Analysis of raw iron ores in Kenya: case study of Mwingi north constituency in Kitui county

Abstract

Accurate prediction of downstream processing performance of a mineral ore is critical to resource evaluation and development decisions, where significant cost and productivity benefits can be realized through early determination of an ore’s properties and processing potential. This study aimed at investigating the chemical, qualitative and quantitative composition of raw iron ore from the deposits in Katse area (Mwingi North Constituency in Kitui County) which lies in the Mozambique mobile belt. The quality of the iron ore was evaluated to establish its suitability as a raw material for iron production in Kenya. Samples were obtained along the perimeter vertices and centre of a land parcel measuring 150m2 with each excavation being 50cm length, 50 cm width and 500cm depth. Detailed studies were conducted to establish the composition and properties of the 5 samples. X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Atomic Absorption Spectrometry (AAS) techniques were employed in the investigation. XRD studies revealed magnetite (above 86%) as the major mineral with subordinate amounts of hematite and quartz. XRF studies indicated a high content of iron (above 80%) with minor amounts of (5% Al2O3, < 5%TiO2, 1-44% SiO2, <1% of MnO, P2O5, SO3, K2O, V2O5). AAS experiment results indicated that the Iron content was above 90% with minor amounts of SiO2, Al2O3, CaO, MgO, Na2O, K2O, TiO2 and MnO elements. The quality of this ore was compared to generalized world market standards and ores from other nations. The results indicated that Katse ore is a rich Magnetite grade with Fe content above 80% with minor amounts of hematite, quartz and clay as the major gangue (<1% SiO2 and <1% Al2O3) and low contents of the deleterious elements ( <1 %), which correspond to acceptable levels for commercial iron ores.