ISERME - 2020

Permanent URI for this collectionhttp://192.248.9.226/handle/123/16969

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International Symposium on Earth Resources Management & Environment 2020 [Pre-Text]
(2020)
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Fragmentation optimization in aggregate quarrying in Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Edirisinghe, EAAV; Kaluarachchi, KAUM; Lakmal, WYP; Samaradiwakara, GVI; Hemalal, PVA; Chaminda, SP; Dissanayake, DMDOK; Dassanayake, ABN
Blasting is an essential task in aggregate quarrying industry for rock fragmentation. Rock fragmentation, which is the fragment size distribution of blasted rock material, is used in mining industry as an index to estimate the effect of bench blasting. The extent of rock fragmentation in the blasting process influence the efficiency of all the subsystems such as loading, hauling and crushing in mining operations. To achieve an optimum rock fragmentation a blast with optimized controllable parameters should be designed so that the effects of the uncontrollable parameters could be minimized. Many countries such as Australia, USA, Canada, UK and Russia use Numerical Modelling based software for bench blast simulations, in order to optimize the blasts. However, in Sri Lanka up to now, these methods are not used, and ordinary methods using the experience from previous blasting sequences are practiced. The main objective of this research is to design the most economic blast that will give the optimum fragmentation, using “JKSimBlast – 2DBench” software. To validate the modelling, fragmentations from five blasts were assessed using “Split Desktop” software, and the results obtained were compared with the predictions carried out by JKSimBlast software followed by Kuz-Ram fragmentation model.
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Technical, socio-environmental & procedural limitations in Sri Lankan quarry industry from mining professionals perspective
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Garusinghe, JP; Serasinghe, KDBJ; Khan, WM; Hemalal, PVA; Jayasundara, DRT; Jayawardena, CL; Dissanayake, DMDOK; Dassanayake, ABN
Over 2500 quarry sites are currently in operation to cater the large requirement of rock aggregates in Sri Lanka. The concerns of this industry are not limited to the environmental and social aspects but significantly influence its own functionality. Even though such instances are common and under regular discussions, documented evidence and efforts to methodically resolve them finds to be limited. Hence, only the adverse effects of the quarrying industry are mostly highlighted, sidelining the opportunities for sustainable development. This research attempts to systematically document the issues in the quarrying industry in Sri Lanka to address them based on three categories; Technical, Socio-environmental and Procedural. As an initial exercise the collected survey data was categorized on district basis, quarry grade, respondent’s skill level and the nature of the interviews conducted. Through cross analysis of these data clusters the most common concerns were extracted to prioritize according to the level of significance. Afterwards, statistical significance of the relationships among the issues so far identified was computed mainly using Chi-squared-test and Binary Logistic Regression. Findings of this pilot study can be used for future policy development, even though they are dominantly represented by the Colombo, Kalutara and Gampaha districts.
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An investigation of industrial mineral mining methods in Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Thanujan, T; Subasinghe, MAIIJ; Vettinathan, S; Dharmaratne, PGR; Hemalal, PVA; Chaminda, SP; Jayawardena, CL; Dissanayake, DMDOK; Dassanayake, ABN
Sri Lanka is endowed with a rich base of industrial minerals despite its small land area. Traditional and modernized mining methods are employed to mine graphite, limestone, beach mineral sand (ilmenite, rutile, zircon and garnet), apatite, calcite, dolomite, quartz, feldspar, clay, kaolin, silica sand, mica and rock aggregate. Notably, some deposits have not been optimally exploited to their potential. Moreover, Sri Lanka does not have comprehensive information and documentation in the mining context. The mining method is selected on the basis of respective geology of the deposit, hardness of the ore and rock, depth, thickness and other geological aspects etc. The extraction of narrow steeply dipping vein deposits and deposits at great depth are significantly challenging and need specified selective mining techniques. In the study, currently practiced mining technologies, Cutand- Fill mining at Bogala, Open-stopping at Kahatagaha mines, open cast mining at Aruwakkalu Limestone quarry and mineral sand mining at Pulmoddai were investigated. The investigation was carried out through interviews and field visits. Site characteristics of each mine were tabulated, and the mining procedures were discussed. Mining methods employed at Kahatagaha and Pulmoddai were traditional while Bogala and Aruwakkalu utilize more systematic technologies. It is recommended to investigate and conduct indepth analysis in the second phase of the study for technological improvements.
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Mining-induced subsidence prediction by displacement discontinuity method
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Badrul, AKM; Alam, YJ; Fujii, Y; Alam, AKMB; Razo, SA; Ahmed, SM; Dissanayake, DMDOK; Dassanayake, ABN
It is essential to predict the mining-induced subsidence for sustainable mine management. The maximum observed subsidence having a noticeable areal extent due to Northern Upper Panels (NUP) and Southern Lower Panels (SLP) at the Barapukuria longwall coal mine is 5.8 m and 4.2 m, respectively, after the extraction of a 10 m thick coal seam. The mining-induced subsidence was simulated by the Displacement Discontinuity Method (DDM). The numerical model considered the effects of the ground surface, mining panels, faults, and the dyke. The predicted and the observed subsidence due to the mining of NUP and SLP were compared varying Young's modulus, and the 0.10 GPa Young's modulus was found to be the best match. The effects of the faults and the dyke in the calculation were found to be negligible. Future subsidence was predicted by considering 30 m extraction of the thick coal seam as 15.7 – 17.5 m in NUP and 8.7 – 10.5 m in SLP. For proper/sustainable mine management, the mining authority might need to count on this subsidence issue.
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analyzing the temporal variation of groundwater level in Attanagalu oya basin using numerical models
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Vinu, I; Udayanga, RMK; Chaminda, SP; Dassanayake, ABN; Dissanayake, DMDOK; Dassanayake, ABN
Scarcity for drinking water becomes one of the enormous threats around the world due to the increase in population, climatic fluctuation and pollution. Sri Lanka is considered as a country with little or no water scarcity when reckoning the whole country as one unit. However, several local regions have been identified with temporal water scarcity. Attanagalu Oya basin which covers almost the entire Gampaha district is a major hydrologic feature in determining the groundwater characteristics of the region. In this study, the temporal groundwater variation of the Attanagalu Oya basin was quantitatively analyzed. Using the data obtained from data loggers and field surveys, a numerical model for the groundwater in the basin was designed by using two software modelling approaches, a self-written Fortran code and Visual MODFLOW by USGS. Fortran code is mainly used for runoff modelling and Visual MODFLOW is for subsurface modelling. The quantitative variation obtained from the model was then examined temporally and spatially to correlate the upstream to downstream flow and monsoonal recharging impacts. The possible reasons for the observed deterioration and variations in the groundwater quantity can be contemplated as keys to providing recommendations for sustainable management of the groundwater resources in the basin.
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Rare 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, ABN
The 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.
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Mineralogical 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, ABN
Rare 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.
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Developing a casing design for the extraction of petroleum in Mannar basin, Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Harshapriya, IMP; Maduranga, GMS; Sandaruwan, SAL; Wickrama, MADMG; Dissanayake, DMDOK; Dassanayake, ABN
To develop an economical casing design program for the Mannar Basin which is safe, and risk minimized, knowledge on Pore Pressure Gradient, Fracture Pressure Gradient, Casing Performance Properties and Casing Design Criteria’s are important. Previous studies present the Hottman and Johnson (1965) method and D-exponent method-Eaton (1975) as accurate methods to predict the pore pressure gradient of the Mannar Basin and the Eaton (1969) method as the most accurate method to predict the Fracture Pressure Gradient of the Mannar Basin. The data extracted from the final well reports and pressure reports of the pearl 1 well of the Mannar Basin are analyzed using the above models to accurately predict the Pore and Fracture pressure gradients of the Mannar Basin. A specific casing design program is developed to suit the conditions of the Mannar Basin by selecting the casing setting depths and sizes and calculating the casing performance properties of Burst, Collapse and Tension, concerning the predicted pore pressure and fracture pressure gradients.
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Assessment 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, ABN
Sri 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.
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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.
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Remote sensing analysis of urban heat island effect in Colombo city from 2001-2019
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Dissanayake, DMDOK; Jeyakanth, K; Kurugama, KAKM; Ruwanthi, TPC; Dissanayake, DMDOK; Dassanayake, ABN
Urban Heat Island (UHI) is a metropolitan area where the temperature is several degrees higher than surrounding rural areas. In the context of UHI phenomenon, Land Surface Temperature (LST) was estimated using Landsat satellite images covering Colombo city, which is one of the main commercial metropolitan cities in South Asia. Results revealed that UHIs have expanded into northern, eastern and south eastern regions of Colombo city within the period 2001-2019. The Land Use change indicated the rapid urbanization. The correlation of Normalized Difference Built up Index (NDBI) and Normalized Difference Vegetation Index (NDVI) with LST were analyzed and obtained negative correlation between NDVI & LST and positive correlation between NDBI & LST at four time period (2001,2009,2016 & 2019) indicating the vegetation can weaker the UHIs while built up land can strengthen the UHIs. The results of Albedo analysis show that the low albedo materials have more potential influence towards formation of UHI. Finally, according to the ecological evaluation of the city using Urban Thermal Field Variance Index (UTFVI), 27% of the area is experienced worst case of heat stresses remaindering that mitigation measures should be applied in future urban planning to uplift the quality of lives and environment.
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Feasibility 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, ABN
Monazite 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).
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Monitoring 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, ABN
Sri 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.
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Heavy mineral sands in Kirinda area, deposit characteristics and extraction potential
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Fernando, AKN; Perera, EMNS; Saranga, LS; Vijitha, AVP; Dissanayake, DMDOK; Dassanayake, ABN
Kirinda fishery harbour is dredged out periodically to pump out sand to maintain its depth. Sand samples (n= 38) were collected from the dredged-out sand pile covering all the regions and were analysed for mineralogy, particle size distribution (PSD) and microscopic observation. Mineralogical analysis via X-ray Diffraction (XRD) revealed positive availability of heavy minerals such as Ilmenite, Rutile and Zircon in different forms of compounds. As per the results of PSD test, more than 90% of the particles lay below 250 μm size. The highest percentage of the distribution fall in the range of 180 μm - 212μm. With the comparison of PSD graphs and geometrical parameters (mean, skewness, sorting, kurtosis) obtained from results, it can be concluded that the sand in the study area is well sorted. The X-Ray Fluorescent (XRF) test was carried out to find the enrichment ratio of heavy minerals. There was a considerable increment in the enrichment ratio of samples before and after Wilfley separation. But the percentage of heavy minerals in the samples is not up to upper continental crust limits of economically minable heavy minerals.
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Selective precipitation of lanthanum and neodymium oxides from pulmoddai monazite, sri lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Udayakantha, KGI; Chameera, SADK; Kulogin, S; Rohitha, LPS; Dissanayake, DMDOK; Dissanayake, DMDOK; Dassanayake, ABN
Pulmoddai is the largest known deposit of heavy mineral sand in Sri Lanka. Because of the high concentration of Rare earth elements (REEs), Pulmoddai deposit’s value is considered to be economically enhanced by extracting REEs. Lanka mineral sand produces 100-120 tons of monazite per year and is currently treated as a waste. This crude monazite consists of Light rare earth elements and the radioactive element of Thorium (Th) and Uranium (U). The objective of this work was to develop a systematic scientific process to separate phosphate ion, radioactive elements and Neodymium and Lanthanum oxides from this monazite. In today's age, many extraction methods are used to extract the REEs. But it does have some limitations in Sri Lankan context. Hence, this study was carried out using a process of selective precipitation. Dephosphorization was carried out in alkaline media with different Sodium hydroxide concentrations of 50, 60, 70, 80% (w/v) at temperature 150 0C for 4 hours at 1atm. The optimum dephosphorization was observed in 80% (w/v) of NaOH concentration. Digested rare earth hydroxides were neutralized by using 60% (w/v) of hydrochloric acid at temperature 90 0C for 1 hour at 1atm. 2% (w/v) of oxalic acid was used in the rare earth chloride solution for removing impurities. Rare earth oxides (REOs) were obtained at 900 0C using calcination of rare earth oxalates. RE oxides were dissolved using 80% (w/v) HCL. In selective precipitation, 15% (w/v) NH4OH with KMnO4 were added to isolate Lanthanum and Neodymium hydroxides from RE chloride solution at controlled pH 4. Once again, 15% (w/v) NH4OH with KMnO4 at regulated pH 8.5 was applied to separate Lanthanum and Neodymium hydroxides. To obtain their oxide forms, these two hydroxides were calcinated at 900 0C.
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Adaptation to future flooding in a lowland city - a case of Jakarta city
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Kazama, S; Januriyadi, NF; Kure, K; Dissanayake, DMDOK; Dassanayake, ABN
Proceedings of ISERME 2020 ISERME 2020 104 Adaptation to Future Flooding in a Lowland City, - A Case of Jakarta City - *Kazama1 S, Januriyadi2 NF and Kure3 K 1Department of Civil and Environmental Engineering, Tohoku University, Japan 2Universitas Pertamina, Indonesia 3Toyama Prefectural University, Japan *Corresponding author – so.kazama.d3＠tohoku.ac.jp Abstract Hydrological model and inundation model are applied to Chilliun River Baisn including Jakarta City, capital of Indonesia to evaluate countermeasures as the adaptation in the future. For the future projection, rainfall data was made using 8 GCMs with statistic downscaling and bias correction. Future scenarios were prepared for land use change, land subsidence and 3 RCPs. Structural and non-structural countermeasures were evaluated as the adaptation for flooding. Only landuse change to 2050 increases 99% flood damage cost (almost double from current situation) and only land subsidence to 2050 increase 95% one. The combination of land use change and land subsidence makes 226% higher damage cost in 2050 than current one. This calculation shows the emphasis of both influences. Heavier downpour makes higher damage cost by flooding. Only future rainfall increases 77% and 99% on mean flood damage (annual expected damage costs) in around 2050 and 2100, respectively. However, the range of damage cost by each GCM is large and some models show the decrease of damage cost in 2050. The combination of land use, land subsidence and climate change shows 5 times damage cost to current situation.
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Estimation of the number of SARS CoV-2 infections in a sewershed based on wastewater-based epidemiology
(Department of Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Yifan, Z; Wakana, O; Chikako, M; Masaaki, K; Daisuke, S; Dissanayake, DMDOK; Dassanayake, ABN
The importance of wastewater-based epidemiology (WBE) has recently gained global attention, since scientific reports indicate that the concentration of viruses in wastewater is closely linked to the number of patients in a sewershed. WBE is thus expected to be a powerful tool in the current COVID-19 worldwide pandemic for epidemic surveillance and decision-making support. However, the feasibility of this approach remains unclear due to the inherent uncertainty and insufficient understanding of the factors involved. In this study, by taking aspects such as population size, sewage network layout, environmental conditions, and virus detection efficiency into consideration, we developed a mathematical model for estimating the number of infected individuals in the sewershed based on WBE. To test the sensitivity of the model, the number of infected individuals required for successful detection was determined using the Monte Carlo simulation.

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