ISERME - 2020
Permanent URI for this collectionhttp://192.248.9.226/handle/123/16969
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Browsing ISERME - 2020 by Author "Dushyantha, NP"
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- item: Conference-Full-textAssessment of rare earth element potential in intrusive rocks special reference to massenna zircon granite(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Jayasuriya, JHAATS; Jayathilake, RGMA; Jeyakumar, J; Batapola, NM; Dushyantha, NP; Abeysinghe, AMKB; Premasiri, HMR; Dissanayake, DMDOK; Dassanayake, ABNSri Lanka has a geological setting that favors the presence of rare earth elements (REEs), which are currently identified as the most critical and strategic elements in the world. Previous geochemical studies show that intrusive rocks, such as carbonatites, pegmatites and granitoid rocks could be enriched of REEs. Therefore, this research is focused on assessing the REE potential in pegmatites with special reference to the zircon granite in Massenna. The collected samples from the focused areas were subjected for XRD analysis and monazite, apatite, allanite, bastnaesite, and loparite were found as the major RE minerals. Moreover, Massenna zircon granite has the highest REE potential, particularly LREEs and Y, compared to other pegmatites. The presence of REEs in the in-situ soil and sediment samples indicate that, REEs have been transported through weathering and erosion processes of the zircon granite, thus proving the REE potential in the source rock. Furthermore, REEs are mostly associated with felsic minerals rather than mafic minerals. Therefore, this research clearly provides insights of REE potential in the pegmatite bodies in Sri Lanka and more REE explorations need to be carried out in these prospects.
- item: Conference-Full-textFeasibility of extraction of cerium dioxide (CeO2) from monazite at Pulmoddai(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Rasanjalee, PHAU; Delaksana, S; Sampath, MD; Dushyantha, NP; Batapola, NM; Dissanayake, DMDOK; Rohitha, LPS; Dissanayake, DMDOK; Dassanayake, ABNMonazite concentration in Pulmoddai mineral sand deposit in Sri Lanka is 1.38%. Its Rare Earth Elements (REE) composition is about 61%. Currently, only heavy minerals are separated and cerium rich monazite is discarded. Therefore, the study is focused on finding feasibility of extraction of CeO2 from Pulmoddai monazite. The research was conducted under four stages, removal of phosphate ions, removal of radioactive elements, purified Rare Earth oxide (REO) preparation and selective separation of CeO2. The optimum concentration of NaOH solution is found as 80% (w/v)/ 20M. Alkaline digestion was done for 4hrs at 150oC by adding 25 ml of NaOH to 25 g of monazite, followed by acid leaching with 50 ml of 60%(w/v) HCl at 90°C for 1hr. Concentration of 20 g/L (0.22M) oxalic acid should be added to the RE chloride mixture until the complete precipitation of RE oxalates. Purified REO was obtained by calcination at 900°C for 2hrs using RE oxalate precipitated. Purified REO was used to recover CeO2 by subjecting to selective precipitation. Selective precipitation of CeO2 was carried out using solid form of KMnO4 and (15wt%) Na2CO3 solution with maintaining average pH value 4 by manual addition of Na2CO3 solution ([15 g /100 L]/0.001M).
- item: Conference-Full-textMineralogical exploration for rare earth element potential in Kalutara coastal areas(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Jayasinghe, HGH; Jayasinghe, SMNM; Mohomad, HH; Ratnayake, NP; Abeysinghe, AMKB; Dushyantha, NP; Dissanayake, DMDOK; Dassanayake, ABNRare Earth Element (REE) quantity is a main factor that determines the wealth of a country. The main aim of this study is to discover a new REE deposit that can contribute to the Sri Lankan economy. Calido Beach is a coastal region where Kalu-river joins the sea in Kalutara, Sri Lanka. In this study, this coastal region is divided into four divisions as Kalutara North (KN), Kalutara South (KS), Sand Spit (SS) and river delta. Beach sand (n=5) and river sediment (n=30) samples were collected covering all four divisions and analyzed for mineralogy, grain size distribution and microscopic observation for prospecting unconventional Rare Earth Mineral (REM) sources. Analysis for mineralogy of samples via X-ray Diffraction (XRD) test revealed positive availability of REMs such as Monazite (Ce), Monazite (Nd), Xenotime and Bastnasite. According to grain size distribution (GSD) test results, it was found that sediments in delta had a lesser time for sorting before deposition with relevance to beach sand. Nourishment of REMs into the shore by sea waves and other sources (Beruwala placer deposit, offshore sources) increases the amount of REM content in the study area and the minable quality of beach sand as an economically viable REE source.
- item: Conference-Full-textMonitoring beach profile changes and modelling nourishment scenarios for Ratmalana beach(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Gunasekara, MP; Madushani, EK; Govinath, J; Ratnayake, NP; Samaradivakara, GVI; Dushyantha, NP; Gunasinghe, GP; Silva, KBA; Dissanayake, DMDOK; Dassanayake, ABNSri Lanka is an island nation endowed with a wide range of coastal resources, greatly contributing to the Gross Domestic Product. Coastal erosion is a major issue related to the beaches in Sri Lanka. In this regard, Ratmalana beach is critically important as a potential tourism destination due to its proximity to the capital city and the accessibility to a coastal railway station. To develop a beach as a tourist destination, it is importance to monitor the beach profile changes and find out the remedial measures for erosion prevention. For such a management plan, either hard or soft engineering solutions can be utilized. Out of the soft engineering solutions, the most reliable solution is beach nourishment. In this research, Ratmalana beach was regularly monitored and a numerical model was built by utilizing the public domain of XBeach to model the hydrodynamics in the area. Finally, two nourishment scenarios were modelled, and the optimum nourishment scenario is determined. Beach profile monitoring and calculated sand budget indicates that there is significant erosion during the stormy weather season. Based on grain size analysis, Ratmalana beach has a broad grain size distribution. According to the modelled nourishment scenarios, profile nourishment has shown better performance.
- item: Conference-Full-textRare earth elements exploration in river sediments (Belihul oya and Samanala wewa areas, Sri Lanka)(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Dilshan, MWRR; Prabhashan, HPM; Kalaishanthan, K; Dushyantha, NP; Batapola, NM; Premasiri, HMR; Abeysinghe, AMKB; Dissanayake, DMDOK; Dassanayake, ABNThe global REE deposits are mostly associated with carbonatites, alkaline igneous rocks, ion adsorption clay deposits and placers. In this context, previous geochemical studies of alluvial beds in Sri Lanka have disclosed significant concentrations of REEs. Moreover, the Walawe river basin is located at the boundary between Highland Complex and Vijayan Complex, which is a highly mineralized belt. Therefore, this study is focused on assessing the REE potential of stream sediments in Samanala-wewa reservoir and its upstream and downstream areas (i.e. Walawe river basin). The collected samples (n=26, covering 9 locations associated with Walawe river, Belihul Oya, Hiriketi Oya and Denagan Oya) were processed (< 63 μm grain size) and analyzed using XRD to identify their mineralogy. Monazite, bastnaesite, loparite and xenotime are the major RE minerals found in these samples. Additionally, the sampling locations were confined to six stream paths and a correlation was found between the stream order, and the number of REEs present at the location. Overall, this study provides a qualitative interpretation of the REEs present in the stream sediments of the study area. However, detailed quantitative analyses are required to further assess the true REE potential in this prospect.
- item: Conference-AbstractREE Potential in carbonatite deposits: a case study of Eppawala carbonatite(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Batapola, NM; Dushyantha, NP; Premasiri, HMR; Abeysinghe, AMKB; Rohitha, LPS; Ratnayake, NP; Dissanayake, DMDOK; Ilankoon, IMSK; Dharmaratne, PGR; Dissanayake, DMDOK; Dassanayake, ABNRare earth elements (REEs) are currently the most strategic elements in the world due to their significance in the diversified technological applications. Currently, a total of 478 million tonnes of REE resources is disseminated across the world, which is dominated by the carbonatite deposits. The most common REE-bearing minerals found in carbonatites are bastnaesite, apatite, monazite, allanite and parisite. In this regard, the Eppawala carbonatite in Sri Lanka could be considered as a potential REE resource. The Eppawala carbonatite occurs in high-grade meta-sedimentary and igneous rocks of the Precambrian Wanni Complex as massive intrusions. In the Eppawala carbonatite, bed rock is mainly composed of calcite (~90%), dolomite (5-9%) and magnesite (accessory carbonate mineral), whereas chloro-fluor-hydroxyapatite, fluorapatite and carbonate-fluorapatite are present in a secondarily developed phosphate-rich regolith. The Eppawala carbonatite is enriched of REEs (~291-1962 ppm) with higher concentrations of LREEs. However, despite these evidences, only a few REE prospecting studies have been carried out in the Eppawala carbonatite. Therefore, detailed REE prospecting studies are recommended to discover the full potential of this prospect, followed by development of suitable REE extraction processes.