GB1017677A - Production of dead-burned refractory materials - Google Patents

Abstract

A fired refractory shape is made by blending a batch of normally-occurring magnesite, dolomite or limestone carbonate rock or a mixture thereof, all of which is - 28 mesh, and 40-90% of which is - 625 mesh (Tyler), with 1-10% aqueous binder, preferably water, there being no more than 5% naturally-occurring R2O3 components other than those occurring naturally in the rock, and no more than 5% total R2O3 components, and the batch material containing not less than 90% total carbonate, shaping the blend under a pressure at least 10,000 lbs. per linear inch, calcining, and dead-burning, the latter at a temperature of at least 3000 DEG F. Preferably 86%, even 100%, of the batch is - 200 mesh, shaping is effected at 20,000-30,000 lbs. p.l.i. pressure (normally at room temperature) and calcining and dead-burning are carried out in the upper third and central portions of a single shaft kiln respectively. Alternative binders are aqueous solutions of acids, gums or dextrin. Iron oxide or alumina may be present in the blend as naturally-occurring or added R2O3 components and silica, clay or titania may also be present. One suitable starting-material analyses 96.5% CaO, 1.4% SiO2, 1.3% MgO, 0.6% Al2O3, 0.2% Fe2O3, 43.2% ignition loss (natural limestone). Specifications 926,148 and 949,082 are referred to.