Abstract: A process for applying a refractory castable onto a surface, comprising the steps of: (a) introducing metered amounts of a clay-free, dry refractory castable into a delivery hose, the dry refractory castable having an alumina content of about 40-95%; (b) conveying the dry refractory to a dispensing assembly under pneumatic pressure; (c) introducing water and a set modifying admixture into the dry refractory prior to dispensing the refractory castable from the dispensing assembly; and (d) spraying the hydraulic refractory castable onto a surface.

Abstract: A method of applying a refractory castable material to the surface of a structure comprising the steps of thoroughly mixing a refractory castable material comprised primarily of aggregate and a cementitious binder; conveying the refractory material under pressure through a delivery hose to a dispensing nozzle; and adding hydrated lime to the refractory castable material prior to application by the nozzle.

Abstract: A refractory castable comprised of:about 45% to about 75% by weight high alumina grain;about 2% to about 35% by weight silicon carbide;about 1% to about 8% by weight carbon;about 1% to about 8% by weight calcium aluminate cement; andabout 1% to about 10% by weight fine magnesium aluminate spinel,the spinel having a grain size of less than about 150 .mu.m (100 Tyler mesh) and being comprised of about 10% to about 33% by weight magnesium oxide (MgO) and about 67% to about 90% by weight alumina (Al.sub.2 O.sub.3).