Abstract: A method of detecting an open arc in a DC plasma arc furnace which is based on detecting a linear decrease in the log of the magnitude of the frequency spectrum of the voltage between the anode and cathode.

Abstract: A method of detecting an open arc in a DC plasma arc furnace which is based on detecting a linear decrease in the log of the magnitude of the frequency spectrum of the voltage between the anode and cathode.

Abstract: A metallurgical vessel having a cylindrical upper end section and a top section fitted to the upper end of another section to form a top closure of the vessel about a central opening through which to extend a gas injection lance for injecting gas into the vessel. Top section is formed as a two-part domed construction comprising an outer annular panel welded to the vessel top section and an inner annular panel removably fastened to outer panel, both panels being formed with inwardly concave curvature so as to form together the continuously domed top section. The two panels are fastened together by clamping bolts extended through outturned flanges formed on annular flanges standing up from the panels. On release of bolts panel is removable to provide access to the interior of the vessel.

Abstract: Metal lumps or pebbles are produced by introducing a molten metal stream into a stream of water in a direction which is substantially the same as the direction of the water stream and at a velocity which is substantially the same or slightly less than the velocity of the water stream.