorganismsP. fluorescens, P. putida , P. rhizospaera , M ciceri , B. megaterium , A. acetiWere found to form zona pellucida. EspeciallyA. acetiOf the zeolite was most clearly formed. In other wordsA. aceti(Phosphate solubilizing ability) is the highest.

[Experimental Example 2]

Microbial phosphate ( PO ₄ ^{2 -} Solubility analysis

The dissolution degree of phosphoric acid (PO ₄ ^{2 -} ) was analyzed using Reyes minimal medium to which calcium phosphate (CaPO ₄ ), aluminum phosphate (AlPO ₄ ) and iron phosphate (FePO ₄ ) were added. Experimental conditions were as follows: 30 g of glucose (30 g; Ca ₃ (PO ₄ ) ₂ (5.39 g / L); AlPO ₄ (4.24g / L); or FePO ₄ (5.24 g / L) in a 50 mL conical tube and incubated at 30 ° C in a shaking incubator at 180 rpm. Total phosphorus (P) and calcium (Ca), aluminum (Al), iron (Fe) concentrations (PO ₄ ^{2 -),} the phosphate was analyzed using (Inductively coupled plasma) ICP equipment concentration IC (Ion Chromatography) Equipment.

FIG. 3 is a graph showing the phosphate solubility and total phosphorus and total calcium solubility of each microorganism in a Reyes minimal medium supplemented with calcium phosphate (Ca ₃ (PO ₄ ) ₂ ) FIG. 5 is a graph showing the phosphate solubility and total phosphorus solubility of each microorganism in the Reyes minimal medium with aluminum phosphate (AlPO ₄ ) added thereto. FIG. 5 is a graph showing the total solubility and total solubility of aluminum in the iron phosphate (FePO ₄ ) FIG. 3 is a graph showing the phosphate solubility and total phosphorus and total iron solubility of the microorganisms in the Reyes minimal medium. FIG.

As a result, as shown in FIGS. 3 to 5, the phosphate leaching efficiency showed a maximum within 2-3 days of culturing, and thereafter decreased.

It can be seen that about 6% of calcium is dissolved by the action of the phosphate-dissolving microorganism and by A. lipoferum , P. rhizospaera , and B. megaterium in case of calcium (Fig. 3).

While aluminum was only dissolved in about 3% by A. aceti (Figure 4).

The degree of iron dissolution is very low, with almost no iron leaching (Fig. 5), compared to a phosphate dissolution of 2 4%, which is believed to have appeared as if the leached iron was utilized by microorganisms and not leached.

Total phosphate, calcium, aluminum, iron solubility results of microorganisms after 3 days of culture in the minimum medium of calcium phosphate, aluminum phosphate and iron phosphate addition No Microorganism name Solubility (%) a1 a2 b1 b2 c1 c2 One Pseudomonas rhizosphaerae DSM 16299 6.8 6.9 1.5 0.03 2.7 0.02 2 Pseudomonas putida DSM 291 6.3 3.6 0.2 0.3 3.2 0.02 3 Pseudomonas fluorescens DSM 50090 4.3 4.5 1.3 0.13 2.8 0.06 4 Bacillus megaterium DSM 32 5.7 7.5 0.7 0.07 3.5 0.01 5 Paenibacillus polymyxa DSM 36, 3.0 4.1 0.4 0.4 2.6 0.01 6 Ensifer meliloti DSM 30135 0.7 2.3 1.5 0.02 4.0 0.01 7 Azospirillum brasilense DSM 1690 0.4 1.9 1.2 0.01 2.4 0.03 8 Azospirillum lipoferum DSM 1842 3.7 6.4 0.8 0.03 3.9 0.03 9 Mesorhizobium ciceri 3.0 3.9 1.3 0.05 3.0 0.03 10 Acetobacter aceti DSM 2002 12.5 32.5 2.6 1.0 4.7 0.40

a1: Total phosphate (PO ₄ ^{2 -} ) solubility in Reyes minimal medium with addition of calcium phosphate (Ca ₃ (PO ₄ ) ₂ )

a2: Total calcium dissolution ability in Reyes minimal medium containing calcium phosphate (Ca ₃ (PO ₄ ) ₂ )

b1 Solubility of total phosphate (PO ₄ ^{2 -} ) in Reyes minimal medium with aluminum phosphate (AlPO ₄ ) addition

b2: Aluminum phosphate (AlPO ₄ ) addition In the Reyes minimal medium, the total aluminum solubility

c1: Solubility of total phosphate (PO ₄ ^2- ) in Reyes minimal medium containing iron phosphate (FePO ₄ )

c2: Total iron solubility in Reyes minimal medium with iron phosphate (FePO ₄ )

Recovery of rare earth metals from monazite

Based on the above results, we tried to recover rare earth metals by applying phosphate photolytic microorganisms to monazite, a rare earth containing mineral. The metal content of the monazite used in this study is shown in Table 2. In a conical tube of 50 mL, 30 mL of Reyes minimal medium having a concentration of glucose of 30 g / L was added, 5 g of monazite was added, 3 mL of pregrown bacteria was inoculated 30, and 180 rpm shaking incubator for 9 days, and the concentrations of cerium and lanthanum, rare earth metals, in the leaching solution were measured independently. Concentrations of cerium and lanthanum were measured by ICP. 6 is a graph showing the degree of rare earth dissolution in monazite by the phosphate-dissolving microorganism. It was confirmed by A. aceti that about 6 mg / L of cerium and 3 mg / L of lanthanum leached out from the monazite ore (Fig. 6 and Table 3). Approximately 0.5 1 mg / L of cerium and lanthanum were leached from monazite by A. brasilense , A. lipoferum , P. rhizospaera and M. ciceri .

Metal content of monazite Element Content (wt.%) One CeO ₂ 3.41 2 La ₂ O ₃ 2.06 3 Nd ₂ O ₃ 0.78 4 Pr ₆ O ₁₁ 0.27 5 SiO ₂ 13.26 6 Al ₂ O ₃ 0.99 7 Fe ₂ O ₃ 36.66 8 CaO 9.92 9 MgO 7.5 10 K ₂ O 0.11 11 SrO 2.37 12 TiO ₂ 0.09 13 MnO 2.6 14 P ₂ O ₅ 6.36

Leaching of rare earth elements (cerium, lanthanum) according to microorganism after 4 days of culture in the minimal medium of rayees supplemented with monazite No Microorganism name Rare Earth Solubility (mg / L) Ce (cerium) La (lanthanum) One Pseudomonas rhizosphaerae DSM 16299 0.32 0.18 2 Bacillus megaterium DSM 32 0.23 0.17 3 Mesorhizobium ciceri 0.12 0.17 4 Acetobacter aceti DSM 2002 5.74 2.83

Having described specific portions of the present invention in detail, those skilled in the art will appreciate that these specific descriptions are only for the preferred embodiments and do not limit the scope of the present invention. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (5)

(a) preparing a medium;
(b) adding monazite to said medium;
(c) introducing at least one phosphate-soluble microorganism selected from the group consisting of Azospirillum brasilense , Azospirillum lipoferum , and Acetobacter aceti into the medium of step (b);
(d) culturing the phosphate-dissolving microorganism of step (c); And
(e) leaching the rare earth metal from the monazite using the cultured phosphate-dissolving microorganism in step (d), wherein the rare earth metal is extracted from the monazite using the phosphate-dissolving microorganism.
The method according to claim 1, wherein the culture medium of step (a) has a carbon source content of 25 g / L to 35 g / L.
delete The method according to claim 1, wherein the microorganism in step (c) is Acetobacteraceti DSM2002.
The method for extracting rare earth metals according to claim 1, wherein the step (d) comprises culturing for 8 to 10 days using a phosphate-soluble microorganism in monazite.

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