Abstract: The present invention relates to an article having an integrated contact surface, such as a melting vessel, and compositions for forming the article. The composition for forming the articles, such as melting vessels, includes from about 25% to about 99% binder material including clay and zirconia or a blend of alumina and zirconia. The composition also includes from about 1% to about 75% by weight of a filler material. The surface of the an article formed from the composition, such as a melting vessel, essentially is comprised of the binder material. The body of the melting vessel includes a blend of binder material and filler material. The present invention also relates to a process for making an article, such as a melting vessel from the composition.

Abstract: The invention relates to a bottom structure of a suspension smelting furnace to be used in a smelting furnace (1), in the reaction space (2) whereof of sulfidic raw material containing metal, such as copper, nickel or lead, is smelted in the presence of an oxygen-bearing gas and slag-forming agent, in order to render the metal in a form that is advantageous for further treatment, and where the created molten phases (5, 6) are settled onto the bottom (3) of the smelting furnace in order to separate the molten phases form each other, when the temperature of the molten phases is within the range 1150-1450° C. According to the invention, the bottom structure includes at least one arched lining layer (7) inclined in the longitudinal direction of the smelting furnace, so that the temperature on the surface (89 that is opposite to the surface that gets into contact with the molten phase is below 800° C.

Abstract: The invention relates to a fire resistant substance and to a method for producing a fire-resistant lining. The fire-resistant substance contains MgO sinter and up to 5 wt. % of a reducing agent selected from the group consisting of substances that contain carbon. The lining has several layers with decreasing quantities of reducing agents.

Abstract: A container for molten metal which uses heat of solidification for heating the molten metal.

Abstract: A lining for a bottom of a metallurgical vessel, comprising an impact pad having a plurality of close-packed, pre-formed, high-temperature, high-density refractory bricks, the pad having an upper impact surface, and a monolithic slab of a high-temperature refractory material encasing the pad, the slab encasing the pad wherein the upper surface of the impact pad is exposed.

Abstract: The invention relates to a refractory batch containing at least one refractory metal oxide component, at least one binder component, such as resin or pitch, if appropriate antioxidants, at least one carbon carrier, such as soot and/or graphite, and reinforcement fibers which are formed from a stainless steel material, which at the temperatures of use forms a coat of the refractory metal oxide on its surface, and to a shaped body made from the batch and to a process for producing the shaped body.

Abstract: The present invention is: a cooling apparatus, capable of extending the service life of a blast furnace by suppressing the molten-iron-induced erosion of a carbon brick in the sidewall of a blast furnace bottom by preventing the cooling ability for the carbon brick from deteriorating, structured to bond a metal cooler to the carbon brick with an adhesive containing carbon powder, a synthetic resin and a hardening agent, and form a bonding layer containing 50 mass % or more, preferably 50 to 85 mass %, of solid carbon between the cooler and the carbon brick; and a cooling apparatus according to the above further structured to embed anchor bolts at an end in the carbon brick, have the other end of the anchor bolts pierce the cooler, and fasten the cooler to the carbon brick with the anchor bolts by tightening lock nuts with washers having a spring function provided between the nuts and the cooler.

Abstract: The invention relates to a bottom structure of a suspension smelting furnace to be used in a smelting furnace (1), in the reaction space (2) whereof of sulfidic raw material containing metal, such as copper, nickel or lead, is smelted in the presence of an oxygen-bearing gas and slag-forming agent, in order to render the metal in a form that is advantageous for further treatment, and where the created molten phases (5, 6) are settled onto the bottom (3) of the smelting furnace in order to separate the molten phases form each other, when the temperature of the molten phases is within the range 1150-1450° C. According to the invention, the bottom structure includes at least one arched lining layer (7) inclined in the longitudinal direction of the smelting furnace, so that the temperature on the surface (89 that is opposite to the surface that gets into contact with the molten phase is below 800° C.

Abstract: A lining for use in a blast furnace preferably for use in furnaces burning bio fuels, e.g. straw or wood chips or wood shavings and the like as well as ovens in power stations where fuel having a biological origin is used includes an interior surface which is in contact with slag particles. The interior surface is clad by elements (3, 4, 12) made by a ceramic or semi-ceramic material and an insulation of a cement based foam material is arranged in one or more layers (17). The foam material is advantageously placed between the interior surface and an exterior load carrying construction which for example can be a steel pillar arranged exterior of the blast furnace. With a lining for blast furnace as describes above the risk of a collapse in the insulating material is avoided at the same time it is avoided that the interior wall deteriorates due to the chemical composition of the slag particles which are present in the bio fuelled oven.

Abstract: A refractory nozzle is provided for a metallurgical vessel, in particular for steel melts, wherein the nozzle has a flow-through opening with an upper end, a lower end, and an inner wall laterally enclosing the flow-through opening. In order to improve known discharge nozzles, in particular with regard to their thermal shock resistance, a heater and/or a thermal insulating material, that dissolves or bums upon contact with fluid steel, is arranged along the inner wall in the flow-through opening.

Abstract: Improvements to an insulating cover for covering an opening in a torpedo car are disclosed. The insulating cover includes upper and lower wire mesh layers and an insulating layer positioned between the wire mesh layers. A support rod may be provided which extends beyond the ends of the upper and lower wire mesh layers. A pair of support rods in an “X” configuration may be provided which extend beyond the side edges of the upper and lower wire mesh layers. Tie devices secure the wire mesh layers together and hold the insulating layer in position. At least one ferromagnetic plate is provided, whereby each ferromagnetic plate provides a lift point for lifting the insulating cover, such as with an electromagnet or the like. Methods for constructing the embodiments of the insulating cover are also disclosed.

Abstract: The invention concerns a crack-free insulating refractory material made from a composition comprising 20-80% by weight of a ceramic matrix, 5-40% by weight of insulating microspheres, 0.5-15% by weight of one more binders, 5-20% by weight of a metal or a metal alloy able to melt during the preheating or the first minute of use and 0-25% by weight of water. The ceramic matrix is preferably comprised of vitreous and non-vitreous grains.

Abstract: A method of handling liquid non-ferrous metals in which the liquid metal is treated while coming into contact with a solid refractory material. The invention is characterised in that the solid material is Ti3SiC2. According to one preferred embodiment, the liquid material is aluminium or aluminium alloys.

Abstract: A refractory shape is described for transferring molten metal in a continuous casting operation. The shape includes an inner surface made from an unfired composition comprising a calcium rich grain, a hydration-resistant grain, 6-28 wt. % carbon, and a binder. The unfired composition may also include an antioxidant and silica. The inner surface resists spalling and alumina deposition.

Abstract: A door for molten metal holding furnaces which includes a fixed plate with charging and inspection hole provided with two supports positioned at the sides of the charging hole and with two vertical wings positioned on an upper part of the plate and two guides are hinged to the two vertical wings and directed downwards, beyond a lower edge of the charging hole. A closing panel with gasket is equipped with lateral pins that are housed in the guides for making the closing panel slide along the guides. One or more pressure mechanisms act on lower ends of the guides and rotate the guides so as to bring the closing panel in contact with the plate and press the panel against the hole or to move it away from the plate.

Abstract: The coated device contains a coating for use with corrosive environments at high temperatures. The device has a bond coat consisting essentially of, by weight percent, 0 to 5 carbon, 20 to 40 chromium, 0 to 5 nickel, 0 to 5 iron, 2 to 25 total molybdenum plus tungsten, 0 to 3 silicon 0 to 3 boron and balance cobalt and essential impurities to provide sulfidation resistance at high temperatures. A zirconia-base ceramic coating covers the bond coat for heat resistance. Optionally, a boride or carbide coating covers the zirconia for additional resistance to erosion.

Abstract: A refractory component is provided for use in a metal producing or refining process in which the component is at least partially immersed in molten metal. The component including a graphite member (2) and a refractory sleeve (10) that covers at least part of the graphite member. A recess (12) is provided in the surface of the graphite member (2) and the refractory sleeve (10) is located in the recess.

Abstract: The invention provides a colloidal refractory system for an electric arc furnace or another pyrometallurgical converter having a hearth, a shell, and a roof. The colloidal silica refractory includes alumina having a range of about 55 percent through about 90 percent by weight, silicon carbide having a range of about 2.5 percent through about 30 percent by weight, silica having a range of about 2 percent through about 20 percent by weight, and carbon having a range of about 0.1 percent through about 4 percent by weight. An aqueous colloidal silica binder provides the silica. The colloidal refractory system has high-temperature strength and resists the attack from slag and off-gases.

Abstract: In the continuous casting of molten metal, the invention describes a refractory article for reducing deposition of inclusions on a surface contacting the stream of molten metal. The article comprises a first composition and a second composition on at least a portion of the contacting surface. The second composition includes a resin-bonded refractory composition comprising a refractory aggregate and a reactive metal. The resin-bonded refractory composition reduces deposition of inclusions relative to standard carbon-bonded or castable refractories. The second composition is particularly effective as a nose of a stopper rod or a liner for a nozzle, shroud or slide gate plate.

Abstract: In the continuous casting of molten metal, the invention describes a refractory article for reducing deposition of inclusions on a surface contacting the stream of molten metal. The article comprises a first composition and a second composition on at least a portion of the contacting surface. The second composition includes a resin-bonded refractory composition comprising a refractory aggregate and a reactive metal. The resin-bonded refractory composition reduces deposition of inclusions relative to standard carbon-bonded or castable refractories. The second composition is particularly effective as a nose of a stopper rod or a liner for a nozzle, shroud or slide gate plate.

Abstract: The present invention is: a cooling apparatus, capable of extending the service life of a blast furnace by suppressing the molten-iron-induced erosion of a carbon brick in the sidewall of a blast furnace bottom by preventing the cooling ability for the carbon brick from deteriorating, structured to bond a metal cooler to the carbon brick with an adhesive containing carbon powder, a synthetic resin and a hardening agent, and form a bonding layer containing 50 mass % or more, preferably 50 to 85 mass %, of solid carbon between the cooler and the carbon brick; and a cooling apparatus according to the above further structured to embed anchor bolts at an end in the carbon brick, have the other end of the anchor bolts pierce the cooler, and fasten the cooler to the carbon brick with the anchor bolts by tightening lock nuts with washers having a spring function provided between the nuts and the cooler.

Abstract: A lining for a bottom of a metallurgical vessel, comprising an impact pad having a plurality of close-packed, pre-formed, high-temperature, high-density refractory bricks, the pad having an upper impact surface, and a monolithic slab of a high-temperature refractory material encasing the pad, the slab encasing the pad wherein the upper surface of the impact pad is exposed.

Abstract: An unburned carbon-containing refractory suitable for lining a molten metal container, which can prevent deformation of the outer steel shell, improve the life of the container, suppress reduction in molten steel temperature, and minimize energy losses without sacrificing the life of the wear lining. A molten metal container capable of reducing energy losses and having stable durability is also provided. The unburned carbon-containing refractory contains a refractory aggregate and 30% by weight or less of a carbon raw material containing at least graphite, wherein the carbon content X (% by weight) and the thermal conductivity &lgr;(W/m° C.) of the refractory satisfy the relationship: &lgr;≦0.8X+7, and the refractory contains 20 parts by weight or more of a refractory aggregate having an apparent porosity of 10% or smaller and a greater size than 1 mm per 100 parts by weight of the total of the refractory aggregate and the carbon raw material.

Abstract: A one-piece, composite open-bottom casting mold with integral withdrawal section is fabricated by thermal spraying of materials compatible with and used for the continuous casting of shaped products of reactive metals and alloys such as, for example, titanium and its alloys or for the gas atomization thereof.

Abstract: The invention relates to an alkaline (basic), refractory ceramic hollow item.

Abstract: A system and method for performing hydrothermal treatment includes reactor vessel formed with a pressure bearing wall surrounding a reactor chamber. A liner protects the wall from exposure to temperature extremes, corrosives and salt deposits. The liner is formed with three layers: a non-porous, corrosion resistant primary layer; a porous layer; and a non-porous, secondary layer. The porous layer is sealed between the primary layer and the secondary layer. The liner is positioned in the reactor chamber with the secondary layer facing the pressure bearing wall of the reactor chamber and the primary layer facing the reactor chamber. Connectors extend through the wall of the reactor vessel and the secondary layer to allow a fluid to be pumped through the porous layer to maintain the temperature of the liner. The connectors also allow for sampling of the fluid within the porous layer to detect leaks in the primary layer.

Abstract: A tubular thermal sprayed melt containment component for transient containment of molten metal or alloy wherein the tubular member includes a thermal sprayed inner melt-contacting layer for contacting molten metal or alloy to be processed, a thermal sprayed heat-generating layer deposited on the inner layer, and an optional thermal sprayed outer thermal insulating layer. The thermal sprayed heat-generating layer is inductively heated as a susceptor of an induction field or electrical resistively heated by passing electrical current therethrough. The tubular thermal sprayed melt containment component can comprise an elongated melt pour tube of a gas atomization apparatus where the melt pour tube supplies molten material from a crucible to an underlying melt atomization nozzle.

Abstract: An element portion of a thermistor element is composed of a mixed sintered body (MM′)O3·AOx of a composition of a complex perovskite oxide presented as (MM′)O3, and a metallic oxide presented as AOx. In said complex perovskite oxide (MM′)O3, M is at least one element selected from the elements of the groups 2A and 3A excluding La in the Periodic Table, and M′ is at least one element selected from the elements of the groups 3B, 4A, 5A, 6A, 7A and 8 in the Periodic Table. Said metallic oxide AOx is a heat-resistant, metallic oxide having a melting point of 1300° C. and more, and a resistivity of AOx itself at 100° C. in the form of a thermistor element is 1000&OHgr; or more.

Abstract: An article suitable for contact with molten metal, comprising at least one wall formed from refractory material, the wall including a region having a thermal conductivity which is lower than that of the refractory material. The lower thermal conductivity region of the wall of the article may be an air-filled cavity in the wall, and the article may be a feeder sleeve.

Abstract: A graphite-containing monolithic refractory material comprises at least one component selected from alumina and alumina-magnesia spinel, which are divided into selected particle size regions, artificial graphite having a selected average particle size, and pitch powder. The refractory material may optionally comprise a selected amount of silicon carbide having a selected average particle size. The graphite-containing monolithic refractory material exhibits excellent casting workability at a low moisture content, and both excellent corrosion resistance and spalling resistance. The refractory material is suitable as a casting monolithic refractory material for lining a topedo ladle car.

Abstract: The present invention is directed to molten metal vessels and molten metal holding furnaces containing a molten metal vessel. The molten metal vessel has a double-layer structure that includes an inner layer vessel in the form of a nonoxide-containing fired casting, and an outer vessel layer made from a calcium silicate refractory. The inner layer of nonoxide-containing fired casting can be obtained by firing in a reduced atmosphere a box-shaped vessel having an open upper side and prepared by casting a monolithic refractory comprising primarily of a silicon carbide material or silicon nitride material. The outer vessel layer of calcium silicate refractory can be obtained by casting calcium silicate monolithic refractory around the inner vessel layer, and thereafter curing, solidifying and drying the resulting casting.

Abstract: Refractory wall structure for a blast furnace, in particular for a metallurgical furnace, such as for example a blast furnace with a high process temperature during operation, which wall structure is subjected to a high thermal loading. The wall structure comprises a steel outer wall, a refractory lining consisting of one or more layers of a well heat-conducting material on the inside of the outer wall, and a cooler for cooling the refractory wall structure, whereby the wall structure also comprises a permanent, well heat-conducting metallic filling in a gap in the refractory wall structure, which filling has been molten inside the gap and then after solidifying forms a low heat resistance across the gap.

Abstract: An annularly shaped piece (28) formed from refractory material is provided for a tundish (1) for continuous casting of metals for enclosing a plasma torch (18) for heating liquid metal (4). The interior wall (29) of the annularly shaped piece defines a space which widens with progression toward the bottom, the piece having an upper opening (30) and a lower opening and accommodating penetration of the lower end region of the torch (18) into the space. The annularly shaped piece (28) is fixed to a cover (24) or to the refractory walls (3) of the tundish (1), and/or is fixed to one or more dividing walls (10) which delimit a heating compartment (13) in the interior of said tundish (1), wherewith the space defined by the interior wall (29) of said piece (28) widens with progression toward the bottom of the tundish (1).

Abstract: A vessel for metallurgical purposes, for transporting molten metals, having a metal casing which accommodates a refractory lining, is composed of individual tubular lengths. Two reinforcement rings which run in the circumferential direction and are integrated in the metal casing at an axial distance from one another, and on which two bearing lugs are arranged opposite one another on the outside and are supported by in each case one plate which is connected to the reinforcement rings. If appropriate a lid attachment is fastened to the vessel edge, which lid attachment is frustoconical in cross section. The first reinforcement ring, which lies closer to the base, has an upwardly directed extension, which is designed in the form of a projection, in the area of the plate, which is designed as a shield segment. The, and the second reinforcement ring, which lies further away from the base, has a downwardly directed extension, which is designed in the form of a projection, in the area of the shield segment.

Abstract: The invention concerns a refractory material comprised essentially of vitreous or amorphous silica and presenting an improved resistance to corrosion by molten metals, principally aluminium. It contains at least 0.1% and no more than 10% by wt. of barium sulfate. It has a crystallized silica content of less than 10% and it is comprised of at least 75% vitreous or amorphous silica.

Abstract: A sintered metal ceramic crucible suitable for high temperature induction melting of reactive metals without appreciable carbon or silicon contamination of the melt. The crucible comprises a cast matrix of a thermally conductive ceramic material; a perforated metal sleeve, which serves as a susceptor for induction heating of the crucible, embedded within the ceramic cast matrix; and a thermal-shock-absorber barrier interposed between the metal sleeve and the ceramic cast matrix to allow for differential thermal expansions between the matrix and the metal sleeve and to act as a thermal-shock-absorber which moderates the effects of rapid changes of sleeve temperature on the matrix.

Abstract: A nozzle for use in continuous casting of steel simultaneously provides resistance to adhesion of Al.sub.2 O.sub.3 inclusions, damage resistance, and spalling resistance. The refractory material of at least the interior surface of the nozzle and/or the portions to come into contact with molten steel is composed of amorphous silica and alumina and has a chemical composition of 5 to 40 percent by weight of SiO.sub.2, 60 to 95 percent by weight of Al.sub.2 O.sub.3, and 3 percent by weight or less of unavoidable impurities.

Abstract: The invention provides a ladle for the preparation of metal comprising a metal case (1) provided, on its inner surface, with a refractory wall lining (3) and a refractory bottom lining (4) with a taphole (5), characterized in that the surface of the refractory bottom lining (4) in contact with the metal in preparation is a concave surface having at every point a slope in the direction toward the taphole (5).The invention also provides a method for producing such a refractory bottom lining.

Abstract: An interconnected precast module refractory leveling assembly for a metallurgical vessel is disclosed. The precast modules of the instant invention compensate for the sloping bottom of a metallurgical vessel. At least one precast module is disposed in each of two partial rings each of which is essentially a mirror image of the other so that the height of the leveling assembly varies substantially uniformly from a high point where the two mirror image portions join to a low point 180 degrees of arc displaced therefrom where the two portions again join. Each of the refractory precast modules has a slight taper in height so that the ends of each precast module are the same height as the juxtaposed ends of the adjoining precast module.

Abstract: A ladle brick leveling set for high temperature molten metal ladles in which specially shaped refractory bricks are disposed in a slightly sloping geometrical configuration so as to compensate for a sloping bottom of a high temperature molten metal ladle. The bricks are disposed in two partial rings each of which is essentially a mirror image of the other so that the height of the leveling set varies substantially uniformly from a high point where the two mirror image portions join to a low point 180 degrees of arc displaced therefrom where the two portions again join. Each of the refractory bricks has a slight taper in height so that the ends of each brick are the same height as the juxtaposed ends of the adjoining bricks.

Abstract: A refractory-lined high temperature reaction vessel comprises a refractory ring lining constructed of refractory brick, a cooler, and a heat transfer medium disposed between the refractory ring lining and the cooler. The refractory brick comprises magnesia (MgO) and graphite. The heat transfer medium contacts the refractory brick and a cooling surface of the cooler, and is composed of a material that accommodates relative movement between the refractory brick and the cooler. The brick is manufactured such that the graphite has an orientation providing a high thermal conductivity in the lengthwise direction through the brick that is higher than the thermal conductivity in directions perpendicular to the lengthwise direction. The graphite preferably is flake graphite, in the range of about 10 to 20 wt %, and has a size distribution selected to provide maximum brick density.

Abstract: A pulverulent fiber-reinforced spray mix is disclosed in which about 0.02 to 0.3 wt. % of flexible, thermoset polymer fibers resistant to decomposition at a temperature up to about 400.degree. F. are added for each 100 wt. % of other solids in the mix to form a mix which both avoids formation of mat-like structures in the dry hopper of refractory spray apparatus and provides a sprayed lining that is resistant to cracking and peeling during dry-out and preheat. The invention also comprises sprayable compositions formed by admixing water with the mix.

Abstract: Refractory materials (typically refractory bricks) having the exposed working surface treated to form a silica sand glazed surface for their utilization in iron ore reduction reactors, for example of the moving bed type, fluidized bed type, rotary kilns, or the like, and method and apparatus for treating refractory bricks before installation as well as for treating refractory linings already installed in existing iron ore reduction plants, which produce direct reduced iron (DRI), prereduced iron ores, or the like. Some operational problems, involving adherence and buildup of aggregates from small metallic iron particles on the refractory lining of said reduction reactor, are minimized with a corresponding decrease in operating costs and an increase in the availability of the DRI producing plant.

Abstract: A pyrolytic boron nitride crucible is disclosed which is suitable for producing a single crystal of a semiconductor compound of Group III and V by the LEC method. The crucible comprises a side part and a bottom part. The bottom part has an absorption coefficient of light of wavelengths between 3,700 cm.sup.-1 and 6,500 cm.sup.-1 of at most 1.7 and/or the absorption coefficient of light of wavelengths between 3,700 cm.sup.-1 to 6,500 cm.sup.-1 of the bottom part is less than that of the side part by at least 0.5. In the crucible, the heat conduction from the bottom part to material melt in the crucible is strengthened, so that the convection flow of the material melt is suppressed and the temperature distribution in the crucible can be easily controlled.

Abstract: A refractory-lined high temperature reaction vessel comprises a refractory ring lining constructed of refractory brick, a cooler, and a heat transfer medium disposed between the refractory ring lining and the cooler. The refractory brick comprises magnesia (MgO) and graphite. The heat transfer medium contacts the refractory brick and a cooling surface of the cooler, and is composed of a material that accommodates relative movement between the refractory brick and the cooler. The brick is manufactured such that the graphite has an orientation providing a high thermal conductivity in the lengthwise direction through the brick that is higher than the thermal conductivity in directions perpendicular to the lengthwise direction. The graphite preferably is flake graphite, in the range of about 10 to 20 wt %, and has a size distribution selected to provide maximum brick density.

Abstract: The procedure for manufacturing fireproof crucibles for steel-processing ladles, in which aluminum deoxidation is carried out for the total quenching of liquid steel, is such that a monolithically hardening fireproof mass with a proportion of silicon dioxide is placed between the inside wall of the ladle and a reusable plug that is installed therein. After the plug has been removed, the ladle is put into use again, at which time a layer that contains alumina builds up on the hot side of the fireproof crucible and a highly sintered layer of greater hardness forms behind this. It is intended that a procedure such as this should simplify the reestablishment of the fireproof lining when the limits of use are reached, in view of the use of a layer that contains alumina and the highly sintered layer located behind this on the inside wall of the crucible.

Abstract: The disclosed invention provides a method of forming refractory linings for maintaining refractory linings against attack by corrosive materials such as those present in steel manufacture. The method entails spraying an aqueous mixture of a refractory composition that includes at least one refractory material onto the working surface of a refractory lining. Spraying is performed to provide one or more layers of the refractory composition on the refractory lining after each exposure of the lining to corrosive materials such as those incurred in steel manufacture.

Abstract: The present invention pertains to an electrically conductive, dry, refractory ceramic mass based on a refractory oxidic matrix material containing a source of carbon, such as graphite, carbon black or petroleum coke.

Abstract: The present invention discloses a low density basic refractory lining material with improved resistance to corrosion by molten slag and metal that is especially adapted for use as a disposable liner in molten metal containing vessels. This material incorporates hollow ceramic microspheres of alumina, silica or mixtures thereof, having diameters of between about 5 and 500 microns as a density reducing material. This material may also include a stiffening agent, a set retarding agent, a foaming agent to further reduce the density, a plasticizer, and a low temperature binder. The addition of the ceramic microspheres has been found to provide reduced open porosity, improving resistance to corrosion. Also, the invention relates to methods for applying the disposable lining and vessels which include the lining applied thereon.

Abstract: A rigid ceramic refractory base for a plural-stack annealing furnace is assembled atop a base support structure utilizing a novel set of cast refractory segments, including spaced pairs of C-shaped inner segments that each are surrounded by a sub-set of outer segments. Defined between each set of inner segments and its surrounding sub-set of outer segments is a circular inner seal positioning trough that opens upwardly, and that has a tapered cross section that narrows with depth. A resilient but reinforced inner seal of novel form is installed in each of the troughs, with each of these seals utilizing upper and lower blankets of refractory fiber material that sandwich a plurality of elongate refractory fiber modules arranged end-to-end to circumferentially fill the trough.