Armco Inc.

Armco Steel Corporation

Bohus Brezny

A refractory shape having improved resistance to erosion in metal melting vessels and high modulus of rupture, comprising an anhydrous refractory material, an anhydrous organic binder, from 0.3% to about 30% finely divided elemental carbon having a particle size ranging from 0.01 to about 1 mm, and from 0.3% to about 10% particulate elemental magnesium, based on the weight of the refractory shape. Addition of both elemental carbon and elemental magnesium results in a synergistic improvement in slag erosion resistance.

Erosion-resistant refractory

A steel refining furnace and refractories therefor having improved thermal conductivity may be achieved by the use of refractory bricks containing 31/2 to 51/2% residual carbon and having metal plates and the like associated therewith externally and, in many instances, internally. The cold face of the brick should be protected by a metal shell. Such a brick will have high thermal conductivity to achieve a cooler hot face of the basic oxygen furnace lining whereby to improve and decrease the rate of slag erosion in the furnace and to improve the thermal shock resistance of the refractory lining. An improved furnace is realized by utilizing the novel brick in specific areas thereof such as under the lip ring and in the trunion areas. Preferably the brick itself will be a pitch bonded magnesia refractory having an internal and external metal casing (chemically bonded by combining the refractory grains with prescribed amounts of coal tar pitch, carbon and/or grahite, tempering the mixture, pressing it into bricks while adding the metal elements, and drying them), or an external metal casing of burned pitch impregnated refractory (direct bonded by molding and firing, at high temperatures on the order of 3000.degree. F., 1650.degree. C., whereafter the bricks are impregnated with carbon in some form and the metal elements are added). The metal elements must be prevented from oxidation, thus the requirement for the presence of residual carbon in the brick and the use of a metal shell to shield the cold face thereof from oxygen penetration.

Basic oxygen furnace and refractories therefor having improved thermal

A composition which improves the hot strength of chemically bonded refractory shapes such as brick. The composition is comprised of refractory brickmaking size graded magnesia and chrome ore grain in a weight ratio between 90/10 and 30/70. The major portion of chrome ore grains must be smaller than 28 mesh; preferably, therefore, such chrome ore grains should be of a size that will pass 28 mesh screens and stay on 200 mesh screens. The lime (CaO) silica (SiO.sub.2) ratio is in the range of 0.2 to 2.5 depending on the total silica content of the system. Such silica content should never be more than about 2.5% by weight on the basis of an oxide analysis of the whole mix, but it may be as low as about 0.5% on the same basis. When the silica content is low (0.5 to 1.3%), the lime/silica ratio may be either high (1.8 to 2.5) or low (0.2 to 1.0). When, however, the silica content is high (1.4 to 2.5%), the lime/silica ratio must be low (0.2 to 1.0). In some embodiments of the invention metal elements, internal and/or external, such as plates and the like, may be incorporated with the shape, preferably in situ, as the chemically bonded refractory shape is formed.

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Middletown, OH, United States of America

Bohus Brezny