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In that study, a proposal for the rate at which A.ferrooxidans can oxidise pyrite is the ability to use ferrous iron to generate a ferric iron catalyst : Fe 2+ + 1 ⁄ 4 O 2 + H + → Fe 3+ + 1 ⁄ 2 H 2 O. Under the above acidic conditions, ferric iron (Fe 3+) is a more potent oxidant than oxygen, resulting in faster pyrite oxidation rates.
The chemistry of oxidation of pyrites, the production of ferrous ions and subsequently ferric ions, is very complex, and this complexity has considerably inhibited the design of effective treatment options. [6] Although a host of chemical processes contribute to acid mine drainage, pyrite oxidation is by far the greatest contributor.
Pyrite oxidation is sufficiently exothermic that underground coal mines in high-sulfur coal seams have occasionally had serious problems with spontaneous combustion. [47] The solution is the use of buffer blasting and the use of various sealing or cladding agents to hermetically seal the mined-out areas to exclude oxygen.
The possibility of using microorganisms in biomining applications was realized after the 1951 paper by Kenneth Temple and Arthur Colmer. [9] In the paper the authors presented evidence that the bacteria Acidithiobacillus ferrooxidans (basonym Thiobacillus ferrooxidans) is an iron oxidizer that thrive in iron, copper and magnesium-rich environments. [9]
The pyrite is stable until exposed to air, at which point the pyrite rapidly oxidises and produces sulfuric acid. The impacts of acid sulfate soil leachate may persist over a long time, and/or peak seasonally (after dry periods with the first rains).
When ferrous iron (Fe 2+) is oxidized to ferric iron (Fe 3+) at mine sites, Fe 3+ spontaneously reacts with water and iron-sulfur compounds like pyrite to produce sulfate and hydrogen ions. [8] During this reaction ferrous iron, which can be utilized by Ferroplasma, is also regenerated leading to a "propagation cycle" where pH is lowered. The ...
Sharon Stone characterized "uneducated" Americans as "ignorant" and arrogant" just weeks after the 2024 U.S. presidential election during a panel discussion in Italy.
Diagenesis (/ ˌ d aɪ. ə ˈ dʒ ɛ n ə s ɪ s /) is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust. [1]