Abstract: A metal oxide barrier and a connecting method for solving the problems in which sectors of an existing cold crucible are connected by means of a mica plate and the mica plate is damaged due to arcing and the like and in which the sectors are strongly connected by means of the mica plate and thus are difficult to replace and maintain. A cold crucible, comprising a metal oxide barrier, according to the present invention can prevent arcing, enables reduction of damage on the edge part of a water cooling sector due to a molten material and thus enhances durability. Moreover, the metal oxide barrier can easily be replaced compared to an existing mica plate and thus enables easy maintenance and repair.

Abstract: The product of a molten alkali metal metalate phase separation can be processed into a purified metal from a metal source. Metal sources include native ores, recycled metal, metal alloys, impure metal stock, recycle materials, etc. The method uses a molten alkali metal metalate as a process medium or solvent in purifying or extracting high value metal or metal oxides from metal sources. Vitrification methods using the silicate glass separation phase can be prepared as is or can be prepared with a particulate phase distributed throughout the silica glass phase and encapsulated and fixed within the continuous glass phase. Tungsten metal can be obtained from an alkali metal tungstate. A typically finely divided tungsten metal powder can be obtained from a variety of tungsten sources including recycled tungsten scrap, tungsten carbide scrap, low grade tungsten ore typically comprising tungsten oxide or other form of tungsten in a variety of oxidation states.

Abstract: A graphite crucible for electromagnetic induction-based silicon melting and an apparatus for silicon melting/refining using the same, which performs a melting operation by a combination of indirect melting and direct melting. The crucible is formed of a graphite material and includes a cylindrical body having an open upper part through which a silicon raw material is charged into the crucible, and an outer wall surround by an induction coil, wherein a plurality of first slits are vertically formed through the outer wall and an inner wall of the crucible, and a plurality of second slits are vertically formed from an edge of the disc-shaped bottom of the crucible toward a center of the bottom.

Abstract: Disclosed herein are a graphite crucible for electromagnetic induction-based silicon melting and an apparatus for silicon melting/refining using the same, which performs a melting operation by a combination of indirect melting and direct melting. The crucible is formed of a graphite material and includes a cylindrical body having an open upper part through which a silicon raw material is charged into the crucible, and an outer wall surrounded by an induction coil, wherein a plurality of slits are vertically formed through the outer wall and an inner wall of the crucible such that an electromagnetic force created by an electric current flowing in the induction coil acts toward an inner center of the crucible to prevent a silicon melt from contacting the inner wall of the crucible.

Abstract: A combustion tube mounting system releasably mounts a combustion tube to an aperture in the floor of a furnace housing. The combustion tube has a base assembly with a cam and can be manually or automatically unlocked by cam pins in the floor for selectively engaging the cam for lowering the combustion tube from the floor of the furnace. When a new combustion tube is placed on the lower seal assembly and raised, it automatically aligns and engages the upper furnace seal and engages cams on the floor of the furnace housing which lock the combustion tube in place as it is introduced into the furnace.

Abstract: Disclosed are vessels used for melting material to be injection molded to form a part. One vessel has a body formed from a plurality of elongate segments configured to be electrically isolated from each other and with a melting portion for melting meltable material therein. Material can be provided between adjacent segments. An induction coil can be used to melt the material in the body. Other vessels have a body with an embedded induction coil therein. The embedded coil can be configured to surround the melting portion, or can be positioned below and/or adjacent the melting portion, so that meltable material is melted. The vessels can be used to melt amorphous alloys, for example.

Abstract: A low temperature melting furnace using an external cooling passage includes a wall including a plurality of metal sectors, each metal sector including a cooling passage formed along a longitudinal direction thereof, and an extension tube provided outwardly from the wall and connected to the cooling passage.

Abstract: An induction melting furnace having an asymmetrical sloping bottom. The melting furnace includes: an induction coil member provided on the melting furnace so as to melt waste contained in the furnace by vitrification; a bottom unit provided in a lower part of the melting furnace, the bottom unit asymmetrically sloping downward in a direction toward a glass discharge port that is formed through the bottom unit; and a cooling member integrated with the bottom unit. Due to the asymmetrical sloping bottom of the furnace, waste in the furnace can be completely melted and can be easily discharged to the outside and, accordingly, the time and cost required to treat the waste are reduced and this improves work efficiency when treating the waste. Further, due to the insulation material, the melting furnace can be protected from electric damage that may be caused by electric arc.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: The present invention provides a metal sector and a cold crucible induction melter having the same. The cold crucible induction melter includes a wall formed of a plurality of metal sectors insulated by an insulator. Each metal sector includes an inner curved portion which forms an inner surface of the wall and is convex inward relative to the wall, an outer planar portion which forms an outer surface of the wall, and a side planar portion which connects the inner curved portion to the outer planar portion.

Abstract: A cold crucible induction melter includes an induction coil and a melting furnace. The induction coil serves as a water cooled segment to directly transmit an induced current to a molten material in the cold crucible induction melter (CCIM), improving energy efficiency. Simultaneously, the structure of the CCIM is simplified and enables a smooth discharge even when the molten material consists of a ceramic or a metal material with a high melting point. The cold crucible induction melter heats and melts waste using an induced current which is generated in a water cooled segment by a high frequency current that is applied to the induction coil. The water cooled segment and the induction coil are disposed in a vertical direction so that the induced current that is generated by the induction coil is directly transmitted to the molten material.

Abstract: An analytical induction furnace and method for combusting conductive sample materials (500) utilizing a crucible for holding a sample within the induction furnace. Less than one gram of accelerator material is then inserted into the crucible with the sample and the induction furnace is activated for a predetermined time period (503) for thoroughly combusting the sample and accelerator. In some instances, no accelerator is required with the sample at frequencies of approximately 4.5 MHz. The invention provides for the induction furnace that is actuated in an RF frequency range between 2-9 MHz with little to no accelerator for thoroughly melting the sample for use in an analytical instrument.

Abstract: The introduction of spray formed metals into critical applications in the aircraft engine and power generation industries has been hampered by the possibility of erosion of oxide particles from a crucible lining or pouring nozzle in conventional spray forming equipment. These oxide particles may become inclusions that limit low-cycle fatigue life of parts. Use of a cold-walled induction guide (CIG) with an electrical insulation layer between copper CIG elements and the liquid metal offers a means of delivering ceramic-free alloys to a spray system with improved efficiency. CIG design options facilitated by a new oven-brazed fabrication technique resolve induction coil environmental isolation issues, correct thermal strain tolerance problems, facilitate dual frequency induction designs, allow improved electrical coupling efficiency and thermal efficiency, result in improved melt flow initiation, and facilitate disassembly without damage from the solidified melt.

Abstract: A continuous- or intermittent-melt induction furnace useful for heating and/or melting semi-conductor or other materials includes an induction coil, a susceptor switchable between open and closed electric circuit modes, and a crucible. The susceptor is inductively or resistively heated in the closed circuit mode and transfers heat to material in the melting cavity to make it susceptible to inductive heating. The susceptor is then switched to the open circuit mode and the susceptible material is directly inductively heated to melt remaining solid material. A cone-shaped flow guide in the melting cavity improves molten material flow to improve the ability to draw small-particle material into the melt and increase crucible life due to improved heat uniformity. A trap passage communicating with the melting cavity and an exit opening in the crucible allows the flow of material through the exit opening to be controlled by pressure differentials on either side of the trap passage.

Abstract: Apparatus and method are provided for heating and melting of materials by electric induction heating of susceptor components in a crucible of the furnace. The susceptor components comprise at least an array of susceptor rods arranged around the inner perimeter of the crucible. A susceptor base may also be provided in the crucible with connection to one end of the susceptor rods. One or more susceptor tubes may also be used within the interior volume of the crucible. Alternating current flow through one or more induction coils surrounding the exterior of the crucible generate magnetic flux fields that couple with the susceptor components to inductively heat the susceptor components. Heat from the susceptor components transfers to the material in the crucible to heat and melt the material.

Abstract: Process for combustion and vitrification of waste in which at least one oxygen plasma jet is associated with a continuous melting device by high frequency direct induction. The crucible is composed of a continuous external shell and a sole plate, both cooled by a liquid circulating in internal channels. The inductor is placed below the sole plate. There is a gravity drain valve at the bottom or on the side.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Process for combustion and vitrification of waste in which at least one oxygen plasma jet is associated with a continuous melting device by high frequency direct induction. The crucible is composed of a continuous external shell and a sole plate, both cooled by a liquid circulating in internal channels. The inductor is placed below the sole plate. There is a gravity drain valve at the bottom or on the side.

Abstract: An induction furnace includes an induction coil, an electrically non-conductive crucible having an inner diameter disposed within the induction coil, and an electrically conductive member disposed below the crucible and having an outer diameter which is further from the induction coil than is the inner diameter of the crucible. Due to the non-conductive nature of material disposed within the crucible at lower temperatures, the induction coil initially inductively heats the conductive member, which transfers heat to the material to melt a portion of the material. Once the material is susceptible to inductive heating (usually upon melting) the susceptible material is inductively heated by the induction coil. During the process, inductive heating of the material greatly increases as inductive heating of the conductive member greatly decreases due to low resistivity of the molten material and due to the molten material being closer to the coil than is the conductive member.

Abstract: The invention relates to a method and a device for producing colored glasses. The aim of the invention is to obtain a paricularly intimate mixture and to enable a quick change of the melt at the same time. To this end, the following procedure steps are applied: a melt made of a compound or fragments of glass is produced, the glass melt is further processed in at least one additional vessel, the melt is supplied to a skull device (3) (skull pot or skull channel) during subsequent processing, a dye is supplied (6, 6.1) to the melt after the melt was in the melting station (1) but before the melt enters the skull device (3) or while said melt is in the skull device.

Abstract: A continuous- or intermittent-melt induction furnace useful for heating and/or melting semi-conductor or other materials includes an induction coil, a susceptor switchable between open and closed electric circuit modes, and a crucible. The susceptor is inductively or resistively heated in the closed circuit mode and transfers heat to material in the melting cavity to make it susceptible to inductive heating. The susceptor is then switched to the open circuit mode and the susceptible material is directly inductively heated to melt remaining solid material. A cone-shaped flow guide in the melting cavity improves molten material flow to improve the ability to draw small-particle material into the melt and increase crucible life due to improved heat uniformity. A trap passage communicating with the melting cavity and an exit opening in the crucible allows the flow of material through the exit opening to be controlled by pressure differentials on either side of the trap passage.

Abstract: A structural component for a device for the treatment of melts, especially of glass melts, having a base body of metal or of a metal alloy and a cooling system in which a cooling medium is led through the structural component for the leading-off of heat. The base body is provided with a coating of a material the decomposition temperature of which lies below the temperature of the melt, and the cooling system is designed and arranged in such manner that the temperature of the boundary layer of the melt that immediately surrounds the structural component lies below the decomposition temperature of the coating material.

Abstract: Vertical segments of a side wall of a crucible for an induction furnace are assembled at an adjustable, invariable position by screws screwed into tapped holes of a flange common to all segments. A precise assembly is thus obtained producing no deformation and no internal stresses. The segments are coated with a ceramic coating for their protection and to prevent formation of electric arcs. Junction edges of faces are rounded to achieve the same effect. Water cooling boxes of the lower furnace hearth are similarly constructed. The apparatus can, as an example, be applied to vitrification techniques.

Abstract: The invention relates to a skull pot for melting or refining glass or glass ceramics, comprising a pot wall (1), a pot base, and an induction coil (3) which surrounds said pot wall and through which high-frequency energy can be coupled into the contents of the pot. The pot wall is made up of a ring of metal pipes (1.1) which can be connected to a cooling medium, slot-type intermediate chambers being provided between adjacent metal pipes. The pot base has a run-off for the melt. The metal pipes (1.1) that form the pot wall (1) arm short-circuited with each other above the base in order to increase the degree of efficiency of the skull pot and especially, in order to even out the temperature profile of the melt throughout the depth of the melt.

Abstract: A method for solidification-controllable induction melting of alloy with cold copper crucible employs the vacuum induction furnace with cold crucible to melt metals, particularly active metals, to obtain alloy ingots having directionally solidified structure at the same time. By using the cold crucible also as a solidification mold in the melting of metal materials, controlling working parameters of the induction furnace, and changing the copper crucible design, it is possible to control the solidified structure of the melted alloy and obtain high quality ingots having impurity-free and directionally arranged or fine-crystalline structure. The problem of low metal melting efficiency in the conventional vacuum induction furnace with cold crucible due to loss of a large amount of heat carried away by cooling water for cooling the crucible can therefore be overcome.

Abstract: This invention is provided for improvement of corrosion-resistant property of a crucible and for promotion of safety in a pyrochemical reprocessing method for the spent nuclear fuel. The spent nuclear fuel is dissolved in a molten salt placed in the crucible. In a pyrochemical reprocessing method, the nuclear fuel is deposited, and the crucible (2) is heated by induction heating. Cooling media (5, 6) are supplied to cool down, and a molten salt layer (7) is maintained by keeping balance between the heating and the cooling, and a solidified salt layer (8) is formed on inner wall surface of the crucible.

Abstract: An upper ring for an induction furnace. The upper ring is cast as one piece in a holder off of the furnace. The precast upper ring may be used as a replacement for the cast in place upper rings present on previously installed furnaces or may be used in the construction of new furnaces. The electromagnetic induction coil of the furnace may be modified to include cooling turns at its upper end when the holder with the one piece cast upper ring is installed on the furnace.

Abstract: An upper ring for an induction furnace. The upper ring is cast as one piece in a holder off of the furnace. The precast upper ring may be used as a replacement for the cast in place upper rings present on previously installed furnaces or may be used in the construction of new furnaces. The electromagnetic induction coil of the furnace may be modified to include cooling turns at its upper end when the holder with the one piece cast upper ring is installed on the furnace.

Abstract: A device for the melting or purifying of inorganic substances, in particular of glass, which comprises a number of metal tubes which may be attached to a cooling medium and which are arranged next to each other, in such a way that together they form a container, a high frequency coil for the injection of energy into the container contents and a plastic coating for the metal tubes, the decomposition temperature of which lies below the temperature of the melt. The cooling system is configured and arranged such that the temperature of the boundary layer of the melt, immediately surrounding the component, lies below that of the decomposition temperature of the coating material.

Abstract: A method for solidification-controllable induction melting of alloy with cold copper crucible employs the vacuum induction furnace with cold crucible to melt metals, particularly active metals, to obtain alloy ingots having directionally solidified structure at the same time. By using the cold crucible also as a solidification mold in the melting of metal materials, controlling working parameters of the induction furnace, and changing the copper crucible design, it is possible to control the solidified structure of the melted alloy and obtain high quality ingots having impurity-free and directionally arranged or fine-crystalline structure. The problem of low metal melting efficiency in the conventional vacuum induction furnace with cold crucible due to loss of a large amount of heat carried away by cooling water for cooling the crucible can therefore be overcome.

Abstract: According to the invention, the skull pot is provided with the following characteristics: a pot wall (1), a bottom (3) and an induction coil (9) which surrounds the pot wall (1) and by means of which high-frequency energy can be coupled into the contents of the pot. The pot wall (1) is made of a ring of metal pipes (1.1) which can be connected to a cooling medium. Slits are embodied between adjacent metal pipes (1.1). The metal pipes (1.1) are bent at a right angle at the upper ends thereof in such a way that said pipes extend towards the outside, when the pot wall (1) is viewed from above, and form a collar (2). The collar (2) is surrounded by an additional wall (upper wall 4). The upper edge of said wall is situated on a higher level than the collar (2) in such a way that the melt covers the collar (2) during operation.

Abstract: Apparatus suitable for vitrifying nuclear waste comprises a tunable microwave cavity connected by a first wave guide to a source of microwave energy; cooling coils for cooling the exterior of the cavity; a hopper for loading particulate fusible material to the interior of the cavity; within the cavity a crucible made of melted and re-solidified fusible particulate material; an exit-chamber connected by a second waveguide to a second microwave source; and a pipe for supplying argon gas to the exit chamber so that a plasma torch can be generated. The separating of the crucible form the cavity walls by unmelted material gives significant advantages in case of cleaning and reduced energy consumption.

Abstract: An attachment apparatus for a heater for attaching the heater, which is configured in an almost circular shape in its side view and cut at a circumferential portion thereof to form opposite circumferential end portions, to an external peripheral portion of a heated member of a cylindrical or column shape, includes a pair of stop metal members fixed near the circumferential end portions of the heater and a spring, both end portions of the spring engaged with the stop metal members in a state being pulled by the stop metal members with a predetermined tension, respectively, the opposite circumferential end portions of the heater are attracted to each other and so the heater is elastically adhered to the external peripheral portion of the heated member.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An induction heating and melting system uses a crucible formed from a material that has a high electrical resistivity or high magnetic permeability, and one or more inductor coils formed from a wound cable consisting of multiple individually insulated copper conductors to form an induction furnace that, along with its associated power supply, provides a compact design. The system components are air-cooled; no water-cooling is required. The crucible may alternatively be shaped as a tunnel or enclosed furnace.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An induction furnace includes material between the crucible and the coil to enable easy removal when the crucible needs to be replaced. The material is made up of a slip plane material and reinforcement, and preferably comprises a laminate of flexible mica paper and glass fabric.

Abstract: An induction melting system uses a crucible formed from a material that has a high electrical resistivity or high magnetic permeability and one or more inductor coils formed from a wound cable consisting of multiple individually insulated copper conductors to form an induction furnace that, along with its associated power supply, provides a compact design. The system components are air-cooled; no water-cooling is required. The induction melting system is particularly useful for separating metal from scrap, casting molds directly from the induction furnace, and providing a continuous supply of molten metal.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An increased diameter wire is formed by drawing a feed wire through a cooled nozzle located in a cooled crucible, and through a liquid metal bath contained within the crucible. Liquid metal freezes onto the feed wire as it passes through the bath, thereby increasing the diameter of the feed wire to form an increased diameter wire product. The invention is particularly suited to forming a wire from a metal composition that would undesirably react with refractory apparatus.

Abstract: An assembly includes a tapping device for flow therethrough of molten material and a cooled inductor to be connected to an electrical source and mounted with respect to the tapping device to be inductively coupled to one of the tapping device and the molten material flowing therethrough. The inductor includes an electrically conductive induction coil having therethrough at least one cooling passage. Each cooling passage has connected thereto at least one supply line for supply thereto of cooling fluid and at least one discharge line for discharge therefrom of the cooling fluids.

Abstract: A guide tube structure for flux concentration is provided. The discharge guide tube comprises a central orifice that extends from a source of metal to an outlet in the discharge guide tube for directing a stream of melt therethrough; a structure that generates an electromagnetic field in the discharge guide tube; and an interior discharge guide tube flux concentration configuration that is capable of concentrating at least one of heat, electromagnetic field, and electromagnetic flux onto the stream of melt that flows through the central orifice. The electromagnetic field is applied at a substantially constant level.

Abstract: A solid charge of metal or alloy is placing in a crucible melting chamber defined by a monolithic refractory tubular sleeve disposed on a water cooled metallic base, an energizing induction coil disposed about the sleeve to inductively heat the solid charge to a molten state in the melting chamber including forming a skull of solidified metal or alloy on inner surfaces of the sleeve and base to confine the molten charge, and removing the molten charge from the melting chamber, leaving the skull in place on the inner surfaces of the sleeve and base. The crucible can be reused in melting another solid charge of metal or alloy after the molten charge is removed.

Abstract: A melting furnace for insulating materials is provided with a cooled crucible (10) having continuous metal side malls, a partitioned and cooled bottom (12) and at least one induction coil (28) placed under the bottom which serves as the sole heating means. The depth of the melting bath contained in the crucible and the excitation frequency of the induction coil are selected so that the depth and half of the inside radius of the crucible are less than the skin thickness of the bath.