Browsing by Author "Elakneswaran, Y."

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item: Conference-Extended-Abstract
An alternative underground hoisting system for Kahatagaha underground graphite mine, Sri Lanka- a case study
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Ekanayake, E.M.K.B.; Dissanayake, K.G.T.D.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Hoisting systems used in underground mines are essential for the transportation of equipment, personnel, mined ore and thus for the productivity of an underground mine. It consists of various components in which there are shear wheels, winches, wire ropes, lift cages, carriage boxes and electric motors. The safety and reliability of the hoist depends on its design, therefore proper and accurate design of a hoist is essential. A properly designed hoisting system also supports to increase underground productivity as well. Kahatagaha underground graphite mine is the deepest underground graphite mine in Sri Lanka, where the deepest level is 2080 feet below from the surface. The main lift operates up-to 1130 feet level from the surface and there are 5 inclined winzes equipped with pneumatic winches and hanging wooden boxes with the support of wire ropes for hoisting or lowering men and material as hoisting method from 1130 feet level to 2080 feet step by step between main underground levels. This hoisting method is very primitive and it has many bottlenecks when going to increase underground production, productivity and safety. This paper aims to provide a solution for current hoisting system & it`s issues mentioned above and presents the benefits of proposed hoisting system for Kahatagaha underground graphite mine. In fact, a cost-effective and safe hoisting system is a great support for any underground mine so that the proposed design would be a good alternative against the primitive system still in operation.
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
Assessment of biodiesel production potential and capacity analysis utilizing animal fat waste
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Upamali, W..M.A.; Wijesekara, E.R.J.M.D.D.P.; Amarasinghe, A.M.P.C.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
New Anthony's Farm, a major chicken producer in Sri Lanka, generates significant wastewater during production. This study aims to find a solution for the sludge produced in their treatment plant. Animal fats, a common waste in various industries, require expensive treatment due to environmental regulations. They mainly consist of triglycerides (90-95%), which are further made up of fatty acids like saturated (SFAs), monounsaturated (MUFAs), and polyunsaturated (PUFAs). Animal fat waste offers valuable opportunities for industrial use, but its improper disposal poses significant environmental threats. Sustainable management and utilization of this waste are crucial to protect the environment and extract valuable resources. First, an FFA (Free Fatty Acids) test was done for the top and bottom animal waste fat samples taken from the fat separation Dissolved Air Floating unit in the wastewater treatment plant in 'Anthony's Farm. The NaOH base with the Phenolphthalein indicator titration method was used for this FFA identification. After that, acid treatment was performed to reduce the FFA value of these samples, 60 0C hot water washing was done to purify the animal waste fat sample, and biodiesel was produced by transesterification. Direct transesterification was not obtained for the bottom sample, so the resulting liquid layer was centrifuged at 3000 rpm for 15 minutes and trans-esterified. After that, both samples were used to produce bioethanol. There, the top sample was directly used for bioethanol production without pretreatment, and bioethanol was produced using the glycerol layer of the bottom sample. The acid treatment was done with an H2SO4 Acid-to-fat ratio of 12:1, Temperature around 64°C, and pH - around 7, and it was reduced the FFA value of the top sample from 20.72% to 12.60%, and the initial FFA value of the bottom sample, which was 3.36%, was reduced to 2.80%. Considering this FFA value, the bottom sample seems to have more potential for biodiesel production. Also, the flash point of the biodiesel produced in this way was measured using the Flashpoint analyser, and it was found to be 55.5 0C.
item: Conference-Full-text
Assessment of seasonal and spatial water quality changes in Kelani river, sri lanka
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Rathnayake, A.G.S.N.; Luxman, R.; Udayanga, N.A.P.; Chaminda, S.P.; Ishankha, W.C.A.; Gunawardhana, L.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
The deteriorating water quality of the Kelani River over time has negatively affected environmental health and sustainability. This study aims to determine the relationship between land use types and its impact on the water quality within the Kelani River basin. The analysis utilized a dataset comprising 23 parameters related to water quality, spanning 17 sampling locations along both the primary river and its tributaries from 2003 to 2023. IBM SPSS Statistics (Version 26), was utilized for data analysis, focusing on 7 water quality parameters (pH, dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD), nitrate, phosphate, and turbidity) that were influenced by land use. From this analysis, 6 sampling locations were selected to represent various segments of the stream, including Aguruwella and Nakkawita for the upstream segment, Pugoda Ela and Wak Oya for the middle stream, and Rakgahawatte Ela and Maha Ela for the downstream segment. This study utilized a combination of GIS and statistical methods over 4 years with a 6-year time interval (2004, 2010, 2016, and 2022). The land use maps were generated by categorizing area into 4 land use types as agricultural area, vegetation area, built-up area, and others, using maximum likelihood supervised classification. Accuracy assessment using the kappa coefficient revealed that overall accuracy was greater than 85 %, for all six sub-catchments across all four years. From the analysis, it shows that the water quality parameters are significantly varied spatially and temporally. From upstream to downstream and over time, water quality has declined. Regression analysis shows the relationship between land use types and 7 water quality parameters. pH, DO, COD, BOD, and nitrate show a correlation with built-up lands, pH, DO, COD, nitrate and turbidity with vegetation areas, and phosphate with agricultural areas. Moreover, this study highlighted, built-up lands and agricultural lands negatively influenced the water quality, while vegetation areas positively influenced. By identifying the correlation between land use types and water quality, this study helps to preserve and enhance the water quality of the Kelani River basin by implementing proper land use management strategies.
item: Conference-Abstract
Comparative analysis of mechanical and mineralogical properties of rocks from maddhapara granite mine, Bangladesh
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Alam, A.M.K.B.; Fujii, Y.; Dipu, N.H.; Ghalib, F.H.; Sajib, A.I.; Ullah, A.S.M.W.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
This study presents a comprehensive analysis of the mechanical and mineralogical properties of rocks collected from Maddhapara Granite Mine (MGM) in the northern region of Bangladesh. The research focuses on the characterization of two main categories of rocks, distinguished by their color and mineral composition, namely the dominant black rock and the flashy colored rock. Microscopic studies were conducted to categorize the rocks, leading to the identification of minerals such as quartz, feldspar, amphibole, and biotite within the rock samples. The black rock was classified as Tonalite, with specific mineral compositions, while the flashy colored rock was identified as granite, exhibiting distinct mineral proportions. The research further delves into the physical properties of the rocks, including density, effective porosity, P-wave velocity, S-wave velocity, and Uniaxial Compressive Strength (UCS). Notably, UCS tests were performed to characterize stress parameters such as crack closure stress, crack initiation stress, crack damage stress, and peak stress for both rock types. The results revealed significant differences in stress levels and mechanical responses between the two rock types, with tonalite exhibiting higher stress levels and distinct mechanical behaviors such as plastic deformation and shear deformation, compared to the granite. These variations are attributed to the dominating minerals present in each rock type, particularly amphibole and quartz for tonalite, and feldspar and quartz for granite. The findings of this study have implications for the stability of drifts and stopes in mining operations, as the mechanical responses of the rocks, influenced by their mineralogical composition, may impact their suitability for various engineering applications. This research contributes to the understanding of rock properties in the context of mining engineering, providing valuable insights for the assessment and utilization of rocks from MGM and similar geological formations.
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 Full-text
Developing relationships among grindability, chemical composition and particle size of raw material mix at Aruwakkalu Limestone for Cement Production
Mendis, BSM; Jayathunga, THGS; Madurapperuma, HH; Rohitha, LPS; Dharmarathne, PGR; Hemalal, PVA; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.
In this research study, the relationship among chemical constituents (SiO2, Al2O3, Fe2O3, CaO, MgO, Cl-, SO3, Na2O and K2O) and raw meal grindability are investigated on raw meal samples taken from the output of ball mill. The X - ray Fluorescence analysis is used to check the chemical composition and grindability is checked in the form of residue test of No 212 sieve residue. The distribution curves of the variables were analyzed to examine the skewness of the distribution. The Pearson’s Coefficient of Correlation analysis was performed on each two variables to identify any linear mathematical relationship between variables. The time series analysis was carried out to find the best fitting curve between grindability and the variables. Scatter plot analysis was finally performed and the results show the effect of chemical components and particle size distribution of raw meal were found to be range correlated on the raw meal grindability. The most suitable chemical constituent range to improve the grindability of raw meal are given based on 68% , 95% and 99% confidence intervals. The quality parameters such as Lime Saturation Factor, Alumina Ratio and Silica Ratio also evaluated based on chemical constituent values of 68%, 95% and 99% confidence intervals.
item: Conference-Full-text
Enhancing stockpile inventory management through UAV- based volume estimation: a case study of salt stockpiles in Hambantota mahalewaya
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Perera, M.T.R.D.; Wijesundara, K.K.G.I.; Jayawarna, M.D.; Chaminda, S.P.; Madhurshan, R.; Samarakoon, K.G.A.U.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Accurate volume estimation of stockpiles is crucial in industries such as Mining, Construction, salt, and Agriculture to optimize resource utilization. This study evaluates the effectiveness of Unmanned Aerial Vehicles (UAVs) compared to Differential Global Positioning System (DGPS) and Total Station (TS) methods for volume estimation of outdoor salt stockpiles in Hambantota Mahalewaya, Southern province of Sri Lanka. The inventory identified two stockpiles, stockpile 1 and stockpile 2, with volumes of 1832.25 m3 and 819 m3, respectively. An optimal elevation of 55m was utilized for UAV surveys, and the results were compared with DGPS and TS measurements. UAV surveying factors affecting errors, including image resolution, Ground Control Points (GCPs), and image processing software, were assessed for both stockpiles. Survey time and cost for each method were also analyzed. Pix4dMapper and Agisoft Metashape software processed UAV images, while Civil3D software processed DGPS and TS data. Results indicated that increasing UAV survey elevation reduced volume error percentages for both stockpiles, with and without GCPs. For Stockpile 1, UAV volume estimation showed a 0.88% difference from the actual volume, compared to 4.81% for DGPS and 3.35% for TS. Conversely, for Stockpile 2, UAV estimation differed by 0.95%, while DGPS and TS showed differences of 0.56% and 0.10%, respectively. UAV surveys proved efficient in terms of survey time and labor intensity. Despite technological advancements, challenges remain, particularly in addressing topographical variations for accurate volume estimation. To improve UAV-based estimation, addressing bottom elevation discrepancies by establishing fixed benchmarks on flat terrains was suggested. Nonetheless, UAV-based approaches offer fast and relatively reliable results, indicating their potential for widespread adoption.
item: Conference-Full-text
Experimental synthesis of zeolites from pre-processed coal fly ash using the microwave irradiation method
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Amirthavarman, V.; Perera, A.W.B.M.; Madhuwantha, G.L.S.; Fernando, W.A.M.; Jayawardena, C.L.; Wickrama, M.A.D.M.G.; Iresha, H.; Elakneswaran, Y.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Coal power plants contribute by an excess of 40% to the generation of electricity worldwide. Coal fly ash (CFA), being a dominating by-product of coal power generation, is unique due to its physicochemical properties such as thermal stability, chemical inertness, compressive strength, and adsorption. However, reducing the inherent impurities of CFA, which is heterogeneous, has proven to enhance its ability to be valorised into different second-generation products of high value. Pre-processing has been a successful method in eliminating impurities of CFA, and washing cycles method is the preprocessing technique used in this study. Zeolites, a second-generation product from CFA, are well known for their excellent adsorption properties due to their high surface area and porosity, being an optimal solution for wastewater treatment. Also, the microwave irradiation method has proven to be useful and rapid in synthesising zeolites. This study investigates the effect of pre-processed CFA obtained through optimised utilisation of wash cycles, compared to raw CFA, and the feasible conditions of zeolite synthesis from CFA which have undergone the wash cycle preprocessing technique. NaOH concentration and microwave irradiation power were considered as key parameters. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) were utilised to verify the enhanced nature of CFA after pre-processing, and formation of zeolites. The results of XRD infer that Mullite (Al4+2xSi2-2xO10-x) is the major crystal match for CFA obtained from the site. Also, pre-processed CFA yields a better qualitative phase analysis with Mullite than raw CFA, with the former having a peak coverage of Mullite that is approximately three-fold than the latter. Furthermore, according to the experimental results, zeolite L and zeolite Na-Y were produced from the process, having an optimal NaOH concentration of 2.5M and microwave irradiation power of 300W. These findings have been corroborated using XRD and SEM with EDS analyses, and we recommend further extension of the frontier to check the viability of zeolite formation with other critical parameters, paving way to an effective treatment of wastewater.
item: Conference-Abstract
Feasibility study of iron extraction from laterite
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Vejitha, D.G.G.; Nuwansiri, W.M.R.; Bandara, H.M.V.W.R.; Rohitha, L..P.S.; Guluwita, S.P.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
This study investigates the feasibility of extracting iron from laterite, a low iron-bearing rock, with a focus on the economic viability of the process. The aim to develop a feasible method to extract Iron from Lateritic rock. The laterite samples were collected from Panirendawa, Pelpitigoda and Padukka. Mineralogy of the laterite was investigated by means of X -ray Diffraction (XRD) analysis, whereas chemical composition of the sample was determined by using Energy Dispersive X-ray analysis (EDX). The pelletization process was used to enhance iron recovery. Economic viability is evaluated through a detailed cash flow analysis that considers operating costs, revenue from iron extraction, and potential market factors. Iron extraction was done using the laboratory type cupola. The main results indicate that laterite contains significant iron content within the range of 30-40% and aluminium 25-27%. The cash flow indicates it is not a potential source for extraction iron only, however using a zero wastage multi-disciplinary process, slag can be used to produce bricks because of high aluminium silicate content of the slag. In conclusion, this study establishes the feasibility of iron extraction from laterite, showcasing it’s not an economical process however using a zero wastage multi-disciplinary process it is economically viable.
item: Conference-Abstract
Forecasting the impact of land utilization on flood vulnerability through machine learning and remote sensing in Athuraliya and Akuressa divisional secretariat
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Sujahath, M.S.M.; Senarathna, H.D.K.; Saranga, K.H.G.R.; Dissanayaka, D.M.D.O.K.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Akuressa and Athuraliya Divisional Secretariats in Sri Lanka frequently experience severe damage to human lives, infrastructure, and economic growth due to floods. These floods are often caused by elements like land use patterns, urbanization, and environmental degradation. This study aims to establish the connection between flood vulnerability and land use as importantly necessary for effective disaster management and mitigation strategies. Therefore, this research provides useful knowledge on flood vulnerability prediction based on land use patterns that can be used by policymakers, urban planners, and disaster management authorities for decision-making on proactive measures that will reduce the negative impacts caused by flooding while building resilience in the region. The primary purpose of this research is its innovative and essential because no earlier study has applied these cutting-edge techniques to assess flood risks in this area. Consequently, there is a significant gap in the current knowledge base and practice. Therefore, this research is intended to understand the land utilization situation in the area and how it affects flood vulnerability, identify environmental key variables that contribute to flood susceptibility, and use machine learning models including XGBoost, Random Forest, and CatBoost for predicting flood susceptibility. The latter also uses DEM derived factors with geological, soil, land use/land cover data, distance from roads and rivers to provide a closer understanding of flood conditioning factors within the study area. The XGBoost algorithm gave an accuracy score of 0.91 throughout the other utilized Machine Learning models, confirming how well machine learning performs when it comes to predictions. The results from the machine learning model were then used to determine the feature importance according to each conditioning factor that influences floods. Based on these feature importance values; a future risk map was generated using ArcGIS software. Therefore, this research indicates that prediction-based planning is more effective than post event-based recovery measures in building resilient and sustainable communities prone to flooding like Akuressa and Athuraliya Divisional Secretariat. In addition, these findings show that Machine Learning (ML) and Remote Sensing (RS) have potential for improving on-flood forecasting techniques as well as mitigating measures.
item: Conference Full-text
Ground penetration radar obseravtions at Kahagolla Landslide and evaluation of potential failure mechanism
Dissanayake, SW; Pathirana, GPNA; Sandaruwan, MKS; Abeysinghe, AMKB; Premasiri, HMR; Weerawarnakula, S; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.
The term landslide is used to describe a wide variety of processes that result in the perceptible downward and outward movement of soil, rock and vegetation under gravitational influence. The material may move by falling, sliding, spreading, or flowing. Landslide disaster is caused to produce a significant impact to the economy of the country and caused to create number of social and enviromentalimpacts. This research was forced on studying the methods that can be used for evaluating the potential mechanism of Kahagolla landslide by applying geotechnical and geophysical techniques. The study was based on slow moving landslide located near the Kahagolla Estate. It belongs to Haputhale District Secretariate divisionin Badulla district.This study involves the use of Ground Penetrating Radar (GPR) and existing borehole information.GPR, technique used for defining underground structure, providing a time effective survey that yield high resolution data making it suitable for shallow and deep subsurface analyzing. The results were validated using the available borehole information. The GPR survey information revealed a close relationship with the borehole data. Hence, an optimum combination of GPR survey and borehole drilling can be proposed for cost controlling in landslide monitoring and instrumentation programme. After interpretation of GPR observations, could identify some of active slip surfaces and their depths from the ground surface.
item: Conference Full-text
Impact of corporate social responsibility disclosure on organizational performance of metal quarries in Colombo District
Bataduwaarachchi, DL; Fernando, JMMP; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.
Rapid growth of infrastructure development of Sri Lanka increases the demand for the metal. Therefore even in the fast urbanizing Colombo district has to maintain and increase the production of metal from the quarries. It has lead to communityquarry site conflicts. In this situation corporate social responsibility is used to keep moving smooth of organisational performance of the quarry sites. The aim of this research is to find the best way to utilize corporate social responsibility for Colombo district quarries to get their organisational performance high. Using 40 quarry site managers, survey was conducted to find their organisational performance level and involvement level of five independent corporate social responsibility criteria: economic, legal, environmental, ethical and philanthropic. It has shown that the philanthropic criterion of corporate social responsibility has the highest significance for positive impact for organisational performance, while next is economic criterion of corporate social responsibility. The corporate social responsibility activities, which are based on other three criteria, have no impact on organisational performance of Colombo district quarries. Present practice of corporate social responsibility activities are highly philanthropic basis and very less on economic criteria basis compared to all other four criteria. Therefore quarry industry of Colombo district has to focus on corporate social responsibility economic criteria while continuing corporate social responsibility philanthropic criteria on first place. It is expected that this study will contribute to the knowledge area of corporate social responsibility initiatives in quarry industry of Colombo district, Sri Lanka.
item: Conference-Abstract
The Impact of physiochemical conditions on hydrogen stability and storage in depleted carbonate hydrocarbon reservoirs
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Lino, K.A.K; Elakneswaran, Y.; Hiroyoshi, N.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Hydrogen fuel derived from renewable energy and low-CO2 fossil sources has an immense decarbonization role in electricity generation, energy storage, transportation, and heavy industry. However, its lightweight nature necessitates a large storage capacity to enable its instrumental utilization. Underground hydrogen storage (UHS), particularly within readily accessible depleted hydrocarbon reservoirs (DHR), emerges as a promising solution, offering substantial, cost-effective, and secure storage capabilities. Yet, the risk of hydrogen loss due to both biotic and abiotic phenomena poses a challenge to the safety and integrity of these storage sites. In this study, we investigated the effects of mineralogy, salinity, pressure, and temperature on the interactions of hydrogen/brine/mineral and the rate of hydrogen loss within carbonate DHRs. Utilizing three distinct brine and limestone rock samples, we conducted static batch simulations across temperatures of 50-130°C and pressures ranging from 15 MPa to 30 MPa over a year-long storage cycle period, using PHREEQC and MATLAB. The results show that the dissolution of H2 and formation of CH4 and H2S increased with the increase in reservoir temperature and pressure at a rate of 1:2, respectively. In the various brine and mineral compositions studied, the lowest risk of H2 loss rate (<20%) was shown to be 115-130℃ (at 17MPa); meanwhile pressure above 18 MPa (at 50℃) indicated the highest risk of loss (>50%)—with even much loss percentage >85% above 19 MPa. Moreover, the mineral sample with the highest reactive mineral composition (25 wt%), had 80% H2 loss within the initial 50 days of the storage period across all pressure and temperature conditions, indicating a potential one-month risk of 50% loss within such mineralogy. However, in rock samples with over 90 wt% calcite and a 2 wt% reactive composition, H2 molality increased 4-fold on average across the storage period, salinity, temperature, and pressure condition, highlighting the dominant influence of mineralogy, particularly the reactive component, over temperature and pressure considerations in carbonate mineral systems. The findings, in summary, indicate that high temperature (~120℃), low pressure (~17 MPa), and reactive rock mineral (<2 wt%) may be appropriate physiochemical conditions to limit H2 loss risk below 20% during its storage in carbonate DHR
item: Conference Full-text
Key factors of metastable phase formation for strength development in steel slag and dredged soil mixtures
Toda, K; Otake, T; Sato, T; Sato, H; Weerakoon, N; Nishimura, S; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.;
The usage of by-products from industrial activities, as construction resources is awaited in Japan to decrease the environmental impacts. Steel slag from ironworks and dredged soil extracted beneath the ports are examples for such resources. Recently, it is discovered that mixtures of steel slag with dredged soil are hardened. This discovery may expand their application into building materials for undersea construction which may solve the problem. Nonetheless, different combinations of a type of steel slag and dredged soil from various areas show gaps in strength development. The relationship between mixing condition and strength development is not clarified, making the mixture difficult to be utilized for the above application. Understanding of the hardening mechanism of the steel slag-dredged soil mixture would enable the prediction of the strength with a particular combination of steel slag and dredged soil. To achieve it, clarifying the secondary mineral formation that contributes to hardening is essential. Previous studies suggested that the strength development was related to the pozzolanic reaction, which results in cementation by the formation of calcium silicate hydrates (C-S-H). Key factors in the pozzolanic reaction are the increase in pH of the pore water and the supply of calcium and silica ions to pore water. While calcium supply is determined to be Ca(OH)2 in steel slag which also increases pH by its hydration, silica supply is only suggested to be originated in dredged soils. The objective of this study is set to understand the effects of silica-bearing phases in dredged soil on the strength development of steel slag-dredged soil mixture. In this study, dredged soils from various sampling locations (A, B, C and D) and steel slag from ironworks-1 were mixed for the investigation. The unconfined compressive strength showed mixtures with soil-A exhibits the highest strength, followed by those with B, C and D. Firstly, the silica ion which is most likely to be supplied from dredged soils was investigated. The biogenic silica content and inorganic amorphous silica such as volcanic glass content were quantified. XRD analysis showed no significant difference between the mineralogical compositions of all the dredged soils including clay minerals. Then, the effect of humic acid which may limit the supply of soluble calcium is quantified and its functional groups are analysed to see the effect on strength development of the mixtures. Through geochemical modeling for estimation of C-S-H formed from above silica supply, we suggest that the silica supply from each silica-bearing phase of dredged soils may be the driving force for the pozzolanic reaction for the strength development.
item: Conference Full-text
Optimization of the distance between twin tunnels by stress analysis
Ebell, DA; Rajamohan, V; Jasinthan, P; Dassanayake, ABN; Samaradivakara, GVI; Wickrama, MADMG; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.
In this research, the stress characterization around twin-tunnels passing through a hard rock mass mostly consisting of Charnockitic Gneiss, Biotite Gneiss and Garnet Granulitic Gneiss in Kaluganga Development Project was analyzed by Boundary Element Method numerical solutions. The distribution and magnitude of major and minor principal stress contours, mean stress, differential stress, total displacement, maximum shear strain, and strength factor contours around the tunnels were simulated using the “Examine 2D” software. Examine 2D is a plane strain boundary element programme for calculation of stresses and displacements around underground and surface excavations in rock. Modeling results show that the countour values of the strength factor around the tunnel is greater than 1 when the distance between tunnels is 4.2 m which is the actual designed distance between the twin tunnels. When the distance is less than 4.2 m, model results shows that the strength factor reaches 1 in 1.88 m, and the excavation becomes unstable.
item: Conference Full-text
Optimizing the specific charge for limestone blasting at Aruwakkalu Limestone Quarry
Perera, WDS; Epa NBM; Neligama, DA; Hemalal, PVA; Dharmaratne, PGR; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y.
The objective of this research is aimed at optimizing the specific charge for limestone blasting at Aruwakkalu limestone quarry without leading to poor fragmentation of the blasted material. Thus, in reducing costs incurred during drilling and blasting activities, specific charge plays a vital role in open pit blast design as it affects many operational costs in mining activities. Therefore, at the quarry, specific charge is calculated for each blast and is monitored and maintained. Blasting parameters such as spacing and burden are already optimized at quarry according to the empirical formulae published by Langefors and Kihlstrom (1976).Therefore, when optimizing specific charge, it was first decided to change blasting parameters having the greatest effect on fragmentation such as spacing, burden, and charging method and evaluate the fragmentation of the blasted material because it is often difficult to optimize several blasting parameters simultaneously. Since fragment size directly affects crushing, a computer aided model called ‘Split Desktop’ was used to analyse fragmentation of material using digital photographs. Results of the four test blasts were analysed on cost basis. Thus, the blast geometry which resulted the lowest cost and the fragmentation within a manageable level is recommended to be practiced at the quarry in future.
item: Conference-Abstract
A predictive model derived from sattellite data and selected water quality parameters for invasive plant dynamics in north Bolgoda lake
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Gowsiga, A.; Kayooran, S.; Sriyasantha, P.D.S.H.; Gohulan, H; Dassanayake, D.M.S.M.; Jayawardena, C.L.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
The proliferation of aquatic weeds and algae in water bodies, such as Water Hyacinth coverage in North Bolgoda Lake, underscores potential pollution concerns associated with prolonged plant growth on surface water, changing nutrient levels and subsequently the water quality. This study aims to develop a regression model employing remote sensing techniques to identify and map the spatial distribution of invasive plants, primarily Water Hyacinth, in North Bolgoda Lake. Integration of surface temperatures derived from the Thermal Infrared (TIR) band of Landsat-8 satellite data facilitated by the field measurements of selected parameters are the main components of this research. Utilizing TIR band 10 data, converted into Lake Surface Water Temperature (SWT) imagery, alongside the surface water temperature measurements from pre-identified locations and computed Dissolved Oxygen (DO) and Chemical Oxygen Demand (COD) values for the same locations includes the main data used for the study. Lake SWT and DO, COD gathered from 30 locations during February and March 2024, revealed a linear inverse correlation between Lake SWT, COD, and DO. A composite map was generated for the selected locality of the North Bolgoda Lake with all the above information including provisions for precision enhancements by continuing insertion of field data. Despite the involvement of limited parameters this dynamic map could serve as a preliminary model for recognizing the behaviour of invasive plants and their impact on the selected elements of the waterbody. Further, this could be extended to determine the lake bottom dynamics, behavioural characteristics of the water column and the potential for encountering contaminations. It is recommended to develop this map by including further parameters and replicate the same methodology to cover the North Bolgoda Lake extent to assist authorities to make informed decisions. This study merges the satellite-derived data with ground-truth measurements to validate and refine the predictive models, ensuring their accuracy and reliability in forecasting. Utilizing spatial autocorrelation techniques this predictive framework could be further improved.
item: Conference-Full-text
Review on biochar for enhancing biogas production from anaerobic digestion of food waste
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Delpitiya, D.M.M.L.; Ariyarathna, S.M.W.T.P.K.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Food waste is the major waste fraction in municipal solid waste and is indeed a significant issue in society, with substantial economic, environmental, and social impacts. Various technologies exist to manage food waste, including animal feeding, anaerobic digestion, composting, incineration, and landfilling. Among these technologies, anaerobic digestion is the most recognized, efficient, and sustainable method. It can produce biogas and nutrient-rich fertilizer simultaneously. Because of the high organic load of food waste and the presence of mass nutrients, it is a suitable substrate for the anaerobic digestion process. However, the anaerobic digestion process faces challenges such as process instability, slow rate of biogas generation, and sudden failure of biogas generation due to susceptibility to inhibitors. All these challenges have affected its efficiency. Biochar has been identified as a promising alternative to address most of the drawbacks in the anaerobic digestion process and enhance methane production. Biochar is a carbon-rich material produced through thermochemical conversion processes. Because of its specific properties, such as its high specific surface area, porous structure, adsorption capacity, buffering capacity, and a higher number of functional groups, it has the potential to enhance biogas production in anaerobic digestion processes. Biochar exhibits pH buffering properties, enhances the enrichment of functional microbes, alleviates the effects of inhibitors, and accelerates the process of direct interspecies electron transfer. This paper reviews the effectiveness of biochar as an additive in the anaerobic digestion process of food waste. It further examines the properties of biochar, the factors influencing these properties, and the mechanisms through which biochar enhances the AD process.
item: Conference-Abstract
A Statistical analysis of urban location data obtained from smartphones for disaster response
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Jayasundara, D.R.T.; Kularatne, M.K.B.D.; Samarakoon, K.G.A.U.; Jayawardena, C.L.; Iresha, H.; Elakneswaran, Y.; Dassanayake, A.; Jayawardena, C.
Technological advancements in device hardware and application software platforms have enabled smart phones to be used for multiple purposes as an all-in-one hand-held device. Its readily availability among majority of individuals, ease of use as a compact unit with access to remote storage and capacity to communicate makes it a perfect tool for emergency response specially with reference to disaster management provided having sufficient reception. Nevertheless, its embedded location services facility which communicates with the GNSS not only facilitates navigation, location sharing etc. but also capable of producing geo-tagged information, which could be vital under emergency conditions. Hence, this study statistically evaluates the reliability of location data recorded from a combination of smartphones and hand-held GPS units under selected urban environmental conditions. Commonly available four devices and a combination of applications were performed at five locations over a period of two months as the data collection for this exercise. The results reveal, regardless of the device and software combinations the location readings approximately follow the Gaussian distribution. However, a varying functionality has been observed in certain locations despite the consistency in environmental factors. Also, the mobile phones demonstrated a reasonable consistency among them in most of the horizontal positioning coordinate display events, despite the differences extracted from statistical analysis. Except in one location the smartphones indicated a significant difference in linear location data when compared with those obtained by handheld GPS. Analysis of Variance (ANOVA) was conducted to test the differences at 5% significance level. There is a growing emphasis on capturing records of geo-tagged spatio-temporal data not only to enhance the smartphone user experience but also for the disaster response considering the capability of smartphone to determine positions. Through this research, valuable insights into the performance of smartphones as tools for spatial data collection are sought to be provided, and best practices for location-based applications are aimed to be informed.