Abstract: Large, dense chromic oxide refractory blocks containing from about 80% to about 98% chromic oxide are made by firing a green block comprising, in addition to the chromic oxide, titania and a colloidal silica having a surface area of at least about 90 m.sup.2 /g. Blocks having porosities as low as 0% are made in either an oxidizing or a reducing atmosphere. The blocks are crack-free and have a good resistance to corrosion by molten glass.

Abstract: Air heated outside the calcining zone of a shaft kiln is passed through raw material in a hopper mounted above the kiln in order to preheat the raw material. In one embodiment the preheating air is heated by an excess air burner which communicates with the hopper. In another embodiment, the hot calcined material is cooled by forcing cool air through it and the heated air is utilized as preheating air by directing it through a by-pass conduit which connects the cooling zone of the kiln with an extension of the hopper. In neither embodiment does the preheating air constitute combustion supporting air.

Abstract: This invention relates to a modular insulating article for insulating the interior of a high temperature furnace. The article comprises an outer shell-like form made of a ceramic fiber blanket, and interior layers made of ceramic fiber blanket material. The interior layers are disposed in planes which are parallel to the walls of the furnace. The layers are joined to each other and to the outer shell by means of an anchor pin and/or cement. The module is attached to the furnace wall by a mechanical anchor, preferably a "T" shaped stud, or refractory cement. The module has improved insulating value because of the disposition of the blankets and provides for the use of a high heat resistant blanket near the hot face and of lower cost high insulation blankets adjacent to the furnace wall.

Abstract: An Alumina-chromic oxide refractory composition comprising the following ingredients:Tabular alumina: 55-98%Calcined alumina: 0-10%Chromic oxide: 1-25%Fume silica: 1-4%Phosphate Compounds: 0-18%The addition of fume silica or volatilized silica improves porosity, reheat expansion, and thermal shock resistance.

Abstract: A tile which forms part of a wear-resistant lining that covers a metal backing has a tapered hole and is held against the backing by a fastening device which fits into the tapered hole. The fastening device includes a threaded element that projects from the backing into the hole and an anchor that threads over the threaded element. The anchor fits completely within the tapered hole and has a tapered side wall, the taper of which corresponds to that of the hole.

Abstract: A gun for applying moistened refractory material to the interior surface of a furnace wall while the furnace is still heated includes an extended material tube or pipe long enough to reach into the furnace, and through this tube passes an airstream having dry granular refractory material entrained in it. Near its outer end the tube is encircled by a closure which defines an annular chamber to which water is supplied, and this chamber communicates with the interior of the tube through apertures arranged in at least one circumferential row so that the water in the chamber sprays into the tube and mixes with the refractory material. Beyond the closure the tube is fitted with a nozzle extension where thorough mixing of the water and refractory material occurs. A nozzle tip having an oval discharge opening is fitted onto the outer end of the nozzle extension and the moistened refractory material issues from the discharge opening. The tip may be straight or at an angle.