Abstract: A device for filtering dust from air drawn by apparatus from a factory shop or building, for example a steelmaking shop, including a plurality of dust extractors which have a total capacity at least equal to the air throughput of the drawn air. The extractors have regulators by which they can be regulated individually or in groups. Preferably each extractor is associated with an individual dust extractor and also each extractor preferably has its own individual cleaning system. The extractors are preferably of the dry filter bag type.

Abstract: This invention relates to a shroud for a steel making electric-arc furnace which surrounds the electric-arc furnace main body for sound- and dust-proofing, having doors provided in the side wall of the shroud to permit the scrap bucket to move in and out of the shroud and an opening of a minimum width in the suction port of a dust collecting suction duct on the top wall to permit transverse movement of the bucket lifting means to the center of the electric-arc furnace main body.

Abstract: A substantially spherically-shaped electric melting furnace includes a carbon-lined crucible. The interior of said crucible is sealed from the atmosphere outside the crucible and a vacuum pump and venturi device control the atmosphere within the crucible by removing oxygen therefrom. A feeder lock allows material to be fed into the crucible without interfering with the atmospheric control of the crucible and a tap hole adjacent the lower portion of the crucible allows molten material to be removed. When used in the manufacture of mineral wool insulation, slag is fed into the crucible to be melted and the molten slag from the tap hole is delivered to a fiberizing device.

Abstract: An electric furnace for fusing of fusible metal/non-metal oxide compounds, for example slag, having a side wall of steel, a plurality of electrodes depending into the furnace, a coolant distributing conduit surrounding the furnace near its upper end, and a tapping valve located in the side wall of the furnace between its upper and lower ends, the furnace being operated by melting the slag to form a melt, the outer layer of which is in contact with the inner surface of the furnace side wall which is frozen by the chilled coolant flowing over the outer surface thereof, to thereby form a frozen slag lining on the side wall inner surface which is continuously replenished as it is depleted.

Abstract: A gas collection apparatus for use in open electrical smelting furnaces is disclosed. The apparatus comprises an annular body about the outer circumference of the furnace and sealed to the top edge of the furnace on one side thereof with a sloped wall extending into the furnace on the other side to a depth below the normal height of the charge in the furnace.