A refractory composition is formed by preparing a set retarded fresh cementitious composition formed from a class C fly ash, a set retardant such as boric acid, and an alkali activator such as an alkali metal citrate salt, and contacting the set-retarded fresh cementitious composition with a pH regulator, such as an alkali metal hydroxide or alkali metal carbonate. The set retarded mixture provides workability and avoids equipment fouling caused by premature setting, while the alkali activator provides rapid setting when desired. The cementitious composition is shaped into a brick, panel, slab, concrete fire log, or the like and allowed to harden. The hardened cementitious composition can be heated to form a dried cementitious composition, and further heated to produce a high strength refractory composition. Fibers and/or aggregates may be included.

In order to address the technical problem of allowing an unshaped refractory material using a spinel-containing alumina cement to provide further improved corrosion resistance and slag infiltration resistance while reducing the occurrence of crack/peeling, an unshaped refractory material is provided which comprises a refractory raw material mixture having a particle size of 8 mm or less, with the refractory raw material mixture having an alumina cement at least a part of which is a spinel-containing alumina cement, and, with respect to 100 mass % of the refractory raw material mixture, the alumina cement contains CaO in an amount of 0.5 to 2.5 mass %, and the spinel-containing alumina cement contains spinel in an amount of 3.5 to 10.5 mass %.

The disclosure provides a refractory brick system comprising a chromia refractory brick for operation in the slagging environment of an air-cooled gasifier. The chromia refractory brick comprises a ceramically-bonded porous chromia refractory having a porosity greater than 9% and having carbon deposits residing within the pores. The brick may be further comprised of Al.sub.2O.sub.3. The air-cooled gasifier generates a liquefied slag in contact with the refractory brick and generally operates at temperatures between 1250 C. and 1575 C. and pressures between 300 psi to 1000 psi, with oxygen partial pressures generally between 10.sup.4 and 10.sup.10 atm. The refractory brick performs without substantial chromium carbide or chromium metal formation in the low oxygen partial pressure environment. The inclusion of carbon without chromium carbide formation provides for significant mitigation of slag penetration and significantly reduced refractory wear.

A refractory composition and processes for manufacture are provided where the compositions possess improved refractory alkali resistance and superior handling properties. Compositions and processes for their manufacture may include a plurality of ceramic particles and a binder sintered to the particles wherein the binder includes crystalline aluminum orthophosphate distributed as the result of an in situ reaction of aluminum metaphosphate with alumina. Kits provided according to the invention provide materials for use in manufacture of a composition where the kit includes aluminum metaphosphate and a nonfacile additive.

A full-fiber burner brick and a preparation method thereof, comprising mixing alumina crystal fiber and amorphous ceramic fiber with both of them being a combination of fibers of different lengths gradations, and moreover adding fine powder fillers of different particle size gradations and supplementing other additives. This enables the internal structure of the product more uniform, increases the bulk density of the product, and also benefits the suction filterability of fiber cotton blank, and is conducive to forming and improving the strength of the blank. The surface of the brick body is further provided with a coating, which can effectively protect the cotton fiber of the brick body fiber from harsh environments, improve its high temperature resistance, and help to extend the service life of the burner brick.

A method of producing refractory brick includes heating a spent Claus catalyst, reducing a particle size of the catalyst, dry mixing the catalyst with cement to form a dry mixture, adding water to the dry mixture to form a castable mixture, casting the castable mixture in a mold, curing the mold, and drying the mold to form the refractory brick.

A castable refractory material for use in the manufacture of refractory products including fused silica, ceramic fibre, microsilica and a bonding material comprising colloidal silica.

A foamed colloidal silica binder having a total porosity of about 50% to about 95% by volume can be used to make porous refractory compositions and refractory articles having a porosity of about 25% to about 75% by volume. The foamed colloidal silica binder endures mixing with refractory ingredients to form the porous refractory composition, casting the refractory composition into a refractory shape, and drying the shape to form to refractory article, without significant collapsing of the foam. The resulting lightweight refractory articles are useful in a wide variety of insulating and weight-reducing applications.

The invention relates to a refractory dry vibratable mix which sets at room temperature when water is added, for use in metallurgical vessels and comprising a refractory main component, a binder and a retarder.

There is a high-temperature tube bundle reactor built from material derived from metal oxides such as alumina-zirconia. The heat exchange surfaces of the reactor have a specific surface finish, and the bulk matrix of the material of the various components of the reactor has a specific grain, pore size and porosity characteristics. There is also a high-temperature redox process using the reactor.