Abstract: Provided are a dielectric ceramic composition of forsterite system for microwave and millimeter-wave application and a method for forming the same. Here, the dielectric ceramic composition having a small dielectric loss is used for communication devices used at microwave and millimeter-wave bands. The dielectric ceramic composition includes forsterite (Mg2SiO4) as a main element and titanium oxide (TiO2), which is partially substituted for silicon (Si) in forsterite. The dielectric ceramic composition is obtained by using 56 to 57 wt % of MgO, 33 to 42 wt % of SiO2, and 1 to 11 wt % of TiO2, and adding an additive including Li ions as a sintering aid for improving a sintering characteristic. The dielectric ceramic composition is formed by mixing MgO, SiO2, and TiO2, calcining the mixture to form forsterite powder, adding an additive including Li ion, for example, Li2CO3, and shaping and sintering the mixture.

Abstract: To provide a ceramic composition and a ceramic wiring board that can be formed by the firing at a low temperature of 1,000° C. or less, has high strength and is advantageous when electronic component regions utilizing a ceramic layer are formed thereon. A raw ceramic material or calcined powder thereof having a composition consisting of 100 parts by mass of a main component that consists of 52 to 62% by mass of SiO2, 12 to 22% by mass of MgO, and 21 to 32% by mass of CaO and 0.5 to 3 parts by mass of a boron component in terms of the oxide form is molded and fired to obtain a ceramic composition that contains a diopside crystal as a primary crystal. By forming a wiring layer with conductive material on a substrate made of the ceramic composition, a ceramic wiring board is obtained.

Abstract: Alkaline earth metal basic silicate particles having a silicate of an alkaline earth metal on the surfaces of the alkaline earth metal hydroxide particles, and having an SiO2/MO (M is an alkaline earth metal) molar ratio as a whole in a range of from 0.01 to 0.90. The particles are useful as a stabilizer for the chlorine-containing polymers.

Abstract: A ceramic sintered body comprising from 90 to 99.8% by volume of cordierite and from 0.2 to 10% by volume of mullite based on 100% by weight of a total sum of the contents of the cordierite and the mullite, and having a density of 2.48 g/cm3 or more.

Abstract: It is an object of the present invention to provide a polycrystalline MgO deposition material which is capable of obtaining a good discharge response characteristic over a wide temperature range. Additionally, it is another object of the present invention to provide a plasma display panel with an improved luminance and a material for the plasma display panel which can remarkably reduce the number of address ICs without lowering the panel luminance. In order to achieve the objects, there is provided an improvement of a polycrystalline MgO deposition material for a passivation layer of the plasma display panel. A characteristic structure is that the polycrystalline MgO deposition material is formed of a sintered pellet of polycrystalline MgO, of which MgO purity is more than 99.9% and relative density is more than 90%. Further, a Si concentration in the polycrystalline MgO is more than 30 ppm and less than 500 ppm.

Abstract: A fired spinel complex oxide is produced by firing a mixture containing a slag by-produced in chromium refining, a reducer, and a silica-containing material, and is essentially composed of: 29 to 40 percent by weight of Fe2O3; 15 to 20 percent by weight of Al2O3; 9 to 14 percent by weight of MgO; 0 to 4 percent by weight of Na2O; 9 to 17 percent by weight of Cr2O3; 14 to 20 percent by weight of SiO2; and 2 percent by weight or less of CaO. The fired spinel complex oxide shows a Cu—K? X-ray diffraction pattern in which the ratio (b/a) of the diffraction peak intensity of the silica-containing material (b) in the vicinity of 2?=26.7° to the {113} plane diffraction peak intensity (a) in the vicinity of 2?=36° is 0.1 or less.

Abstract: A method of preparing beta-spodumene bodies from a plastic batch comprised entirely of minerals, absent a glass component. The resulting structure has a stoichiometry of 1:1:4 (Li2O:Al2O3:SiO2) to 1:1:11 (Li2O:Al2O3:SiO2), and exhibits a low coefficient of thermal expansion, high porosity and high strength, and is suitable for automotive catalytic converter substrates requiring a fast light-off time. There is also provided a ceramic article having a solid-solution of beta-spodumene ranging in molar ratio from 1:1:4 Li2O—Al2O3—SiO2 to 1:1:11 LiO2—Al2O3—SiO2 wherein a component selected from the group consisting of magnesium oxide (MgO), manganese oxide (MnO), and cobalt oxide (CoO) is substituted for lithium oxide (LiO2) at 10 to 65 mole %, and optionally a minor phase of mullite (3Al2O3-2SiO2) in an amount of up to 50% by weight.

Abstract: The invention relates to a batch composition for producing a refractory ceramic shaped body, to a shaped body produced therefrom and to the use thereof. The components used are: 68 to 97 wt.-% molten magnesite, sintered magnesite or mixtures thereof, 3 to 20 wt.-% CaO and 0 to 25 wt.-% of a third component.

Abstract: The present invention relates to novel ceramic media or ceramic media coatings comprising mainly magnesia, silicon dioxide, and alumina, with forsterite and spinel as the dominant crystalline phases, which show high resistance to alkali attack at high temperature. Ceramic materials having these characteristics are particularly well suited for use as heat-exchange media in regenerative thermal oxidizers (RTOs) for the wood process industry.

Abstract: Ceramic mass and thermal transfer media suitable for use in thermal regenerative oxidizers made using a mixture of a ball clay, talc and optionally a dolomitic limestone have enhanced resistance to environments containing halogens and hydrogen halides. The media preferably comprises less than 0.25% by weight of alkali metal, expressed as the oxide, and has a cordierite: silica phase ratio of less than 1.2:1, as determined by X-ray diffraction.

Abstract: A ceramic filter for trapping and combusting diesel exhaust particulates composed of an end-plugged cordierite honeycomb structure exhibiting a pore size distribution as determined by mercury porosimetry in which the quantity d50/(d50+d90) as related to pore size distribution is less than 0.70, a soot loaded permeability factor Sf, as defined by the equation [d50/(d50+d90)]/[% porosity/100], of less than 1.55, and, a coefficient of thermal expansion (25-800° C.) of no greater than 17×10−7/° C. The ceramic filter further exhibits a median pore diameter, d50, of at least 4 micrometers and up to 40 micrometers. A method of making the filter is provided.

Abstract: Refractory investment material for forming a positive replication of a tooth structure on which a high-alumina based porcelain tooth restoration is to be formed, the material being formed from a refractory powder which includes alumina mixed with a liquid carrier comprising an aqueous dispersion of silicon dioxide.

Abstract: A ceramic sintered body comprising from 90 to 99.8% by volume of cordierite and from 0.2 to 10% by volume of mullite based on 100% by weight of a total sum of the contents of the cordierite and the mullite, and having a density of 2.48 g/cm3 or more.

Abstract: Ceramic mass transfer media suitable for use in thermal regenerative oxidizers made using a mixture of a clay, talc and optionally a dolomitic limestone have enhanced resistance to environments containing halogens and hydrogen halides.

Abstract: A low-temperature firing ceramic composition contains Sr2MgSi2O7 crystals forming a major crystal phase of the composition. This composition can be produced, for example, by a process including the steps of (a) mixing together a silica powder, a magnesia powder and a strontium oxide powder to obtain a powder mixture; (b) subjecting the powder mixture to a calcination at a temperature of 1,000-1,200° C. to obtain a calcination product containing Sr2MgSi2O7 crystals; (c) mixing the calcination product with alumina powder, boron oxide powder, lithium oxide powder, binder and ethanol to obtain a powder mixture; (d) granulating the powder mixture; (e) shaping the resulting granules into a green body; (f) compacting the green body by a hydrostatic pressing (CIP); and (g) firing the resulting compact in an atmosphere of air, thereby obtaining the composition.

Abstract: The invention relates to a batch composition for producing a refractory ceramic shaped body, to a shaped body produced therefrom and to the use thereof. The components used are: 68 to 97 wt.- % molten magnesite, sintered magnesite or mixtures thereof, 3 to 20 wt.- % CaO and 0 to 25 wt.- % of a third component.

Abstract: The invention discloses a refractory material derived from a mixture comprising: potassium phosphate, magnesium oxide, tricalcium phosphate.

Abstract: The invention relates to free-flowing refractory castable material and castings produced therefrom. Refractory nonbasic and basic refractory castable materials have been known for a long time. The traditional refractory castable materials have thixotropic properties and must be lined sing vibration technology. In the past, free-flowing refractory castable materials were solely based on alumina raw materials. Attempts to produce an aqueous, highly concentrated basic suspension which would Coma the basis of free-flowing refractory castable materials failed to meet the requirements in terms of theological properties and a low degree of to hydration of the MgO-based materials. It is the aim of the invention to provide the above-mentioned refractory castable material for the monolithic lining or repair of high-temperature equipment and for the production of refractory castings. This is achieved by providing a fine-grained and a mixed fine and coarse-grained alternative.

Abstract: A crystallized glass composition contains a principal ingredient comprising SiO2, MgO and Al2O3 and contains about 2 to 20 parts by weight of B2O3 relative to 100 parts by weight of the principal ingredient. In a ternary diagram, the weight ratio (SiO2, MgO, Al2O3) lies within a region surrounded by point A (44.0, 55.0, 1.0), point B (34.5, 64.5, 1.0), point C (35.0, 30.0, 35.0) and point D (44.5, 30.0, 25.5).

Abstract: Ceramic mass transfer media suitable for use in thermal regenerative oxidizers made using a mixture of a clay, talc and optionally a dolomitic limestone have enhanced resistance to environments containing halogens and hydrogen halides.

Abstract: A dry refractory composition having superior insulating value. The dry refractory composition also may have excellent resistance to molten metals and slags. The composition includes filler lightweight material, which may be selected from perlite, vermiculite, expanded shale, expanded fireclay, expanded alumina silica hollow spheres, bubble alumina, sintered porous alumina, alumina spinel insulating aggregate, calcium alumina insulating aggregate, expanded mulllite, cordierite, and anorthite, and matrix material, which may be selected from calcined alumina, fused alumina, sintered magnesia, fused magnesia, silica fume, fused silica, silicon carbide, boron carbide, titanium diboride, zirconium boride, boron nitride, aluminum nitride, silicon nitride, Sialon, titanium oxide, barium sulfate, zircon, a sillimanite group mineral, pyrophyllite, fireclay, carbon, and calcium fluoride.

Abstract: The present invention is directed at sintered ceramic articles exhibiting a crystalline phase assemblage comprising, by weight, of 65-95% cordierite and 5-35% of a secondary phase selected from the group consisting of mullite, magnesium-aluminate spinel, and sapphirine and having a bulk analytical composition consisting essentially of about, by weight, 32-51% SiO2, 35-49% Al2O3, 7-16% MgO. Furthermore, the ceramic articles exhibit an effective strength of greater than about 3000, a CTE of less than about 15×10−7/° C., over the temperature range of 25° C., to 1000° C., and a total intrusion porosity, as measured by a Hg intrusion method, of at least 20%. This invention also relates to a method for producing a sintered ceramic article having the aforementioned cordierite and secondary minor phase mixture.

Abstract: A synthetic silicate pellet is provided having a component(s) of calcium and magnesium, either together or in the alternative. Such pellet is further provided with either an aluminate silicate binder and/or an ion flow catalyst. The synthetic silicate pellet has use as a glass batch component.

Abstract: A method of bonding a metal to a ceramic or two ceramic materials including the steps of melting a polycrystalline magnesium orthosilicate compound; and applying the melted polycrystalline magnesium orthosilicate compound between two materials which are metal with a ceramic, or two ceramic materials, or two metallic materials, bonding using the polycrystalline magnesium orthosilicate to bond the two materials together.

Abstract: The invention relates to a porous ceramic used for producing alkali ion water. The ceramic of the invention includes finely particulate zeolite having an average particle size of 0.1 to 40 &mgr;m and an alkali ion producing material as components. Besides the above components, the invention preferably comprises a fibrous mineral and/or a clay mineral. To produce the ceramic of the invention, a slurry obtained by grinding zeolite by a wet process, a slurry obtained by grinding the alkali ion producing material and the clay mineral by a wet process and a slurry obtained by grinding the fibrous mineral are first mixed and stirred to prepare a mixed slurry. This mixed slurry is then dried and fired to obtain a sintered body.

Abstract: A method of making polycrystalline magnesium orthosilicate including the steps of contacting a silica based clay material with magnesium oxide; and sintering the magnesium oxide contacting the silica based clay material to cause a solid state diffusion of the magnesium oxide into the silica based clay material to thereby produce polycrystalline magnesium orthosilicate. Single crystalline magnesium orthosilicate can be made by melting under controlled conditions, the polycrystalline magnesium orthosilicate.

Abstract: This invention is directed to ceramic metal composite useful as a refractory and having improved abrasion, corrosion, and oxidation resistance. The ceramic metal composite of the present invention is comprised of ceramic refractory aggregate, metal particulate, and a nonaqueous binder wherein the ceramic refractory aggregate, metal particulate, and binder residuals react to form a three-dimensional ceramic-metal matrix. The ceramic-metal matrix is further stabilized by bonds between the metal particulate, reaction products of the metal particulate, and the ceramic refractory aggregate.

Abstract: A microporous insulation material contains an ingredient which exhibits a phase transition and functions to maintain temperatures attained by an object shielded by the microporous insulation material, during exposure of the microporous insulation material to a high temperature environment, at an acceptable level over a given period of time. The insulation material is especially suitable for insulating flight data and voice recorder systems. The microporous insulation material contains inorganic particulate material; endothermic compounds, (optionally) an opacifier, inorganic fiber and preferably, a dry resin or other binder. The inorganic particulate material can comprise only hydrophilic material or both hydrophilic and hydrophobic material.

Abstract: In the ceramics having a low heat conductivity, silicon nitride is contained as a main component, a composite oxide or a separate phase thereof and transition metal elements having 66 to 75 of atomic number are dispersed into a substrate, and a minute layer grown continuous to the substrate is formed on the surface of the substrate. The composite oxide is at least one of 3Al.sub.2 O.sub.3. 2SiO.sub.2, 2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2, 2MgO.SiO.sub.2 and 4MgO.5Al.sub.2 O.sub.3.2SiO.sub.2. The adding quantity of the composite oxide and the separate phase thereof is 15 to 60 wt. % in terms of the composite oxide. The adding component of transition metal elements having 66 to 75 of atomic number is less 10 wt. % in terms of oxide of the transition metal elements.

Abstract: The present invention is ceramic article of stabilized zirconia wherein the stabilized zirconia has a molar ratio of rare earth oxide:zirconia of from 1:99 to 15:85, at a weight percent of from about 97 to 75. The ceramic article includes smectite clay from about 3 to 25 weight percent wherein the article is a mass of sintered particles having a continuous tetragonal phase having dispersed therein monoclinic phase particles having size of less than 100 nm.

Abstract: The present invention relates to a refractory binder that comprises a mixture of aqueous phosphate and silica sol. The silica sol has been found to gel and set in a surprisingly effective and useful way. Preferably, the refractory binder further incorporates a small amount of magnesia as an accelerator. The present invention also provides a method of binding a refractory material such, for example, as alumina, zirconia mullite or aluminium silicate by using a refractory binder according to the invention.

Abstract: A ceramic and method of producing the same are disclosed, the ceramic having as principal ingredients natural zeolite and shells, wherein silver nitrate, magnesium oxide, potassium oxide, sodium oxide selenium oxide and ferric oxide are added thereto, and the resultant mixture fired to produce a granular ceramic. The granular ceramic enables the production of deoxidized water having an appropriately low oxidation reduction potential, for use as drinking water and the like.

Abstract: Castable refractory for a slide gate plate is mainly formed of alumina raw material and amorphous carbon raw material of 2 to 15 wt %, and contains silicon carbide and/or boron carbide, the total content thereof being equal to 0.5 to 10 wt % (the content of boron carbide is equal to or less than 3 wt %, and when the content of boron carbide is less than 0.5 wt %, silicon carbide is set to 3 wt % or more), 2 to 10 wt % magnesia of 1 mm or less in particle size, 0.2 to 3 wt % silica fine powder of 5 micrometers or less in particle size, and 0.1 to 5 wt % salt of condensate of formalin and aromatic sulfonate.

Abstract: A thermal shock-resistant alumina-mullite composite material and a preparation method thereof which are capable of concurrently obtaining the compactness of the material and a mullite formation. The material is comprised of 4.about.30 weight % of one aluminum silicate selected from the group consisting of kaolinite, silimanite, and kyanite, 75.about.94 weight % of Al.sub.2 O.sub.3 based on the total amount of Al.sub.2 O.sub.3, and 0.5.about.6 weight % of an alkaline earth metal oxide, wherein the weight ratio of the alkaline earth metal oxide to SiO.sub.2 is 1:2.about.1:3. The composition is first sintered at a temperature of 1450.degree..about.1650.degree. C. for 1.about.5 hours, then cooled down to 1000.degree. C., and then crystallized at a temperature of 1200.degree..about.1500.degree. C. for 1.about.20 hours. This composition is usable to a maximum temperature 300.degree. C.

Abstract: A microporous insulation material contains an ingredient which exhibits a phase transition and functions to maintain temperatures attained by an object shielded by the microporous insulation material, during exposure of the microporous insulation material to a high temperature environment, at an acceptable level over a given period of time. The insulation material is especially suitable for insulating flight data and voice recorder systems. The microporous insulation material contains inorganic particulate material; endothermic compounds, an opacifier, inorganic fiber and preferably, a dry resin binder. The inorganic particulate material can comprise only hydrophilic material or both hydrophilic and hydrophobic material.

Abstract: The dielectric ceramic composition for use with a laminated capacitor to be used in a high frequency region improves in costs of manufacturing by lowering the temperature of calcination as relatively high as from ca. 1,200.degree. C. to 1,500.degree. C. required for conventional ones and by reducing the expensive costs of electricity required otherwise by the manufacture of conventional ones. The dielectric ceramic composition contains a magnesium silicate-zinc component, an alumina component and a strontium titanate component, as represented by formula:Z(Mg.sub.a Zn.sub.(1-a)).sub.x SiO.sub.x+2 --YAl.sub.2 O.sub.3 --ZSrTiO.sub.3wherein a is equal to or larger than 0.1 and equal to or smaller than 0.8; and x is equal to or larger than 0.67 and equal to or smaller than 1.5; and wherein a molar ratio (%) of the magnesium silicate-zinc component, as represented by (Mg.sub.a Zn.sub.(1-a)).sub.x SiO.sub.x+2, to the alumina component, as represented by Al.sub.2 O.sub.

Abstract: The present invention is a ceramic article of magnesium-X silicate, wherein X represents lithium, sodium, potassium or other monovalent ion from about 0.1 to 2 weight percent, and yttria stabilized zirconia and alumina composite from about 99.9 to 98 weight percent wherein the yttria stabilized zirconia has a molar ratio of yttria to zirconia of from 0.5:99.5 to 5:95 and the alumina comprises from 0.1 to 50 percent of the yttria stabilized zirconia and alumina composite.

Abstract: The present invention is a ceramic article of magnesium-X silicate, wherein X represents lithium, sodium or, from about 0.1 to 2 weight percent, and yttria stabilized zirconia from about 99.9 to 98 weight percent wherein the yttria stabilized zirconia has a molar ratio of yttria to zirconia of from 0.5:99:5 to 5:95.

Abstract: A whiteware ceramic composition is provided comprising a filler, 4 to 10% by weight of a flux having a median particle size of below 6 microns, a prefired ceramic material milled separately from the other components, and raw clay constituting from 5 to 20% by weight of the composition. Fired whiteware made by firing the composition of the invention is also disclosed.

Abstract: The disclosed invention is directed to novel ceramic compositions, and to stabilizer compositions for use with those ceramic compositions. The ceramic materials are formed of rare earth chromium oxides that include a novel combination of stabilizing compounds. Also, dryer or sterilizer devices which incorporate these ceramic compositions for generating infrared radiation for drying or sterilizing various articles.

Abstract: A castable refractory which comprises a matrix, making up 100 wt % in total, composed of 3-20 wt % of magnesia clinker having a particle diameter smaller than 0.21 mm and containing more than 95 wt % of MgO and 0.5-3.0 wt % of alumina cement in terms of CaO, with the remainder being alumina, and 0.1-3 wt % of ultrafine powder of amorphous silica and 41-100 wt % of alumina coarse grains having a particle diameter of 10-50 mm, both in terms of outer percentage of the amount of the matrix.

Abstract: A castable refractory which comprises a matrix, making up 100 wt % in total, composed of 3-20 wt % of magnesia clinker having a particle diameter smaller than 0.21 mm and containing more than 95 wt % of MgO and 0.5-3.0 wt % of alumina cement in terms of CaO, with the remainder being alumina, and 0.1-3 wt % of ultrafine powder of amorphous silica and 3-9 wt % of alumina coarse grains having a particle diameter of 8-20 mm, both in terms of outer percentage of the amount of the matrix.

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: Compositions for refractory materials and methods for providing the compositions are described. A synthetic forsterite-rich refractory sand composition includes a mixture. The mixture includes: a) a carbon bridging agent, the carbon bridging agent being present in the mixture in a proportion of from approximately 5 to approximately 15 percent by weight of the mixture; and b) a synthetic forsterite-rich sand, the synthetic forsterite-rich sand being free-flowing, having a MgO:SiO.sub.2 weight ratio of at least approximately 1.2, a specific gravity of approximately 3 g/cm.sup.3, a void volume of less than approximately 50 percent by volume of the synthetic forsterite-rich sand, and a fusion point of at least approximately 1610.degree. C., wherein i) at least approximately 50 percent by weight of the synthetic forsterite-rich sand is forsterite, and ii) from approximately 3 to approximately 27 percent by weight of the synthetic forsterite-rich sand is maghemite.

Abstract: A refractory of the invention is used in casting operation, which has good spalling resistance and corrosion resistance. The refractory includes: 0.0357-2.6548 wt % of amorphous silica particles having a specific surface area within a range of 15-30 m.sup.2 /g; 8.8495-28.5612 wt % of alumina particles having a particle diameter within a range of 10-50 mm; 1.3986-18.1715 wt % of at least one of fused magnesia and sintered magnesia, which contains 0.6993-10.9041 wt % of magnesia having a maximum particle diameter under 44 .mu.m; 0.6993-13.630 wt % of alumina cement; and 45.4545-88.1417 wt % of alumina. When the refractory is used, at lease one of fused magnesia and sintered magnesia surrounds the alumina particles, which react together to generate spinel to thereby form micro-crack layer around the alumina particles for preventing propagation of cracks in a refractory structure.

Abstract: A synthetic forsterite-rich refractory sand composition for use as a taphole nozzle refractory sand for a sliding gate system of a steel ladle, the synthetic forsterite-rich sand composition including a mixture, the mixture including: a) a carbon bridging agent, the carbon bridging agent being present in the mixture in a proportion of from 5 to 15 percent by weight of the mixture; and b) a synthetic forsterite-rich sand, the synthetic forsterite-rich sand being free-flowing, having a MgO:SiO.sub.2 weight ratio of at least 1.2, a specific gravity of approximately 3 g/cm.sup.3, a void volume of less than approximately 50 percent by volume of the synthetic forsterite-rich refractory sand, and a fusion point of at least 1610.degree. C. At least 50 percent by weight of the synthetic forsterite-rich sand is forsterite; and from 8 to 27 percent by weight of the synthetic forsterite-rich sand is maghemite.

Abstract: The invention provides a ceramic body and a method of manufacturing such a body. The body is characterized by its composition, which comprises 20-30 at. % of magnesium, 20-30 at. % of silicon, 40-60 at. % of nitrogen and maximally 15 at. % of oxygen. A preferred composition corresponds to the formula MgSiN.sub.2-x O.sub.x, where x is smaller than 0.5. The manufacture of the ceramic body in accordance with the invention is simpler and cheaper than that of aluminium nitride, and a number of properties of said ceramic material are better than those of the known aluminium oxide.

Abstract: Disclosed is a porous sepiolite having an improved water-resistance and thermal shock resistance obtained by grinding, moisture-conditioning and molding sepiolite, and then calcining said molded sepiolite at a temperature in the range of about 650.degree. C. to about 800.degree. C. Also disclosed is a porous sepiolite having a large specific surface area, wherein the pores having a pore diameter of 50 angstroms or less have a specific surface area in the range of from 40 to 200 m.sup.2 /g and in which no less than 20% of the total surface of the sepiolite is occupied with the pores having a pore diameter of 50 angstroms or less and wherein the pore distribution curve of the sepiolite has a main peak at a pore diameter of no more than 50 angstroms. This sepiolite is obtained by grinding, moisture-conditioning and molding sepiolite, calcining the same at a temperature in the range of about 650.degree. to about 800.degree. C., and then subjecting said calcined sepiolite to an acid treatment.

Abstract: A process for obtaining a synthetic refractory sand for use in steelmaking, said synthetic refractory sand being free-flowing, comprising at least 50% forsterite, having semi-angular and irregularly shaped grains, lenses and flat grains, a specific gravity of approximately 3 g/cm.sup.3, a void volume of less than approximately 50%, a coefficient of thermal expansion of approximately 1.09.times.10.sup.-5 and a fusion point of at least 1610.degree. C. including the steps of: (a) agglomerating a mixture comprising a particulate starting material selected from the group consisting of serpentine-containing asbestos tailings and an enstatite-containing product produced by calcining serpentine-containing asbestos tailings and from 10% to 25%, based on the total weight of mixture, of magnesium oxides or precursors of magnesium oxides with an aqueous binder solution to obtain agglomerates of said mixture; (b) calcining said agglomerates at a temperature of from 1200.degree. C. to 1500.degree. C.