Abstract: Alpha alumina particles are made by heating particles of alumina with an aqueous solution containing a dissolved fluorine-containing compound and an acid; separating the particles from the solution and then calcining the particles at a temperature not greater than about 1025° C. The alumina particles preferably have an LOI in the range of about 1-20 wt. %; more preferably about 1-6 wt. %. Alpha alumina particles of the invention are more readily ground into smaller particles than alpha alumina particles made by calcining at higher temperatures. The remaining soda in the alpha alumina is found to be highly soluble in hot water. The process produces low soda content (0.01 wt. % Na2O or less) alpha alumina crystals from alumina feedstocks with 0.5 wt. % or more initial soda levels. The alpha alumina crystals produced are as large as 30-40 microns. Most typically; the size range is between 2 and 8 microns.

Abstract: A method for the production of aluminum hydroxide, including reacting water in the liquid phase and aluminum at a pH above about 12.4. In this pH range, aluminum hydroxide is produced at acceptable rates both for aluminum surface areas above 75,000 mm.sup.2 /g and for aluminum surface area of less than about 50,000 mm.sup.2 per gram, and even down to 20 mm.sup.2 per gram. According to an alternative view of the invention, it is characterized by the production of aluminum hydroxide by reacting aluminum with liquid water containing choline. Aluminum hydroxide particles having unique morphologies are obtained.

Abstract: A process for producing alpha alumina particles includes steps of precipitating alumina hydrate from an aqueous sodium aluminate solution by treatment with alumina hydrate seed material and alpha alumina promoter particles; and calcining the precipitated alumina hydrate in the presence of a mineralizer. A preferred mineralizer is aluminum fluoride. The process produces alpha alumina particles having a plate-like shape and an average size of less than about 1.5 microns.

Abstract: A lightweight, porous, ceramic material is made by mixing a slurry containing a foaming agent until a constant volume of foam is achieved. The foam is then pumped or poured into a mold or form where it sets up into a cellular structure. The formed foam is then cured, dried and heated at elevated temperatures. The slurry used in making the foam is made from ceramic particles, water, foaming agent and bonding materials. The bonding materials function to provide an initial bond as the foam is generated to prevent foam collapse, a low temperature bond after the foam structure is set, cured and dried, and a final bond after heating to elevated temperatures. In a preferred embodiment, the ceramic particles used are alumina.