Mineral and textural transformations in mixtures of Al-rich and Al–K-rich clays with firing: Refractory potential of the fired products

The present work analyses a set of cylinders manufactured by pressing and fired from 1000 °C to 1270 °C, which are composed pure Al-rich rocks (bauxite) mixtures bauxite with Al–K-rich clays. aim the study is determine mineral textural transformations that take place in firing their influence on physical properties final products order evaluate refractory potential comparing them various commercial bauxites. To this end, raw samples were analysed X-ray diffraction, fluorescence, optical field emission scanning electron microscopy, significant (e.g. density, linear shrinkage, porosity, colour, water absorption, thermal conductivity point load resistance) determined cylinders. was mainly formed boehmite, kaolinite hematite whereas illite- kaolinite-rich clay quartz, illite kaolinite. Kaolinite, boehmite not detected at and, temperature upwards, mullite, corundum, γ-Al2O3, hercynite, ilmenite, cristobalite vitreous phase formed. Changes rising associated mineralogical changes. increases density shrinkage related formation crystallization correlate decrease absorption conductivity. changes colour content each temperature, resistance greater higher corundum content. Both play an important role mixtures, since mixed similar lower temperatures those