Gfe Gesellschaft Fur Elektrometallurgie MIT Beschrankter Haftung

Gesellschaft Fur Elektrometallurgie Mbh

Gunter Duderstadt

Rudolf Fichte

Friedrich Breuer

Karl Brotzmann

Fritz Stadler

Werner Dresler

Peter Kunert

Gerd Nassauer

The invention relates to a method of rapidly decarburizing a high-carbon ro-alloy with oxygen for avoiding an undesirable oxidation of the principal alloying elements, especially chromium or manganese, comprising blowing an oxidizing gas under the surface of a bath of molten ferro-alloy from one or more gas-jacketed nozzles in an amount ranging between substantially 3 and 15 m.sup.3 S.T.P. per metric ton of ferro-alloy with reduction of the carbon content of the ferro-alloy at a rate of about 0.2% to 1%. Comminuted solids, especially particles of oxides of alkaline-earth metals such as powdered lime, may be admixed with the oxidizing gas to prevent the ejection of molten metal from the bath.

Method of rapidly decarburizing ferro- alloys with oxygen

A ferro-alloy, namely ferrochrome or ferromanganese, is refined by being heated to at least 100.degree. C above its melting point to form a bath whereupon oxygen is blown into the melt, below the bath surface, within a protective gas envelope. The rate of oxygen blowing is so chosen that 1% of carbon is oxidized within a period not to exceed about ten minutes, preferably not more than five minutes.

Method of refining ferro-alloys

A hign-carbon ferro-alloy, specifically ferrochrome or ferromanganese, is carburized in a converter in which oxygen or air is blown from below into the melt together with a surrounding protective gas. With the bath preheated to a temperature somewhat higher than the melting point of the ferro-alloy, the oxygen is introduced at such a rate that its reaction with the chromium or the manganese locally superheats the bath, in a region well below the surface and spaced from the converter walls, to a temperature high enough to let the resulting oxides react endothermically with the carbon. This reaction takes place in combustion zones believed to be localized in gas bubbles formed above the injection nozzles, the oxidation of the ferrous and nonferrous constitutents occurring at the interface between the gas and the melt with formation of a very thin and highly reactive oxide skin around each bubble. Some high-melting oxides of chromium or manganese may remain after the oxygen blow but can be reduced by blowing in powdered lime, after and possibly also with the oxygen, and by the deposition of solid or liquid reducing agents on the bath surface. A minor fraction of the ferro-alloy may be added in solid form to hold down the bath temperature.

Process for refining high-carbon ferro-alloys

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Hosel, Germany

Gunter Duderstadt