Use of bauxite from Cameroon for solid state sintering and characterization of calcium dialuminate (CaO·2Al2O3) refractory cement
Résumé
Well crystallized matrices of CaO·2Al2O3 were successfully sintered using three bauxites (BX3, BX55 and BX8) containing respectively 80.2; 89.4 and 91.1 wt% of Al2O3 and the appropriate amounts of lime. XRD data on the solid state sintered samples at 1550 °C show crystalline CaO·2Al2O3 as the major phase. The XRD pattern of the clinker made with BX3 showed relatively low intensities of CaO·2Al2O3 peaks compared with BX55 and BX8, together with CT and AT additional phases which were not identified in BX55 and BX8. This difference in composition was explained by the Al2O3 content and the high concentration of Fe2O3 (8.7 wt%) and TiO2 (7.1 wt%) in BX3 and was correlated to the difference in densification (3.17 g/cm3 for BX3 and 2.95 cm3 for BX55 and BX8) and specific area (0.72 m2/g for BX3 and 0.85 m2/g for BX55 and BX8). The Young modulus increased from 35.5 GPa (BX3) to 39.4 GPa (BX55). Unlike the Al2O3 content, the variation of the Young modulus indicated that the reactions of sintering and densification conducting to CaO·2Al2O3 are sensitive to the iron and titanium content.