Abstract: A plasma electric arc furnace having a plasma torch that creates a flame which impinges upon a surface of a bath of material to be heated. The impingement creates physical agitation and convection currents around the locus of impingement. Mixing currents are created on opposite sides of a motion path of the locus when this locus is moved. A motion device coupled to the plasma torch moves the torch so that the locus follows a motion path wherein portions of the mixing currents at least partially overlap one another thereby providing greater agitation of the bath and increased efficiency of agglomeration of metallic particles suspended in the bath.

Abstract: The device for mounting and withdrawing a plasma torch in an apparatus at high pressure and temperature comprises in combination: at least one circular sealing element (2) interposed between the inner surface of a sleeve (3) and a nose (12) of the torch (4) and surrounding the nose, devices (6, 13) for balancing the pressures on each side of a valve (5) within the sleeve, and devices (18,23) for cooling the sealing element. The devices for balancing the pressures on each side of the valve comprise a communication pipe (6) by-passing the valve (5) and a tap valve (13) inserted in the pipe.

Abstract: An apparatus for preparing metallic radioactive waste material for storage is disclosed. The radioactive waste material is placed in a radiation shielded enclosure. The waste material is then melted with a plasma torch and cast into a plurality of successive horizontal layers in a mold to form a radioactive ingot in the shape of a spent nuclear fuel rod storage canister. The apparatus comprises a radiation shielded enclosure having an opening adapted for receiving a conventional transfer cask within which radioactive waste material is transferred to the apparatus. A plasma torch is mounted within the enclosure. A mold is also received within the enclosure for receiving the melted waste material and cooling it to form an ingot. The enclosure is preferably constructed in at least two parts to enable easy transport of the apparatus from one nuclear site to another.

Abstract: A method and apparatus for heating molten steel in a steel making operation is disclosed, and which includes a refractory lined vessel having an open top, a removable cover adapted to overlie the top, and at least one plasma arc torch mounted so as to extend through the cover at an angle of about 60.degree.. The arc gas for the torch includes a substantial percentage of nitrogen, which permits a higher power level as compared to conventionally used argon, and the mass flow rate of the arc gas is maintained at a sufficiently high level to produce a continuous blast of gas which impinges at an angle upon any slag formed on the surface of the molten steel with sufficient force to move the slag and expose the underlying molten steel. As a result, the attachment of the arc to the underlying molten steel is facilitated, and the impingement of the gas contributes to the mixing of the steel to avoid heat stratification.

Abstract: A silicon smelting furnace and a process for utilizing this furnace for the production of silicon is described. The process involves a process in which equilmolar proportions of silicon carbide and silicon dioxide are charged to the reaction zone of a silicon furnace. Above the furnace is placed a shaft containing particulate carbon in the amount of 2 moles of carbon per mole of silicon dioxide charged to the reaction zone. As energy is applied to the reaction zone, molten silicon, gaseous silicon monoxide, and gaseous carbon monoxide are formed, the gases passing through the shaft of carbon, converting the carbon to silicon carbide. The silicon carbide, so formed, is combined with an equimolar proportion of silicon dioxide, and the cycle is repeated. Aside from an initial charge of silicon carbide, the feeds to the smelting furnace are silicon dioxide and carbon, silicon carbide being formed concurrently in a bed of carbon separated from the furnace reaction zone during the smelting cycle.

Abstract: A plasma furnace including an upper chamber having three electrodes radially spaced from an ore feed tube. The ore is gasified by a plasma arc in a central crucible and allowed to condense in the space between the central crucible and an outer crucible. The outer crucible forms the boundary between the upper chamber and a lower chamber. The lower chamber is filled with molten copper which acts as a filter. Since there is no agitation in the lower chamber, molten ore entering from the upper chamber separates between a fraction containing heavy metals which is drained from a sump, and a fraction containing lighter materials which is decanted through an overflow tube.

Abstract: A transferred arc torch is comprised of a first electrode surrounded by a coil. A second electrode is positioned adjacent to the first electrode so as to provide a small gap therebetween for striking an arc. The second electrode is configured to enable the arc to be transferred therefrom. The transferred arc torch may be used in conjunction with a vessel to provide a unique plasma reactor.

Abstract: An auxiliary plasma arc fed by an auxiliary circuit serves for igniting a plasma arc, fed by a main circuit, of a plasma burner provided in a metallurgical furnace vessel.To increase the service lives of the burners, the electrode of the plasma burner and the melting stock charged in the furnace vessel are applied to the auxiliary circuit, with the main circuit switched off, and an auxiliary plasma arc is ignited between the plasma burner and the melting stock, whereupon the plasma burner is moved back from the melting stock, thereby lengthening the auxiliary plasma arc, and subsequently the main circuit is applied to the plasma burner and to the melting stock, and the plasma arc is ignited.

Abstract: An improved plasma arc reactor is provided with variably positionable electrodes, including a cylindrical anode electrode having an inner, frustoconical cavity providing a reaction chamber and a spherical cathode ball electrode mounted therein. Between these electrodes an arc discharge is induced and sustained to heat and ionize an inert gas to produce an arc plasma for refining raw material introduced into the reaction chamber. A magnetic induction coil is mounted around the outer diameter of the anode electrode to thereby establish a magnetic field to rotate the arc discharge and plasma within the reaction chamber.

Abstract: A method and apparatus for heating molten steel in a steel making operation is disclosed, and which includes a refractory lined vessel having an open top, a removable cover adapted to overlie the top, and at least one plasma arc torch mounted so as to extend through the cover at an angle of about 60.degree.. The arc gas for the torch includes a substantial percentage of nitrogen, which permits a higher power level as compared to conventionally used argon, and the mass flow rate of the arc gas is maintained at a sufficiently high level to produce a continuous blast of gas which impinges at an angle upon any slag formed on the surface of the molten steel with sufficient force to move the slag and expose the underlying molten steel. As a result, the attachment of the arc to the underlying molten steel is facilitated, and the impingement of the gas contributes to the mixing of the steel to avoid heat stratification.

Abstract: Apparatus for supplying thermal energy to a metal melt present in a receiving vessel after having been discharged from a melting furnace, the receiving vessel having a central axis, the apparatus includes at least two plasma torches disposed above the melt in the receiving vessel to direct a transferred electric arc at the melt, the torches being operated with alternating current and with a gas which is inert to the melt, while being cooled with water.Apparatus according to the invention includes a cover over the top of the vessel, the cover having a passage for the electrodes, and a component establishing a gas-tight seal between the cover and the electrodes.

Abstract: A plasma burner comprises an electrode holder which carries a tubular outer electrode and a coaxially arranged central electrode, and an electrical current supply source, which can be coupled via current feeders to the outer and central electrodes respectively. Also a device is provided for feeding gas into the region of the electrodes, between which an arc is produced for plasma formation. The tubular outer electrode has a first cooled, arc-inactive tube section, consisting of electrically conductive metal, and an adjoining second arc-active uncooled tube section, which consists of heat-resistant and electrically conductive material, and which is releasably connected to the first tube section. The arc passes between the second tube section and the neighboring arc-active section of the coaxial central electrode.

Abstract: An apparatus and method for heating a metallic melt with plasma torches is disclosed which is characterized by its ability to reduce the amount of contamination that is introduced into the metallic melt during the heating process. The apparatus and method includes a furnace chamber having a hearth for receiving a metallic melt. Mounted to the furnace chamber are a pair of plasma torches and an external electrode that is adapted to contact the metallic melt contained in the hearth. A separate direct current power supply is provided to operate such plasma torch. During operation of the apparatus, two separate circuits of opposite polarity are established through the metallic melt utilizing the plasma torches and the external electrode in contact with the melt. While these circuits are maintained, the external electrode is withdrawn from contact with the melt, thereby establishing a single series circuit which includes both plasma torches, both power supplies and the metallic melt.

Abstract: An anode system for plasma heating usable in the tundish of a continuous casting apparatus, which is economical and simple in structure and can enjoy a long service life, and comprises a dam member provided on the bottom surface of a tundish near and along a side wall or an over-flow wall of the tundish to form a space or gap therebetween, an electrical conductive member with its end portion exposed to the space or gap and the other end electrically connected to a power source, said dam member having a height higher than a level of molten metal remaining after the pouring of the molten metal from the tundish, but lower than a minimum level of molten metal normally contained in the tundish.

Abstract: An electric furnace, in particular a plasma furnace, includes an electrode axially displaceable and pivotable in an electrode retaining device. In order to provide for a freedom of motion as large as possible to the electrode, thereby reliably preventing local overheatings of the material to be heated and melted, the electrode is mounted on the electrode retaining device by a spherical bearing so as to be universally movable. The electrode is axially displaceably guided in the bearing and is movable relative to the bearing by at least one adjustment device engaging at the bearing with one end and at the electrode with the other end. At least two adjustment devices, which are directed at an angle to each other, seen in the axial direction of the electrode, are each hinged to the electrode retaining device with one end and to the bearing with the other end.

Abstract: In a process for the production of calcium carbide in a shaft furnace, a plasma arc (plasma torch) is generated by the introduction of electric energy with the help of a plasma burner device penetrating the upper cover of the shaft furnace. A counter electrode is provided in the bottom part of the shaft furnace. About the plasma arc or torch, a burden mixture of calcium-oxide and carbon-containing substances is concentrically introduced so as to form a protective mound of solid burden components on the inner wall of the furnace. In order to provide an operationally safe process by using plasma burners, with which both coarse and fine-grain burden components may be employed and with which calcium carbide is obtained in higher yields with an improved utilization of the energy consumed, the burden mixture is used separately as a coarse-grain fraction and as a fine-grain fraction.

Abstract: A toroidal pile of raw material is contained in a toroidal melting pot provided in the lower portion of a furnace and a ring plasma torch is mounted over the toroidal pile of the raw material. A ring plasma arc, driven electromagnetically and rotating azimuthally between the torch and the pile, heats a certain portion of the pile intermittently and periodically. Fine grains are produced in such portion of the pile of raw material that is not heated directly by the plasma arc and collected through a discharge port provided around the major axis of the toroidal melting pot.

Abstract: With a method for producing metals, the raw material is melted in a metallurgical vessel by at least one plasma burner directed from top to bottom. In order to be able to protect the furnace brickwork from too strong a thermal load exerted by the plasma jet, and to make available the energy supplied by the plasma burner to melting and reducing the fine ore to as large an extent as possible as well as to prevent an agglomeration of the raw material to be used, the raw material is topcharged into the metallurgical vessel in the form of fine particles directed parallel to the plasma jet so as to peripherally surround the same. Oxygen-containing gases and carbon are bottom-blown into the vessel through the melt. A foamed slag is formed in the vessel, surrounding the plasma jet over its total height and the flow of supplied raw material particles peripherally.

Abstract: A method for making an aluminum nitride powder comprises atomizing a molten aluminum into a nitriding atmosphere of N.sub.2 gas of elevated temperature and solidifying the finely divided liquid particles of aluminum which have been nitrided.

Abstract: In a direct-current-operated, gas-vortex stabilized high-voltage arc furnace with hollow electrodes and a vortex chamber, the gas to be heated is blown in tangentially to the common axis of the electrodes. In the hollow electrodes, the ratio of the internal diameter of the cathode to that of the anode is 1.6 to 2.5, and the spacing between the electrodes is 0.9 to 0.7 times the internal diameter of the cathode. In the method of operation of the arc furnace, the momentum flow of gas to be heated is at least 10 kg m/s.sup.2, the gas entering into the vortex chamber is at a gas velocity of at least 10 m/s and pressures in the vortex chamber range from 1.5 to 10 bar (absolute).

Abstract: An apparatus and process for the reduction in a plasma stream of a feed material including a comminuted metal oxide, a slag former and a reductant utilizing an enclosed horizontal reactor having a reduction chamber and a filter chamber therein separated by an either common partition having a plurality of holes therethrough or a refractory lined passageway. Coke filter media in the filter chamber act to filter out entrained molten metal contained in the plasma stream with the partition or passageway preventing entry of the coke from the filter chamber into the metal bath contained in the reduction chamber thereby limiting the amount of carbon entering the metal produced. Unreduced metal oxide is provided in the slag layer of the metal bath to maintain the stoichiometric ratio between the metal and reductant in the reduction chamber.

Abstract: There is disclosed a plasma melting furnace through the side wall of whose cylindrical furnace body a plurality of downwardly directed plasma burners are guided, whose mouths project into the furnace interior. In order to avoid several rechargings, which has been common so far, in particular with scrap of low apparent density, and to be able to charge continuously, without endangering the plasma burners by electric flashovers between parts of the charge material and the burner mouths or falling-down materials and by maintaining the inert gas atmosphere within the furnace, the cover of the furnace interior comprises a shoulder-likely re-entering part projecting upwardly. This part is closeable by a lid and delimits a central charging opening whose diameter is smaller than the diameter of the circle on which the mouths of the plasma burners are arranged.

Abstract: This invention relates to the construction and use of plasma arc furnaces; more particularly it relates to a transferred arc mode of operation in such furnaces. In more detail a plasma arc furnace according to this invention comprises at least two stationary plasma torches positioned at or near the upper end of a furnace chamber and directed downwardly at an inclined angle towards an electrically conducting vessel for containing melt produced in the furnace and at least one electrical return anode connection made to said vessel at a point above the point of coalescence of the arcs produced, in use, by the torches.

Abstract: A plasma melting furnace includes one or more plasma burners penetrating the furnace lining, in particular a plasma burner projecting vertically into the interior of the furnace. In order to ensure a most uniform stress on the lining by the heat radiation, the inner surface of the lining is designed to be inclined, converging upwardly.

Abstract: A thermal plasma generating electrode assembly of the type having a central, water-cooled electrode and an outer sheath defining therewith a path for gas is provided. The sheath is made as a non-water cooled sheath of a high melting, electrically conductive material to avoid damage to the electrode as a result of stray arcing by attracting such stray arcing to the sheath rather than the electrode. In addition the electrode can be retractable within the sheath to enable the latter to be employed for making initial electrical contact with the co-operating electrode of opposite polarity for the purposes of "striking" or initiating the arc upon start-up.

Abstract: In an arrangement for the production of steel from solid and/or liquid charging materials, such as pig iron, heavy scrap and light scrap, a liftable and lowerable heating-refining arrangement and, if desired an arrangement for supplying further additions are positioned in a refactorily lined refining vessel. In order to be able to use as high a scrap portion of the materials charged as possible without substantially increasing the time required until the end of the refining operation per charge, the heating-refining arrangement consists of a plasma burner, a jacket surrounding the plasma burner for supplying oxygen, and a cooling jacket surrounding that jacket, a counter-electrode being arranged in the bottom of the refining vessel.

Abstract: An X-ray marker device. The device comprises a body member and a single suction cup attached to the bottom of the body member. X-ray opaque indicia are formed on the face of the body member. The suction cup temporarily secures the body member to a substantially flat surface, such as an X-ray film holder.

Abstract: A plasma melting furnace includes a water-cooled bottom electrode of copper and a temperature probe connected with the bottom electrode. A wearing part of steel is provided in the bottom of the furnace, covering the bottom electrode. At least one counter electrode is arranged at a distance above the wearing part for the formation of the plasma jet. In order to prevent the risk of a melting through of the bottom electrode as far as to its water-cooled section on account of a secondary arc, a metal layer is provided between the bottom electrode and the wearing part. The metal layer is formed by a metal having a low thermal conductivty and a low melting point, as compared to copper, as well as a high melting enthalpy. Preferably, a metal layer of lead or its alloys with tin and/or zinc is provided.

Abstract: A plasma-arc furnace comprises a casing with plasma torches, particularly ree torches, mounted therewithin in symmetrical relationship relative to the vertical axis thereof. Each of these torches comprises a body provided with a nozzle and an axial conduit for feeding a plasma-forming gas therethrough, and a cylindrical electrode disposed within said conduit. According to the invention, the distance between the centers of working ends of electrodes disposed within adjacent plasma torches is not more than 15 diameters of the electrode.

Abstract: A plasma melting furnace includes a furnace body, a covering cap, one or more electrodes penetrating the bottom of the furnace body, and at least three plasma burners penetrating the furnace wall or the covering cap and arranged so as to be inclined towards the bottom. In order to achieve a high melting performance with a simultaneously low energy consumption, charging openings are provided in the covering cap for the continuous melting of small-sized material, such as light scrap and iron sponge. Their vertical axes are located in a plane extending through the angular symmetry of the normal projection of the axes of two neighboring plasma burners as well as between two vertical planes each extending perpendicular to the normal projections of the individual burner axes.

Abstract: Disclosed are a method and apparatus for manufacturing sponge iron by the continuous reduction of iron oxides in a shaft utilizing recirculation gases. Reaction gas is removed from the shaft furnace, substantially cleaned of all CO.sub.2 and H.sub.2 O, and then divided into at least two flow portions one of which is passed to a gas generator comprising a plasma burner. A reducing agent such as pit coal is injected together with an oxidant into the hot gas from the plasma burner so as to form a gas mixture comprised primarily of CO and H.sub.2, which gas mixture is then mixed with the other flow portion of the cleaned reaction gas in such proportion that the temperature of the resulting reduction gas is suitable for the reduction of iron oxides in the shaft furnace.

Abstract: A plasma reactor, in which particulate matter is caused to interact with low temperature plasma (i.e. below 100,000 K.) comprises spaced stationary electrode structures 2, 11 of which at least one is annular, between which an arc or arcs 7 is established by a power supply which may include a thyristor (SCR) 9. The arc is pulsated and caused to orbit or circulate round the or each annular electrode structure to form a conical plasma zone between the electrodes, while particulate solids are introduced through inlets 5 to enter the plasma zone and interact with the plasma therein. Extended dwell periods and highly effective interaction are brought about by circulation and pulsation of the arc and a high particle population density.

Abstract: An apparatus for filling a container with radioactive solid wastes comprises a melting furnace for melting the wastes and a feed-in device for feeding the wastes into the melting furnace. The wastes introduced into the feed-in device through a charge port are fed laterally and fed from an inlet formed in the side wall of the melting furnace into the melting furnace. The wastes fed into the melting furnace are melted therein, and a resultant melt is poured from an outlet formed in the side wall of the melting furnace into a top-open container placed under the outlet.