BITUMINOUS COAL/ A04

Cortesia del Gobierno de BRITISH COLUMBIA. Ministerio de Enegia y Minas

IDENTIFICATION

SYNONYM:

Metallurgical coal, coking coal, humic coal.

COMMODITIES (BYPRODUCTS):

Coal, coke, (coal liquids, tar, gas).

EXAMPLES:

Line Creek (082GNE020), Quintette (093I010, 011, 019, 020); Sydney coalfield (Nova Scotia, Canada), Sydney coalfield (Australia).

GEOLOGICAL CHARACTERISTICS regrese arriba

CAPSULE DESCRIPTION:

Seams of black coal hosted by clastic sedimentary rocks. Coal is banded bright and dull. Generally hard with well developed cleats.

TECTONIC SETTINGS:

Stable continental basins; shelves on the trailing edge of continents; foreland (molasse) basins; back-arc basins.

DEPOSITIONAL ENVIRONMENT / GEOLOGICAL SETTING:

An area of slow sedimentation in fresh water with few or no marine incursions. Can be produced by fault blocks associated with strike-slip movement to limit sediment influx. Delta; shoreline swamp; raised swamp; lake; floating vegetation mats.

AGE OF MINERALIZATION:

Generally older than Tertiary; major deposits are Cretaceous, Permian or Carboniferous in age.

ASSOCIATED ROCK TYPES:

Sedimentary rocks exhibiting evidence of non-marine deposition; carbonaceous mudstones; siltstones and sandstones often with cross- stratification and other sedimentary structures of fluvial/alluvial or deltaic origin.

DEPOSIT FORM:

Coal seams generally conform with regional bedding; sometimes seams are deposited in areas of local subsidence, such as fault-controlled blocks. Seams may be thickened/deformed by faulting, folding and shearing. Seams may pinch- out or split on a local or regional scale.

TEXTURE/STRUCTURE:

Bituminous coal is usually composed mostly of clarain and vitrain. Footwall sediments are often penetrated by roots or weathered to clay (seatearth).

COAL SEAMS / ASSOCIATED MINERAL MATTER:

Bituminous coal has Rmax values in the range of 0.5 to 2.0 %. In outcrop it can contain up to 15 % moisture. It usually contains a high percentage of the maceral vitrinite; at higher ranks liptinite is difficult to detect; the amount of fusinite is variable. Mineral matter is in the coal seams as rock bands, as finely intermixed material of authogenic or detrital origin (inherent mineral matter) and as secondary material deposited in fractures and open spaces. Inherent mineral matter includes pyrite, siderite and kaolinite. It may be dissimilar to that of the surrounding rocks.

WEATHERING:

Weathering of the bituminous coal reduces the calorific value by oxidizing the carbon-hydrogen complexes. It also destroys the agglomerating (coke making) properties. Minerals such as pyrite oxidize to sulphates. Secondary carbonates are formed. These transformations may further damage the coking properties.

ORE CONTROLS:

The geometry of the seam/seams is controlled by sedimentary features, such as extent of the delta, trend of the shoreline, and trend of sand-filled river channels. Deformation (faulting and folding) is also important.

ASSOCIATED DEPOSIT TYPES:

Sub-bituminous coal ( A03 ), anthracite ( A05 ), shale-hosted Ni-Zn-Mo-PGE ( E16 ), phosphate - upwelling type (F07).

COMMENTS:

Bituminous coal is widely used for coke making by the steel industry because of its agglomerating properties.

EXPLORATION GUIDES regrese arriba

GEOCHEMICAL SIGNATURE:

Geochemistry is generally not used as a prospecting tool for coal.

GEOPHYSICAL SIGNATURE:

Bituminous coal has a low density. Resistivity is variable to high. Surface techniques include direct-current profiling, refraction and reflection seismic, and gravity. Subsurface or bore-hole techniques include gamma logs, neutron logs, gamma-gamma density logs, sonic logs, resistivity logs and caliper logs.

OTHER EXPLORATION GUIDES:

Presence of: a down-slope coal bloom; nonmarine sediments; coal spar. Presence of methane escaping through the surrounding sediments.

ECONOMIC FACTORS regrese arriba

TYPICAL GRADE AND TONNAGE:

Numerous tests quantify the coking ability of bituminous coal, they measure rheology, melting and petrographic properties of the coal as well as the chemistry of the ash. The gross heating value of bituminous coal is 27 to 33 MJ/kg on an ash-free moist basis. Net useable heat will be lower because of the presence of ash. Mine tonnages generally range from 10 to 1000 Mt

ECONOMIC LIMITATIONS:

Coal is a bulk commodity which is expensive to transport. Bituminous coal has a high market value because of its coking properties and high heating value. The ratio of tonnage to useable heat is good so that there is a lower proportion of waste material (such as water, fly ash and slag) generated than for other ranks of coals.

END USES:

Coke; steam generation in turbines for electrical generation.

IMPORTANCE:

Generally bituminous coal is used for coke making, weathered and non- agglomerating bituminous coal is utilized for power generation. Only source for coke used in the steel industry.

REFERENCES regrese arriba

  • Armstrong, W.M., Fyles, J.T., Guelke, C.B., Macgregor, E.R., Peel, A.L., Tompson, A.R. and Warren, I.H. (1976) : Coal in British Columbia, A Technical Appraisal; B.C. Ministry of Energy, Mines and Petroleum Resources, Coal Task Force, 241 pages

  • Cope, J.H.R., Duckworth, N.A., Duncan, S.V., Holtom, J.E.B., Leask, A.L., McDonald, K.A. and Woodman, S.P. (1983) : Concise Guide to the World Coalfields; compiled by Data Bank Service, World Coal Resources and Reserves, IEA Coal Research.

  • Matheson, A. (1986) : Coal in British Columbia; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1986-3, 169 pages. .

  • Smith, G.G. (1989) : Coal Resources in Canada; Geological Survey of Canada, Paper 1989-4, 146 pages.


  • Cortesia del Gobierno de BRITISH COLUMBIA. Ministerio de Enegia y Minas
Business contact: Commentaries, proposals or details for negotiation: Mr. Jorge Perazzo
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