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Sulfuric material refers to soil material that has a pH of less than 4 owing to the oxidation of sulfidic material. [ 27 ] Sulfidic material refers to “soil materials containing detectable inorganic sulfides (≥0.01% sulfidic sulfur) that can exist as horizons or layers at least 30 mm thick or as surficial features”, [ 27 ] and is further ...
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 strong acidification of the medium caused by pyrite oxidation releases bicarbonate ions (HCO − 3) or carbon dioxide (CO 2) along with calcium (Ca 2+) and sulfate ions (SO 2− 4). Full pyrite oxidation can be schematized as: 2 FeS 2 + 7.5 O 2 + 4 H 2 O → Fe 2 O 3 + 4 H 2 SO 4. The sulfuric acid released by pyrite oxidation then reacts ...
Jarosite is a basic hydrous sulfate of potassium and ferric iron (Fe-III) with a chemical formula of KFe 3 (SO 4) 2 (OH) 6.This sulfate mineral is formed in ore deposits by the oxidation of iron sulfides.
Post-diagenetic alteration may take place through reactions such as pyrite oxidation: 3O 2 + 4FeS 2 → Fe 2 O 3 (hematite) + 8S E = −789 kJ/mol. and siderite oxidation: O 2 + 4FeCO 3 → 2Fe 2 O 3 (hematite) + 4CO 2 E = −346 kJ/mol. Secondary red beds formed in this way are an excellent example of telodiagenesis.
It is the mirror process of In Situ Chemical Oxidation (ISCO). ISCR is usually applied in the environment by injecting chemically reductive additives in liquid form into the contaminated area or placing a solid medium of chemical reductants in the path of a contaminant plume. [ 1 ]