GB1003501A - Burned basic refractory shapes - Google Patents

Abstract

A dead-burned basic refractory grain contains up to 1% SiO2, CaO equal to 3 to 4.5 times the proportion of SiO2 and not more than 1% of Cr2O3, A12O3 and Fe2O3 together, the balance being dead-burned MgO. It is microscopically characterized by direct attachment of magnesite or periclase crystals to each other. The CaO and SiO2 content is preponderantly present in spaced disconnected pockets between the periclase and is largely present as tricalcium silicate. A shape prepared from the above grain may consist partially or completely of a dead-burned grain of the above analysis, the remainder being dead-burned magnesia. The grain may be fired at a temperature >3000 DEG F. to obtain a shape with good periclase-to-periclase bonding, subsequently crushed to a grain and refired at a temperature <3000 DEG F. Alternatively, the firing may be in one stage at <3000 DEG F. The refractory shape may be impregnated with with 6-8% of a cokable, non-aqueous carbonaceous material (e.g. tar or pitch). The drawings (not shown) are micrographs illustrating a refractory according to the invention and also a prior art refractory. The shapes have a high modulus of rupture at 2300 DEG F. and are suitable as linings for oxygen steelmaking furnaces.