PRODUCTION OF REFRACTORY CRUCIBLES USING CERAMIC RAW MATERIALS FROM SOME SELECTED STATES IN SOUTH WEST NIGERIA

Abstract

There is a high demand in the metallurgical, glassmelting, alchemical, chemical laboratories and among local jewelers for refractory crucibles that can withstand high temperatures. Unfortunately refractory crucibles seems not to have witnesses the desired development in Nigeria despite its potentials at helping in maximizing the ceramic raw materials potentialities, reduce dependency on importation of ceramic wares and provide job for the teeming unemployed Nigerian youths. This research is therefore aimed at developing refractory crucibles using ceramic composition from the available ceramic raw materials from some selected states in South Western Nigeria. The study is hinged on the objectives at identifying the source of ceramic raw materials that can be used for the production of refractory crucibles from some selected parts of South Western Nigeria; assessing the chemical and physical properties of the local ceramic raw materials using Xray Fluorescence Spectrometer (XRF); producing refractory crucibles using slip casting method; and carrying out standard refractory tests such as drying and firing shrinkage, water absorption, thermal shock re- resistance and refractoriness on the locally produced crucibles. The production of refractory crucibles was carried out using experimental procedures by analyzing selected raw materials sourced using two selected locations in South West Nigeria. Chemical analysis was carried out on the locally sourced ceramic raw materials using X-ray Fluorescence Spectrometer (XRF). Five different body compositions were formulated using quadaxial blend of 36 recipes and are labeled as samples A, B, C, D and E respectively. The crucibles were produced after preparing and mixing raw materials using slip casting. They were dried and fired in a gas kiln above 13000C for 6 hours. The result of the standard tests carried out on the locally produced refractory crucibles showed drying shrinkage between 5.26% - 11.11%, firing shrinkage between 2.78% - 5.56%, total shrinkage between 10% - 15%, water absorption between 0.36% - 0.72%, density between 0.3g/cm3 - 0.46 g/cm3 and compressive strength between1.43N/mm2 – 1.65 N/mm2. All the five crucible samples show good response to thermal shock and maintained their refractoriness above 13000C. Crucible sample A which consists of 10% Ikere Ekiti ball clay, 50% Ikere Ekiti kaolin, 30% Ikere Ekiti calcined kaolin and 10% Awo quartz was observed to have given the best composition for the production of refractory crucibles. The drying shrinkage, firing shrinkage, total shrinkage, water absorption, density and compressive strength values of crucible sample A are 8.11%, 5.41%, 12.5%, 0.37%, 0.46g/cm3 and 1.65N/mm2 respectively. The result showed that quadaxial mixture of ceramic raw materials compounded from Ikere Ekiti ball clay, Ikere Ekiti kaolin, Ikere Ekiti calcined kaolin and Awo quartz can be used for the production of refractory crucibles. The locally produced refractory crucibles can be used for melting substances that have their melting points below 13000C.