Browsing by Author "Dilshara, RMP"

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item: Conference-Full-text
Assessing the potential of critical metals and rare earth elements in lateritic soils of the Southwestern region of Sri Lanka
(Department of Earth Resources Engineering, 2023-08-28) Herath, HMIA; Piyumangi, WAM; Kanishta, KPMK; Abeysinghe, AMKB; Ratnayake, NP; Premasiri, HMR; Batapola, BDNM; Dilshara, RMP
Laterites are currently considered potential targets for critical metals (CMs) exploration considering their near-surface occurrence, large dissemination, and enrichment of CMs in lateritic soil during weathering. Although prominent lateritic formations are found in Sri Lankan geological terrain, the potential for CMs has not been explored yet. Therefore, the present study assesses the potential of CMs in laterites of the southwestern part of the country. 60 samples were collected covering the overall study area and processed for critical metal analysis. The metal concentrations of CMs: Al, Ni, V, Cr, As, Sr, Co, Sc, and REEs were determined from inductively coupled plasma-mass spectrometry (ICP-MS) and Li, Fe, and Al concentrations were determined from atomic absorption spectroscopy (AAS). According to the analysis, critical metals such as Cr, V, Ni, and Th were significantly high in laterite samples ranging from 42-419, 116-583.4, 274 – 1498, and 33 – 472 mg/kg, respectively. REE and other critical metals considered in the study including Co and Cu, showed comparatively low potential. The findings of the study emphasise that laterite soil has significant potential for Ni, V, and Cr, especially in low grades. The conclusion is this analysis will benefit future CMs' exploratory investigations by providing insights into the potential of CMs in Sri Lankan laterite deposits.
item: Conference-Full-text
Exploration and characterization of potential iron ore occurrence in Pelpitigoda, Sri Lanka
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Wijethunge, HP; Appuhamy, RPMC; Vilojan, M; Ratnayake, NP; Abeysinghe, AMKB; Premasiri, HMR; Rohitha, LPS; Dushyantha, NP; Batapola, NM; Dilshara, RMP; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
Iron is widely used across industries in worldwide, with an annual usage of over 1.8 billion tonnes, steadily increasing over decades. Due to this high consumption of iron, it is crucial to find new sources of iron. Therefore, this research project was designed with the objectives of exploring the potential iron occurrence and characterize the mineralogy and geochemistry of the Pelpitigoda area. The methodology comprises two phases. In the initial phase, geological settings were studied to understand the rock formations and structures surrounding the area. It was followed by a magnetic susceptibility survey to identify variations and anomalies, along with systematic sample collection across the deposit. The phase two was completed with laboratory analysis, including sample preparation, colorimetry, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Notably, colorimetry results from phase two indicated iron content ranging between 40-60 wt% in the samples, with XRD analysis identifying goethite as the predominant mineral, alongside magnetite, hematite, and gibbsite. XRF results revealed an average iron content of 38.47 wt%. Furthermore, ICP-MS analysis showed lower potential for valuable metals like V, Cr, Co, Ni, and Zn in the area. The significance of this research lies in its potential to identify a new iron ore occurrence in the Pelpitigoda area. The comprehensive characterization of the mineralogy and geochemistry provides valuable insights into the composition and distribution of iron-bearing minerals in the area. Future work entails completing the last phase of roasting the samples to extract iron oxide, followed by comprehensive laboratory testing of the prepared samples.
item: Conference-Abstract
Extraction potential of nickel from native hyperaccumulator plants from Ginigalpelessa serpentinite deposit
(Department of Architecture University of Moratuwa, 2024) Dilshara, RMP; Abeysinghe, AMKB; Premasiri, HMR; Ratnayake, NP; Senarath, WTPSK; Ratnayake, AS; Dushyantha, NP; Batapola, NM; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
Serpentine soils are low-grade Ni resources that have been utilized widely to extract Ni to meet its burgeoning demand in the renewable energy sector. However, the economic impracticability of Ni recovery by conventional mining techniques has been directed towards Ni phytomining, in which native hyperaccumulators grown in serpentine soils are used for commercial Ni recovery. In this context, the Ginigalpelessa serpentinite deposit in Sri Lanka harbors a wide variety of plants that can accumulate high Ni concentrations from the soil. Despite the promising Ni potential (0.4-1.7%) in the Ginigalpelessa serpentinite deposit, the lack of detailed studies on the hyperaccumulation ability of native plant species and proper extraction methods retards the commercial application of Ni phytomining in this deposit. Therefore, the present study carried out ex-situ phytomining trials using two native hyperaccumulator species namely, Crotalaria verrucosa and Apluda mutica. The harvested biomasses were then incinerated to produce Ni-rich bio-ores, which were analyzed for Ni concentration using Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The bio-ore of C. verrucosa contained 7,279 ± 106 mg/kg of Ni whereas the bio-ore of A. mutica showed 3,867 ± 39 mg/kg of Ni. The bio-ore of A. mutica was used for the leaching experiments due to its highest abundance in the deposit. The leaching assays were carried out with A. mutica bio-ore under different pulp densities (100 g/L and 200 g/L) and H2SO4 concentrations (1 mol/L and 5 mol/L). The bio-ores used in leaching experiments were produced from an open flame and muffle furnace (at 550 ⁰C). The highest leaching efficiency was observed as 59% in open burnt samples (leachate Ni concentration = 649 mg/kg and total Ni concentration = 1,098 mg/kg) under 100 g/L pulp density and 5 mol/L H2SO4 concentration. The overall low leaching efficiency of bio-ore can be attributed to the formation of an aluminum silicate matrix (Al2O3.2SiO2) during leaching experiments which inhibits the Ni leaching. Therefore, the present study requires further investigations to optimize the leaching efficiency to implement a sustainable Ni extraction method for the local serpentinite bodies. Financial assistance from the Senate Research Committee, University of Moratuwa (Grant no: SRC/LT/2021/15) is acknowledged.
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Geochemical distribution of selected elements in serpentinite deposit in ginigalpelessa, Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, Sri Lanka, 2022-12-23) Dilshan, RADP; Sageenthan, A; Weerangana, NGN; Premasiri, HMR; Ratnayake, NP; Abeysinghe, AMKB; Dushyantha, NP; Batapola, NM; Dilshara, RMP; Jayawardena, CL
Serpentinite deposits are well known for their natural enrichments of heavy metals (Ni, Cr, Co) and depletions of macro nutrients (Ca, Mg), which have caused different ecological and health impacts in the surrounding areas. In addition, they are considered as potential sources for rare earth elements (REEs). While Ginigalpelessa, the largest serpentinite deposit in Sri Lanka, has been the focus of several toxicological studies, to date, there have been no significant studies related to geochemical distribution of heavy metals, macro nutrients, and REEs in the deposit. Therefore, the present study is focused on the assessment of geochemical distribution of selected elements (Ni, Cr, Co, Ca, Mg, and REEs) in the deposit. Accordingly, concentrations of these elements in 30 rock and soil samples were analyzed and their geochemical distributions were studied using the results of the present study and literature. Ni (6629 ppm) and Cr (35875 ppm) showed the highest enrichments in the deposit, whereas all the studied heavy metals have exceeded the permissible levels of the World Health Organization. In addition, a low Ca/Mg ratio was observed in the deposit, which explains the inhibition of plant growth in the deposit. Moreover, the identified areas with high enrichments of Ni, Cr, and Co using the prepared geochemical distribution maps will be useful in the spot remediation for toxicity in the deposit. Since serpentine soil is recognized as a low-grade source for Ni, low-grade extraction techniques such as phytomining and bioleaching are recommended to extract valuable metals from the Ginigalpelessa deposit.
item: Conference-Full-text
Heavy metal contamination in the water of a semi-urban lake – Bolgoda lake, Sri Lanka
(Department of Earth Resources Engineering, 2023-08-28) De Silva, NJC; Malinda, KMDRP; Elankeeran, T; Dilshara, RMP; Batapola, BDNM; Ratnayake, NP; Premasiri, HMR; Abeysinghe, AMKB
Urbanisation and industrialisation have intensified the heavy metal contamination in inland water bodies. Therefore, this study investigates the recent status of heavy metal pollution in the water of the Bolgoda Lake in Sri Lanka, a semi-urban inland water body that receives both treated and untreated municipal and industrial discharge from the surrounding area. A total of 11 lake water samples were analysed by Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) to determine the concentrations of As, Cd, Cr, Co, Cu, Ni, Pb, and V. Their mean concentrations in the Bolgoda Lake water were 0.661 ± 0.264 ppm, 0.010 ± 0.004 ppm, 0.090± 0.018 ppm, 0.007± 0.002 ppm, 0.043± 0.039 ppm, 0.002± 0.001 ppm, 0.662± 0.264 ppm, and 0.091 ± 0.018 ppm, respectively. However, the derived contamination factors of the analysed heavy metals revealed that Bolgoda Lake is highly polluted with Cd (22.0) and V (13.2), whereas moderately polluted with Pb (1.8). Compared to previous studies, heavy metal contents in Bolgoda Lake water have increased significantly, especially Cd and Pb. Therefore, Cd, V, and Pb can pose the greatest threat to the ecological environment of Bolgoda Lake, thus effective strategies such as treatment or recycling of wastewater and industrial discharges are needed to protect this lake from further contamination.
item: Conference-Abstract
Identification of potential minerals/rocks in Sri Lankan geological terrain as source of potassium (K) fertilizer
(Department of Earth Resources Engineering, University of Moratuwa, Sri Lanka, 2022-12-23) Nivethithan, T; Ariyawansha, KAPM; Dahlan, ACA; Abeysinghe, AMKB; Ratnayake, NP; Premasiri, HMR; Dushyantha, NP; Batapola, NM; Dilshara, RMP; Jayawardena, CL
Due to the agricultural intensification in Sri Lanka, there is a high demand for potassium (K)-fertilizer inputs. However, in the Sri Lankan geological setting, the presence of major potash sources is minimum though the K- bearing minerals and rocks are abundant. Therefore, exploration of K-bearing mineral deposits is essential to cater the demand of K-fertilizer in the country. In this regard, this research is focused on investigating the K-bearing minerals and rocks in Sri Lankan geological terrain which can be used as K-fertilizers directly or as alternatives for currently available K-fertilizers. During sample collection, K-bearing minerals, such as feldspar and mica and K-bearing gneiss rock samples were collected from Matale, Kaikawala and Kadugannawa areas. Processed samples were subjected to analyse major oxide concentrations and K concentrations and surface topography. Analyses revealed that the highest actual potassium concentrations were presented in orthoclase feldspar (10.35 w/w%) and then biotite mica (9.95 w/w%) whereas other rocks showed the lowest. Based on the results, biotite mica (Kaikawala) and biotite gneiss (Matale) displayed the highest potential for K recovery, whilst the least potential for K recovery was shown in orthoclase feldspar (Kaikawala). However, further studies are recommended to develop this K-fertilizer and to assess whether its application is economically viable.
item: Conference-Abstract
Spatial distribution of heavy metals in sediments of the Negombo Lagoon, Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, Sri Lanka, 2022-12-23) Nanayakkara, CJ; Partheepan, N; Kumarapperuma, MY; Ratnayake, NP; Premasiri, HMR; Abeysinghe, AMKB; Dushyantha, NP; Batapola, NM; Dilshara, RMP; Jayawardena, CL
Heavy metals accumulate in the sediments of aquatic environments due to poor water solubility. Their toxic effect poses a significant threat to living organisms. Negombo Lagoon, a vital aquatic ecosystem in Sri Lanka, has become vulnerable to heavy metals mainly from urbanization-related anthropogenic activities. Previous research in this respect has sampling points restricted to the boundary area. Since the heavy metal concentration is a static parameter, continuous research needs to keep the data updated. This study aims to investigate the spatial distribution of several heavy metals (Cr, Ni, Co, Cu, As, Cd, and Pb) in the surficial sediment of the Negombo Lagoon. Fifteen grab sediment samples were collected from the lagoon and analyzed for heavy metal concentration and grain size. The range of concentrations of each metal in test samples were between (78.07 - 222.68 mg/kg) Cr, (376.7-1298.05 mg/kg) Ni, (15.875-43.74 mg/kg) Co, (32.45-112.79 mg/kg) Cu, (20.17-55.81 mg/kg) As, (0.30-1.4 mg/kg) Cd, and (16.57-70.97 mg/kg) Pb. Heavy metal concentrations and sediment grain sizes show significant spatial variation over the Negombo lagoon area. Heavy metals were highly concentrated in locations, where finer sediments are accumulated (i.e., towards the eastern and southern part of the lagoon). Heavy metal concentrations were found to be increased with the decreasing grain size. High heavy metal concentrations are also found at places where there is a river discharge. Among the sources which feed heavy metals into Negombo Lagoon anthropogenic activities such as municipal and industrial waste disposal, rapid urbanization, shipping, and naval activities etc. have a significant impact.