ANTHRACITE A05

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

IDENTIFICATION

SYNONYM:

Hard coal, stone coal, smokeless fuel.

COMMODITIES (BYPRODUCTS):

Coal, carbon.

EXAMPLES

(British Columbia - International/Canada ): Klappan (104H020,021,022), Panorama South (104A082); Canmore (Alberta, Canada), Pennsylvania coalfields (USA).

GEOLOGICAL CHARACTERISTICS regrese arriba

CAPSULE DESCRIPTION:

Seams of black coal hosted by clastic sedimentary rocks. Coal is well cleated with bright and dull bands. Anthracite often exhibits a high lustre and is not dusty.

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 formed in fluvial/alluvial deltaic settings.

DEPOSIT FORM:

Anthracite seams generally conform with regional bedding. Seams are often thickened/deformed by faulting, folding, shearing and thrusting. Seams may pinch-out or split on a local or regional scale.

TEXTURE/STRUCTURE:

Anthracite is usually composed mostly of the lithotypes clarain and vitrain.

COAL SEAMS / ASSOCIATED MINERAL MATTER:

Anthracite has Rmax values over 2.0 %. In outcrop anthracite can contain up to 5 % moisture. It usually contains a high percentage of the maceral vitrinite but because of the high rank the rheological and chemical differences between vitrinite and the inert macerals are small. Liptinite is difficult to identify at the anthracite rank. 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 anthracite reduces the calorific value by oxidizing the carbon-hydrogen complexes. Minerals in the mineral matter will also oxidize. Pyrite oxidizes to sulphates. Secondary carbonates are formed.

ORE CONTROLS:

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

ASSOCIATED DEPOSIT TYPES:

Bituminous coal ( A04 ), shale-hosted Ni-Zn-Mo-PGE ( E16 ), phosphate - upwelling type (F07).

COMMENTS:

Anthracite is the highest rank coal. At this rank agglomerating properties have been destroyed and heating value decreased somewhat from the maximum obtained by low-volatile bituminous coal. Anthracite releases little smoke when burnt.

EXPLORATION GUIDES regrese arriba

GEOCHEMICAL SIGNATURE:

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

GEOPHYSICAL SIGNATURE:

Anthracite 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 adsorption logs, gamma-gamma density logs, sonic logs, resistivity logs and caliper logs.

OTHER EXPLORATION GUIDES:

Presence of down-slope coal bloom; fresh water depositional structures; coal spar. Presence of anthracite seams can also be detected by escaping methane.

ECONOMIC FACTORS regrese arriba

TYPICAL GRADE AND TONNAGE:

The heat value of anthracite is good and similar to that of medium-volatile bituminous coal. Gross heating values are 30 to 33 Mj/Kg on an ash-free moist basis. Net useable heat will be lower because of the presence of ash. The mine reserves of anthracite generally range from 10 to 100 million tonnes. They are generally smaller than the strip or open pit thermal or metallurgical coal mines.

ECONOMIC LIMITATIONS:

Anthracite is a bulk commodity which is expensive to transport. Anthracite as low-ash lumps can be more than twice as valuable as bituminous coal, in which case it is shipped widely. Sold as fine anthracite briquettes with a moderate ash content, it has about the same dollar value as bituminous thermal coal.

END USES:

Source for carbon. Specialized smelting applications, smokeless fuel for heating.

IMPORTANCE:

As low-ash large lumps it is an important source of carbon in the chemical 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
51 1 2638212 (spanish please) 1—602-499 2708 (USA)
jperazzo@miningperu.com
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