| Project/Area Number |
10650918
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
KONISHI Yasuhiro Osaka Prefecture University, College of Engineering, Associate Professor, 工学部, 助教授 (90167403)
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| Co-Investigator(Kenkyū-buntansha) |
ASAI Satoru Osaka Prefecture University, College of Engineering, Professor, 工学部, 教授 (90081348)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Sulfur cycle / Bioleaching / desulfurization / Thermophile / Sulfur bacteria / Sulfate-reducing bacteria / Sulfide / Phototroph / 硫化水素 / 光合成硫黄細菌 / 低品位紘 |
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| Research Abstract |
In this report we describes a biohydrometallurgical treatment of sulfide minerals (sphalerite and chalcopyrite), in which the sulfur cycle (metal sulfide → sulfate → hydrogen sulfide → elemental sulfur) is artificially constructed using several bacteria associated with the sulfur cycle, and the microbial sulfur transformations are utilized for the leaching of valuable metals from sulfide minerals and for the post-treatments of the bioleaching residue. In the sulfide leaching with sulfur-oxidizing bacteria, the acidophilic thermophile Acidianus brierleyi was found to solubilize the sulfides much faster than the common leaching mesophile Thiobacillus ferrooxidans. In the biological downstream processing, sulfate ions accumulated in the leach solution were biologically reduced to hydrogen sulfide through the use of sulfate-reducing bacteria such as Desulfovibrio desulfuricans and Desulfovibrio vulgaris. After that, the biogenic hydrogen sulfide was oxidized to elemental sulfur using photo
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trophic bacterium Prosthecochloris aestuarii, and the formed elemental sulfur was recovered as a precipitate. In the metal recovery operation, gel beads of alginic acid could be used as a biopolymer sorbent for collecting dissolved metals in the pregnant solution. Because the sorption of heavy metal ions by the alginic acid gels was strongly dependent on the solution pH, all of the heavy metals collected in the gel phase was completely released into the liquid phase when the solution pH was decreased to pH 1.0.
Batch tests were conducted to obtain rate data and optimize various process parameters for the individual bioprocesses such as the bioleaching of sulfide mineral, the bioconversion of sulfate to elemental sulfur via hydrogen sulfide, and the recovery of heavy metals by the biopolymer beads. The rate data indicated that the bioleaching process was the rate-determining step (the slowest step) in the proposed biotreatment process. Under the conditions determined as optimum for the bioleaching with A.brierlery, it took a week to achieve high extractions (greater than 80% leaching) of valuable metals from sphalerite and chalcopyrite. Less
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