Iron Enrichment In Laterites Soils From Selected Regions In Kenya Using Magnetic Separation

Abstract

Laterites also known as murrams from selected sites in the Republic of Kenya were analyzed for chemical and mineral content with particular interest in iron. In Kenya, laterites are only used mainly for surfacing roads. This study set out to show that laterites can be converted to high-quality iron ore which should make any country self-reliant in as far as supply of metallic iron is concerned. The samples of the study were obtained from Tunyai Division, in Tharaka Nithi County, in the Republic of Kenya. The samples were concentrated by heating charcoal/laterite mixtures in the ratios of 1:10 by mass in a slow current of air and in the temperature range of 500-700oC. Elemental analysis was carried out on both the raw laterites and the heat treated samples using Atomic Absorption Spectroscopy and EDTA Titrations. The minerals present were determined using a Bruker D8 Advance Diffractometer. The results of elemental analysis showed that, raw laterites contain 28-31 percent by mass iron. After the heat treatment, the level of iron, in the heat-treated sample had increased to 55-64 percent by mass. Iron ore with this level of concentration is usually what is put in a blast furnace during extraction of iron from iron ores. The X-ray diffraction data confirmed that, iron in the raw laterites was present predominantly as the minerals goethite and hematite. Heat treated laterite was found to have magnetite, formed from the goethite and hematite. The iron present in laterites was, therefore, concentrated using magnetic separation.