ABSTRACT
The effect of thermal pre-treatments on the beneficiation of Ndit Ilmenite resource has been investigated in this work. The Ilmenite resource is located at Ndit village, in Bogoro Local Government Area, Bauchi State, Nigeria. The sample was sourced from four different points at 50m interval apart. The samples were homogenized then pulverized, sieved and analyzed for their chemical and mineralogical compositions using X-ray Fluorescence (XRF), X-ray Diffractometer (XRD), Scanning Electron Microscope/Energy Dispersive Spectroscope (SEM/EDS) and Petrological microscope respectively. The chemical analysis of the head sample revealed that the Ilmenite resource contained 41.50% TiO2, 21.78% Fe2O3, 15.85% Al2O3, and 18.20% SiO2 as the major minerals, 1.18% Nb2O5 as the minor mineral, 0.20% TaO5, 0.65% MnO and 0.64% others as trace minerals. The mineralogical analysis of the Ndit Ilmenite sample revealed the presence of Ilmenite (FeTiO3), Rutile (TiO2) as major, Alumina, Silica and other trace associated minerals as minor in the matrix of the Ilmenite resource. The SEM analysis revealed that the minerals grains are smaller in sizes, and are separated by grain boundaries. The SEM images of the Ilmenite samples also, revealed non-interlocking of minerals grains with varying sizes. Ilmenite phase is seen as the grey portion, the white portions are the Rutile Phases and Hematite is the dark portions in the matrix of the Ndit Ilmenite sample. The liberation size and work index of the sample was found to be -355+250Âm and 9.35kWh/t respectively. The thermal treatment (Calcination and Roasting) of the Ilmenite sample enhances the transformation of some proportions of Ilmenite to Rutile phase and formation of Anatase, Ilmenorutile and Magnetite phases in the matrix. The optimum thermal conditions obtained for calcination treatment is; Temperature (650oC), Time (60 minutes) which gave 58.0%TiO2 phase, while the optimum thermal conditions for roasting treatment is; Temperature (300oC), Time (60 minutes) which gave 47.1%TiO2 phase. Beneficiation of the thermally treated ( Calcination and Roasting) Ilmenite sample employing Two stage (double) magnetic (high intensity) - to - gravity (airfloatation) separation method reported an upgrade in the assay of mineral of interest to 82.87% TiO2 (49.72% Ti) with a recovery of 65.13% for calcined sample and 85.64% TiO2 (51.38% Ti) with a 69.03% recovery for the roasted sample. The percentage of TiO2 obtained in the concentrates surpasses and met the requirements of 48% - 51% TiO2 as minimum rutile content for rutile ore and 50% TiO2 content as minimum for Ilmenite ore. A process flow-sheet was also developed for the beneficiation of the Ndit Ilmenite resource using the results of the tests and analysis carried out. Therefore, the Ndit Ilmenite resource can be said to be another source of Titanium bearing mineral that can be explored, beneficiated and used in the nation's metallurgical industries.
