Browsing by Author "Wijewardhana, T.D.U."

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    Geochemical Variations of Prospective Heavy Mineral Deposits Bordering the Coastline of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2021) Subasinghe, H.C.S.; Ratnayake, A.S.; Wijewardhana, T.D.U.; Sameera, K.A.G.
    Heavy minerals with a specific gravity greater than 2.9 g/cm3 such as ilmenite (FeTiO3), rutile (TiO2), leucoxene (altered ilmenite), zircon (ZrSiO4), monazite ((Ce,La,Nd,Th)PO4), garnet ((Ca,Mg,Fe,Mn)3(Al,Fe,Mn,V,Cr)2(SiO4)3), sillimanite (Al2SiO5), and magnetite (Fe3O4) have gained global attention as a result of modern technological advances. In this regard, the mining and processing of these heavy minerals are a timely requirement to uplift the mineral industry and the economy of Sri Lanka. Therefore, the objective of this study is to investigate the geochemical variations of prospective heavy mineral deposits along the coastline in order to identify locations with economically significant concentrations of heavy minerals. Field excursions were carried out to identify the potential of heavy mineral placers in Sri Lanka. Sediment samples were collected from ten locations covering both the shoreline and raised beaches. X-ray fluorescence (XRF) analysis was used to determine the major and trace element compositions of sediments. When compared to average Upper Continental Crust (UCC) values, major and trace element variations show the enrichments of TiO2, Fe2O3, La, Ce, Zr, Cr, Nb, Th, and V. The abundance of TiO2, Fe2O3, and Zr, and visual examination of samples suggest the presence of higher concentrations of heavy minerals such as ilmenite, rutile, and zircon in the prospective locations. Moreover, the abundance of trace elements such as La, Ce, and Th implies the presence of rare earth elements (REEs) bearing heavy minerals such as monazite and zircon. In contrast, major elements (Al2O3, Na2O, and K2O) and large- ion lithophile elements (Ba and Rb) were significantly depleted compared to UCC values. Based on the XRF data and visual examination, it can be concluded that all the studied locations such as Verugal, Dickwella, Kosgoda, Payagala, Beruwala, Kalutara, Dharga Town, and Aruwakkalu can be identified as potential sites for heavy mineral placers. Finally, proper quantification is required to estimate economic grade and to determine mining feasibility. Keywords: Heavy minerals; Geochemical variation; Economic concentrations; Coastline of Sri Lanka
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    Upgrading of Sri Lankan Ilmenite by Ball Milling Induced Carbothermic Reduction
    (Uva Wellassa University of Sri Lanka, 2019) Wijewardhana, T.D.U.; Ratnayake, A.S.
    Ilmenite (FeTiO3) and rutile (TiO2) are titanium bearing heavy minerals. The existence of ilmenite percentage (70-72%) is much higher than rutile percentage (8%) in the northeastern coastal area of Sri Lanka. The value of rutile is higher than ilmenite. Though there are many chemical methods for upgrading ilmenite, physical method is cost effective for Sri Lanka. This research was carried out to analyze the optimum temperature under specific conditions for upgrading ilmenite using physical method. Upgrading was carried out using magnetically separated ilmenite sample from Lanka Mineral Sands, Pulmoddai. Mixture of ilmenite and activated carbon samples were milled using planetary ball mill for one to four hour separately. Subsequently milled samples were treated with activated carbon and heated for two hours at temperature of 800 °C, 900 °C, 1000 °C, 1100 °C and 1200 °C. Crystallinity and functional groups of the treated samples were determined using X-ray diffractometer (XRD) and Fourier transform infrared (FTIR), respectively. Particle sizes of the treated samples were determined using dry sieving method. Intensity, broadness and number of titanium dioxide (TiO2) XRD peaks in treated samples were increased with the time during the studied four hours. FTIR analysis indicates initial ilmenite contains Fe=O, Fe-O and Fe-OH stretching vibrations. The upgraded ilmenite sample contains Ti-O stretching vibrations with more broadness instead of Fe=O and Fe-OH stretching vibrations. Particle size of the four hour milled samples was laid in between 44 to 74 microns. Characterization results show that the amount of TiO2 and their crystallinity were increased. The annealing temperature can be reduced up to 1000 °C during the studied four hours. Therefore, Sri Lankan ilmenite can be upgraded by ball milling induced carbothermic reduction.