Investigation on the Beneficiation Methods for Local Iron Ore for Making Steel

Abstract

The iron and steel industries are prominent in the Kenya’s industrialization process. Iron is basically made by smelting of iron ore charged with coke in a blast furnace. Kenya has ample iron ore deposits which are yet to be fully utilized for the development and economic growth of the nation. There are iron ore deposits in some counties like Taita-Taveta, Tharaka-Nithi and Busia. This study showed that the iron ores from these areas are of low grade. Results for chemical analysis of iron (Fe) ores available in Kenya showed that iron ores have different iron composition ranging between 12.9-50.9% with the remainder being impurities/gangue. Gangue was mainly silica and alumina except for the samples from Tharaka-Nithi which has titania. The percentages are low compared to the recommended values for iron ore to be charged into blast furnace. These low grade iron ore has to be upgraded/beneficiated. The methods of beneficiating the ores include; gravity separation, dense media separation, froth flotation and magnetic separation. Due to availability of equipment and cost considerations magnetic separation and froth flotation methods were applied in this research. Magnetic technique improved the iron grade to 17-60% iron. The improved iron ores are suitable for making pellets or sinters and the 60% iron grade is good for blast furnace. For the flotation method, the ore was improved by between 2-12%. Of the two beneficiation processes the magnetic separation is suitable for Tharaka-Nithi and Taita-Taveta ores while froth flotation is better for the Busia iron ores. From the micrographs, iron ore is seen as the main compound for Tharaka-Nithi and Taita-Taveta ores. Busia iron ore has the lowest grade and the mineralogy study reveals silica as the main feature on the polished surfaces. The presented results provide relevant information for the Government of Kenya and prospective investors intending to set up a steel plant in the country to process the local ores.