Abstract: Silicon or silicon alloy exhibiting low surface oxidation as a result of a surface silica layer of less than 2 nm, and production processes by means of grinding under a minimally-reactive atmosphere in the presence of an oil or by atomization in a vacuum or in a minimally-reactive gas under reduced pressure.

Abstract: The invention relates to a process for the preparation of silicon carbide whiskers by the reaction, in a non-oxidizing atmosphere, at a temperature of at least 1300.degree. C., of a charge composed of a mixture of carbon black and a source of silicon oxide, in which process the carbon black has an oxidability rate (measured by heating in air for 30 minutes at 600.degree. C.) of at least 85%, the silicon oxide source has a grain size of less than 100 .mu.m and the rate of rise in temperature between 1300.degree. and 1600.degree. C. is less than 30.degree. C.min.sup.-1 per minute if a static atmosphere prevails and at most 25.degree. C.min.sup.-1 if gas percolated. A stage of from 5 min to 5 h at 1600.degree. C. is optionally carried out.The carbon is preferably introduced into the reaction mixture in an over-stoichiometric quantity relative to the silica.The excess carbon is removed at the end of the reaction by oxidation in air at about 600.degree. C.

Abstract: The invention concerns a process for the recovery of combustible gases in an electrometallurgy furnace comprising an external metal casing (1) and an internal refractory lining (2), in which at least one oxidized compound is reduced by means of carbon, the various components being introduced into the furnace in the form of a divided charge (6) (A) which moves progressively downwardly towards the reaction region (C), passing through a sintering region (B). The combustible gases produced in the reaction region are collected by suction, by means of a plurality of apertures (8) provided in the external metal casing (1) and the internal refractory lining (2) and disposed at a level corresponding to the lower portion of the divided charge (A) and before it passes into the sintering region (B).

Abstract: The invention relates to a process for obtaining manganese- and silicon-based alloys by silico-thermal means in a ladle.An oxidized liquid slag, usually originating from earlier metallurgical operations and still containing from 10 to 40% of manganese in the form of MnO is treated by a silicon-based reducing alloy (silicon content of at least 60% and preferably at least 70%) with agitation.A slag which is substantially exhausted of manganese and a metal containing more than 60% and generally more than 70% of manganese and from 5 to 40% and preferably from 10 to 35% of silicon are thus obtained.

Abstract: The invention relates to a pyrometallurgical process for the treatment of complex metal ores, such as oceanic nodules, containing, in particular, manganese and copper, in which the ores are subjected to reducing fusion to produce a primary slag, containing all the manganese, and a primary alloy containing copper, nickel and cobalt. The primary slag which is then decoppered, may be used for the production of ferro or silicomanganese, while the secondary alloy is recycled for the reducing fusion step.