A COMPARATIVE STUDY ON THE REFRACTORY PROPERTIES OF SELECTED CLAYS IN NORTH CENTRAL NIGERIA

Niger is a resource rich country. Nevertheless, despite the relative abundance of local raw materials needed for the production of refractory materials for its process industries, Nigeria is heavily engaged in the importation of these materials. This study presents the results of comparative analysis and evaluation of the refractory properties of some selected clay deposits in Nigeria’s North Central region with a view of determining their suitability for use as refractory materials. Characterization of Maikunkele, Tammah, Otaiko and Bukuru clays were carried out using an Atomic Absorption Spectrophotometer (AAS) and published data from previous studies were obtained for Tatiko, Beji and Nyikangbe clay. Result of analysis shows that the clay samples are high silicate clays with moderate alumina content, low ferrous oxide content and possess very low contents of other metal oxides. The low iron content gives the clays with the exception of Nyikangbe clay rather whitish appearances establishing their suitability for paint, chalk, and earthenware manufacturing. Maikunkele clay which had an impressive refractoriness value of 1710 oC making it the most excellent for ferrous metal handling and furnace wall lining with Tammah, Otaiko and Bukuru clays posting nearly 1700 oC. Tatiko, Beji and Nyikangbe clays had refractoriness below 1400 o C. Maikunkele clay’s thermal shock resistance also outperformed the others at 28 heating and cooling cycles, with 22, 17, and 20 cycles for tammah, Otaiko, and Bukuru clays; against less than or equal to 10 cycles for Tatiko, Beji and Nyikangbe clays. More so the linear shrinkages of all the studies clays were within permissible limits for refractory clays at between 7-10 %.