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 II. Ore deposits

Collection:: Economics Books

CHAPTER XI ORES OF ALUMINIUM INCLUDING BAUXITE ALuMiNTUM—USES AND SEPARATION—Aluminium Al; at. wt, 27:1; sp. gr, 26; melting-point, 1210° F.; tensile strength about 17 tons per square inch; electrical conduc. tivity about 614 per cent. that of copper) is the commonest metal in the crust of the earth, and in the whole earth is less abundant only than iron. Its many useful properties will doubtless render it second only to iron in service to man. Owing to its strong affinity for oxygen it always occurs in nature as compounds, and its separation as a metal has been achieved with difficulty. It has a beautiful silvery white colour and does not tarnish. It is light and can be drawn out into thin sheets and wire. It resists corrosion by organic products, so that it can be safely used for the cooking and preservation of food. Its electric conductivity is so high in proportion to its weight that it may provide the cheapest electric cables. Its great affinity for oxygen renders it a powerful reducing agent, and owing to the high heat (5500° F.) generated by the oxidation of fine aluminium powder it is used for welding, as a violent explosive, and as an incendiary material. It unites with other metals in many alloys invaluable from their combined lightness and strength. Aluminium was isolated in small globules in 1845, and its production was begun in 1854 by St. Claire de Ville ; but it was first prepared on a commercial scale in 1885, and its production was increased by the electrolytic processes of Héroult (1886) and Hall (1892); it was obtained by the fusion of cryolite, the double fluoride of sodium and alumin- ium mined from a vein in gneiss in Greenland. The em- ployment of aluminium on a great scale only became possible after the Bayer process enabled it to be extracted electrically [Zn

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