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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 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.
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.
These soils contain iron sulfide minerals (predominantly as the mineral pyrite) and/or their oxidation products. In an undisturbed state below the water table, acid sulfate soils are benign. However, if the soils are drained, excavated or otherwise exposed to air, the sulfides react with oxygen to form sulfuric acid. [1]
The Great Oxidation Event (GOE) or Great Oxygenation Event, also called the Oxygen Catastrophe, Oxygen Revolution, Oxygen Crisis or Oxygen Holocaust, [2] was a time interval during the Earth's Paleoproterozoic era when the Earth's atmosphere and shallow seas first experienced a rise in the concentration of free oxygen. [3]
Pyrite oxidation. Far less common are degradation and pop-outs caused by the presence of pyrite (FeS 2), a Fe 2+ disulfide (– S-S –) very sensitive to oxidation by atmospheric oxygen, that generates expansion by forming less dense insoluble iron oxides (Fe 2 O 3), iron oxy-hydroxides (FeO(OH), or Fe 2 O 3 ·n H 2 O) and mildly soluble ...
F. acidophilum obtains energy by oxidation of the ferrous iron in pyrite using oxygen as a terminal electron acceptor. This process produces sulfuric acid as a by-product, leading to further acidification of its environment. Its type strain is YT.
A pyrite cube has dissolved away from host rock, leaving gold particles behind. Oxidized pyrite cubes. Within the weathering environment, chemical oxidation of a variety of metals occurs. The most commonly observed is the oxidation of Fe 2+ by oxygen and water to form Fe 3+ oxides and hydroxides such as goethite, limonite, and hematite. This ...