Synthesis optimization of fireclay refractories from lithomargic clay

Lithomargic clay, underlaying Awaso bauxite deposit, is a non-plastic clay material and therefore limits its utilization as a refractory material. Its plasticity has been enhanced by admixing 20 mass-% Mfensi clay as a binding material. The admixed clay samples were prepared by mixing, semi-dry moulding, drying and firing at 1350 and 1400 °C, respectively in a muffle furnace at varying soaking time (30-120 min) to optimize the synthesis conditions. The synthesized refractory bricks were characterized based on their bulk density, apparent porosity, linear firing shrinkage and compressive strength. The crystalline phases after firing were determined using X-ray diffraction technique. The results show that the physical and mechanical properties of the fired bricks depend on both the synthesis temperature and soaking time. For energy efficient production of this type of refractories, bricks can be produced at relatively low temperature (1350 °C) for 120 min to achieve optimum strength.