Abstract: A heat exchanger and especially a blast preheater (or cowper) for blast furnaces with refractory lining, insulating layer and steel jacket is described, the insulating layer of which is designed so that a steel jacket temperature of from 20.degree. to 60.degree. C. can be set and that said steel jacket is made of chromeless structural steel having a molybdenum content in the range from 0.01 to 2% by weight. The blast preheater (or cowper) has a prolonged service life and a low tendency to nitrate tension crack corrosion of the jacket sheet, for which reason it is very suitable for use in a process for the temperature control of gas and blast for the blast furnace. The process is suitable for blast preheaters (or cowpers) with external or internal combustion chamber or checker chamber and downstream collector ducts.

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: Compositions for forming carbon-containing refractory brick or shape comprising a refractory filler, a binder for said filler and a hardening agent for said binder, said binder comprising a mixture of polymers formed by the homopolymerization of resorcinol. Compositions for forming a carbon-containing refractory brick or shape as above described are also disclosed in which a basic refractory filler is employed and hardening agents are unnecessary. Methods of forming carbon-containing refractory brick or shape are also disclosed involving milling of a dry binder comprising a mixture of polymers formed by the homopolymerization of resorcinol with the refractory filler or mixture of a solution of such a binder material with the refractory filler, either of which may be conducted at ambient temperature.

Abstract: A refractory slide gate for a container dispensing molten material is comprised of a metal-supporting can filled with a low-fired coherent bonded refractory. The refractory is formed into a coherent refractory body within the metal supporting can and is directly affixed thereto, without the use of refractory mortar. An orifice through the refractory controls the flow of molten material.

Abstract: A non-aqueous taphole mix comprising a binder, a non-aqueous solvent for the binder and a refractory filler, the binder comprising a mixture of polymers formed by the homopolymerization of resorcinol and a hardening agent. Also disclosed are carbon-containing specialties comprising a binder, a solvent for the binder, and a refractory filler, the binder comprising a mixture of polymers formed by the homopolymerization of resorcinol and a hardening agent.

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: A fast response ceramic ignitor which is particularly adapted for use with household current as a replacement for gas pilot lights, the ignitor being formed from pure lanthanum chromite, or lanthanum chromite which has been doped with combinations of niobium, magnesium, or strontium ions in quantities sufficient to provide desired electrical resistivity characteristics.

Abstract: Expanded perlite is coated with polysiloxane, the coating dried, and subsequently strengthened by heating to form an attrition-resistant, non-porous, particulate filler suitable for inclusion in polymeric materials to reduce their bulk density.

Abstract: Thermal insulation of particulate expanded perlite that forms a low density, settle-resistant mass due to the coating of the perlite particles with a material rendering the individual particles slightly tacky.

Abstract: Improved periclase refractories are prepared by using an alkyd resin binder for tempering and pressing periclase grains into refractory shapes such as bricks. The pressed shapes are dried and fired. After firing, the refractory shapes are impregnated under vacuum with molten pitch and can then be used as lining in basic oxygen steelmaking furnaces. The fired refractory bricks have a greatly improved modulus of rupture at 1482.degree. C. of 3000-4000 p.s.i. The alkyd resin is generally incorporated in amounts of 2.5 to 4.5 weight percent.The green strength of the alkyd resin bonded bricks can be improved by adding a strong organic acid to the alkyd resin prior to mixing it with periclase grains. The green strength of bricks produced from such a mixture is between 30 and 40 p.s.i.

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 is provided for treating diatomaceous earth filteraids having a beer-soluble iron content of less than about 0.01% to further reduce the beer-soluble iron content by maintaining the filteraids in contact with a relatively small volume of an acid. In the filteraids so produced, the beer-soluble iron content can be reduced by as much as 70% to 100%. In making the filteraids of this invention, sulfuric acid in about 0.1 to about 3.0 normal solution can be used to treat the starting filteraids.

Abstract: Expanded perlite is coated with polysiloxane, the coating dried, and subsequently strengthened by heating to form an attrition-resistant, non-porous, particulate filler suitable for inclusion in polymeric materials to reduce their bulk density.

Abstract: Particulate unexpanded perlite is introduced to an expansion apparatus that utilizes the combustion of a gas as a source of heat. The particulate perlite is mixed with a combustible gas, air from a first source and oxygen and thereafter introduced to a burner section. The amount of oxygen introduced is in the range of from 1.5 to 16 weight percent of the amount of air introduced. The amount of combustible gas in the mixture is related to the air input from the first source, being in the range of 1 volume of combustible gas to 2 to 6 volumes of air.

Abstract: Particulate perlite fines are agglomerated to increase the apparent particle size by forming a mixture of the perlite fines with a compound such as boric acid capable of being substantially converted to B.sub.2 O.sub.3 at elevated temperatures. The mixture is heated while mixing to convert the compound to B.sub.2 O.sub.3 and to at least partially coat the particulate perlite.The mixture is then heated above the melting point of B.sub.2 O.sub.3 to agglomerate the perlite fines. The product of this process has particular utility as an improved filter aid.

Abstract: A method of decreasing the electrical resistivity of a rare-earth chromite material by substituting bivalent metal ions for some of the chromium or rare-earth ions therein. The method includes applying a solution containing the bivalent metal ions to the rare-earth chromite under vacuum conditions, drying the solution on the chromite, and diffusing the bivalent metal ion into the rare-earth chromite by firing the chromite in a controlled atmosphere.

Abstract: Improved, low-cost filter aid materials are made from polyurethane and related polymers. A foam of the polymeric material is comminuted to eliminate substantially all closed cells. The resulting particles are graded to a desired average particle size.