Browsing by Author "Ilankoon, IMSK"

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item: Conference-Full-text
Assessing different methods of salt removal techniques from offshore sand
(Department of Earth Resources Engineering, 2008-05) Ilankoon, IMSK; Jayarathne, LGR; Karunanayake, KDP; Thamilinpamalar, N; Wimalarathna, WMNJ; Vijitha, AVP; Ratnayake, NP; Karunaratne, S
Usage of offshore sand as an alternative to inland river sand is beneficial due to the various environmental impacts of river sand mining in Sri Lanka. However, higher amount of chloride ions in the sea sand can corrode the reinforcements of the concrete. Therefore it's necessary to identify suitable, low cost and efficient method to remove cl* ions from the sea sand. In this study, three different salt removal techniques; mechanical washing, natural washing and recently introduced grain to grain collision were evaluated using samples from beach sand, river sand, offshore sand and old stock piled offshore sand. Relative salt content and absolute cl* content were measured using conductivity measurements and titration, respectively. Mean grain size and other textural parameters were calculated using sieve analysis. Results indicate lOOg of sand soaked in 200ml of water, required approximately 10 minuets to remove salt from sea sand. Natural removal of chloride by rainwater shows one year of Monsoon rain is more than sufficient to remove salt from even 10 m thick piles of sea sand. However, grain to grain collision does not show significant capacity to remove salt.
item: Article-Full-text
A comparison of global rare earth element (REE) resources and their mineralogy with REE prospects in Sri Lanka
(Elsevier, 2020) Batapola, NM; Dushyantha, NP; Premasiri, HMR; Abeysinghe, AMKB; Rohitha, LPS; Ratnayake, NP; Dissanayake, DMDOK; Ilankoon, IMSK; Dharmaratne, PGR
Rare earth elements (REEs), a group of 17 elements comprises 15 lanthanides, scandium and yttrium, are largely attracting the world’s attention due to their importance in a wide variety of advanced technological applications. Global REEs production is mainly sourced from resources, such as carbonatites, alkaline igneous rocks, placers, laterites, and ion-adsorption clays. Recently, REE demand has been escalating, especially due to the REE applications in renewable energy and defense sectors, expecting a worldwide shortage of REE supply in the future. Therefore, REEs have been widely accepted as strategic elements in the world, which compels to prospect for new and alternative REE resources. In this context, Sri Lanka has a favorable geological setting which implies the presence of REE mineralization. Previous geochemical studies in Sri Lanka have reported significant concentrations of REEs in different geological formations and mineral resources. Accordingly, Pulmoddai and other beach placer deposits, Eppawala carbonatite, alluvial placer deposits, and pegmatites have been identified as potential REE resources in Sri Lanka. Monazite, apatite, allanite, and zircon are the primary rare earth (RE) minerals found in the preceding resources. The Pulmoddai mineral sand deposit is considered as the most potential REE resource in the island, which is enriched in monazite containing more than 61% of light rare earth elements (LREEs). Similarly, Eppawala carbonatite contains high concentrations of LREEs. However, despite their significant REE enrichments, to date, no attempt has been made to recover these REE prospects, which essentially conceals their potential of catering for both local and global REE supply chains.
item: Conference-Abstract
Exploration for potential sources of rare earth elements in Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Batapola, NM; Ratnayake, NP; Abeysinghe, AMKB; Premasiri, HMR; Rohitha, LPS; Dushyantha, NP; Ilankoon, IMSK; Dissanayake, DMDOK; Dharmaratne, PGR; Dissanayake, DMDOK; Jayawardena, CL
The global demand for rare earth elements (REEs) has been skyrocketing lately due to their excessive usage in numerous high-technologies. Therefore, the current study explores the REE potential in different geological formations of Sri Lanka. Accordingly, REE geochemistry and mineralogy of granites at Massenna (n=10), Arangala (n=6), and Thonigala (n=16); Eppawala phosphate deposit (EPD) (n=20); Ratthota pegmatite (n=6); southwest beach placers (n=18); and Walave alluvial placers (n=20) were analysed by the Inductively- Coupled-Plasma Mass-Spectrometer (ICP-MS) and X-ray Diffractometer (XRD), respectively. Based on the results, only EPD (2676.0-6486.3 mg/kg), Arangala (1634.9-4031.6 mg/kg), and Massenna (65.3-2153.4 mg/kg) showed high total REE (TREE) contents, and they contained REE minerals, such as apatite, monazite, rinkite, mosandrite, and eudialyte. Currently, carbonatites and ion-adsorption clays are the dominant REE sources in the world, and commercial REE extractions are only focused on the minerals: bastnaesite, monazite, and xenotime. In this context, the EPD is the most potential REE source in Sri Lanka (0.46% REO), especially for light rare earth elements considering not only its high TREE content but also the carbonatitic origin and the mineralisation of apatite and monazite. However, the EPD should be further explored for mineralogy, composition, and impurities to assess its viability as a future REE source in Sri Lanka.
item: Conference-Abstract
Exploration of potential sources for extraction of rare earth elements (REEs) in Sri Lanka
(Department of Earth Resources Engineering, 2019-08) Dushyantha, NP; Batapola, NM; Premasiri, HMR; Abeysinghe, AMKB; Rohitha, LPS; Ratnayake, NP; Dissanayake, DMDOK; Ilankoon, IMSK; Dissanayake, DMDOK; Samaradivakara, GVI
Rare Earth Elements (REEs) are a set of seventeen chemically similar elements in the periodic table, including fifteen metallic elements of the lanthanide series. Yttrium and Scandium. REEs are significantly used in numerous high-tech applications in sectors, such as metallurgy, military, petroleum and agriculture. Therefore, REEs are considered as critical and strategic elements i n the industrial revolution towards a green economy i n the future. However, China is the world's largest producer, consumer and exporter of REEs, currently controlling more than 90% of the global supply. According to the recent Chinese industrial policies, they have reduced their REEs export in 2010 in order to build up a REEs stockpile for future domestic uses. As a result, currently, REEs supply is at a risk of disrupting i n the world market, which has created many concerns among REEs stakeholders. Thus, worldwide explorations for REEs are carried out to prospect new potential sources. In this context, Sri Lanka is a country, which has geological settings implying the presence of probable primary REEs sources (e.g. apatite in carbonatites, granitic and synitic pegmatites, granitic rocks and hydrothermal veins) and secondary REEs sources (e.g. mineral sand, gem gravel, stream sediments, clay deposits and laterite deposits). According to previous studies in Sri Lanka, considerable contents of REEs have already been identified in a few locations of the country, such as well-known monazite deposit in Pulmoddai containing Cerium (28%), Lanthanum (15%), Neodymium (10%), Promethium (3%), Samarium (2%), Gadolinium (2%) and Yttrium (1%).Therefore, aforesaid potential sources will be explored as a worthwhile approach to address the impending REEs problems i n both local and global context. However, available resources on land w i l l not be enough to cater the future demand, and therefore, offshore sources, including upwelling areas in southern coast of Sri Lanka are also needed to be investigated as a promising solution for future REEs scarcity. However, effectiveness of extraction of REEs depends on the quality of the resources and the degree to which the resources have been explored. Based on the REE concentrations in aforesaid sources, novel extraction technologies will be developed to get the maximum benefits to the Sri Lankan mineral industry and ultimately to the national economy of the country.
item: Article-Full-text
Geochemical exploration for prospecting new rare earth elements (REEs) sources
(2023) Dushyantha, N; Ratnayake, N; Premasiri, R; Batapola, N; Panagoda, H; Jayawardena, C; Chandrajith, R; Ilankoon, IMSK; Rohitha, S; Ratnayake, AS; Abeysinghe, B; Dissanayake, K; Dilshara, P
Rare earth elements (REEs) are globally considered as critical elements due to their indispensable applications in various high-tech industries. With the ever-increasing demand, identified primary REE resources will not be able to fulfil the global requirements and thus exploration and exploitation of secondary REE deposits are essential. This work is designed to prospect REE potential in lake sediments in the proximity of the Eppawala Phosphate Deposit (EPD) in Sri Lanka. In this context, surface and core sediment samples were collected from 2 upstream lakes and one downstream lake (connected to a man-made water canal, namely Jaya-Ganga) with respect to the EPD. In the downstream, the average total rare earth element (TREE), light REE (LREE) and heavy REE (HREE) concentrations of the surface sediments were 1011.3, 904.6 and 66.6 mg/kg, respectively. The corresponding average values in downstream core sediments were 858.7, 719.3 and 100.2 mg/kg, respectively. The results suggested that the downstream lake sediments contained a high TREE content with a significant LREE enrichment compared to the upstream lake sediments. The EPD was identified as the main REE source and Jaya-Ganga, which flows across the EPD, was the main transport medium in this study. Phosphate-bearing minerals, such as fluorapatite and hydroxylapatite, derived from the EPD act as the REE carriers where REEs substitute isomorphous in the mineral lattice. Since REE grade is relatively high compared to some of the reported secondary REE sources, the downstream lake sediments could be a potential secondary source for REEs for future exploitation.
item: Conference-Abstract
REE 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, ABN
Rare 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.