Phase composition, microstructure and properties of alumina-chromia refractories

Six alumina- chromia co-clinkers were processed from Egyptian chrome ore as well as chinese bauxite and magnesite with different proportions by firing up to 1550 degreesC. Two samples were selected on the basis of their densification parameters and microstructure. The selected co-clinkers were subsequently graded, moulded and refired up to 1700 degreesC. Technological properties of the fired briquettes were investigated by means of densification parameters, spalling resistance and load bearing capacity. Co-clinker fired up to 1550 degreesC and containing 70 wt % bauxite: 30 wt % chromite without any addition of magnesite gives the highest bulk density (3.14 g/cm3). It is mainly composed of corundum s.s beside some spinel s.s and pseudobrookite phase. Briquettes made from this co-clinker show high refractoriness under load and spalling resistance. Such briquettes can be assessed in the production of shaped and unshaped alumina-chromia refractories for various applications.