Utilization of Kwale ilmenite ore in production of refractory firebricks

Abstract

In this study, Kwale Ilmenite Ore, Eburru Kaolin, Eburru Fireclay and Mukurweini Ball Clay were used to formulate refractory firebricks for incinerator internal lining. The effects of particle size distribution, water to binder to grog ratio, curing and Kwale Ilmenite Ore on the compressive strength, bulk density and apparent porosity of firebricks were investigated. Atomic Absorption and X-Ray Diffraction Spectrophotometric analysis were used to determine the elemental oxide and mineral phase composition of the samples respectively. 2.5 % iron III oxide by weight was used as the basis for formulation of grog and binder. 100 parts Eburru Kaolin, 100 parts Eburru Fireclay and 33 parts Mukurweini Ball Clay was used as the grog formulation while 3 parts of Mukurweini Ball Clay and 2 parts of Eburru Kaolin was used for binder formulation. % Kwale Ilmenite Ore, particle size distribution, grog to binder ratio, % water and curing were varied in formulations. The firebricks were pressed at 50 tons with a hold time of 1 minute, dried away from direct sunlight for 3 days, fired at 1200 OC for 12 hours and cooled to 24 OC for 48 hours in the furnace. The compressive strength at room temperature, bulk density and apparent porosity were determined for different formulations. Eburru Kaolin was found to contain 24.74% Al2O3, 72.64 % SiO2 and 0.71% iron III oxide; Eburru Fireclay 26.63% Al2O3, 66.40% SiO2 and 2.78% Fe2O3; Mukurweini Ball Clay 36.85% Al2O3, 55.38% SiO2 and 3.86% Fe2O3 and Kwale Ilmenite Ore 44.60 % TiO2 and 53.20 % Fe2O3. 2 parts of Kwale Ilmenite Ore, 43 parts of Mukurweini Ball Clay, 100 parts of Eburru Kaolin and 100 parts of Eburru Fireclay by dry weight produced firebricks with optimal chemical composition 27.53 % Al2O3, 65.87 % SiO2, 3.43 % TiO2, 2.08 % Fe2O3 and 1.09 % others. Particle size distribution of 2 parts coarse, 1 part medium and 2 parts fines, water to grog to binder ratio of 7:13:30 by weight gave the optimal bulk density, compressive strength at room temperature and apparent porosity of 1. 64g/cm3, 20.0 N/mm2 and 36.87 % respectively. 3.43% Kwale Ilmenite Ore formulated firebricks gave optimal bulk density, compressive strength and apparent porosity of 1.59g/cm3, 20.6N/mm2 and 36.45% respectively. The compressive strength increased from 20.0 to 20.6N/mm2 and apparent porosity reduced from 3.87% to 3.45 %. This was attributed to the presence of Kwale Ilmenite Ore in the formulation.