GB666780A - Improvements relating to alloy addition agents - Google Patents

Abstract

A self-reducing alloy addition agent comprises a mixture of an oxide of a metal selected from the group consisting of molybdenum, chromium, tungsten and vanadium with calcium carbide, the particles of calcium carbide being stabilized by a coating of a waterproofing carbonaceous material, e.g. a substantially non-volatile petroleum oil, which also acts as reducing agent for the metal oxide. The calcium carbide may be partly replaced by a more highly reactive reducing agent such as silicon, ferro-silicon, aluminium, magnesium or calcium silicide which is present in amount less than one quarter of the total amount of reducing agent cyclone separator in such a quantity that incomplete separation takes place, the unseparated particles being the smaller ones. The particles large enough to be separated are screened out of the respective fractions, which now contain the incompletely separated fines. These are, separately or together, further treated in a cyclone giving full separation. The separations are carried out in a suspension which may be magnetite and in this case the magnetite is separated out as shown in Fig. 1. The fine particles are recovered by thickening and the water thus obtained used for washing the screened products. Alternatively, in Fig. 2, the heavy fine particles of the mixture to be separated are used to form the medium. In this case a classification step on the fine heavy fraction recovers the medium and a froth flotation step removes the medium from the light fines. Specifications 601,063, 601,166, 604,368 and 655,957 are referred to. The Specification as open to inspection under Sect. 91 includes also suitable layout of plant. This subject-matter does not appear in the Specification as accepted.