Bacteria leaching

Also called microbial refining. A method of refining by using microorganisms to leach useful metals from minerals and ores. The microorganisms are the sulfur-oxidizing bacteria Thiobacillus and the iron-oxidizing bacteria Ferrobacillus . The carbon source required for growth is carbon dioxide from the air, and to assimilate it, they use the energy liberated by the oxidation of sulfur and sulfur compounds, or the oxidation of Fe ^II to Fe ^III . There are two theories about the leaching of metal ions from ores and minerals by microorganisms: one is that the metabolic products (sulfuric acid, ferric sulfate, etc.) produced by the action of microorganisms act indirectly, and the other is that the microorganisms directly act on the metals in the ore and leach them. Useful metals are leached from low-grade ores (copper content around 0.5%), residual ores, ores that are difficult to dress and smelt, and concentrates using various leaching methods and the action of microorganisms. In the case of copper, the leachate is introduced into a copper collection tank containing iron scraps, and the iron is replaced with copper, resulting in the recovery of precipitated copper (70-90% metallic copper). Copper is actually being recovered from ore tailings in a mine in Utah, USA. There is also potential for the recovery of other metals, such as uranium, manganese, molybdenum, zinc, and nickel. [See other terms] Sulfur bacteria, iron bacteria

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

微生物精錬ともいう．微生物を利用して，鉱物，鉱石中の有用金属を溶出して精錬する方法．微生物は硫黄酸化細菌Thiobacillus，鉄酸化細菌Ferrobacillusである．生育に必要な炭素源は空気中の二酸化炭素で，これを同化するために硫黄および硫黄化合物の酸化，あるいは Fe^Ⅱの Fe^Ⅲへの酸化によって遊離したエネルギーを利用する．微生物による鉱石，鉱物からの金属イオンの浸出については，微生物の作用により生成した代謝産物(硫酸，硫酸第二鉄など)による間接的な作用説と，微生物が直接鉱石中の金属に作用して浸出する説とがある．低品位鉱(銅含有量0.5％ 前後)，残鉱石，選鉱，製錬の困難な鉱石，および精鉱から種々の浸出法と微生物の作用によって有用な金属を溶出する．銅の場合，浸出液を鉄くずの入った収銅槽に導き，鉄と銅を置換させて沈殿銅(金属銅として70～90％)を回収する．アメリカのユタ州内の鉱山で，選鉱廃さいから銅の回収が実際に行われている．銅以外にウラン，マンガン，モリブデン，亜鉛，ニッケルなどの金属の回収について可能性がある．[別用語参照]硫黄細菌，鉄細菌

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