Abstract: A method for improving the density and other properties of caustic magnesia and sintered periclase. To improve the density of sintered periclase, acid or acid salt is admixed with magnesium hydroxide, followed by caustic-firing, pressing and high-firing. If desired, the admixture is dried before caustic-firing. Alternatively, the step of caustic-firing may be omitted. To improve the density and compactability of caustic magnesia, acid or acid salt is admixed with magnesium hydroxide, followed by caustic-firing. If desired, the admixture is dried before caustic-firing. Preferably, acetic acid is used.

Abstract: Perlite board made from expanded perlite and a binder having the property of permanent tackiness in the dry state. The board may be made by expanding the perlite, adding a tacky resin emulsion to the perlite, drying the mixture and forming it into a board-like product.

Abstract: Fire resistant, loose-fill, thermal insulation made of a mixture of particulate expanded perlite and cellulose fiber. The mixture is rendered non-settling and resistant to separation by applying a permanently tacky material to the particulate expanded perlite.

Abstract: A monolithic refractory composition including from about 63% to about 90% by weight high purity Al.sub.2 O.sub.3 ; from about 2% to 8% by weight crystalline silica having a particle size of -200 mesh; from about 2% to 6% by weight high purity Cr.sub.2 O.sub.3 ; from about 1% to 8% by weight high purity kaolin clay having a particle size of -10.mu. (micron); and from about 5% to 15% by weight phosphate binder. About 1-5% water may be substituted for Al.sub.2 O.sub.3. Preferably, the high purity Al.sub.2 O.sub.3 is a mixture of tabular alumina and calcined alumina and the phosphate binder is H.sub.3 PO.sub.4.

Abstract: An external plating arrangement for improved effectiveness in sealing off the cold end face of a refractory body, wherein the side walls of the body are sheathed with metal plates and planar portions extend normally from the plates and overlie the cold end face for encasing the perimeter of the cold end face. A separate metal plate may cover the cold end face, the planar portions having a form of elongated tabs for overlying the end plate. Alternatively, the planar portions may be right triangular for completely covering the cold end face, or one of the planar portions may be rectangular for covering the cold end face, the other planar portions being elongated tabs overlying the rectangular plate.

Abstract: Improved carbon-containing, chemically bonded, refractory compositions, usually magnesia or alumina base, including about 1% to 20% by weight carbon and about 0.5% to 10% by weight steel fibers, low carbon steel fibers, or stainless steel fibers of about 10-50 mm in length and about 0.1 mm to about 1.0 mm in diameter of any cross-sectional shape distributed in the carbon-bearing matrix and bonded thereto. Other fibers compatible with both the intended application and the base composition may also be used.

Abstract: A method of increasing the magnesia content in dolomite sinter produced from dolomite. Crushed dolomite is calcined to form a physical mixture of particulate magnesium oxide (MgO) and calcium oxide (CaO) and the mixture is hydrated to develop a size differential between the calcium hydroxide and the magnesium hydroxide. The hydroxides are dried without dehydration and separated into two component portions on the basis of size. One portion of the mixture is rich in Ca(OH).sub.2 and the other is rich in Mg(OH).sub.2. The portion of the mixture primarily comprised of Mg(OH).sub.2 is then calcined to form the synthetic sinter.