Abstract: The invention relates to a process for the separation and recovery of non-ferrous metals from zinc-bearing residues, in particular from residues produced by the zinc manufacturing industry. The process comprises the steps of:—subjecting the residue to a flash or agitated bath fuming step, thereby producing an Fe bearing slag and Zn- and Pb-bearing fumes; and—extracting the Zn- and Pb-bearing fumes and valorizing Zn and Pb; characterized in that CaO, SiO2 and MgO are added as a flux before or during the fuming step so as to obtain a final slag composition with: formula (I) all concentrations being expressed in wt %. The invention also relates to a single-chamber reactor for Zn-fuming equipped with one or more submerged plasma torches as heat and gas sources. [ Fe ] [ SiO 2 ] + [ CaO ] [ SiO 2 ] + [ Mg ? O ] 3 > 3.5 ; ? ? 0.1 < [ CaO ] [ SiO 2 ] < 1.

Abstract: A melting furnace for smelting scrap includes a heating device extending through a wall of the furnace in order to supply melting energy, wherein the heating device including a tubular body, which encloses a flow channel. Further, the furnace includes a heating zone formed by a longitudinal section of the tubular body configured as an electrodeless plasma torch including an inductive heating coil which encloses the flow channel coaxially. An injection pipe is disposed in a central manner in the flow channel extending up or into to the heating zone, wherein the injection pipe is enclosed by a gas guiding pipe coaxially and at a radial distance. An annular channel is arranged between the injection pipe and the wall of the flow channel for supplying a cooling gas.

Abstract: Organic waste material is pneumatically transported within air and mixed rewith by swirling flow through an annular injector passage of varying radial width into a reaction flow passage of an eductor nozzle section receiving the output plume of a plasma torch for initiating therein thermal gasification of the waste mixture. The plasma torch plume projects from the eductor section into a diffuser section within which thermal gasification is continued before discharge of gasified waste.

Abstract: An electric arc furnace comprises a closed melting vessel and includes a roof through which metal to be molten is charged into the melting vessel. At least one electrode extends into the melting vessel and generates an electric arc and forms a molten metal bath. At least one oxygen lance can be extended into the melting vessel for injecting oxygen into the molten metal bath and create a reaction where the carbon monoxide is generated. Gas is exhausted from the melting vessel and the carbon monoxide gas concentration of the exhaust gas is measured. A post combustion chamber receives the exhaust gas and provides post combustion of the exhaust gas. Post combustion oxygen is injected into the melting vessel in an amount sufficient to provide post combustion based on the amount of oxygen necessary for post combustion of the exhaust gas and the post combustion chamber.

Abstract: A method for providing main gas into a pool of molten metal, which is particularly useful for use in an electric arc furnace. The method employs combustion of secondary oxygen with fuel to form a flame envelope around a main gas stream which protects the main gas from entrainment of ambient gases as it passes through the headspace of the furnace. This enables the gas to retain to a substantial degree its original force upon injection into the headspace and thus may be injected into the furnace at a safe distance from the molten metal surface while still achieving substantially complete penetration into the molten metal.

Abstract: A waste-melting furnace includes a furnace body, a rotary heat-resistive vessel which is arranged inside the furnace body and into which waste is to be fed, and a transferred arc type torch plasma gun and a water-cooled electrode arranged above the rotary heat-resistive vessel, the plasma gun and electrode being opposed to each other.

Abstract: Apparatus suitable for the thermal conversion of methane to hydrocarbons of higher molecular weight, comprising an elongated reactor 1 provided with an inlet 5 for supplying a gas mixture containing methane (process gas) and an outlet at the opposite end, the reactor over a first part towards the inlet end having a plurality of electric heaters 3 surrounded by sheaths 4. The heaters, e.g., electric resistors, which are spaced apart and are substantially parallel with respect to one another, are arranged in substantially parallel rows perpendicular to the axis of the reactor so as to permit circulation of the process gas and/or effluent between the sheaths and/or between the sheaths and walls 22 separating two consecutive rows. The heaters heat the passages by successive independent cross sections substantially perpendicular to the axis of the reaction. Towards the outlet end, the reactor further comprises an injector for supplying cooling fluid, which cools the effluent.

Abstract: Chemical waste is burned in oxygen using an electric plasma flame to heat a stream of gas which contains at least 70% by weight oxygen. Liquid waste in fine droplet form is introduced into the gas stream via a two-fluid atomizer using a carrier gas also preferably oxygen. The total amount of oxygen present is at least 30% more than required for complete combustion of the liquid waste. The reaction mixture is maintained at a temperature of at least 1450.degree. C. for a time of at least 2 milliseconds prior to cooling rapidly of the reaction products to a temperature below 300.degree. C.

Abstract: A method of preparing a melt for mineral fibre production wherein a mixture of mineral fibre-forming raw materials is introduced into a shaft furnace and is heated to melting temperature by a plasma gas stream formed in a plasma torch and wherein waste material from mineral fibre production is introduced into the plasma gas stream by a rotatable screw conveyor mounted in a feed pipe, the melt formed in the shaft furnace is being discharged from the bottom of the furnace and passed to a fiberizing apparatus in which it is converted into mineral fibres.

Abstract: An electric furnace comprising a container having electrically isolated wall segments useful for melting materials, particlularly ceramics, is disclosed.The electric fornace's side walls are constructed from electrically isolated segments, which cause electric current from a plasma torch to be concentrated on the material in the furnace to be melted rather than diverted to the walls of the furnace.

Abstract: A furnace for producing a melt for mineral wool production includes a shaft for preheating and melting of the raw material. A water-cooled grate is disposed in the bottom portion of the shaft, which supports a bed of ceramic filling bodies as well as the raw material. A combustion chamber is disposed underneath the shaft, which has a bottom portion for collecting the melt dripping from the shaft and an outlet for melt tapping. At least one main burner is disposed in the combustion chamber. Auxiliary burners are disposed above the grate. The bottom surface of the combustion chamber is larger, preferably 20 to 400% larger, than the transverse cross-sectional area of the shaft.

Abstract: Apparatus and method for the disintegration of waste by subjecting the waste within a closed chamber to plumes of an electrically generated high temperature plasma. The chamber is lined with an array of nozzles to produce the plumes and the nozzles are supplied with a cooling gas at all times. The nozzles are energized to produce the plumes in a predetermined sequential manner so that the waste is destroyed in steps, or bites. The gas containing the products of disintegration is withdrawn and filtered. One embodiment comprises a portable device capable of disintegrating waste over a large area such as at a waste dump site.

Abstract: In a method for the preparation of a melt for the production of mineral wool a raw material is introduced at the top of a shaft furnace and heated to melting temperature partly with a hot gas formed by plasma heating and partly with a hot gas formed by combustion of one or more gaseous hydrocarbons, the latter gas stream being introduced at a level at which the temperature does not exceed 1250.degree. C., and the melt formed is discharged at the bottom of the shaft furnace.

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: A system is provided for positioning a pair of electrodes on either side of the end portion of an optical fiber extending through a contact, to establish an arc through a cross-aperture in the contact and across the fiber to melt the fiber into a lens, which assures close control of the arc and which prolongs the life of the electrodes. The tips of the electrodes are positioned to lie slightly within opposite ends of the cross-aperture, to avoid establishing an arc between the electrodes which passes around the contact instead of through the cross-aperture. The electrodes are spaced apart by at least about eight times the diameter of the optic fiber, to avoid deposition of vapors from the heated optic fiber onto the electrodes. The cross-aperture extends to the tip of the contact, so the contact can be moved along its axis to a position where the electrodes lie on opposite sides of the fiber end portion.

Abstract: A plasma feed nozzle 3 for a furnace 1 which has a tubular mixing chamber 7 open at one end to the furnace, a plasma torch 13 which provides superheated gases axially to the central portion of the mixing chamber 7, shroud gases which enter the end of the mixing chamber opposite the end open to the furnace in such a way as to swirl as it moves axially through the mixing chamber 7 to provide a temperature profile which is substantially hotter in the central portion of the mixing chamber 7 than adjacent the wall portion thereof and a particulate feed nozzle 25 disposed to direct particulate material to the central portion of the mixing chamber.

Abstract: A system is described for forming a lens at the end of an optical fiber which extends through a hole in a contact, so the tip of the lens lies at a desired lens position located a predetermined distance rearward of the tip of the contact. The fiber is fixed to the contact at a position wherein the tip of the fiber lies forward of the desired lens position, at about the tip of the contact. The contact is positioned vertically, with the tip of the fiber pointing upwardly, and an arc is passed across the end portion of the fiber, to initially heat and bulge out a location on the fiber spaced rearward of the tip. As the fiber is heated, the tip portion falls into the bulging portion, while the bulging portion moves down, with the heating continued long enough so that the tip of the molten ball of glass lies at the desired lens position.

Abstract: A system is provided for forming an end of an optical fiber into a lens, which produces a lensed fiber having an especially smooth lens surface and high strength near the intersection of the lens and the rest of the fiber. A lens is formed by establishing a pair of electrodes on opposite sides of a fiber end portion and establishing an arc between the electrode tips for a sufficient current and time to melt the fiber end portion into a lens, with the arc being repeatedly terminated and restarted at a rate of thousands of times per second.

Abstract: An apparatus and method is disclosed which is adapted to consolidate and melt reactive metallic materials, and to produce a "first ingot" which is suitable for subsequent evaluation and qualification under existing specifications for such materials in the aerospace industry. The apparatus comprises an enclosed heating chamber adapted to be substantially evacuated of air, and a hearth is positioned within the chamber for supporting the metallic material to be melted. Also, a plasma arc torch is mounted to the heating chamber, which is operable in the transfer arc mode wherein an arc extends from the rear electrode of the torch to the hearth. The rear electrode of the torch is of elongate tubular configuration, which permits a major portion of the length of the arc to be located within the torch itself, which permits the torch to deliver a high level of power in the vacuum environment within the heating chamber.

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: A furnace for the sintering of refractory or ceramic materials using plasma heated gases. The furnace comprises a sintering chamber with strategic positioning of the plasma torch inlets and exhaust outlet, a furnace temperature controlling device during sintering so that the article being sintered does not decompose. The devices which can be used for controlling the temperature of the furnace during sintering include: (1) Tangential injection of a secondary colder gas stream into the hot primary plasma gas stream; (2) Utilization of a plasma torch or torches which can be temperature controlled to achieve stable and lower plasma gas temperatures; and (3) Introduction of a secondary cooler gas directly into the furnace sintering chamber.

Abstract: As apparatus and method is disclosed which is adapted to melt metallic fines, and which is useful for processing metallic fines into a useful form. The apparatus may also be used in the smelting of metallic oxides, and in combining metals in an alloying process. The disclosed embodiment of the apparatus includes a furnace having a hearth, a pair of tubular residence chambers each extending upwardly from the hearth, a first plasma torch mounted at the upper end of each residence chamber, and a second plasma torch mounted for heating the material on the hearth. The powdered or granular material is fed into the upper end of each residence chamber, such that the material is at least partially melted from the heat of the first torch while falling through the residence chamber, and the material is further heated and completely melted on the hearth by the second torch.

Abstract: The invention relates to a method and a means for facilitating the replacement of plasma generators and for minimizing the heat losses during installation of a plasma generator in a shaft furnace, particularly for plasma generators of the type comprising cylindrical electrodes between which an electric arc is generated, the bases of the arc being caused to rotate by means of electric field coils arranged around said electrodes. To achieve this at least the field coil (7) surrounding the electrode nearest to the nose (12) of the plasma generator, together with its connections for coolant and electricity, is permanently secured in the wall (1) of the shaft furnace in conjunction with the opening (6) for insertion of the plasma generator (11) into the shaft furnace.

Abstract: A metallurgical plasma melting process wherein a plasma burner and a separate start-up burner disposed alongside same in the same port have their axes intersecting in the furnace at an acute angle. Only the start-up burner is operated initially to form a crater in material in the furnace. Thereafter the plasma burner is ignited and the start-up burner is turned off when the plasma burner is operating at full efficiency.

Abstract: In a method for supplying thermal energy by means of a plasma arc heater to a reactor filled with solid, lump reduction material, the thermal energy is supplied via an outer or transferred arc, one electrode of which is formed by the heater and the other electrode of which is formed by the reduction material in the reactor.

Abstract: A burden of either or both CaO or CaCO.sub.3 and coal is melted and reduced by a plasma torch established between a plasma burner penetrating the upper structure of a furnace and an electrode in the bottom of the furnace to produce CaC.sub.2. The burden is supplied to the furnace from above and the CO produced by the reaction flows upwardly through the unreacted burden to pre-heat and pre-reduce it.

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: A melting furnace or cupola utilizing electric arc heaters to provide an arc-heated air stream to melt loose metal chips as well as larger pieces of metal scrap. In one embodiment, the arc-heated gas stream and metal chips are directed into a melting segment with the melted chips and gas stream passing therefrom into the furnace through a tuyere. In another embodiment an electric arc heater serves as a tuyere for the furnace with the metal chips being fed into the arc-heated stream at the outlet of the arc heater. The chips and arc-heated air stream immediately enter the furnace wherein melting of the metal chips occurs. With either embodiment, recycling of the gases in the furnace and metal chip preheat can be provided.

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 metallurgical plasma melting furnace for the melting of metals and alloys is provided with a substantially cylindrical melting vessel and a plurality of plasma burners disposed in burner openings in the walls of the vessel for creating flow stable plasma arcs. The vessel includes a first vertical cylindrical domain and a second vertical cylindrical domain divided by a vertical longitudinal plane and wherein the burners are located in the first cylindrical domain facing the second cylindrical domain and positioned such that the points of intersection of the projections of the burner axes are disposed in the second cylindrical domain and the distance between the intersection points is less than the radius of the vessel.

Abstract: In a method of, and arrangement for, producing molten pig iron or steel pre-material iron-oxide-containing raw-material particles are top-charged into a fluidized bed formed of carbon particles and an oxygen-containing carrier gas. When passing the fluidized bed, the raw-material particles are heated, reduced and smolten. In order to achieve a better utilization of energy with such a method, i.e. to considerably lower the total energy input, additional energy is supplied to the fluidized bed by plasma heating.

Abstract: A tuyere for injecting hot reducing gases into a furnace is provided with an inlet pipe and a plasma oven whose gas outlet axis is inclined to the longitudinal axis of the tuyere. The angles which the outlet axis of the plasma oven and the inlet pipe form with the said longitudinal axis are such that the longitudinal axis is parallel to the vector sum of the amount of movement of the gases from the plasma oven and the inlet pipe respectively .

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 gas generating shaft substantially filled with a solid reducing agent and a plasma burner arranged in the lower portion of said shaft. An oxidant is injected 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.