The Elements of economic geology

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Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Document type:: Monograph

Structure type:: Chapter

Title:: Part V. Mineral fuels

Collection:: Economics Books

COAL AND ITS CLASSIFICATION 263 >d he a0 le y 1€ n aS d of e ” 1 a a Ke: e : “3 g ) 3 7) material recorded as brown coal; and the quantity in the State is estimated as 30,000,000,000 tons ; it is being worked there for use as briquettes, and the generation of electricity. Brown coals are generally of Kainozoic age. The best- known English deposit, at Bovey Tracey in Devonshire, is Oligocene. The vast deposits in Germany and Russia are Lower Kainozoic. The lignite of Alberta, which is estimated at over 100,000,000,000 tons associated with twice as much black coal, is Cretaceous. Some Paleozoic deposits have been preserved as brown coal, such as that of Malovka, and the Papier Kohle of Toula in Russia. Brack Coat (exclusive of Cannel Coal)—Black coal ranges from a variety of lignite to anthracite, and includes three chief varieties, sub-bituminous, bituminous, and anthracite. The chief member of the series is bituminous coal. That term is a misnomer, as it was based on the view that coal contains bitumen which had been injected into a bed of earth. The insolubility of coal shows that it contains no bitumen, which can be made from it by destructive distillation. Sub-bituminous coal or black lignite differs from brown coal by being black, harder, and having less moisture; it differs from bituminous coal by splitting into slabs instead of breaking into rectangular fragments. It contains up to about 40 per cent. of moisture. The ash is often low, but varies indefinitely; if it exceed 50 per cent. the material becomes valueless. The fuel varies in heat value from 6000 to 16,000 B.T.U. Its age is generally Lower Kainozoic or Upper Mesozoic. Bituminous coal or ordinary house coal is black, usually laminated, and breaks along vertical joints known as cleat into rectangular or columnar pieces. The lustre varies from dull to brilliant. The coal is friable so that it soils the hands. It ignites readily and burns with a bright yellow flame. Its average specific gravity is about 1-3. The moisture is from 2 to 10 per cent. The ash in the varieties used commercially ranges from about 5 to 12 per cent. though it rises to 50 per cent., and passes into coaly clay or sandstone. The percentage of fixed carbon varies from 40 to 80 per cent; the sulphur is usually, in the varieties worked, from % to 2 per cent.; some seams contain 10 per cent. or more. Its calorific value varies from 10,000 to 16,000 B.T.U.

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