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.