Abstract: A castable refractory composition comprising: (a) 50-90 vol. % coarse particulates having a particle size between about 1 and 60 mm; and (b) 10-40 vol. % fine filler materials having a particle size distribution of between 0.0001 to 3 mm.

Abstract: A method for manufacturing a reinforced cementitious columnar structure comprising: (a) providing a mold having a cavity which corresponds to a shape and size of the columnar structure; (b) filling the cavity with dry coarse particulates to form a formed dry body comprising 50-90 volume percent coarse particulates having a particle size between about 1 and 60 mm so as to form a core volume; (c) introducing a slurry of cementitious material containing an amount of fine material which has been determined beforehand, the fine material having a particle size smaller than the size of interstitial voids of the coarse particulates into the core volume, the fine material and the cementitious material filling the core volume and the cementitious material infiltirating and encapsulating the coarse particulates, and the fine material remaining within the core volume; (d) curing the slurry of cementitious material to form the reinforced cementitious columnar structure; and (e) separating the mold from the reinforced ceme

Abstract: A process for the manufacture of grinding elements composed of aluminum oxide, the process including the steps of (a) mixing aluminum oxide with from 0.5 to 2.5 Wt. % of an organic binder based on the aluminum oxide to provide a mixture; (b) granulating the mixture to form a granulate; (c) molding the granulate into molded pieces having grinding element shapes by applying pressure thereto; and (d) firing the molded pieces at a temperature ranging from 1500.degree. C. to 1850.degree. C. in a vertical kiln to produce grinding elements comprised of aluminum oxide.

Abstract: Process for recovering coarsely crystalline alumina hydrate from bauxite according to the Bayer process wherein, in the presence of fine seed crystals, agglomerates are initially formed in a supersaturated sodium aluminate solution at 80.degree. to 65.degree. C. The agglomerates are then conducted through a first cascade of crystallizers and, after cooling to 55.degree. to 45.degree. C., through a second crystalizer cascade. A crystal suspension is extracted from the last crystallizer of the second crystallizer cascade and fractionated into fine seed crystals and coarse product crystals.