Studying the interaction of raw materials in Low Cement Spinel Castables

In this study six different combinations of raw materials that have the potential of being used in Low Cement Spinel Castables are investigated. These are bauxite and calcined magnesite, calcined alumina and calcined magnesite, refractory cement and microsilica, calcined alumina and microsilica, bauxite and mill scale, calcined alumina and mill scale. Proper combinations of each two are mixed with 6% water, pressed in a die, dried and fired for 2 hrs. at 1400 C, then the phases were studied by XRD. By considering refractory and low melting phases, it could be concluded that bauxite is a stable aggregate that can be used extensively and microsilica is a binder with problems which must be reduced to a very low level. For in situ spinel formation of MgAl2O4, calcined alumina and calcined magnesite combinations work the best and for Hercynite (FeAl2O4) formation calcined alumina and mill scale are a suitable combination.