Abstract: Computer-implemented methods and apparatus are provided for predicting/estimating (i) a non-equilibrium viscosity for at least one given time point in a given temperature profile for a given glass composition, (ii) at least one temperature profile that will provide a given non-equilibrium viscosity for a given glass composition, or (iii) at least one glass composition that will provide a given non-equilibrium viscosity for a given time point in a given temperature profile. The methods and apparatus can be used to predict/estimate stress relaxation in a glass article during forming as well as compaction, stress relaxation, and/or thermal sag or thermal creep of a glass article when the article is subjected to one or more post-forming thermal treatments.

Abstract: Computer-implemented methods and apparatus are provided for predicting/estimating (i) a non-equilibrium viscosity for at least one given time point in a given temperature profile for a given glass composition, (ii) at least one temperature profile that will provide a given non-equilibrium viscosity for a given glass composition, or (iii) at least one glass composition that will provide a given non-equilibrium viscosity for a given time point in a given temperature profile. The methods and apparatus can be used to predict/estimate stress relaxation in a glass article during forming as well as compaction, stress relaxation, and/or thermal sag or thermal creep of a glass article when the article is subjected to one or more post-forming thermal treatments.

Abstract: The invention relates to a melt composition for the production of man-made vitreous fibers and man-made vitreous fibers comprising the following oxides, by weight of composition: SiO2 39-43 weight % Al2O3 20-23 weight % TiO2 up to 1.5 weight % Fe2O3 5-9 weight %, preferably 5-8 weight % CaO 8-18 weight % MgO 5-7 weight % Na2O up to 10 weight %, preferably 2-7 weight % K2O up to 10 weight %, preferably 3-7 weight % P2O5 up to 2% MnO up to 2% R2O up to 10 weight % wherein the proportion of Fe(2+) is greater than 80% based on total Fe and is preferably at least 90%, more preferably at least 95% and most preferably at least 97% based on total Fe.

Abstract: A glass making process comprising a step of fining the molten glass in a fining vessel comprising a top wall portion not in direct contact with the molten glass, and a side wall portion in direct contact with the molten glass, wherein the top wall portion has a temperature T(top), the side wall portion has a temperature T(side), and T(top)?T(side)?10° C., and a glass fining system. The invention is particularly useful for glass fining systems comprising a metal fining vessel made of precious metals such as Pt and/or Pt—Rh alloys.

Abstract: A device for the refining of a glass melt at high temperatures according to the skull pot principle is provided. The device includes a skull crucible having walls that are constructed from a plurality of pipes, a high-frequency coil for coupling electrical energy into the contents of the skull crucible, and an inlet and an outlet of the skull crucible being arranged in a melt surface region of the glass melt, wherein the inlet and the outlet are essentially arranged lying opposite one another.

Abstract: A current conducting melting vessel within which glass can be melted is provided. At least two induction heating coils are provided at selected locations proximate to the melting vessel. Power is selectively supplied to the coils to thereby selectively energize the coils so that the mutual induction of current in a non-energized heating coil adjacent to an energized heating coil is prevented via a switching element in power supply circuitry associated with the non-energized coil.

Abstract: An apparatus for manufacturing a float glass includes a bottom block in which molten metal is stored and floats, a loop block which covers the bottom block and has at least one hole formed therethrough, a heater installed through the hole, and a fragment intercepting member for preventing fragments generated at the loop block from falling onto the bottom block through the hole.

Abstract: Glass raw material particles are dropped from an oxygen combustion burner 24, and the glass raw material particles are heated by a flame F of an oxygen combustion burner 24 and a thermal plasma P, to melt the particles. Liquid glass particles 30 produced by the melting fall downwardly in a melting tank 12, and fall on a surface of a molten glass liquid G in the melting tank 12. Then, an upper layer G1 of the molten glass liquid G is heated by electrodes 40, 40 of a heating apparatus 38 provided in the melting tank 12. By this method, air and residual gas generated in the molten glass liquid G and the liquid glass particles 30 fallen onto the surface of the molten glass liquid G, become bubbles, surface and are smoothly discharged.

Abstract: The melter includes a vessel and structure for introducing waste material into the vessel. Waveguide structure is provided for introducing millimeter wave electromagnetic radiation into the vessel to heat the waste material. A gyrotron is a preferred source for the millimeter wave electromagnetic radiation.

Abstract: A method of applying ultrasonic acoustic energy to a glass melt by monitoring a glass melt temperature TY and transferring ultrasonic acoustic energy from an ultrasonic transducer to the glass melt at a controller power PC and a controller frequency vC through an ultrasonic probe positioned in the glass melt is provided. According to the method, the controller power PC is controlled in response to at least (i) the monitored glass melt temperature TY and (ii) a reference glass melt temperature TR. The controller frequency vC is controlled in response to at least (i) one or more input parameters from a temperature-viscosity curve characterizing the glass melt, (ii) one or more input parameters from one or more temperature dependent impedance response models of the glass melt, and (iii) ?Z, where ?Z represents a degree to which an impedance condition ZY of the ultrasonic probe differs from a reference impedance ZR when the ultrasonic probe is positioned in the glass melt.

Abstract: The invention relates to equipment for refining a load of silicon(s) that comprises a crucible (5) including at least one sole (20) made of a first refractory material having good heat conductivity, means (26, 28) for cooling the sole, a protection member (30) made of at least a second refractory material having low heat conductivity and to be provided between the crucible and the load, and induction heating means (23, 24) of the load including a winding (23) provided in or under the sole.

Abstract: A method for melting inorganic materials, preferably glasses and glass-ceramics, in a melting unit with cooled walls is provided. The method includes selecting the temperature of at least one region of the melt is selected in such a way as to be in a range from Teff?20% to Teff+20%, where the temperature Teff is given by the temperature at which the energy consumption per unit weight of the material to be melted is at a minimum, with the throughput having been selected in such a way as to be suitably adapted to the required residence time.

Abstract: A glass for a display substrate composed of 50 to 70% SiO2, 10 to 25% Al2O3, 8.4 to 20% B2O3, 0 to 10% MgO, 6 to 15% CaO, 0 to 10% BaO, 0 to 10% SrO, 0 to 10% ZnO, 0 to 5% TiO2, 0 to 5% P2O5, 0.01 to 0.2% alkali metal, and from 0.01% to less than 0.4% ZrO2, as expressed in % by mass. The glass can have a ?-OH value of 0.20/mm or more and an area of 0.1 m2 or more. The glass is produced by mixing raw materials to provide the SiO2, Al2O3, B2O3, MgO, CaO, BaO, SrO, ZnO, TiO2, P2O5 and alkali metal contents, electrically melting the raw materials in a melting furnace constructed of a high zirconia refractory; and refining, homogenizing and forming the glass melt.

Abstract: In the method and system for producing glass reduction of reduction-sensitive ingredients in the glass is reduced or preferably is avoided during the melting and fining processes. The glass preferably has a high refractive index. During the process an oxidizing agent is inducted into a fining vessel and preferably also into a melt crucible made of a slit skull that is cooled by a cooling agent. The oxidizing agent is preferably oxygen. Furthermore a system for conducting the method is also described.

Abstract: In the apparatus for producing glass reduction of reduction-sensitive components in the glass melt is reduced or preferably is prevented during the melting and/or fining processes by introducing an oxidizing agent into the glass melt. The apparatus has a melt crucible, a fining vessel, and a device for conducting oxygen and/or ozone into the glass melt in the melt crucible and/or fining vessel, in order to suppress reduction of reduction-sensitive components of the glass melt. A preferred embodiment of the apparatus has a metallic skull crucible, which includes the melt crucible and/or the fining vessel. The apparatus preferably includes a homogenization unit connected to the fining vessel to receive glass melt from the fining vessel in order to further process the glass melt after refining.

Abstract: The present invention aims at providing a silicon electromagnetic casting apparatus which can prevent the outward deflection of a crucible 200 used in the apparatus. This apparatus has a reaction vessel 100, the conductive crucible 200 installed in the reaction vessel 100 and an induction coil 300 installed on the outer circumference of the crucible 200, wherein constant pressure is maintained in the reaction vessel 100 using a prescribed gas and the silicon inside the crucible 200 is solidified after melting it by induction heating by applying voltage on the induction coil 300. In the apparatus, a hard structure 810 made from electrical insulating material is fitted onto the outer peripheral surface of the crucible 200.

Abstract: An apparatus for use in direct resistance heating of a molten glass-carrying vessel, such as a finer or connecting pipe, is provided. The apparatus comprises a flange comprises a plurality of electrically-conductive rings that include an inner ring joined to the vessel's exterior wall during use of the flange and an outer ring that receives electric current during use of the flange. The innermost ring comprises a high-temperature resistant metal preferably comprising at least 80% platinum, and the outermost ring preferably comprising at least 99.0% nickel. This combination of materials both increases the reliability of the flange and reduces its cost. Either one or both of the width or thickness of one or both of the inner or outer rings varies as a function of angular position relative to the vessel. The width and/or thickness of the inner and the outer rings with relation to each other produces a uniform current distribution in the flange and the vessel.

Abstract: There is provided an apparatus and method for making a glass preform with nanofiber reinforcement. The apparatus comprises a container for melting one or more glass components in a mixture comprising the glass components and one or more nanofibers. The container has an opening that allows escape of any gas released from the glass components when the glass components are melted in the container. The apparatus further comprises one or more heating elements for heating the container. The apparatus further comprises one or more electric field devices, positioned exterior to the glass components, that create an electric field in a volume of the mixture in order to orient the nanofibers within the glass components when the glass components are melted in the container.

Abstract: A process for producing silicon which comprises: bringing molten silicon containing an impurity into contact with molten salt in a vessel to react the impurity contained in the molten silicon with the molten salt; removing the impurity from the system.

Abstract: It is an object of the present invention to provide a method and apparatus for efficiently remove bubbles present on a surface of molten glass, which can solve a problem that bubbles remaining on a surface of molten glass are get inside at a time of forming the glass to cause inside bubbles, to thereby provide a glass substrate of good quality, and which can improve productivity of glass substrates; and to provide a process for producing glass employing the above method for removing bubbles. The present invention provides a method for removing bubbles from molten glass, which is a method for removing floating bubbles on a surface of molten glass, wherein a floating bubble on the surface of molten glass is irradiated with at least one laser beam.

Abstract: A method of producing a glass having a SiO2—Al2O3—B2O3—RO based composition, where RO is at least one of MgO, CaO, BaO, SrO and ZnO, a melting temperature corresponding to 102.5 poise of 1570° C. or higher and an alkali content of 0.01 to 0.2% and a ZrO2 content of 0.01 to 0.3%, as expressed in % by mass. And, a method of producing a glass having a SiO2—Al2O3—B2O3- RO based composition, where RO is at least one of MgO, CaO, BaO, SrO and ZnO, a density of 2.5 g/cm3 or less, an average thermal expansion coefficient of 25 to 36×10?7/° C. in a temperature range of 30 to 380° C., a strain point of 640° C. or higher and an alkali content of 0.01 to 0.2% and a ZrO2 content of not less than 0.01% and less than 0.4%, as expressed in % by mass.

Abstract: A glass for a display substrate composed of 50 to 70% SiO2, 10 to 25% Al2O3, 8.4 to 20% B2O3, 0 to 10% MgO, 6 to 15% CaO, 0 to 10% BaO, 0 to 10% SrO, 0 to 10% ZnO, 0 to 5% TiO2, 0 to 5% P2O5, 0.01 to 0.2% alkali metal, and from 0.01% to less than 0.4% ZrO2, as expressed in % by mass. The glass can have a ?-OH value of 0.20/mm or more and an area of 0.1 m2 or more. The glass is produced by mixing raw materials to provide the SiO2, Al2O3, B2O3, MgO, CaO, BaO, SrO, ZnO, TiO2, P2O5 and alkali metal contents, electrically melting the raw materials in a melting furnace constructed of a high zirconia refractory; and refining, homogenizing and forming the glass melt.

Abstract: A method of producing a glass having a SiO2—Al2O3—B2O3—RO based composition, where RO is at least one of MgO, CaO, BaO, SrO and ZnO, a melting temperature corresponding to 102.5 poise of 1570° C. or higher and an alkali content of 0.01 to 0.2% and a ZrO2 content of 0.01 to 0.3%, as expressed in % by mass. And, a method of producing a glass having a SiO2—Al2O3—B2O3—RO based composition, where RO is at least one of MgO, CaO, BaO, SrO and ZnO, a density of 2.5 g/cm3 or less, an average thermal expansion coefficient of 25 to 36×10?7/° C. in a temperature range of 30 to 380° C., a strain point of 640° C. or higher and an alkali content of 0.01 to 0.2% and a ZrO2 content of not less than 0.01% and less than 0.4%, as expressed in % by mass.

Abstract: For permitting temperature manipulation of a melt even at a conductivity below 10?1 ??1 cm?1 and thus permitting refining of the melt at temperatures about 1700° C., the invention provides a method and a device for temperature manipulation of a melt (16), in particular in a refiner unit. The melt (16) is heated at least by ohmic resistance heating with at least two electrodes (4) that are arranged in the melt (16). At least a part of the melt (16) is cooled. The device (1) for temperature manipulation, refining, purification and homogenisation of a melt (16) comprises at least one arrangement for accommodating melt material (36, 16), defining an inner chamber, and at least two electrodes (4) for ohmic resistance heating of the melt (16). The electrodes (4) project into the inner chamber of the arrangement, in particular of a vessel (2).

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: A method for the refining of glass by means of high temperatures in a skull crucible is provided. The method includes introducing a glass melt in the skull crucible through an inlet disposed at an upper region of the skull crucible, heating the skull crucible by irradiation of high-frequency energy, and discharging the glass melt from the skull crucible through an outlet disposed at the upper region, the outlet being disposed at a place essentially lying opposite the inlet.

Abstract: A glass making process comprising a step of fining the molten glass in a fining vessel comprising a top wall portion not in direct contact with the molten glass, and a side wall portion in direct contact with the molten glass, wherein the top wall portion has a temperature T(top), the side wall portion has a temperature T(side), and T(top)?T(side)?10° C., and a glass fining system. The invention is particularly useful for glass fining systems comprising a metal fining vessel made of precious metals such as Pt and/or Pt—Rh alloys.

Abstract: A heating apparatus for the conductive heating of melts, in particular for the rapid melting-down, refining and/or conditioning of melts, is provided. The heating apparatus includes at least one electrode, as well as a first cooling system with a cooling power, which can be set and/or controlled variably.

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: A method and an apparatus for the rapid melting of glasses in a skull crucible is provided. The method and apparatus introduce high-frequency energy into the contents of the crucible by means of a coil arrangement surrounding the skull crucible, in order to heat the melt, and the batch is laid and the molten glass discharged in the upper region of the crucible, and undissolved constituents of the batch are retained by means of a cooled bridge which is immersed in the melt. The glass is taken off above the coil arrangement and is fed for further processing without flowing through the coil region.

Abstract: A current conducting melting vessel within which glass can be melted is provided. At least two induction heating coils are provided at selected locations proximate to the melting vessel. Power is selectively supplied to the coils to thereby selectively energise the coils so that the mutual induction of current in a non-energised heating coil adjacent to an energised heating coil is prevented via a switching element in power supply circuitry associated with the non-energised coil.

Abstract: The invention relates to an apparatus and a method for low-contamination melting of high-purity, aggressive and/or high-melting glass or glass-ceramic. According to the invention, for this purpose a melt is heated in a crucible or melting skull crucible by means of high-frequency radiation and is mixed or homogenized in the melting crucible. It is preferable for a gas nozzle, from which gas bubbles, e.g. oxygen bubbles (known as O2 bubbling), escape into the melt, to be provided at the base of the crucible. This alone makes it possible to achieve surprising multiple benefits in the melting skull crucible. Firstly, unmelted batch which drops into the melt in solid form, for example from above, is melted down more quickly as a result of more intensive mixing with the liquid fraction of the melt, secondly the temperature distribution in the melt is made more even, thirdly a uniform distribution or mixing of different glass constituents is achieved, and fourthly the redox state of the glass can be adjusted.

Abstract: Microwave radiation of frequency 0.1 to 20 GHz, is applied to the melt of viscosity in the range 104 to 101 Pa·s. The outside surface of heated space, where an outlet of the waveguide of microwave radiation is located, can be cooled. The microwave radiation in the melt may be reflected by the reflective metallic elements in the melt back to the place of radiation entry into the melt and shielded from the surroundings by a shielding metallic element. An outlet is provided of at least one waveguide from the source of the microwave radiation, in any direction to the outside surface of the melt, into the space with the melt of a given viscosity. At least one waveguide is led, for example, to the outside surface of the bottom of the channel of the forehearth.

Abstract: A system and method for preparing chalcogenide glass are provided that allow for larger quantities of glass to be produced with lower production costs and less risks of environmental hazards. The system includes a reaction container operable to hold chalcogenide glass constituents during a glass formation reaction, a stirring rod operable to mix the contents of the reaction container, a thermocouple operable to measure the temperature inside the reaction container, and a reaction chamber operable to hold the reaction container. The method includes placing chalcogenide glass constituents in a reaction container, heating the chalcogenide glass constituents above the melting point of at least one of the constituents, promoting dissolving or reaction of the other constituents, stirring the reaction melt, maintaining an overpressure of at least one atmosphere over the reaction melt, and cooling the reaction melt to below the chalcogenide glass transition temperature.

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: The invention relates to a method for changing glass compositions in continuously operated melting installations which has a significantly shortened melt changeover time and therefore lower costs and in which the glass quality is not adversely affected.

Abstract: In the method of making glass a glass melt is formed from starting materials in a melt apparatus, which includes at least one metal part having a metal surface in contact with the glass melt in a first region of the glass melt having a predetermined oxygen partial pressure. This method includes suppressing oxygen bubble formation in the glass melt at a contacting surface between the metal surface and the glass melt; immersing an electrode in a second region of the glass melt not including the first region, which has a lower oxygen partial pressure than in the first region, and electrically conductively connecting the electrode and the at least one metal part. An apparatus for performing the method is also described as well as glasses made by the method.

Abstract: A molten glass supply device is provided, which can solve unavoidable problems for high viscosity characteristics in connection with the conventional molten glass supply device for high viscosity glass. Such problems include improperly high heating cost caused by excessive heat radiation in a melting furnace, reduction in the grade of products deriving from an excess amount of an erosion foreign material and reduction in the product yield. High viscosity molten glass having a property in which a temperature at which the molten glass exhibits a viscosity of 1000 poise is 1350° C. or higher is supplied to a forming device through a melting furnace, a distribution portion in communication with the outlet of the melting furnace, and a plurality of branch paths branching from the distribution portion. In the branch paths, distribution resistance providing portions that provide distribution resistance to molten glass passed through the branch paths are provided.

Abstract: This invention relates to a device for melting or refining glass or glass ceramics. According to the invention, such a device is provided with the following characteristics: a channel which is arranged in an essentially horizontal manner and which is provided with an inlet and an outlet for the glass melt; and an HF coil for coupling HF energy into the melt is allocated to the channel. The channel is made of a plurality of metal pipes in a similar way to a skull pot. Said pipes can be connected to a cooling medium.

Abstract: The invention relates to a process for the production of a glass melt. For the avoidance of the oxygen reboil the process is equipped with the following process stages or steps: a melting stage a refining stage a homogenizing and conditioning stage; in which before the homogenizing and conditioning stage the melt is heated to a temperature of over 1700° C.; in which polyvalent ions are present in the melt in a proportion of at least 0.5% by wt.

Abstract: A method for equalizing temperature differences in molten glass in at least one temperature equalization zone that is in the form of a channel for transporting a glass melt. The equalization zone is located upstream from a tapping point, at which the glass is tapped into a mold in a forming machine, or the like. Resistor heating elements are provided in the temperature equalization zone side walls, bottom wall, and roof. The temperatures of the surfaces of the respective side walls, bottom wall, and roof that are in contact with the resistor heating elements are measured. The resistor heating elements are controlled by an electric controller so that the temperatures of the surfaces are substantially equal to a predetermined tapping temperature of the glass melt.

Abstract: A molten glass supply device is provided, which can solve unavoidable problems for high viscosity characteristics in connection with the conventional molten glass supply device for high viscosity glass. Such problems include improperly high heating cost caused by excessive heat radiation in a melting furnace, reduction in the grade of products deriving from an excess amount of an erosion foreign material and reduction in the product yield. High viscosity molten glass having a property in which a temperature at which the molten glass exhibits a viscosity of 1000 poise is 1350° C. or higher is supplied to a forming device through a melting furnace, a distribution portion in communication with the outlet of the melting furnace, and a plurality of branch paths branching from the distribution portion. In the branch paths, distribution resistance providing portions that provide distribution resistance to molten glass passed through the branch paths are provided.

Abstract: The invention relates to a device for melting or refining glass or glass ceramics. According to the invention, a device of this type is provided with the following characteristics: a plurality of tubes which are U-shaped and arrange side by side so that they form a cage like skull channel that is open on top, and a high frequency oscillation circuit which comprises an induction coil. The tubes can be connected to a cooling medium. The induction coil wraps around the channel in such a manner that winding sections extend along the lateral walls of the channel.

Abstract: A furnace is for melting of glass material, such as glass or glass batch, by use of microwaves. The furnace includes a container which is adapted to hold the glass material, and a device for emitting microwaves. The furnace includes a microwave absorber which is protected by a barrier from being decomposed by the glass material, the microwave absorber being adapted to absorb the energy of the microwaves and emit this energy as heat to the glass material.

Abstract: The invention relates to a method and a device for refining a glass melt according to the skull pot principle. According to the invention, the inlet and outlet are located in the upper area of the crucible and lie diametrically opposite each other.

Abstract: In order to provide a quartz glass crucible distinguished by high purity, high opacity and/or low transmissibility in the IR spectrum, it is proposed on the basis of a known quartz glass crucible of opaque quartz glass with a crucible body symmetrical in relation to a rotational axis, an outer zone (3) of opaque quartz glass transitioning radially toward the inside into an inner zone (2) of transparent quartz glass and with a density of at least 2.15 g/cm3, that according to the invention, the crucible body (1) be made of a synthetic SiO2 granulate with a specific BET surface ranging from 0.5 m2/g to 40 m2/g, a tamped volume of at least 0.8 g/cm3 and produced from at least partially porous agglomerates of SiO2 primary particles.

Abstract: A device and method for the plaining of glasses or glass-ceramics. The device is provided with a melting vat, at least two plaining containers serially connected after the outlet of the melting vat, and at least one of the plaining containers is built in accordance with the skull principle from a plurality of metal tubes comprising a cooling agent connection and a high-frequency device for inductively coupling high-frequency energy into the contents of the plaining container.

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: The Advanced Vitrification System (AVS) Melting Process is a process for vitrification of waste in a disposable canister. In the process, waste is dropped into the disposable canister from the top. While the waste is being dropped into the disposable canister, radiant energy is added to the space above the waste in the canister, such that the temperature of the gaseous atmosphere above the waste is higher than the melting point of the waste. Since only the space above the waste in the canister is heated, the temperature of the melt decreases with increasing depth of the waste in the canister. The decreasing temperature permits a small surface melt volume to be maintained and solidified product to form with increasing depth. The process continues until the disposable canister is filled, then all heating is stopped and the disposable canister allowed to cool to ambient temperature.

Abstract: Present invention suppresses undesirable effects of the bubbles trapped in a silica glass crucible on single crystallization during the pulling process under a high-temperature load. When raw material powder is melted in a mold 1, graphite components of electrodes and impurities contained in the raw material are removed by introducing hydrogen gas and/or oxygen gas immediately after the start of arc discharge. Graphite and impurities are prevented from entering the product crucible, thereby suppressing the volume increase rate of the bubbles and reducing the inner pressure of the bubbles. Gases remaining in voids of an accumulated layer of silica powder formed inside the mold 1 can be replaced with helium gas, by supplying helium gas to the accumulated layer from the mold 1.