Seams mineral occurrences

Basinal Brines as a Source of Sulfur in High-Sulfur Coals. Sulfide minerals, such as pyrite and sphalerite, in coal seams may be deposited from basinal hydrothermal fluids. The occurrence of epigenetic sphalerite in Illinois Basin coals has been described by Hatch et al. (119) and Cobb (120). Whelan et al. (121) studied the isotopic composition of pyrite and sphalerite in coal beds from the Illinois Basin and the Forest City Basin, and suggested that some of the coals were affected by Mississippi Valley-type hydrothermal solutions. 

Mineral Composition Common minor and trace element associations Frequency of occurrence in coal seams Concentration in min. matter Chief occurrences TS... 

The distributions of minerals within the Lower Kittanning seam can be related to depositional environment. Pyrite content is highest in areas which may have experienced brackish conditions. This distribution reflects the availability of iron and sulfur, and pH conditions within the swamp. Whereas much of the pyrite formed syngenetically, observations of sulfide modes of occurrence suggest that marcasite formed epigenetically. 

In the U.S., active coalbed methane extraction has been carried out since the 1950s, and its annual output currently stands at 55 billion m, accounting for about 8% of the total natural gas production. The production of coalbed methane is also underway in Canada, Australia, China, India, and other countries. Most of the coalfields in Russia (Kuznetsk, Pechora, Donetsk, Taimyr, Tunguska, etc.) contain gas. The methane content in such highly metamorphosed coal seams increases with the depth of their occurrence, reaching 40—50 rv /ton. The preliminary degassing of coal seams is a necessary condition for safe operation of the miners and an additional source of methane. The use of coalbed-methane wells is complicated by a low flow rate and its large spread, which can vary from 2 to more than 200 thousand m /day, with t5 ical values of 5—15 thousand m /day [304]. 

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