Abstract: An electric arc furnace has an electrically conductive roof with an electrode opening through which an arcing electrode depends with the opening closed around the electrode by an upstanding tubular electrically insulating refractory column surrounding the electrode and mounting on its top an electrically conductive electrode seal.

Abstract: A DC arc furnace hearth directly contacted by the melt is made from partially metal cased bricks which provide metal-to-metal intercontact while exposed portions of the bricks provide brick-to-brick intercontact.

Abstract: A metal oxide reduction furnace has a shaft holding a verticle column of coke. An electric arc on the side of the lower portion of the column burns a cavity in the coke column and the arc is surrounded by the side wall and inner closed end of the cavity so that high temperatures are obtained. A stream of the metal oxide in particulated form mixed with a reducing agent is projected into the cavity to react endothermically within the cavity and lower the high temperature while reducing the oxide to its metal.

Abstract: A DC arc furnace has power lines arranged completely symmetrically with respect to the arc so as to prevent the arc from bending angularly.

Abstract: A DC arc furnace has shielding between the arc and its power lines preventing or retarding the magnetic field created by the power lines from deflecting the arc.

Abstract: A molten steel ladle has a melt electrode in its side wall near its bottom so a DC arc can be formed with molten metal in the ladle for heating and stirring the metal, the ladle being also used for casting. The melt electrode is free from the ladle's casting nozzle and the outside of the ladle is free from projections extending beyond the ladle's trunions, so the ladle can be crane-carried in the usual manner.

Abstract: A DC arc furnace hearth is formed by brickwork having electric conductors extending through it, the conductors at their bottoms connecting with an electrically conductive layer on which the brickwork is layed and having top ends contacted by a melt contained by the brickwork. Arcing power can be transmitted via the conductive layer and conductors to the melt.

Abstract: A prefabricated unit for a DC arc furnace having a hearth bottom comprising electrically conductive bricks is formed by a metal plate having a cluster of depending metal rods and an electrically non-conductive refractory compound rammed or cast around the rods and the bottom of the plate with the bottom ends of the bars exposed below the compound. The unit is adapted to be installed on the bricks with the bars' bottom ends in electrical connection with the bricks so as to form an electrically conductive hearth for the furnace.

Abstract: A DC arc furnace hearth is formed by a layer of carbon bricks above which an electrically relatively non-conductive refractory compound is rammed to contain a melt, and metal bars or rods inserted through the compound so that their upper ends are exposed to the melt and their bottom ends are in electrical connection with the bricks, forming an electrically conductive hearth. An arcing electrode above the melt can be connected to one pole of DC power and the hearth connected to the other so that an arc is formed between the electrode and melt.

Abstract: A DC arc furnace having a melt or hearth electrode requiring contact by molten metal, has starting electrodes built into the furnace side wall above the hearth and which are contacted by steel scrap initially charged in the furnace. These starting electrodes are fixedly positioned and are part of the furnace construction and are used to provide electrical contact with the steel scrap pile charge during the start-up or melt-down phase while the usual arcing electrode, via its arc with the scrap, provides enough heat to form enough melt to contact the melt of hearth electrode. Thereafter, the arcing current commutates from the arcing electrode to the melt or hearth electrode via this initially formed melt, permitting a complete melt-down thereafter. Being permanent parts of the furnace construction, the starting electrodes need never be removed from the furnace.

Abstract: Iron-chromium alloys, such as stainless steels, are made in a direct arc DC electric arc furnace with a bath of molten steel scrap in the hearth and functioning as the anode with the arcing electrode cathodic, while feeding chromium-oxide to the bath at the arc spot on the bath's surface under conditions causing reduction of the oxide and addition of chromium to the bath.

Abstract: A DC arc furnace operation indicating system provides an indication and possibly a signal or control when during start-up the starting electrode does not make good electrical contact with a furnace charge of solid metal pieces and also thereafter when the shift is made to the melt electrode and it is not in a good electrical connection with the melt after the starting electrode is inactivated preparatory to the furnace going into normal production operation.

Abstract: An arc furnace has an arcing electrode through which a feeding passage is formed for feeding metal oxide particles through an arc and to a melt in the furnace. The arc is powered by DC power with the electrode cathodic and the melt anodic. Carbon is fed as required to reduce the oxides. Electric currents passing through the melt and the arc to the electrode are capable of causing magnetic forces forcing the arc to acquire an angular deflection in a downward direction away from alignment with the electrode's outer periphery and towards the side wall of the furnace in one direction subst antially continuously, during continuous operation of the furnace. Means are provided for electromagnetically causing the arc to continuously rotate, with its deflection, around the electrode.

Abstract: A DC arc furnace melt electrode is formed by a metal bar encased by a refractory encasement forming a passage containing the bar with the latter having an inner end and maintained molten by the melt and an outer end for an electrical connection and maintained solid by cooling. Granules of refractory having higher density than the melt and molten electrode end are submerged in this end to prevent or retard any flow of the molten metal, for the purpose of reducing convection heating of the molten electrode end by the melt in the furnace hearth.

Abstract: A DC arc furnace having one or more arcing electrodes and a melt contact electrode transversely offset from the arcing electrode is provided on the outside of the furnace with control electromagnets which are supplied with DC for the purpose of keeping the arc substantially axially aligned with the arcing electrode. For more positive control of the arc direction, radiation sensing devices are provided and which are arranged to receive more or less radiation from the arc if it wanders away from its desired vertical alignment with the arcing electrode. In turn, these devices are used to control the power supplied to the control electromagnets to alter the strength of their magnetic flux, so that if it wanders from axial alignment with the arcing electrode, the arc is substantially immediately returned to that alignment.

Abstract: A DC electric arc furnace with a furnace enclosure having a hearth containing a melt and with an arcing electrode forming an arc with the melt and made to angularly deflect and rotate by magnetic means forming a rotating magnetic field in the enclosure, is provided with means for sensing areas of the enclosure receiving a maximum intensity of arc radiation because of an asymmetrical charge in the furnace, this sensing means controlling the speed of rotation of the arc so that the arc rotates faster while directing its arc flare at these areas receiving maximum radiation.

Abstract: A direct current electric arc furnace hearth connection of the liquid-solid type is initially installed as a metal billet in an opening in a furnace construction, with water-containing refractory material rammed around the billet. To accelerate drying of the rammed water-containing or moist refractory forming a lining around the billet, metal channels are fixed to the sides of the billet to form longitudinally extending passages interjoined at one end of the billet by one or more transverse holes formed through the billet, so that a U-shaped overall passage is formed. A gas flame is burned at one end of the passage and the resulting hot gases are sucked through the U-shaped passage heating the billet to dry the rammed refractory material.

Abstract: A DC electric arc furnace having laterally offset hearth and arcing electrodes, has the arcing electric power for one of the electrodes carried by a conductor arranged with respect to the furnace hearth to provide an electric field within the furnace and which bucks the field created by the offset electrodes so that the arc formed within the furnace is vertically oriented.

Abstract: Method and apparatus for increasing the life of the lining of a three phase AC electric arc furnace. An electro-magnetic coil, mounted under the furnace and powered by DC or low frequency AC sets up a magnetic field inside the furnace, intersecting the arcs. During consecutive half cycles of the alternating arc current, the arcs are then steered away, alternating between new positions on both sides of the usual hot spot areas on the furnace wall.

Abstract: A metal melt is treated by injecting fluid material into the melt below its surface and which material does not add heat to the melt during the injecting, thus requiring the addition of heat to the melt during the injecting, to maintain the melt's temperature. This heat is added by forming an electric arc between an electrode and the melt, using a DC power supply connected to the electrode and to a connector in contact with a lower portion of the melt, with the electrode connected to make it a cathode and the connector connected with the power supply so that it, and, therefore, the melt, form an anode.