JP2016054736A - Metal extraction method using acidophilic thiobacillus ferrooxidans - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient metal extraction method using organisms from a used electronic equipment part, such as a wasted electronic substrate.SOLUTION: An acidophilic thiobacillus ferrooxidans, Sulfobacillus thermosulfidooxidans NE106G strain, or a microbial mixture containing it is cultured with a dilute sulfuric acid culture medium, in which low concentration ferrous ion is added, and subsequently is brought into contact with a metal-containing electronic part, such as a wasted electronic substrate to extract and recover a valuable metal.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for leaching a useful metal from a metal-containing waste such as a waste electronic substrate using an acidophilic iron-oxidizing bacterium which is a novel microorganism or a mixed culture of acidophilic bacteria.

  Used electronic device parts such as waste electronic boards contain a wide variety of valuable metals such as various rare metals in addition to base metals such as gold, silver, copper, and zinc. At present, metals are recovered and recycled using existing smelting technology, but due to the wide variety of ore types and the low content of each metal, a variety of ore types are recovered and recycled. There are many technical and economic challenges to do.

  Many methods for recovering metals from used electronic equipment parts such as waste electronic substrates by bioleaching using microorganisms have been proposed. For example, Acidithiobacillus ferrooxidans (Non-patent Documents 1 and 2), which are acidic iron-oxidizing bacteria, or mixed cultures of Acidthiothiobacillus ferrooxidans and other bacteria (Non-patent Documents 3 and 4), copper and zinc from waste electronic substrates, Bioleaching of nickel and aluminum has been proposed. In addition, metal leaching from a waste electronic substrate using a moderately high temperature iron-oxidizing bacterium Sulfobacillus thermosulfidooxidans and heterotrophic bacteria has also been proposed (Non-Patent Document 5). In addition to waste electronic substrates, for example, zinc and manganese bioleaching from zinc-manganese secondary batteries using a mixed culture of Sulfobacillus sp. And other bacteria has been proposed (Non-Patent Documents 6 and 7). ). Other than acidophilic iron-oxidizing bacteria, for example, metal leaching using fungi is disclosed (Non-patent Document 8).

Yang, T., Xu, Z., Wen, J., Yang, L. 2009. Factors influencing bioleaching copper from waste printed circuit boards by Acidithiobacillus ferrooxidans. Hydrometallurgy, 97, 29-32. Yang, Y., Chen, S., Li, S., Chen, M., Chen, H., Liu, B. 2014. Bioleaching waste printed circuit boards by Acidithiobacillus ferrooxidans and its kinetics aspect.Journal of Biotechnology, 173, 24-30. Wang, J., Bai, J., Xu, J., Liang, B. 2009. Bioleaching of metals from printed wire boards by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans and their mixture.Journal of Hazardous Materials, 172, 1100-1105. Liang, G., Mo, Y., Zhou, Q. 2010. Novel strategies of bioleaching metals from printed circuit boards (PCBs) in mixed cultivation of two acidophiles.Enzyme and Microbial Technology, 47, 322-326. Ilyas, S., Anwar, M.A., Niazi, S.B., Ghauri, M.A. 2007. Bioleaching of metals from electronic scrap by moderately thermophilic acidophilic bacteria. Hydrometallurgy, 88, 180-188. Xin, B., Chen, B., Duan, N., Zhou, C. 2011. Extraction of manganese from electrolytic manganese residue by bioleaching. Bioresource Technology, 102, 1683-1687. Xin, B., Jiang, W., Aslam, H., Zhang, K., Liu, C., Wang, R., Wang, Y. 2012. Bioleaching of zinc and manganese from spent Zn-Mn batteries and mechanism exploration Bioresource Technology, 106, 147-153. Brandl, H., Bosshard, R., Wegmann, M. 2001.Computer-munching microbes: metal leaching from electro scrap by bacteria and fungi.Hydrometallurgy, 59, 319-326. Johnson, D.B., Macvicar, J.H.M., Rolfe, S. 1987. A new medium for the isolation and enumeration of Thiobacillus ferrooxidans and acidophilic heterotrophic bacteria. Journal of Microbiological Methods, 7, 9-18. Miyata, N., Tani, Y., Iwahori, K., Soma, M. 2004. Enzymatic formation of manganese oxides by an Acremonium-like hyphomycete fungus, strain KR21-2. FEMS Microbiology Ecology, 47, 101-109. Ghauri, MA, Khalid, AM, Grant, S., Heaphy, S., Grant WD 2003. Phylogenetic analysis of different isolates of Sulfobacillus spp.recovered from uranium rich environments and recovery of genes using integron specific primers.Extremophiles, 7, 341 -345. Ilyas, S., Ruan, C., Bhatti, H.N., Ghauri, M.A., Anwar, M.A. 2010. Column bioleaching of metals from electronic scrap.Hydrometallurgy, 101, 135-140. Simkins, S., Alexander, M. 1984. Models for mineralization kinetics with the variables of substrate concentration and population density.Applied and Environmental Microbiology, 47, 1299-1306.

  By using acidophilic iron-oxidizing bacteria belonging to the above taxonomic group, ferrous ions are oxidized in dilute sulfuric acid solution to produce ferric ions. There have been reports of leaching valuable metals from used electronic equipment parts. However, in the conventional report, in order to leach metal efficiently, several to several tens of grams / L of ferrous ions are added, and during the leaching reaction, ferric ions are deposited as iron oxide and deposited. It has been reported often. For this reason, there is room for studying whether bioleaching of waste electronic substrates using acidophilic iron-oxidizing bacteria can be efficiently leached with a lower concentration of iron ions.

  Accordingly, the present invention provides a novel microorganism capable of biologically leaching valuable metals from used electronic equipment parts such as waste electronic substrates by adding a low concentration of ferrous ions, and a biological leaching method using the same. For the purpose.

  In order to achieve the above object, the present inventors show the fastest growth rate in a medium containing ferrous ions of 1 g / L or less from an environmental sample collected in an acidic river basin in Akita Prefecture, and sulfuric acid. An acidophilic iron-oxidizing bacterium having high heavy metal resistance capable of growing in a medium containing 0.1 M each of zinc, copper sulfate, nickel sulfate and manganese sulfate was obtained. Using this mixed culture of acidophilic iron-oxidizing bacteria and pure culture, copper, zinc, cobalt, manganese, and nickel were successfully leached from pulverized waste electronic substrates derived from personal computers. .

  Isolates of acidophilic iron-oxidizing bacteria do not match any of the strains described in the above literature due to their bacteriological properties, and are novel microorganisms applied to bioleaching for metal-containing wastes It was confirmed. Bioleaching of waste electronic substrates was carried out using the mixed culture and pure culture of this strain, and it was confirmed that valuable metals can be efficiently leached even with a conventional iron ion concentration of 1/10 or less. It came.

The present invention provides the following.
[1] Eosinophilic acid belonging to Sulfobacillus thermosulfidooxidans capable of growing at a specific growth rate of 0.15 / hour or more in a medium containing ferrous ions of 1.0 g / L or less Iron oxidizing bacteria.
[2] A base sequence of Nos. 38 to 788 of SEQ ID No. 1 in the sequence listing, or a base sequence having 90.5% or more sequence identity with it;
The base sequence of No. 1 to 873 of SEQ ID NO: 1 in the sequence listing, or the base sequence having 88.7% or more sequence identity with it;
1-878 base sequence of SEQ ID NO: 1 in the sequence listing, or a base sequence having 91.2% or more sequence identity thereto; or 1-888 base sequence of SEQ ID NO: 1 in the sequence listing, or 92 An acidophilic iron-oxidizing bacterium belonging to Sulfobacillus thermosulfidooxidans having a part of a 16S rRNA gene consisting of a base sequence having a sequence identity of 8% or more.
[3] The acidophilic iron-oxidizing bacterium according to 2, capable of growing at a specific growth rate of 0.15 / hour or more in a medium containing ferrous ions of 1.0 g / L or less.
[4] It belongs to Sulfobacillus thermosulfidooxidans having a 16S rRNA gene consisting of the base sequence of SEQ ID NO: 1 in the sequence listing or a base sequence having a sequence identity of 99.9% or more. Acidophilic iron-oxidizing bacteria.
[5] The acidophilic iron-oxidizing bacterium according to any one of 1 to 4, which is Sulfobacillus thermosulfidooxidans NITE P-01909.
[6] An acidophilic iron-oxidizing bacterium having a maximum specific growth rate in a medium containing ferrous ions of 1.0 g / L or less or ferrous ions of 1.0 g / L or less to a metal-containing solid. By allowing acidophilic iron-oxidizing bacteria belonging to Sulfobacillus thermosulfidooxidans, which can grow at a specific growth rate of 0.15 / hour or more in the medium, to act, the metal is leached into the liquid The manufacturing method of a metal solution including the process of obtaining a solution.
[7] A step of growing an acidophilic iron-oxidizing bacterium belonging to Sulfobacillus thermosulfidooxidans in a medium containing ferrous ions of 1.0 g / L or less to obtain a culture; and culturing A method for producing a metal solution, comprising: adding a metal-containing solid to a product, causing the metal-containing solid to act on acidophilic iron-oxidizing bacteria, and leaching the metal into a liquid to obtain a metal solution.
[8] The manufacturing method according to any one of 5 to 7, wherein the metal is any one selected from the group consisting of copper, zinc, cobalt, nickel, manganese, cadmium and tungsten.
[9] The production method according to any one of 5 to 8, wherein the acidophilic iron-oxidizing bacterium is in an isolated form or a mixed culture form.
[10] The production method according to any one of 5 to 9, which is carried out in an open system and / or a non-sterile environment.
[11] The production method according to any one of 5 to 10, wherein the metal-containing solid is a waste electronic substrate or a used electronic device part.
[12] Manufacture of a metal-use product including a step for manufacturing a metal solution defined in any one of 5 to 11, a step of recovering a metal from the metal solution, and a step of using the recovered metal Method.

  According to the present invention, metals such as copper, zinc, cobalt, manganese, and nickel can be efficiently bioleached from used electronic device parts such as a waste electronic substrate in the presence of a low concentration of ferrous ions. . In the method of the present invention, since an acidophilic iron-oxidizing bacterium is cultured in advance and the ferrous ion is sufficiently oxidized, the waste electronic substrate sample is added, so that the contact time of the sample can be shortened, and more precise pH control is performed. Since precipitation of ferric ions can be suppressed, an efficient and economical process can be constructed.

It is a Gram-stained image of the acidophilic iron-oxidizing bacterium NE106G strain ( Sulfobacillus thermosulfidooxidans NITE P-01909). It is a molecular phylogenetic tree showing the phylogenetic classification of the acidophilic iron-oxidizing bacterium NE106G strain based on the 16s rRNA gene sequence. It is a molecular phylogenetic tree showing the bacterial community structure of a mixed culture of acidophilic iron-oxidizing bacteria, which was the source of separation of the acidophilic iron-oxidizing bacteria NE106G. It is the result analyzed by the clone library method of 16s rRNA gene sequence. It is a graph which shows the influence of the ferrous ion density | concentration which gives to the maximum specific growth rate of the mixed culture body containing the acidophilic iron oxidation bacterium NE106G strain. It is the result of the bioleaching using the mixed culture body containing the acidophilic iron-oxidizing bacterium NE106G strain. Waste electronic board samples were pulverized to a particle size of 0.25 mm or less. It is a result which shows the influence of the ferrous ion density | concentration on bioleaching using the mixed culture body containing the acidophilic iron-oxidizing bacterium NE106G strain. Waste electronic board samples were pulverized to a particle size of 0.25 mm or less. It is the result of the bioleaching using the pure culture body of the acidophilic iron-oxidizing bacterium NE106G strain. Waste electronic board samples were pulverized to a particle size of 0.25 mm or less. The base sequence of the 16s rRNA gene of the acidophilic iron-oxidizing bacterium NE106G strain. The shaded range is the location corresponding to the partial sequence of S. thermosulfidooxidans clone MT-13 (873 base length). NE106G and clone MT-13 have different bases at the places marked with asterisks (99 places). The base sequence of the 16s rRNA gene of the acidophilic iron-oxidizing bacterium NE106G strain. The shaded area corresponds to the partial sequence of S. thermosulfidooxidans clone MT-16 (878 base length). NE106G and clone MT-16 have different bases at the locations marked with an asterisk (77 locations). The base sequence of the 16s rRNA gene of the acidophilic iron-oxidizing bacterium NE106G strain. The shaded area corresponds to the partial sequence of S. thermosulfidooxidans clone MT-17 (888 base length). NE106G and clone MT-17 have different bases at the locations marked with an asterisk (64 locations). The base sequence of the 16s rRNA gene of the acidophilic iron-oxidizing bacterium NE106G strain. The shaded range corresponds to the partial sequence of S. thermosulfidooxidans RDB strain (751 base length). The bases of NE106G and RDB strains are different from each other at the places marked with an asterisk (73 places). It is the result of repeated batch culture of bioleaching using a mixed culture containing the acidophilic iron-oxidizing bacterium NE106G. Waste electronic board samples were pulverized to a particle size of 0.25 mm or less.

  The method of the present invention is a dilute sulfuric acid medium containing ferrous ions of 1 g / L or less, and while maintaining the culture temperature at 28 ° C. or higher and 55 ° C. and the pH at 1.8-2.0, the isolate Or after growing the mixed culture body containing an isolate, a waste electronic board | substrate sample is made to contact a culture solution and copper, zinc, cobalt, manganese, nickel, etc. are leached.

  The present invention provides an efficient leaching / recovering method for useful metals from wastes using acidophilic iron-oxidizing bacteria.

[Eosinophilic iron-oxidizing bacteria]
An acidophilic iron-oxidizing bacterium refers to an acidophilic chemically synthesized autotrophic bacterium that assimilate carbon dioxide and oxidize divalent iron or a reduced inorganic sulfur compound to acquire energy unless otherwise specified. The acidophilic iron-oxidizing bacterium that can be used in the present invention is not particularly limited as long as it is resistant to metals such as copper and zinc to be leached and has the ability to oxidize iron. Examples include bacteria belonging to the genus Acidithiobacillus or bacteria belonging to the genus Sulfobacillus. Examples of bacteria belonging to the genus Acidithiobacillus (Acidithiobacillus) are bacteria belonging to Acidithiobacillus ferrooxidans, and examples of bacteria belonging to the genus Sulfobacillus are -The bacteria which belong to thermosulfide oxydans (Sulfobacillus thermosulfidooxidans) or Sulfobacillus thermosulfidooxidans (Sulfobacillus thermosulfidooxidans) are mentioned.

Acidophilic iron-oxidizing bacteria suitable for use in the present invention can be obtained by screening from a sample obtained from a natural source as follows:
Samples containing candidate bacteria obtained from the environment were prepared using Fe-TSB medium supplemented with ferrous ions (pH 2.0), and if necessary, zinc sulfate, copper sulfate, nickel sulfate, manganese sulfate and aluminum chloride Etc. are added and cultured with shaking at 45 ° C. and 100 rpm. The obtained mixed culture of bacteria is appropriately diluted and then seeded on a plate medium having the same composition to which 0.3% gellan gum is added as a gelling agent and cultured at 45 ° C. for 2 weeks. Thereafter, iron oxide is deposited to isolate a colony of iron-oxidizing bacteria having a reddish brown color.

One particularly preferred example of an acidophilic iron-oxidizing bacterium that can be used in the present invention is a bacterium belonging to Sulfobacillus thermosulfidooxidans . In particular, Sulfobacillus thermosulfidooxidans NITE P-01909 can be preferably used in the present invention. This strain was isolated from the acid river basin of Akita Prefecture, Japan by the present inventors, and is incorporated by the National Institute of Technology and Evaluation (NITE) Patent Microorganism Depositary Center (NPMD) (Kazusa Kisarazu, Chiba Prefecture) It has been deposited with the accession number NITE P-01909 on August 1, 2014 in Room 2-5-8, Kamaashi, Room 122, TEL: 0438-20-5580, FAX: 0438-20-5581). In this specification, this strain may be referred to as NE106G strain. The base sequence of 16S rRNA gene possessed by this strain is shown in SEQ ID NO: 1 in the sequence listing.

[Scientific properties]
Sulfobacillus thermosulfidooxidans NITE P-01909 (NE106G strain) has the following scientific properties (sometimes referred to as mycological properties).
Cell morphology: Neisseria gonorrhoeae, 0.8-0.9 × 1.5-2.0 μm
Gram staining: + (undefined)
Culture conditions that allow growth, pH 1.8-2.5
・ 32-55 ℃
・ Can grow on a medium containing 100 mM CuSO ₄ , MnSO ₄ , NiSO ₄ , ZnSO ₄ each. ・ Requires about 250 mg / L of organic substances such as tryptic soy medium and peptone.

[Culture conditions]
Medium: A sulfuric acid-containing TSB medium can be used.
Medium composition: sulfuric acid-containing TBS medium (pH 2)
Solution I
Ammonium sulfate 1250mg
Magnesium sulfate heptahydrate 500mg
Tryptic Soy Medium (TSB, Difco) 250mg
Trace metal salt solution 2mL
1L of distilled water
Solution II
Ferrous sulfate heptahydrate 1940mg
250 mM sulfuric acid 20 mL
Solution III
Dipotassium hydrogen phosphate 5mg
1mL distilled water
After the solution I is sterilized by autoclave, 20 mL of the solution II sterilized by filtration through a filter and 1 mL of the solution III are added. The pH of the medium is appropriately adjusted by changing the sulfuric acid concentration of the solution II.

Trace metal salt solution Calcium chloride dihydrate 3.7g
Boric acid 2.5g
Manganese chloride tetrahydrate 0.87g
Iron chloride hexahydrate 1.0g
Zinc sulfate heptahydrate 0.44g
Sodium molybdate dihydrate 0.29g
Copper sulfate pentahydrate 5.0mg
1L of distilled water

[Proliferation characteristics]
The NE106G strain has at least one of the following properties regarding growth:
(1) In a medium containing ferrous ions of 1.0 g / L or less, preferably 0.1 to 0.8 g / L, a specific growth rate of 0.15 / hour or more, preferably 0.17 / Can proliferate over time.
(2) The largest specific growth rate is highest when the ferrous ion concentration is in the range of 0.1 to 0.8 g / L, more specifically when the ferrous ion concentration is around 0.4 g / L. Become.
At the ferrous ion concentration (several to several tens of g / L) conventionally used in bioleaching for metal-containing waste such as waste electronic substrates, the specific growth rate of NE106G strain Is known to decline.

Therefore, the present invention can be implemented as the following production method:
An acidophilic iron-oxidizing bacterium having a maximum specific growth rate in a medium containing 1.0 g / L or less (for example, 0.1 to 0.8 g / L) of ferrous ions in a metal-containing solid; A sulfone capable of growing at a specific growth rate of 0.15 / hour, preferably 0.17 / hour in a medium containing ferrous ions of 0 g / L or less (for example, 0.2 to 0.8 g / L). A method for producing a metal solution, comprising a step of allowing an acidophilic iron-oxidizing bacterium belonging to Bacillus thermosulfidooxidans to act and leaching the metal into a liquid to obtain a metal solution.

Alternatively, it can be carried out as the following production method:
Propagating acidophilic iron-oxidizing bacteria belonging to Sulfobacillus thermosulfidooxidans in a medium containing ferrous ions of 1.0 g / L or less (for example, 0.1 to 0.8 g / L) A metal solution comprising: adding a metal-containing solid to the culture, allowing the metal-containing solid to act on acidophilic iron-oxidizing bacteria, and leaching the metal into a liquid to obtain a metal solution. Manufacturing method.

  Note that “proliferative” at a specific growth rate means that a condition item (for example, ferrous ion concentration) specified to be a specific condition, unless otherwise specified, under that condition, Condition items that are not specified (for example, temperature, pH, stirring speed, presence / absence / aeration of aeration) indicate that growth can be performed at a specific growth rate when the conditions are suitable for growth. Specific growth rate is defined as the increase in cell mass per unit time.

[Equivalent microorganisms, mixed cultures]
In the present application, not only the NE106G strain, but also microorganisms equivalent thereto, specifically, strains having the same scientific properties as the NE106G strain, or strains having the same growth characteristics, and the following strains can be preferably used.
(1) Eosinophilic acid belonging to Sulfobacillus thermosulfidooxidans that can grow at a specific growth rate of 0.15 / hour or more in a medium containing ferrous ions of 1.0 g / L or less. Iron oxidizing bacteria.
(2) Sulfobacillus thermosulfide having a part of the 16S rRNA gene consisting of the base sequence of No. 38 to 788 of SEQ ID No. 1 in the sequence listing, or the base sequence having 90.5% sequence identity with it Acidophilic iron-oxidizing bacteria belonging to oxydans (Sulfobacillus thermosulfidooxidans), preferably acidophilic, capable of growing at a specific growth rate of 0.15 / hour or more in a medium containing ferrous ions of 1.0 g / L or less Iron oxidizing bacteria.
(3) It belongs to Sulfobacillus thermosulfidooxidans having a 16S rRNA gene consisting of the base sequence of SEQ ID NO: 1 in the sequence listing or a base sequence having a sequence identity of 99.9% or more. Acidophilic iron-oxidizing bacteria.

  In addition, the NE106G strain and microorganisms equivalent thereto can also be suitably used as a mixed culture containing the strain. In the present specification, the present invention may be described using the NE106G strain as an example. However, unless otherwise specified, the description is not limited to other suitable microorganisms including the NE106G strain. This is also true when acidophilic iron-oxidizing bacteria are used, and when any such microorganism is used as a mixed culture. The mixed culture contains the intended microorganism and other microorganisms. Other microorganisms can be microorganisms belonging to different strains, different species, or different genera than the intended microorganism.

[Influence of temperature]
The NE106G strain can maintain good biological activity over a wide temperature range of 30 to 47 ° C. in bioleaching. In particular, a preferable effect can be exhibited at 32 to 45 ° C.

  Therefore, from the viewpoint of efficiently performing bioleaching, in the present invention, the temperature is preferably 32 ° C. or higher, more preferably 35 ° C. or higher, and further preferably 40 ° C. or higher. In any case, it will be preferred that the upper temperature limit be less than 47 ° C. An example of the optimum temperature is 45 ° C.

  In addition, in this invention, when showing a value about the density | concentration or ratio of components, such as a culture medium, the value is a value based on a weight except the case where it describes. Moreover, the value shown about the density | concentration or ratio in an environment is a value of the first time (at the time of a proliferation start) or through a proliferation period except the case where it describes especially.

[Others]
The production according to the invention can be carried out as an open system or under non-sterile conditions. "Open system" or "non-sterile" means that the medium used for production is not sterilized, and when performing batch-type, the transfer from one batch culture to the next is not required under aseptic conditions. Including that. The bioleaching according to the present invention can be carried out batchwise or repeated batchwise.

[Metal-containing solid (waste) raw material]
The waste electronic substrate which is the subject of the method of the present invention is not particularly limited in its origin, and examples include those recovered from waste products such as personal computers, televisions, washing machines, microwave ovens, refrigerators, and industrial equipment. In the present invention, waste electronic substrates are targeted, but metal products and electronic device parts containing copper, zinc, nickel, manganese, chromium, aluminum, and the like can also be used.

[Usage]
The metal can be recovered from the metal solution produced using the present invention. The product to which the present invention can be applied is not particularly limited, and the present invention is useful for producing various products.

[Acquisition of mixed culture, isolation of strain]
Using environmental samples in acid river basins in Akita Prefecture as a seeding source, 2g / L ferrous sulfate heptahydrate (0.4g / L ferrous ion) and 0.01M zinc sulfate, copper sulfate, Eosinophilic iron-oxidizing bacteria were accumulated and cultured using Fe-TSB medium (pH 2) (Non-patent Document 9) supplemented with nickel sulfate, manganese sulfate, and aluminum chloride. The culture temperature was 45 ° C., and the culture was shaken at 100 rpm. The composition per liter of the Fe-TSB medium (pH 2) is 1250 mg of ammonium sulfate, 0.5 g of magnesium sulfate heptahydrate, 2 mL of trace metal salt solution (Non-patent Document 10), 0.25 g of tryptic soy medium (manufactured by Difco). , 0.005 mol of sulfuric acid. The enrichment culture obtained by this culturing operation was used as a mixed culture of acidophilic iron-oxidizing bacteria in subsequent experiments.

  A mixed culture of acidophilic iron-oxidizing bacteria was appropriately diluted and then seeded on a plate medium having the same composition to which 0.3% gellan gum (Wako Pure Chemical Industries) was added as a gelling agent and cultured at 45 ° C. for 2 weeks. Thereafter, four iron-oxidizing colonies of iron-oxidizing bacteria that were deposited with iron oxide and had a reddish brown color were isolated. The obtained isolates were subjected to PCR amplification and base sequence determination of 16S rRNA gene using the oligonucleotide primers shown in Table 1, and as a result of molecular identification analysis, 4 strains had the same base sequence. It was. For this reason, one of them was used as a NE106G strain in subsequent tests. Moreover, it was in agreement with the known strain of Sulfobacillus thermosulfidooxidans in about 99% or more of the base sequence, and it was speculated that the NE106G strain belongs to this species (FIG. 1). However, the nucleotide sequence does not completely match that of the known strain, and is a new strain (see the table below).

  The mixed culture of sulfobacillus thermosulfide oxydans (clone MT-13, MT-16 and MT-17, Non-Patent Documents 5 and 11) used for bioleaching of waste electronic substrates is a figure. As shown in 8 to 10, in the partial sequence of 16S rRNA, MT-13 is 99 sites at 873 bp (11.3%), MT-16 is 878 bp at 77 sites (8.8%), MT-17. Is 888 bp and 64 places (7.2%) are different. In addition, as shown in FIG. 11, the Sulfobacillus thermosulfide oxydans (RDB strain, Non-Patent Document 12) that has been used for bioleaching of metal-containing wastes is 73 locations (9 .7%) different. Furthermore, another Sulfobacillus sp. That has been used in bioleaching of metal-containing wastes is most closely related to Sulfobacillus acidophilus (Non-Patent Document 6, 7) It is a different species from the NE106G strain. The NE106G strain was Gram positive and formed spores (FIG. 2). From these results, this strain was named Sulfobacillus thermosulfidoxidans NE106G strain, and was incorporated by the National Institute of Technology and Evaluation (NITE) Patent Microorganism Depositary Center (NPMD) (Kazusa Kamashizu, Kisarazu City, Chiba Prefecture Room 2-5-8 122, TEL: 0438-20-5580, FAX: 0438-20-5581), deposited on August 1, 2014 with accession number NITE P-01909.

  In the present invention, it was shown that the mixed culture used as the separation source of the NE106G strain has a bioleaching effect. DNA was extracted from this mixed culture, 16S rRNA gene region was amplified using oligonucleotide primers 27f and 1492r (Table 2), and the bacterial community structure was analyzed by the clone library method.

  As a result, it was shown that this mixed culture contains Sulfobacillus thermosulfidooxidans NE106G strain, and in addition, it is composed of bacterial species closely related to Acidicdus genus which is at least an acidophilic heterotrophic bacterium. (FIG. 3).

[Useful metal leaching with mixed cultures]
In order to examine the effect of ferrous ion concentration on the growth of the mixed culture containing the acidophilic iron-oxidizing bacterium NE106G, Fe-TSB medium (pH 1) supplemented with 0.06 to 2.8 g / L of ferrous ions was used. 9), and the decrease in ferrous ion in the medium was measured over time by a colorimetric method using O-phenanthroline. The time course of ferrous ion concentration in the medium was analyzed using the following formula (Non-Patent Document 13), and the maximum specific growth rate was calculated and compared.

However, S: Substrate concentration (mM), S ₀ : Initial substrate concentration (mM), X ₀ : Substrate concentration (mM) necessary to maintain the initial cell density, μ _max : Maximum specific growth rate (h ^{− 1} ), t: time (h).

  The maximum specific growth rate of this mixed culture was shown to be greatest when the ferrous ion concentration was around 0.4 g / L (FIG. 4). It is shown that the specific growth rate decreases at the ferrous ion concentration (several to several tens of g / L) that has been used in bioleaching for metal-containing wastes such as waste electronic substrates. (FIG. 4).

  The waste electronic substrate recovered from the waste personal computer and cut to about 20 mm is further pulverized by a cutting mill (SM200, Retsch) and an ultracentrifugal pulverizer (ZM200, Retsch), and the particle size is 0.50 mm or less, or What was sieved to 0.25 mm or less was used for the test as a test sample. These ground samples were sterilized by dry heat at 105 ° C. for 1 hour before bioleaching.

The bioleaching test was conducted using a 2 L jar fermenter apparatus capable of controlling pH and temperature. While inoculating an acidophilic iron-oxidizing bacterium NE106G strain or a mixed culture containing the NE106G strain in a sterile Fe-TSB medium supplemented with 0.4 g / L of ferrous ions, while maintaining the pH at 1.9, 45 ° C The culture was aerated and stirred for 3 days until the growth reached a stationary phase. Thereafter, a ground sample of the waste electronic substrate was added so as to be 10 g / L, and bioleaching was started under the same culture conditions. The metal ion concentration in the leachate was appropriately diluted with 0.1% nitric acid and then quantified by ICP emission spectrometry. The metal concentration in the waste electronic substrate was sequentially extracted with 10% nitric acid and aqua regia and then quantified by ICP emission spectrometry.
As a result of bioleaching in a mixed culture containing NE106G strain, 48% copper, 68% zinc, 82% cobalt, and manganese in a 24-hour contact time in a system with a substrate grinding sample size <0.25 mm A leaching rate of 70%, 55% with nickel, and a leaching rate of 88% with copper, 81% with zinc, 82% with cobalt, 73% with manganese, and 69% with nickel at a contact time of 72 hours. (Figure 5). In addition, the density | concentration of each metal contained in the waste substrate grinding | pulverization sample 10g / L was 100%. The concentration of each metal was sequentially extracted with 10% nitric acid and aqua regia and then quantified by ICP emission spectrometry. In the case of uninoculated bacteria, the leach rate was 8% copper, 41% zinc, 69% cobalt, 82% manganese, 82% manganese, 44% nickel for 24 hours, 19% copper for 72 hours, 80% zinc. %, Cobalt 91%, manganese 89% and nickel 65%.

  In previous studies (Non-Patent Documents 1 to 6), in order to obtain a comparable metal leaching rate in the same bioleaching test, 3 g / L or more of ferrous ions was added, and almost 1 Since a period of more than a week is required, it was shown that various metals can be leached more efficiently than the prior art by performing bioleaching using a mixed culture containing NE106G strain. .

  In bioleaching using a mixed culture containing the NE106G strain, the concentration of ferrous ion added was changed to 0.2-2 g / L and tested under the same culture conditions as described above. The concentration was shown to be sufficiently effective (FIG. 6).

  Comparing the metal content in the waste substrate before and after bioleaching, the residue after leaching showed a significant decrease in the above copper, zinc, cobalt, manganese and nickel, and a significant decrease in cadmium and tungsten. It has been shown. This result shows that these metals were leached by bioleaching (Table 3).

[Useful metal leaching by isolates]
Stable Fe-TSB medium supplemented with 0.4 g / L ferrous ion is inoculated with the acidophilic iron-oxidizing bacterium NE106G strain (isolated strain), and the growth is steady at 45 ° C. while maintaining at pH 1.9. The culture was aerated and stirred for 3 days until reaching the stage. Thereafter, a ground sample of the waste electronic substrate was added so as to be 10 g / L, and bioleaching was started under the same culture conditions. As a result, in the system with the substrate pulverized sample size <0.25 mm, the leaching rate was 28% for copper, 63% for zinc, 95% for cobalt, 90% for manganese, and 53% for nickel at a contact time of 24 hours. With a contact time of 72 hours, leaching rates of 81% for copper, 93% for zinc, 98% for cobalt, 97% for manganese, and 73% for nickel were obtained (Fig. 7), the same as the mixed culture of NE106G strain. A degree of leaching could be obtained. Therefore, it can be said that the same effect is obtained even when the NE106G strain is used alone.

  In the case of mixed cultures, for pulverized substrate size <0.25 mm, leaching 48% copper, 68% zinc, 82% cobalt, 70% manganese, 55% nickel and 24 hours contact time The rate of contact for 72 hours was 88% copper, 81% zinc, 82% cobalt, 73% manganese, and 69% nickel. Therefore, the use of the isolated strain alone could perform useful metal leaching with high efficiency.

  On the other hand, mixed cultures have concerns that nutrient competition with coexisting heterotrophic bacteria and changes in dominant species may occur, but there is an advantage that the influence of contamination and the like is kept low and handling is easy. In bioleaching (45 ° C., pH 1.9, ferrous ion concentration 0.4 g / L) with a mixed culture containing the NE106G strain, a fifth of the culture solution is drawn every 5-8 days and fresh. Fe-TSB medium and 10 g / L waste electronic substrate (pulverized to <0.25 mm) were added and batch culture was repeated. As a result, the leaching amounts of copper, zinc and nickel did not decrease (FIG. 12). From this, it was shown that this culture body can be used repeatedly.

  The present invention makes it possible to recover various mineral species economically and efficiently from used electronic equipment parts such as waste electronic substrates. In addition, since harmful metals can be removed from used electronic device parts such as waste electronic substrates, the application of the present invention enables appropriate and safe disposal and management of used products.

NITE P-01909

Claims (12)

  Acidophilic iron-oxidizing bacteria belonging to Sulfobacillus thermosulfidooxidans that can grow at a specific growth rate of 0.15 / hour or more in a medium containing ferrous ions of 1.0 g / L or less . 38-788th nucleotide sequence of SEQ ID NO: 1 in the sequence listing, or a nucleotide sequence having 90.5% or more sequence identity with it;
The base sequence of No. 1 to 873 of SEQ ID NO: 1 in the sequence listing, or the base sequence having 88.7% or more sequence identity with it;
1-878 base sequence of SEQ ID NO: 1 in the sequence listing, or a base sequence having 91.2% or more sequence identity thereto; or 1-888 base sequence of SEQ ID NO: 1 in the sequence listing, or 92 An acidophilic iron-oxidizing bacterium belonging to Sulfobacillus thermosulfidooxidans having a part of a 16S rRNA gene consisting of a base sequence having a sequence identity of 8% or more.   The acidophilic iron-oxidizing bacterium according to claim 2, which can grow at a specific growth rate of 0.15 / hour or more in a medium containing ferrous ions of 1.0 g / L or less.   Eosinophilic iron belonging to Sulfobacillus thermosulfidooxidans having a 16S rRNA gene consisting of the base sequence of SEQ ID NO: 1 in the sequence listing or a base sequence having a sequence identity of 99.9% or more. Oxidizing bacteria. The acidophilic iron-oxidizing bacterium according to any one of claims 1 to 4, which is Sulfobacillus thermosulfidooxidans NITE P-01909.   In an acidophilic iron-oxidizing bacterium having a maximum specific growth rate in a medium containing ferrous ions of 1.0 g / L or less on a metal-containing solid, or in a medium containing ferrous ions of 1.0 g / L or less In this way, an acidophilic iron-oxidizing bacterium belonging to Sulfobacillus thermosulfidooxidans that can grow at a specific growth rate of 0.15 / hour or more is allowed to act, and the metal is leached into the liquid to obtain a metal solution. The manufacturing method of a metal solution including a process. Proliferating acidophilic iron-oxidizing bacteria belonging to Sulfobacillus thermosulfidooxidans in a medium containing ferrous ions of 1.0 g / L or less to obtain a culture; and metal in the culture A method for producing a metal solution, comprising a step of adding a contained solid, allowing the metal-containing solid to act on acidophilic iron-oxidizing bacteria, and leaching the metal into the liquid to obtain a metal solution.   The manufacturing method according to any one of claims 5 to 7, wherein the metal is any one selected from the group consisting of copper, zinc, cobalt, nickel, manganese, cadmium and tungsten.   The production method according to any one of claims 5 to 8, wherein the acidophilic iron-oxidizing bacterium is in an isolated form or a mixed culture form. The production method according to any one of claims 5 to 9, which is carried out in an open system and / or a non-sterile environment.   The production method according to any one of claims 5 to 10, wherein the metal-containing solid is a waste electronic substrate or a used electronic device part.   A method for producing a metal-use product, comprising a step for producing a metal solution as defined in any one of claims 5 to 11, a step of recovering a metal from the metal solution, and a step of using the recovered metal. .