GB424663A - Process of and apparatus for the production of molten iron or steel by the direct method - Google Patents

Abstract

424,663. Extracting iron; treating ores. SACHTLEBEN AKT.-GES. FUR BERGBAU UND CHEMISCHE INDUSTRIE, 163, Eintrachtstrasse, Cologne, Germany. Oct. 6, 1933, No. 27594. Convention date, Oct. 6, 1932. [Classes 72 and 82 (i)] [See also Group XII] In the production of molten iron or steel, by the direct reduction of ores &c. in a moving furnace, the silica content of the charge is adjusted, either by the employment of ores containing the requisite amount of silica or by the addition of siliceous materials, so that while the temperature increases, spongy iron and ferrous silicate are formed simultaneously, the latter then reacting with the lime present to liberate ferrous oxide which is reduced to the metallic state and melted with the spongy iron. The charge may be preheated before reduction and the bulk of the volatilizable substances such as sulphur, zinc, &c. will then be expelled or, if there is no preheating, during the reduction of the ore. Fluxes such as fluorspar which reduce the melting point of the slag may be added to the charge and the lime required for the decomposition of the silicates may be added to the charge before or after the preheating of the latter or before its introduction into the reducing furnace or when the charge is already in the furnace. The ore which may be roasted or agglomerated is mixed with about 20 per cent of reducing carbon and is conveyed by the endless band 1 and pipe 2 into a rotary preheating furnace 3 where the more volatile metals such as zinc are removed, e.g. as described in Specification 225,842, [Class 82 (i)]. The preheated material then passes into a shoot 4 where it is mixed with carbon and other additions required for the reduction of ore and thence into a rotary furnace 5 heated by a coal dust burner 6. The waste gases from the furnace 3 pass into the flue 10, past the air preheater 11 into a conduit 12 and thence into a filtering device in which the oxides in the gases are precipitated therefrom. A fan 13 forces air through the preheater 11 and pipe 14 into the burner 6. In a modification, the furnace 3 is dispensed with, the material before entering the furnace 5 being treated in a roasting or sintering apparatus and then passing over a screen into the furnace.