Fried. Krupp Huttenwerke Ag

Wilfried Pulvermacher

Otto Fischer

Helmut Gorges

Heinrich Brod

Wolfgang Rubens

Bernd Koch

An arc furnace roof has a central portion formed by a circular group of individually suspended segments having sides which cooperatively form openings for the passage of arcing electrodes. Each segment is formed by a metal shell having cooling water inlets and outlets and internal baffles causing cooling water to be guided through the shell so that cooling is adequate to avoid the need for lining the bottoms of the segments with thick refractory linings, the bottoms being only coated with a thin layer of refractory electrical insulation. The electrode openings have refractory electrical insulation to isolate the segments from electrode currents.

Arc furnace roof

Disclosed herein is an improvement in a process for preparing a stainless steel of low carbon content from a steel melt containing chromium or chromium nickel of higher carbon content where the process is carried out in a converter having at least one blast nozzle below the molten steel bath level and at least one blast lance above the bath level wherein oxygen is supplied to the steel melt through the blast lance and inert gas is supplied through the blast nozzle during a first refining phase, and in a succeeding refining phase oxygen is combined with inert gas and introduced through the blast nozzles to the steel melt, the proportion of the oxygen being reduced in relationship to the proportion of inert gas with decreasing carbon content of the steel melt. The improvement of the invention permits a decrease in the amount of inert gas supplied during the first refining phase while not significantly increasing the refining time. The improvement resides in employing as at least one of the nozzles one having an axially movable bar within the passageway of the nozzle, the bar being extended through the nozzle passageway to the mouth of the nozzle during the first refining phase and being withdrawn from the mouth of the nozzle during the successive refining phase. By such an expedient, the amount of gas passing through the nozzle in the first refining phase is reduced, and the amount of gas passing through the nozzle in the successive refining phase is increased.

Growing community of inventors

Bochum, Germany

Wilfried Pulvermacher