Ugine Aciers

Georges Marizy

Jean Brancaz

A nozzle is disclosed for use in the decarburization of molten pig iron by means of a jet of oxygen from a lance provided with such nozzle. The nozzle according to the invention is characterized by a divergent portion which, beyond the neck, has a frustoconical part, with an apex angle of between 60.degree. and 70.degree. and preferably between 62.degree. and 66.degree., and wherein an angle of 65.degree. is preferred. The nozzle according to the invention can be used in particular for the decarburization of chromium containing pig iron and makes it possible to achieve very high chromium and iron yields.

Nozzle for an oxygen injection lance for decarburization of pig iron and

A process is disclosed for the decarburization of a molten bath of chromium-containing pig iron which, in a single operation, permits decarburization by means of an oxygen jet and thus permits chromium or nickel chromium steels to be obtained directly, the decarburization of which can readily be completed by a final treatment under vacuum carried out immediately after the injection of oxygen. The process comprises adjusting the temperature conditions of the pig iron bath and regulating the oxygen jet distance from the surface of the bath and speed of oxygen gas so that the impact force of the oxygen creates a gas-metal emulsion within which the carbon contained in the pig iron is oxidized directly by the oxygen. The carbon content is thus rapidly reduced to less than 0.3% whereas the yield of chromium is higher than 97%. The process is suitable for the preparation of all grades of Cr and NiCr stainless steel, which optionally contain additions of Co, Mn or Mo.

Growing community of inventors

Ugine, France

Georges Marizy