Performance Evaluation of Insulating Firebricks Produced from Hydrometallurgically Purified Termite Hill Clay Reinforced with Alumina

Abstract

The performance of insulating firebricks produced from hydrometallurgically purified termite hill clay admixed with varying percentages of alumina cement has been qualitatively evaluated. A large quantity of termite hill clay was mined from a location on the campus of The Federal University of Technology, Akure (FUTA), Nigeria. The bulk of clay was washed in water, the deleterious shafts decanted, the slurry dried in sun for three days and later in the oven at 90 °C for eight hours. The dried clay was then crushed and ground to a fine size of 100 µm, being the average particle size upon the sieve size analysis. Sieved clay was purified hydrometallurgically at a predetermined condition; 1.6 mol/dm 3 of oxalic acid at 90 °C for 150 min. and 200 rev/min agitation. Raw and purified clays were characterized using X-ray diffraction, Scanning Electron Microscopy and Transmission Electron Microscopy. Purified clay samples containing 5 - 20 % alumina were again fired at varying temperatures of 900 °C, 1100 °C, 1300 °C and 1500 °C and tested for some important refractory properties such as permanent linear change, modulus of rupture and permeability. Sample (purified clay + 10 % alumina fired at 1500 °C) that exhibited the best combination of these properties was examined under scanning electron microscope to see the effect of heat and analyzed chemically using the X-ray fluorescence machine to know the precise compositions. Keywords: Insulating firebricks, Hydrometallurgy, Termite hill clay, Purification and Predetermined condition.