GEOCHEMISTRY, MINERALOGY AND BENEFICIATION OF IRONSTONE FROM BIDA BASIN, NIGERIA

Abstract

The Bida Basin is a NW-SE trending inland sedimentary basin in North Central Nigeria that extends from Kontagora in the north to slightly beyond Lokoja in the south and its mesas consist of ironstone layers from which economic iron ore can be won. The stratigraphic succession in the basin comprises the Bida sandstone at the base in the northern part of the basin followed successively upward by the Sakpe, Enagi and Batati formations. The geochemistry, mineralogy and beneficiation study of the ironstone samples from the study area in the northern Bida Basin were studied. Twelve representative samples from the study area were analysed for their elemental content and three samples for mineralogical characteristics using X-ray Fluoresce(XRF) and X-ray diffraction (XRD) techniques respectively while, beneficiation study was carried out on six (6) selected samples using magnetic separation technique. The result of the chemical analysis reveals that the following oxide with their indicated average values are present in the iron ore samples; SiO2 (24.64%), Al2O3 (2.24%), MnO (0.66%), CaO (0.086%), V2O5 (0.03%), P2O5 (0.03%) and Fe2O3(64.05%). From the XRD analysis, the dominant iron bearing mineral is the hematite which account for 71%, followed by quartz which is 21% while magnetite is 8% as the lowest mineral. The recovered iron content of the beneficiated samples ranges from 59.11% to 66.88% with an average of 62.99%. On the basis of the total iron content contained in the iron samples, a grade of 44.79% was determined which put the analyzed iron ore in a low grade class. From the discrimination plot, the analyzed ironstone plotted within the submarine –hydrothermal deposit and magnetite- silicate facies.