Beneficiation of Low Grade Titanium Ores from Selected Sites in Meru, Murang’a and Tharaka Nithi Counties, Kenya
Kariuki, Stephen Warui
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Titanium occurs in more than 70 minerals, but only ilmenite and rutile are used for extraction of titanium dioxide and subsequent extraction of titanium metal. Due to decrease in rutile deposit, ilmenite is used as the alternative source of titanium dioxide. Ilmenite exists as a low grade titanium bearing mineral with less than 5 percent titanium dioxide composition by mass, this percentage is not commercially viable for the extraction of titanium. For it to be used to extract titanium, it must be concentrated to improve the levels to 5 percent and above. Recent geological survey shows that titanium oxide exists as an iron-rich ores in Kenya. Occurrence of these iron-rich titanium ores in laterites has also been documented to be in huge amounts in Kenya. Titanium ores remain largely unexploited in Kenya since the current technology in use is very expensive and often requires a lot of water, a scarce resource, thus limited to only where we have large water bodies, in Kwale. Kenya is composed of 80 % of arid and semi-arid whereas titanium ores spread across the country. These research project show results of the study undertaken to find out whether low grade titanium ores in laterites, can be beneficiated to extractable levels above 5% by heating the raw laterites sample with lantana camara and separate using a strong magnet. The samples were obtained from selected regions of Meru, Murang’a and Tharaka Nithi counties in Kenya. Chemical analysis carried mainly focused on titanium levels in both the raw and heat-treated samples using Atomic Absorption Spectroscopy (AAS). The mineralogical content in raw and thermally reduced laterite samples was done using Brucker D2 Phaser Diffractometer. The results showed that percentage of titanium dioxide in Mbeu and Kaharate ranges from 3 to 7 percent while those from Tharaka Nithi is between 1.6 to 1.77 percent. The beneficiation of the titanium was done by heating raw biomass-sample in the ratio of 1:10 at temperature range of 500 to 800 oC in closed ceramic crucibles. When heated, iron-rich titanium (ilmenite (2θ = 33.12o)), goethite (2θ =21.51o) and haematite (2θ = 54.11o) were converted to maghemite (2θ = 35.6o). On further heating of the magnetically separated products to 1000 oC, the tailing after magnetic separation was observed to have a peak of rutile (2θ = 27.4o), a clear indication that maghemite contains titanium dioxide in its structure. Magnetically separated products from Mbeu and Kaharate contained between 4.7 to 5.82 % and from Tharaka Nithi contained over 5% of titanium dioxide. Bio-waste is a source of syngas which provide heat and reducing agents. Low grade titanium bearing mineral was upgraded to levels that was more than 5 % which is required for extraction of titanium dioxide and subsequent titanium metal. The proposed method of titanium ore concentration introduces local technology that can be used to beneficiate the ores for commercial exploitation.