Spinel refractory aggregates from natural raw materials

Utilization of the magnesium aluminate spinel in refractory applications is briefly reviewed. The synthesis of a magnesia aluminate spinel aggregate f rom natural raw materials is considered in terms of the crystal chemistry o f the spinel structure and expected impurities. Principles for the formatio n of this spinel refractory aggregate from different natural raw materials are presented. The basic concepts were then applied to the reaction of a ba uxitic clay with a natural magnesite. This combination of raw materials has the potential to produce a low-cost refractory aggregate that is a composi te of spinel and forsterite. Experimental results are reported to produce a spinel refractory aggregate containing a small amount of forsterite. It po ssesses low apparent porosity and high bulk density suitable for industrial refractory applications, including steelmaking, aluminum and copper foundr ies and cement production.