Browsing by Author "Abeysinghe, A.M.K.B."

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item: Conference-Full-text
Assessing the applicability of geophysical methods for exploring vein type mica deposits – a case study in Matale district, Sri Lanka
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Wickramasinghe, K.G.K.G.; Arachchige, R.A.N.U.R.; De Zoysa, D.Y..B.; Premasiri, H.M.R.; Abeysinghe, A.M.K.B.; Ratnayake, N.P.; Batapola, N.M.; Dilshara, R.M.P.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A; Jayawardena, C
Mica, a group of silicate minerals characterized by their layered structure, is integral in various industries due to its insulating properties, heat resistance, and aesthetic appeal. Mica is commonly found as pegmatite and vein type deposits. However, vein type mica is extremely difficult to explore because of the complexity of their underlying geology and structural features. Atipola mica mine is one of the well-known mica mining sites in Matale district, Sri Lanka where the exploration of vein type mica deposits is difficult due to their complex geological formation. Therefore, this work attempts to assess the applicability of the Ground Penetrating Radar (GPR) geophysical methods for discovering new mica deposits. The field survey data collecting, and coverage plan were developed to investigate the most appropriate and pertinent area based on preliminary field observations. Since mica mining has emerged as a crucial economic activity in Sri Lanka, this study will also contribute to the investigation and advancement of vein-type mineral deposit exploration in Sri Lanka. Integrating GPR could make it possible to explain the subsurface structure in a non-destructive and appropriate way, which could help with informed mining methods and lead to the right decision regarding the accurate categories of the mineralogy deposit
item: Conference-Full-text
Characterization of heavy minerals in Nilaveli and Batticaloa beach stretches
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Benjamin, R; Anojithan, M.; Lokugamhewa, S.W.; Ratnayake, N.P.; Abeysinghe, A.M.K.B.; Premasiri, H.M.R.; Dushyantha, N.P.; Batapola, N.M.; Dilshara, R.M.P.; Iresha, H.; Elakneswaran, Y; Dassanayake, A.; Jayawardena, C.
The northeastern coast of Sri Lanka is notable for its significant heavy mineral deposits, especially the Pulmoddai deposit (containing 70-85 wt% heavy minerals) and the Verugal deposit (containing 45-50 wt% heavy minerals). However, regions like Batticaloa and Nilaveli remain underexplored and show potential. This study conducted a comparative analysis of these two beaches stretches to characterize their heavy mineral content in beach sand. Twenty-four composite samples were collected along the Batticaloa (n=17) and Nilaveli (n=7) stretches. Bromoform separation was used to determine their heavy mineral contents, followed by petrographic microscopic grain counting to ascertain the volumetric percentage of each heavy mineral type. The results revealed a higher mineral content in the Batticaloa beach stretch (1.20-14.50 wt%) compared to Nilaveli (0.36-6.42 wt%), despite Nilaveli's proximity to the Mahaweli River. The Batticaloa beach stretch showed average contents of 53.14% ilmenite, 2.06% rutile, 6.44% garnet, 31.94% zircon, and 4% monazite, indicating a significant potential for economically valuable monazite. The high heavy mineral content identified in the Batticaloa beach stretch suggests that further detailed explorations are warranted to assess the economic viability of the deposit.
item: Conference-Full-text
Comparative analysis of vertical metal zonation in Ginigalpelessa and Indikolapelessa serpentinite complex
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Mahendran, M; Maduranga, U.K.D.; Amarasinghe, A.A.Y.D.T.; Abeysinghe, A.M.K.B.; Ratnayake, N.P.; Premasiri, H.M.R.; Dushyantha, N.P.; Batapola, N.M.; Dilshara, R.M.P.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Serpentinite deposits in Ginigalpelessa and Indikolapelessa Sri Lanka, are known to exhibit a high supergene enrichment of Ni, Cr, and Co in the regolith due to the prolonged weathering of the underlying serpentinite bedrock. However, no detailed studies have been conducted to determine the vertical zonation of these critical metals in these deposits. The vertical metal distribution of a deposit is significant to delineate its vertical metal enrichment patterns and mobilization which may lead to the identification of efficient exploration and extraction methods. Therefore, this study assessed the vertical zonation of Ni, Cr, and Co in both Ginigalpelessa and Indikolapelessa serpentinite deposits. Twenty-four soil (n=12) and weathered rock (n=12) samples from 4 soil horizons (O, A, B, C) in soil profile were collected and analyzed for Ni, Co, Cr, and Cu by ICP-MS. Our findings revealed high metal concentrations in the soil or highly weathered rock samples over the partially weathered rock samples. The Ginigalpelessa deposit demonstrated4 a higher concentration of Ni, Co, Cr, and Cu compared to the Indikolapelessa deposit. It observed that the concentrations of Ni, Co, Cr and Cu in the topsoil were lower compared to deeper horizons (A, B, and C) in some locations. This may have occurred due to the bioavailability of some metals like Ni, which accumulates in the plants and reduce the concentration in the soil. Conversely, the low bioavailability of Cr compared to the other metals have resulted high Cr concentrations in the surface horizon. In addition, previous studies found that Cr is immobile, whereas Ni and Co are scarcely mobile under the moderate acidic conditions in the serpentine soil. During the weathering process, the slightly acidic rainwater leaches these Ni-like metals from the O and A horizons, resulting their enrichment in the B horizon. However, further studies are necessary to identify the suitable leaching or extraction method to recover these metals from serpentine soil. Therefore, this research contributes to a deeper understanding of vertical metal zonation in serpentinite deposits to facilitate more efficient and sustainable exploration of valuable metals like Ni in serpentinite deposits.
item: Conference-Abstract
Comparison of critical metal potential in beach and offshore sediments of Pulmoddai, Sri Lanka
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Nanayakkara, C.J.; Ratnayake, N.P.; Premasiri, H.M.R.; Abeysinghe, A.M.K.B.; Ratnayake, A.S.; Dushyantha, N.P.; Batapola, N.M.; Dilshara, R.M.P.; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
The global transition towards renewable energy resources for power generation has increased the demand for critical metals (CMs), including rare earth elements (REEs). This rapid growth of demand coupled with geological scarcity and geo-political concerns has posed great challenges in securing the supply chain of CMs. Therefore, prospecting new CM sources worldwide is of timely importance. In this context, the Pulmoddai coastal stretch in Sri Lanka has been recognized as a dynamic deposit with established potential for REEs and other critical metal resources, currently undergoing beach face mining operations. The focus of this study is to compare the critical metal potential in the beach and offshore sediments in Pulmoddai, Sri Lanka, crucial for determining the origin and delineating the extent of this deposit. Twelve onshore and nineteen offshore samples were collected and analyzed for CMs (V, Cr, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, and Cs) and REEs. Based on the results, light REE content (LREE), heavy REE content (HREE), and total REE content (TREE) were computed for both onshore and offshore locations. For onshore sites, LREE, HREE, and TREE ranged respectively from 43.27 to 244.09 ppm, 19.62 to 92.29 ppm, and 62.92 to 336.39 ppm. Conversely, offshore locations exhibited higher concentrations with the corresponding values ranging from 116.12 to 363.62 ppm, 8.57 to 120.93 ppm, and 167.93 to 484.55 ppm. Sr, Ni, and Cr were determined as the most abundant CMs for both onshore and offshore locations. Sr, Ni, and Cr concentrations ranged from 227.17 to 674.58 ppm, 116.17 to 675.88 ppm, and 43.55 to 112.87 ppm respectively for the onshore locations. The corresponding ranges for offshore sites were determined as 370.86-754.30 ppm, 235.43-721.44 ppm, and 32.51-172.62 ppm. The higher CM content in offshore regions suggests an offshore origin to this dynamic deposit, which is enriched by the offshore sediments transported onshore and deposited on a long-term basis. Therefore, regulatory authorities overseeing the mining operations of Pulmoddai deposit should accurately delineate its extent, integrating both onshore and offshore regions as a unified system, rather than solely focusing on prospecting the longshore areas.
item: Article-Full-text
Constraints to rare earth elements supply diversification: Evidence from an industry survey
(Elsevier, 2022) Ilankoon, I.M.S.K.; Dushyantha, N.P.; Mancheri, N.; Edirisinghe, P.M.; Neethling, S.J.; Ratnayake, N.P.; Rohitha, L.P.S.; Dissanayake, D.M.D.O.K.; Premasiri, H.M.R.; Abeysinghe, A.M.K.B.; Dharmaratne, P.G.R.; Batapola, N.M.
Rare earth elements (REEs) are crucial to accomplishing renewable energy targets throughout the world, including electrical vehicles and wind energy. Despite the extensive requirements of REEs, current supply chains are mainly fulfilled by the Chinese rare earth (RE) industry. This has resulted in price volatility, supply chain uncertainties, and RE trade disputes. The authors identified 13 factors as constraints to develop RE supply chains outside China and these constraints were rated by the major RE companies outside China, including RE industry experts. The survey results obtained from RE industry experts have been statistically analysed to ascertain the key factors that affect the development of independent rare earth (RE) supply chains outside China. 4 key factors were identified as statistically important, among them, business uncertainties within the RE industry and the Chinese RE influences on global supply chains being the dominant factors.
item: Article-Full-text
Leaching of rare earth elements (REEs) from lake sediments around Eppawala phosphate deposit, Sri Lanka: A secondary source for REEs
(Elsevier, 2021) Dushyantha, N.P.; Ratnayake, N.P.; Premasiri, H.M.R; Ilankoon, I.M.S.K; Hemalal, P.V.A.; Jayawardena, C.L.; Chandrajith, Rohana; Rohitha, L.P.S.; Abeysinghe, A.M.K.B.; Dissanayake, D.M.D.O.K.; Dharmaratne, P.G.R.; Ratnayake, A.S.; Batapola, N.M.
Rare earth elements (REEs) are widely employed in a spectrum of high-tech applications. Since primary REE resources are limited, secondary REE sources will be crucial to reduce future supply chain gap between REE demand and supply, which is currently about 3000 t per year. In this context, lake sediments around Eppawala Phosphate Deposit (EPD) in Sri Lanka could be considered as a potential secondary REE source since a man-made water canal running across the EPD transports REE-rich materials to the lake sediments. The average total REE (ΣREE) concentration of the downstream surface lake sediments was 804 mg/kg. The REEs were present in lake sediments as 3 fractions, namely, ion-adsorbed, colloidal, and mineral bound fractions. Ion-adsorbed fraction was assessed using less expensive, easy, and environmentally friendly ion-exchangeable leaching by a solution of (NH4)2SO4 under optimum conditions. Experimental results revealed that 34% of ΣREE was leached as ion-adsorbed fraction. In addition, the maximum leachable REE content (i.e. ion-adsorbed and colloidal fractions) was determined as 78% of ΣREE through HCl leaching under optimum conditions. Therefore, acid leaching was proven to be the best leaching process and the results in this preliminary study could be useful to assess low-grade geological resources, especially sediments and soils around major phosphate deposits with similar geological settings.