Suitability of Egyptian carbonaceous clays for the production of insulating bricks

Abstract

Two Egyptian carbonaceous fireclay samples from west central Sinai (Roof and Floor samples) were investigated for their chemical and mineralogical composition as well as microstructure and ceramic properties.These investigation were carried out to assess their suitability for production of insulating shaped products.Wet chemical analysis, XRD, DTA,TG and transmission light microscope methods were applied for revealing composition and microstructure of the raw clays. On the other side, microstructure and densification parameters of four shaped clay batches fired up to 1100-1300 oC were investigated by using reflected light microscope as well as Archimedes water-saturation methods and by determining linear changes and crushing strength of the fired bodies. It is concluded that both of the roof (RCC) and floor (FCC) clay samples can be considered as carbonaceous siliceous kaolinitic clays.The FCC sample contains relatively higher carbonaceous material and Al₂O₃/SiO₂ ratio than the former one. The batch containing 70% (RCC):30 (FCC) can be utilized in processing insulating shaped siliceous fireclay products after firing up to 1300 oC.The fired briquettes are mainly composed of quartz, cristobalite,mullite and glassy phase.They have > 45.0% apparent porosity, 1.50g/cm3 bulk density and 160 kg/cm2 crushing strength. Such lightweight siliceous fireclay bricks can be used as face and / or back refractory lining for insulating industrial furnaces up to 1300 oC.