報告書番号

U95036

タイトル（和文）

石炭の生物加工－１０－－微生物浮遊選炭法の選鉱への応用－

タイトル（英文）

BIOPROCESSING OF COAL -10- -APPLICATION OF MICROBIAL FLOTATION TO MINERAL PROCESSING-

概要 （図表や脚注は「報告書全文」に掲載しております）

微生物浮遊選炭法を選鉱の分野へ応用することを目的に，異なった金属元素を含む硫化鉱物（黄鉄鉱，輝水鉛鉱，輝銅鉱，針ニッケル鉱および方鉛鉱）に対する鉄酸化細菌の吸着性について検討した。また，硫化鉱物の混合試料を用いて微生物浮遊選鉱を行った。鉄酸化細菌は５種類の各硫化鉱物のうち，特に黄鉄鉱へ良好な吸着性を示し，５種類の硫化鉱物が共存する場合にも黄鉄鉱に選択的に吸着することが明らかとなった。また，各硫化鉱物の浮遊性について検討した結果，鉄酸化細菌の添加により５種類の硫化鉱物のうち，特に黄鉄鉱の浮遊性を抑制できることが示された。黄鉄鉱とそれ以外の硫化鉱物それぞれを等量混合した試料を用いて，微生物浮遊選鉱を行った結果，黄鉱鉄を８４％～９５％の範囲で除去することができ，黄鉄鉱以外の硫化鉱物を７３％～１００％の範囲で回収できた。また５種類の硫化鉱物全てを混合した試料についても黄鉄鉱のみを除去することができた。以上のことから，微生物を利用した新しい選鉱法を提案することができたと考える。

概要 （英文）

WE ARE DEVELOPING MICROBIAL FLOTATION FOR COAL DESULFURIZATION AS A NEW COAL UTILIZATION TECHNOLOGY. PYRITE IN COALIS REMOVED BY CHANGING THE SURFACE PROPERTIES OF PYRITE BY BACTERIAL ADHESION. IT IS EXPECTED TO APPLY MICROBIAL FLOTATION NOT ONLY TO COAL DESULFURIZATION BUT ALSO TO MINERAL PROCESSING AS A CONVENIENT PYRITE-REMOVAL METHOD. WE INVESTIGATED THE BACTERIAL ADHESION OF THIOBACILLUS FEROOXIDANS TO SULFIDE MINERALS (PYRITE,GALENA,MOLYBADENITE,CHALOCTITE AND MILLERITE),AND PYRITE REMOVAL FROM MIXTURES OF THESE SULFIDE MINERALSBY MICROBIAL FLOTATION. TO COMPARE THE ADHESION OF T.FEROOXIDANS TO PYRITE WITH THE OTHER FOUR MINERALS,THE SURFACE AREA OF THE MINERALS WHERE BACTERIA COULD ADHERE,WAS MEASURED. UNDERAN SEM,THE ROUGHNESS OF THE MINERAL SURFACES WAS MUCH SMALLER THAN THE SIZE OF THE BACTERIAL CELLS SUGGESTING THAT ROUGHNESS DOES NOT AFFECT BACTERIAL ADHESION TO MINERALSURFACES. THE MICROSCOPIC METHOD IS MORE APPROPRIATE THAN THE BET METHOD AND THE SIZE-DISTRIBUTION METHOD FOR DETERMINING THE ADHERANCE SURFACE AREA OF MINERALS. THE BACTERIAL ADHESION TO PYRITE WAS COMPARED WITHTHAT OF THE OTHER MINERALS. THE AMOUNT OF ADHERED BACTERIA WAS ESTIMATED ON THE BASIS OF THE MEASURED SURFACE AREA THE AMOUNT OF CELLS ADHERED TO PYRITE WAS 421.6 10**8/SQUARE CM. ON THE OTHER HAND,THE AMOUNT OF CELLS ADHERED TO THE MINERALS EXCEPT PYRITE WAS IN THE RANGE OF 77.1 TO160.8 10**8 CELLS/SQUARE CM. THE BACTERIA ADHERE MORE TO PYRITE THAN THE OTHER MINERALS,AND ONLY ADHERE TO THE PYRITE EVEN IF IT IS MIXED WITH OTHER MINERALS. HENCE,T.FERROOXIDANS SELECTIVALY ADHERES TO PYRITE. PYRITE REMOVAL FROM MINERAL MIXTURES (PYRITE AND OTHER MINERAL) WAS INVESTIGATED USING MICROBIAL FLOTATION. REGARDLESS OF THE KIND OF MINERAL MIXED WITH PYRITE,PYRITE REMOVAL WAS IN THE RANGE OF 83.7% TO 95.1% AND MINERAL RECOVERY WAS 72.9% TO 100%. IN THESE CONDITIONS,THE GRADE OF RECOVERED MINERALS WAS IN THE RANGE OF 79.2% TO 86.0%. THE GRADE OF REJECTED PYRITE WAS IN THE RANGE OF 78.7% TO

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