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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.
This disintegration of marcasite in mineral collections is known as "pyrite decay". When a specimen goes through pyrite decay, the marcasite reacts with moisture and oxygen in the air, the sulfur oxidizing and combining with water to produce sulfuric acid that attacks other sulfide minerals and mineral labels.
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.
Pressure oxidation is a process for extracting gold from refractory ore. The most common refractory ores are pyrite and arsenopyrite , which are sulfide ores that trap the gold within them. Refractory ores require pre-treatment before the gold can be adequately extracted. [ 1 ]
Above the water table the environment is oxidizing, and below it is reducing. [7] Solutions traveling downward from the leached zone react with other primary minerals in the oxidised zone to form secondary minerals [ 5 ] such as sulfates and carbonates , and limonite , which is a characteristic product in all oxidised zones.
This Fe-dominant analogue of boussingaultite is sometimes reported from burning coal dumps where it is a product of pyrite oxidation. [ 2 ] [ 3 ] [ 4 ] The mineral crystallizes in the monoclinic crystal system with space group P2 1 /a .
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.
Tree remains that have undergone petrifaction, as seen in Petrified Forest National Park. In geology, petrifaction or petrification (from Ancient Greek πέτρα (pétra) 'rock, stone') is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals.