Production of sintered high alumina refractories from Turkish bauxite ore

Abstract Bauxite ore extracted from Seydis¸ehir-Konya in Turkey has been used for the production of sintered bauxite. The high iron and calcium in the bauxite were decreased to low levels by hydrochloric acid leaching. Temperature and acid concentration significantly affected the level of iron extraction from bauxite. The aluminium dissolution during acid leaching at 6M and below 70°C was ≤2%, and calcium dissolution was over 95%. XRD and XRF of leached bauxite revealed that the level of iron within the bauxite was decreased below 2% and that no significant TiO2 or SiO2 dissolved during leaching. XRD of leached bauxite sintered at 1400-1700°C for 4 h revealed only corundum (α -Al2O3) and mullite (3Al2O3.2SiO2). SEM investigation showed that bauxite grains were in the form of large aggregates. The maximum bulk density obtained at 1700°C was low compared with commercial refractory bauxites and the leached bauxite therefore needed to be sintered for longer times at 1700°C or at higher temperatures.