Abstract: A paint or coating composition which contains only pure Ziroconium containing compounds, and a small amount of NH.sub.4 (OH).sub.2 and acid is applied to the vertical walls of a vacuum arc furnace Copper crucible to form a stable, substantially uniform, coating thereon. The Zirconium coating composition of the present invention is free of Aluminum and Aluminum compounds and consists essentially of Zirconium Oxide suspended in a water-based Zirconyl Nitrate gel, to which small amounts of base and acid have been sequentially added. This coating eliminates the introduction of spurious impurities into the surface of the zirconium ingot formed during vacuum are melting of a zirconium compact.

Abstract: An electric direct-current metal-melting furnace, comprising a vessel (1) having a bottom (11), at least one consumable electrode (2) and at least one fixed electrode (3) which are fed by respective conductors (22; 5). A magnetic screen is interposed between the batch and a part of the conductors connected to the current source (4), so as to master the deflection effects on the arcs attributable to the magnetic fields generated by the conductors. The magnetic screen is arranged along the bottom (11) of the vessel (1), so as to cover at least that part of the bottom which surrounds each connection of a hearth electrode (3) and at least part of the corresponding return conductor (5).

Abstract: A new method of making an electrically conductive hearth in a d.c. furnace is effected by first heating bricks such as magnesite-graphite bricks and the like, from their new commercially available form to high temperatures decresing the normal resistivity of the bricks and thereafter laying the bricks to form the hearth from top to bottom with the heat treated bricks.

Abstract: An electrical metallurgical furnace including a vessel and a bottom electrode positioned in the bottom of the vessel. At least one counter contact is provided connected to the bottom electrode. A support is anchored to the vessel connected to the insulation mounting unit. A tension frame is held by the insulation mounting unit. At least one current cable is provided for engagement with a side of the counter contact. A pivot element is provided for supporting the current cable. A biasing apparatus is provided for urging the pivotally supported current cable into contact with the counter contact.

Abstract: A hearth for use in a furnace, which comprises an upper layer of magnesia containing chromic oxide, a lower layer containing graphite and an organic bonding agent, and an intermediate layer of a mixture of the materials forming the upper and lower layers. The hearth is particularly useful in DC arc funaces, in which steel rods embedded in the bottom act as the anode. The hearth has improved service durability.

Abstract: A waste melting apparatus includes a waste melting vessel placed in a furnace body made of nonmetallic material and an induction heating coil is provided around the furnace body. The waste melting vessel is made of conductive ceramic material such as C-SiC or C-Al.sub.2 O.sub.3 so that the vessel itself generates heat by induction heating to melt waste in the vessel effectively and safely even within a temperature range of 1,300.degree.-1,600.degree. C. The furnace body may be provided with a vertically movable bottom plate for openably closing the bottom of the furnace body permitting the waste to be melted and solidified in the waste melting vessel in a batch-type system. Alternatively, the waste melting vessel may be provided with a melt discharge pipe at the bottom thereof and the discharge pipe downwardly extends through the bottom plate of the furnace body and thereby the waste can be continuously melted and discharged from the melting vessel into a container placed under the discharge pipe.

Abstract: A melting furnace and method for melting metal comprising the injection of inert gas into molten metal at a defined location as a concentrated plume to create localized surface agitation, and high quality refractory surrounding the gas injection means at the furnace bottom.

Abstract: A semiconductive crucible is provided for use in an electric arc furnace. The semiconductive crucible diverts and diffuses the protons around the anode before completing the electric circuit to form an arc, and thereby reduces the risk of a wayward arc reaching and scarring the wall of the mold.

Abstract: Electric arc furnace and method suitable for use in the decomposition of hazardous materials such as polychlorobiphenyls (PCBs) and the like. The furnace has an electrically conductive hearth which is connected electrically to the bottom wall of the furnace shell. The arc producing potential is applied to the upper portions of a central electrode and the outer shell of the furnace, and the arc current flows in a coaxial manner in the central electrode and the side wall of the outer shell. The electrical connection between the hearth and the bottom wall of the outer shell is made by a plurality of electrode plates which extend upwardly from the bottom wall into the hearth. The electrode plates are arranged in a circular pattern of slightly greater diameter than the lower tip of the electrode, and the arc has a radial field component which causes it to rotate about the lower tip of the electrode.

Abstract: In an electric DC are furnace having a vessel with a jacket and a bottom, electrodes are arranged in the bottom which electrodes are comprised of wear and consumable element, penetrating a refractory lining of the vessel for engagement with molten metal in the interior of the vessel. The consumable element being provided with an axial blind bore including a copper sleeve is inserted which sleeve, in turn, receives a heated tubular element for the conduction of cooling medium; a graphite layer is provided in the fireproof lining and extends parallel to the jacket, this layer at least partially embracing and enveloping the consumable electrode element at least to some extent, as far as the length extension of the bottom electrode is concerned.

Abstract: A DC arc or resistance melting furnace has a current supply line and a coolant supply line located in the furnace heart in the connection is constructed so that a point of separation is provided between an attachment assembly for the current and cooling lines and the vessel. The attachment assembly is formed at the terminal and fastened to the furnace vessel at a contact point. When changing the contact electrodes, it is a simple matter to undo the point of separation of the electrodes from the assembly without removing the coolant lines or the whole assembly may be removed.

Abstract: In a direct-current arc furnace, the service life of the bottom electrode can be extended substantially, if the cooling unit cooling the bottom electrode during the melting operations is not switched off during longer stoppages, as has been customary thus far, but continues to be operated at a reduced cooling output during at least a part of the stoppage. The cooling unit is preferably controlled during the stoppage according to such a program and in dependence of the respective measured temperature of the bottom electrode, so that the temperature of the bottom electrode is maintained within a preset range.

Abstract: The contact connection of the contact electrode of an arc or resistance melting furnace with the supply terminal there is arranged at the base plate of the contact electrode a contact pipe which engages into a contact sleeve at the supply terminal includes a contact sleeve which is pressed against the contact pipe by means of a press-on desk.

Abstract: To assure a high degree of operating reliability during operation of pot furnaces, their bath electrode (2, 14, 17, 20) in the pot (1) must be cooled intensively by external cooling. If the pot (1) is in the pot furnace station, cooling of the bath electrode (2, 14, 17, 20) is not a problem. But the case is different when the pot (1) is transported to various stations which can be geographically far apart--e.g., on the one hand, to a melting furnace and, on the other hand, to a continuous casting machine. In the latter case, feed and removal devices for a coolant have been constantly carried with the pot (1). However, this makes a considerable expense necessary. By the dimensioning according to the invention of the bath electrode (1, 14, 17, 20) and/or by attachment of additional cooling bodies (15, 18, 22, 14), the bath electrode (2, 14, 17, 20) can be successfully uncoupled from external cooling (8, 9, 10) over the relatively long handling period that is necessary for operational requirements.

Abstract: Electrically conductive refractory bricks, containing particles (e.g. flakes) of graphite or other electrically conductive material are pressed into the desired final shape but include a plurality of passages, none of which passes completely through the brick. The passages each extend substantially perpendicularly to the predominant direction of the conducting particles.

Abstract: A direct current arc or resistance melting furnace includes a contact electrode produced as an exchangeable assembly outside the furnace and introduced into an opening provided in the bottom of the furnace tank. An annular gap between a refractory lining of the furnace tank and the contact electrode assembly is tamped.For exchanging the contact electrode assembly, it is detached from the lining with the aid of pressure elements (telescoping cylinders) arranged below the furnace tank and lifted upward far enough for the contact electrode to be pulled out of the furnace tank by the grip of a pulling device. Then a new contact electrode assembly is inserted.

Abstract: The electrode structure, embedded in a refractory lining (1) covering the wall (2) of a vessel containing the bath (5) of metal, flush at one (4) of its ends with the inner surface of the refractory lining and projecting at its other end (6) out of the vessel, is of the type comprising an electrically conductive central core (3) extending through the wall (3) of the vessel and a cooling jacket (11) disposed around the central core (3) and in close contact therewith. The feature of the electrode structure is that the central core (3) is connected by its end (6) outside the vessel to an electric supply terminal (7), the zone of the central core (3) adjacent to the outer end (6) and in facing relation to the cooling jacket (11) being electrically insulated from the cooling jacket.

Abstract: An electrically heated melting furnace, preferably a direct current electric arc furnace, having a floor provided with a lining of refractory material and with an electrode comprised of a plurality of electrically conductive paths formed of an electrically conductive material which extends through the lining of refractory material from the inner floor surface toward the exterior, wherein the service life of the lining is improved in that the electrically conductive paths are composed of layers of at least one high melting point nonmetallic material which are connected with the refractory material, and which have a thickness of at most 5 mm.

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: The device according to the invention consists mainly of:an inner part passing through the wall of the furnace and comprising a metal core 7 extended by a cooled plug 10, the free end of the core opposite to the plug being in contact with the molten mass of metal present in the furnace,a sleeve 11 made of thermally conductive material, which is cooled as a result of the circulation of a cooling fluid and which surrounds the core 7,and means 29 of connecting the metal core 7 to an electrical supply.The device according to the invention is characterized in that it also presents a separation space 12, formed between the sleeve 11 and the metal core 7, and an elastic fastening system 33, 34, 35 tending to return the said core 7 to its initial position given by assemblage.The device according to the invention is advantageously used as a hearth electrode in direct-current arc furnaces, specially for the iron and steel industry.

Abstract: A cold hearth melting system has confining side wall area made of high thermal conductivity material and has as its bottom a diaphragm containing an orifice through which metal melted in the cold hearth is discharged. The diaphragm is made, at least in the central portion thereof containing the orifice, of material selected from the group consisting of tungsten, an alloy containing tungsten and having a melting point of at least about 3000.degree. C., cemented tungsten carbide and tantalum carbide.

Abstract: Electrical connecting device to be placed in contact with a molten metallic mass, comprising an elongated metallic body (5) introduced through the wall of a container, to be placed in contact with the metallic bath by one of its ends, the other end constituting a terminal portion (8) projecting to the outside of the container wall, a sleeve (9) made of good thermal and electrical conductive material surrounding and contacting the terminal portion, the sleeve being connected to a charged electrical source and cooled by circulation of a cooling fluid. The device is used when contact between an electrode and a molten mass is required, and eliminates the risk of tapping from excessive melting of the electrode.

Abstract: Bottom electrodes (6) of direct current arc furnaces, especially during the overheating phase of the melting process, are subjected to very high thermal stresses. As a result of a melting bath flow brought about by electromagnetic forces, the heat supply from the overheated melting bath (13) to the bottom of the electrode(s) (6) is increased still further. This is manifested in a melting back of the metallic component (6') of the bottom electrode in the direction of the furnace crucible base (4). When both the metallic component (6') and the non-metallic refractory component (7') of the bottom electrode (6) are arranged in the direction of the electromagnetic field, that is, in the peripheral direction of the bottom electrode (6), the length (l) of the electrode component is greater than its width (b).

Abstract: An electrode assembly for a furnace having a refractory lining. The electrode assembly has a conductive casing which houses a replacement body. The casing is sheathed by a conical refractory component with the broad end of the component disposed at the exterior of the furnace and the narrow end adjacent the head of the electrode. The replacement body of the electrode has a central bore, a chamber at the head of the electrode, an annular slit defined between the replacement body, and an outlet through which a cooling fluid is circulated by a suction pump connected to the electrode through the outlet. The electrode head is arranged in the refractory lining of the furnace to provide a space for the deposit of solidified molten melt which forms a protective layer over the electrode head.

Abstract: A DC arc furnace having an electrically conductive hearth adapted to contain a melt, and at least one arcing electrode above the hearth and adapted to form a heating arc with the melt when the hearth and electrode are supplied with DC power; the hearth having a wear lining directly contacted by the melt and formed by refractory material through which electrical conductors extend from the bottom of the wear lining to its top. A metal plate under the wear lining electrically connects with the conductors and is supported by one or more electrically non-conductive layers of refractory. Power connection to the wear lining is via the plate and a connection with the periphery of the plate.

Abstract: The shape of the furnace hearth (20) in the area of the bottom electrode (6) is defined within limits given by exponential functions, with minimum and maximum values being given for the ratio of the cross section (A.sub.L) of the melting bath (13) to the cross section (A) of the bottom electrode (6) in its melting bath contact surface (6', 7'). The electrode is designed in the shape of a truncated cone, with the cone surface enclosing an angle of at least 20.degree. with the melting bath contact surface. The trumpet-shaped or conical widening of the furnace hearth surface (20) in the area of the bottom electrode makes possible a continuous transition of the current and of the electromagnetic field in this area, by which means the bath movement near to the melting bath contact surface (6', 7') of the bottom electrode (6) is also reduced.

Abstract: The electrode pins for an arc furnace are individually and separately mounted in the bottom of the furnace vessel in that the refractory lining of the vessel is provided with apertures receiving individual refractory perforated bricks traversed individually by an electrode pin, the electrode pin is secured in an insulated fashion to the metal jacket of the vessel and traverses the perforations of the bricks, moreover the pin is connected through appropriate clamping facilities to the cooled anode current feed mounted insulatedly underneath the bottom of the vessel.

Abstract: In a direct current electric arc furnace with at least one movable electrode and at least one part of the bottom of the furnace of electrically conductive material, used as a return electrode, that part of the furnace bottom is formed of an assembly of diverse coacting parts, namely:a easily removable electrically conductive prefabricated element in contact with the metal bath,an intermediate part of electrically conductive granular material,and a terminal metal part, in contact with the intermediate part, electrically insulated from the shell of the furnace, comprising a metal collector plate whose upper surface is in contact with the intermediate part, and having a terminal metal rod on the lower face. That lower face and the metal rod are in contact with a non-conductive refractory material. The extremity of the metal rod protrudes outside the furnace, is cooled and is connected to the power supply. The furnace bottom can also include at least one porous body for blowing gas into the metal bath.

Abstract: A direct-current electric arc furnace for melting metals, including a furnace vessel and at least a pair of electrodes, wherein a bottom electrode is mounted in the bottom of the furnace vessel. In order to be able to remove the bottom electrode, the cross-section of which tapers towards the interior of the furnace vessel, from the outside in the direction of the furnace vessel interior, the bottom electrode is provided with a molded body of a refractory material. The molded body envelopes the bottom electrode and in combination therewith forms an electrode unit. This electrode unit in turn has a cross-section which expands in the direction of the furnace vessel interior or at the most remains the same. In this way, extensive work can be saved by removing the bottom electrode from outside into the interior of the furnace.

Abstract: A direct-current electric arc furnace for melting metals, including a furnace vessel and a bottom electrode mounted in the bottom of the furnace vessel. To prevent molten metal from contacting with current-carrying and liquid-cooled parts of the bottom electrode in the event of an unforeseen break-out of the furnace vessel bottom of the electric furnace, a shielding roof is provided as a guard between the furnace vessel bottom and the current-carrying and liquid-cooled parts. The shielding roof is formed in the shape of a truncated cone and is open downwards. The shielding roof is preferably rigidly joined to the furnace vessel bottom and is formed at least in part with a roof made of refractory material.

Abstract: A direct-current electric arc furnace for melting metals including a furnace vessel and at least a pair of electrodes, wherein a bottom electrode is mounted in the bottom of the furnace vessel. In order to be able to provide good cooling for the bottom electrode, a connecting piece directly or indirectly cooled is provided in contact with the bottom electrode and serves as a contact sleeve. The contact surfaces of the connecting piece expand conically in the direction of the furnace vessel bottom. By pairing the external truncated cone of the bottom electrode with the internal truncated cone of the connecting part, a proper electric and thermal contact is made between the two parts. In addition, the contact sleeve is provided with cooling ducts for a liquid cooling system which further enhances the cooling effect.

Abstract: An electric arc furnace for melting metal, especially steel, includes a container having an upper open ended substantially cylindrical wall portion and a lower cylindrical wall portion extending downwardly therefrom and being closed at the bottom and receiving during operation of the furnace a bath of molten material having an upper level at a predetermined maximum elevation above the bottom of the container. The container includes an outer metal shell and refractory material covering at least the lower wall portion of the shell and the closed bottom. In order to increase the charging volume of the container without essentially changing the height thereof, the upper wall portion has, at a distance of at least 300 mm above the level the bath of molten metal, an inner diameter which is greater than the outer diameter of the metal shell of the lower wall portion.

Abstract: The combination of an electric furnace and a slag retaining pouring spout thereon in registry with a modified tap hole is disclosed. The tap hole located in one end of the electric furnace communicates with the interior thereof and the slag retaining pouring spout is positioned on the electric furnace and in communication with the tap hole. The slag retaining pouring spout is angled upwardly and outwardly with respect to the tap hole and positioned above of the molten metal and slag in the operating electric furnace and receives molten metal from the electric furance when the same is tilted to pour the molten metal through the tap hole. The slag retaining pouring spout has a secondary tap hole therein normally closed with a consumable plug during the operation of the electric furnace and the early tap of the molten metal therefrom into the slag retaining pouring spout.

Abstract: A DC arc furnace has a side wall and an electrically conductive hearth, a roof on top of the side wall and over the hearth, an arcing electrode depending through the roof, a plurality of electrical hearth connections extending from the hearth, a first DC power conductor connecting with the hearth connections to provide current and therefore magnetic field symmetry preventing arc deviations, the first and second conductors are extended from a position horizontally offset from the furnace to a point below the hearth and aligned vertically with the electrode, the first conductor forming at least two branches which extend from the point horizontally in opposite directions to beyond the side wall and upwardly so as to jointly connect with the arcing electrode, the second conductor forming at least two branches which extend horizontally from the point in opposite directions with one branch connecting with one of the hearth connections and the other branch connecting with the other one of the hearth connections.

Abstract: A DC arc furnace has an electrically conductive hearth adapted to contain a melt, and at least one arcing electrode above the hearth and adapted to form a heating arc with the melt when the hearth and electrode are supplied with DC power. The hearth has a wear lining directly contacted by the melt through which electrical conductors extend from the bottom of the wear lining to its top. Layers of electrically conductive bricks are under the wear lining and have a top layer electrically connecting with the electrical conductors, and a melt plate under the layers of the electrically conductive bricks is connected to DC power. The layers of conductive bricks have a bottom layer in electrical connection with the melt plate. The improvement comprises a layer of mixed bricks between the top and bottom layers of the electrically conductive bricks and formed by alternating electrically conductive and non-conductive bricks.

Abstract: A DC arc furnace electrically conductive hearth brickwork wear lining has metal electrical conductors extending through it which are molten for their upper portions when working and by electromagnetic flowing can erode the bricks of the brickwork. To prevent this erosion resistant refractory shields are positioned so as to shield the bricks from such flows.

Abstract: The invention concerns a vacuum arc melting and casting furnace comprising a vacuum chamber, a tilting crucible and a current connection leading to the bottom of the tilting crucible. This current connection consists of a fixed contact and of a co-operating contact arranged on the bottom of the crucible and movable with the tilting crucible. Also provided is an electrode rod for holding an electrode concentrically in relation to the tilting crucible.The fixed contact is secured on at least two current conductors which are substantially coaxial with the electrode rod or electrode. These conductors pass through the vacuum chamber from the top and extend past the tilting crucible, and their distance apart is such that the crucible can be tilted between them into the casting position.

Abstract: A method of producing aluminum is carried out in an electric arc furnace having primary and secondary zones separated by a divider constructed to permit the flow of molten but not gaseous products between zones. The method includes providing a charge of carbon into the primary zone containing a mixture of aluminum and aluminum carbide and providing a charge of alumina to the secondary zone, simultaneously heating the zones to react said carbon with the aluminum to form aluminum carbide in said mixture, flowing the mixture into the secondary zone, reacting the aluminum carbide in the mixture with alumina to form additional aluminum and an aluminum oxycarbide slag, flowing the slag to the primary zone for reaction with the aluminum carbide to form aluminum in the mixture, and tapping aluminum from the secondary zone.

Abstract: An electric furnace or electric arc or resistance melting furnaces comprises a housing with a refractory lining which defines a furnace hearth in the housing and with a plurality of electrodes extending through the refractory having one of their ends terminating in the hearth and the opposite ends extending out of the housing. A plate is arranged in spaced relationship to the housing on its exterior and is connected to the opposite ends of the electrodes. The plate is arranged to define a cooling space outside of the housing which surrounds the electrodes. A cooling fluid is circulated into the cooling space and over the electrodes.

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 reduction cell pot used in the production of aluminum by fused salt electrolysis comprising an outer steel shell, a thermally insulating layer and an inner lining comprised essentially of carbon.At least the lower 80% of the floor insulation, preferably at least the lower 90%, comprises a layer of volcanic ash which has been compacted by mechanical means. The rest of the floor insulation consists of a leakage barrier which protects the volcanic ash from bath components which penetrate the carbon lining.

Abstract: A smelting furnace, the refractory sole (3) of which is contained in a metallic casing (5) having expansion joints (6, 7, 7'), comprises means (18, 19) for cooling the expansion joints, these means enabling to solidify actually any liquid phase that might tend to infiltrate into the joints.

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 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.