Browsing by Author "Hewathilake, H.P.T.S."
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Item Characterisation of “Dummala” Origin in Sri Lanka by XRF, XRD and FTIR(Uva Wellassa University of Sri Lanka, 2019) Subasinghe, H.C.S.; Bandara, T.G.T.A.; Christopher, W.A.P.P.; Hewathilake, H.P.T.S.; Pitawala, H.M.J.C.The term Dummala is a traditional name given to the naturally occurring substance that can be found, either at uppermost crustal levels, mostly under the freshwater swampy areas or as a dried resin like gums from the Dummala tree (Shorea oblongifolia), which is endemic to Sri Lanka. The history of Dummala is dated back to more than 2000 years, where it was used in ayurvedic medication and to make flares in exorcisms and processions. Dummala which is taken out from ground, physically appears as peat-like carbonaceous matter with agglomerated coarse-grained particles. Though, this variety of Dummala is naturally occurring material found in Sri Lanka a firm scientific analysis has not yet been conducted. Therefore, this study aims to characterise the Dummala extracted from the ground, in order to investigate the chemical composition and special properties that might be suitable for the advanced applications. Initially, natural Dummala was dried and 50 g of sample (<53 µm) was obtained by mechanical sieving. X-Ray Fluorescence (XRF) spectroscopic analysis were conducted to identify the chemical composition. Further, Dummala was characterised with X-Ray Diffraction (XRD) analysis for the phase identification and the results showed that this material is partially crystalline. XRF data together with XRD analysis confirmed that Dummala which is taken out from the ground is composed mainly with Magnesium Carbonate, Silica and Sulphur. Further, the present study suggests a carbon content analysis in order to interpret the origin of Dummala.Item Depositional History of Sediments in Eastern Lagoons of Sri Lanka: Sedimentological and Mineralogical Evidences(Uva Wellassa University of Sri Lanka, 2018) Megasooriyal, M.M.T.I.; Adikaram, A.M.N.M.; Hewathilake, H.P.T.S.Characteristics of sediments and minerals are useful in identification of paleodepositional environments. Specially, clay mineralogy shows the specific environmental conditions that are related to the marine or terrestrial environments. Present study used sedimentological and mineralogical characteristics of recent age sediments of Batticaloa lagoon and Kiran lagoon to interpret the depositional environments. Four sediment core samples with an average height of 1 m were collected from both lagoons and analyzed for temporal grain size distributions using mechanical sieving techniques. Vertical profiles of sand and clay mineralogy were investigated by grain counting technique, X-ray diffraction and Fourier-transform infrared spectroscopy. Medium size sediments are the dominant type indicating prevailed moderate energy conditions for the history. Several coarse grain events are recorded in cores which might be originated from storms. Statistical parameters of sediment grain size and Quartz-Feldspar-Lithic fragments triangular diagram of sands show matured riverine continental origin for the depositional history. Main clay minerals of the depositions include kaolinites, smectites, illites and chlorites. Clay mineral profile also confirms the continuous sedimentation history for the past centuries. The results of the study conclude that the recent history of the sediment depositions in eastern lagoons have not been affected by considerable environmental changes except some coarse events such as high energy storms.Item Development of a Novel Composite for Bricks by Laterite, Fly Ash, Sand and Waste Plastic(Uva Wellassa University of Sri Lanka, 2020) Pallege, P.T.S.; Hewathilake, H.P.T.S.Natural aggregate sources are becoming depleted due to high demand in the construction industry and the amounts of disposed waste plastic material are increasing. Hence, researchers are exploring the use of alternative materials instead of natural resources. Therefore, the present invention provides a composite material wherein laterite, sand, chemically unmodified Polyethylene Terephthalate (PET), and fly ash (FA) are mixed in a container to disperse raw material in PET and molded. Initially X-ray diffraction (XRD) analysis have conducted for laterite, FA, and sand to identify major mineral phases. After preparing the sample bricks according to the different proportions of raw materials under four samples series, standard compressive strength (CS) in both dry and wet conditions and water absorption (WA) analysis was conducted. XRD analysis of FA and laterite have confirmed the presence of crystalline silica and kaolinite as major phases respectively and sand has responsible peaks for quartz and feldspar as obvious. The highest CS in wet and dry conditions has recorded for the combination in “series A” which has 35% PET, 25% FA, and 20% laterite and sand. Further, the increasing FA content able to increase CS in wet and dry conditions. Under the higher plastic content breakeven point cannot be detected due to the high plasticity nature. The composite with the highest plastic with only FA has lowest WA of 0.08% but its’ CS is lower than the aforesaid combination in “series A” and this combination has 0.32% of WA which is still below the standard WA to reference. Though higher plastic content in materials is lightweight and suitable for the high seismic active areas, the highly flammable nature stands as a major drawback. Therefore, 35% plastic, 25% FA, and 20% laterite and sand can be taken as a favourable and novel combination for the production of bricks. Keyword: Compressive strength, Water absorption, Plastic, Fly ashItem Development of a Novel Composite Tile using Meetiyagoda Kaolinite Reinforced with Polylactic Acid (PLA)(Uva Wellassa University of Sri Lanka, 2021) Herath, H.M.D.M.I.; Hewathilake, H.P.T.S.Sri Lanka has high quality Kaolinite deposit in Meetiyagoda that govern by the Lanka Ceramic PLC and refined kaolinite has provided to the local ceramic industries. Kaolinite, is a layered silicate clay mineral composed with low shrink–swell capacity and cation-exchange capacity. Mostly ceramic tile production is suffering with cracking, low strength, high weight and less waterproof capacity. Hence, ceramic tile industry has been updating with product advancement gradually since last decades. Specially, the evolution of tile body formulations and technological behavior of clay composite materials have taken in to attention. This trend has taken step forward with introducing novel composites by mixing polymer materials with raw materials. Polylactic Acid (PLA) is a blend composite having low stiffness, high tensile strength and high gas permeability. Therefore, the present study is focused on develop a composite material by mixing PLA and kaolin in order to obtain low weight, high strength and waterproof ceramic tiles. Initially Kaolin samples were collected from Meetiyagoda Kaolinite deposit and all the samples were tested for moisture content & were subjected to physical purification by mixing with distilled water and obtained a milky color clay solution. After that dried clay samples were powdered and 125 micron size fraction was obtained by mechanical sieving. Then while PLA was heating to its melting temperature (1700C), kaolinite was added time to time (ratio in 50:50) into PLA container and mixed using a heat stirrer in 1700C for 30 min to develop a slurry which then set up in a mould. Then the prepared novel composite tile sample was tested on water absorption, compressive strength & crystal structure was tested by using the X- Ray diffraction (XRD).As an overall result the novel tile sample shows almost 0% water absorption with time and also it is very light in weight with a considerable amount of strength. This novel tile can be developed with low temperature (1700C). Therefore, the product is cost effective. Future of this research can be directed to enhance more properties based on what material used to reinforce the kaolinite (Ex: Glass fiber, Silica, graphite) and we can use this reinforced kaolinite as a raw material to develop a novel cement (plaster) to apply in building constructions. Keywords: Kaolinite; PLA; Novel reinforced tile; Water absorptionItem Development Optimisation of Prototype Froth Floatation facility as an advanced physical beneficiation technique to upgrade low grade Sri Lankan vein graphite in Kahatagaha Graphite Lanka Limited(Uva Wellassa University of Sri Lanka, 2020) Amarasiri, P.G.S.C.; Chiranjaya, Y.A.S. U.; Dissanayake, D.M.S.; Hewathilake, H.P.T.S.Presently, Sri Lanka is the sole Vein Graphite (VG) supplier to the world market. Since the best quality VG has been selected in the sorting procedure, low-quality VG remains while leaving a chance for upgrading. The natural hydrophobicity of graphite has been utilized by the Froth Floatation (FF) which is a physical beneficiation technique uses to separate graphite from gangue minerals. Few studies have been conducted for both flake graphite and VG. Therefore, the present study was forced to set up a prototype FF facility to optimize its cell design and identify the pulp density, frother type, and dosage, collector dosage for the economically feasible installation of the FF plant at KGLL. The cylindrical cell was designed with a height of 20 cm and diameter 12 cm. 150 g of ≤ 72 µm VG powder was mixed with different volumes of water to find optimum solid to liquid (S/L) ratio. The effect of the collector and the frothers were determined by varying the kerosene dosage for 0.01g to 0.10g and both Pine Oil (PO) and 4-Methyl-2-pentanol (TMTP) for 0.01g to 0.05g, respectively, while all other factors were kept constant. Resulted floated VG samples were analysed by Carbon Content (CC) (ASTM-C561) and X-ray Florescence (XRF) analyses. The optimum recovery of 80% of VG was achieved with the pulp density of 10% S/L ratio and further, 0.08g of kerosene, 0.02g of TMTP, and 0.04 g of pine oil. Among the two frothers, TMTP was cost-effective and easy to handle than pine oil. The CC of the obtained floated VG graphite has upgraded from 90.2% to 96.58% and comprehensive elemental analysis was confirmed the removal of iron, silica, and other metallic impurities up to 72%. Therefore, the FF plant can be effectively run with the 10% of S/L ratio together with kerosene collector and TMTP frother. Keywords: Vein graphite, Froth-flotation, Surface science, Value additionItem Geochemical Characterization of Magnetite Ore Deposit in Buttala, Sri Lanka(Uva Wellassa University of Sri Lanka, 2019) Athisinghe, A.M.J.N.; Hewathilake, H.P.T.S.; Adikaram, A.M.N.M.Sri Lanka comprises of a fairly large number of valuable mineral deposits. However, most of these deposits have not yet been scientifically investigated, in terms of their origin, grade, mineralogy, quality and the quantity. Iron ore deposits of Sri Lanka are divided into three categories as magnetite deposits, hydrated iron oxide deposits and coppermagnetite type deposits. The largest magnetite deposit of the country is located at Palawatte, Buttala in Uva province. The origin, quality and the quantity of the Buttala magnetite deposit (BMD) is still debatable. Therefore, present study focused to interpret the geochemical characteristics in order to predict the possible sources for the origin of BMD. Rock samples were collected from the pre-determined locations in BMD area. Representative magnetite bearing rock samples and country rock samples were collected mainly from fresh outcrops available at the surface. A detailed geochemical analysis was conducted by X-ray fluorescence (XRF) spectroscopy. The results of major oxides indicated high content of iron (>80%) with minor amounts of SiO2 (7.02%), Al2O3 (5.98%), TiO2 (3.22%), MgO (2.82%), K2O (0.22%), CaO (0.12%) and MnO (0.08%). The spatial distribution plots of trace elements and major elements indicate the mineralization is localized to the hummock of the study area. The depleted concentrations of elements such as Ti and Zr that are considered relatively immobile in hydrothermal fluids suggests the involvement of hydrothermal processes to the formation of BMD. Further, it is recommended a detailed petrographic analysis in order to confirm the hydrothermal origin of the BMD.Item Identify the Potential of Applying Rice Husk Ash and Fly Ash for Cement-Based Grout(Uva Wellassa University of Sri Lanka, 2020) Sabeshan, E.; Hewathilake, H.P.T.S.; Jaliya, R.G.C.Rice husk ash (RHA) is a fine agricultural by-product and commonly the brick industry in Sri Lanka produces a significant amount of RHA as a waste. Similarly, Fly Ash (FA) is resulted as a byproduct of coal power plants (CPP). In Sri Lanka, Nuraichcholai CPP generates about 200,000 MT/year of FA. Previous studies have reported that both RHA and FA have pozzolanic reactivity. Cement-Based Grout (CBG) used in geotechnical and other engineering aspects is expensive since the cost of Portland cement and grout additives. Therefore, the present study aimed to introduce RHA and FA to the CBG as a partial replacement for cement. FA and RHA samples were collected from Nuraichcholai CPP and brick industrial sites respectively. After initial purification, 63-150 µm sieve fraction of both FA and RHA were selected. Cement, FA, and RHA were thoroughly mixed in a small grinder to prepare different grout mixtures. Initially, phase analysis for FA and RHA was conducted by X-ray Diffraction (XRD). Before the solidification, each grout mixture was analysed with the Standard Flow Cone (FC) test and then Compression Strength (CS) test during the curing period of 7th, 28th, and 45th days was conducted. XRD analysis has shown that FA and RHA have the crystalline and amorphous form of SiO2 respectively. FC efflux time in each combination is in the rage of 14.1-17.5 sec. (FC efflux time < 15 sec. ASTM-C939-02). FC efflux time has increased with the increment of RHA amount. This may due to the porous nature of RHA, which tends to reduce the quantity of free water and increase water demand. Except for the FA+cement combination others have CS less than 20 MPa (CS > 20 MPa BSEN 12390-3:2002). The increment of RHA tends to decrease the CS. Hence, the application of FA as an additive for CBG is favourable than the RHA or combination of FA+RHA. Keywords: Rice husk ash, Fly ash, Cement-Based Grout, Compressive StrengthItem Investigation of the Origin of Radioactive Mineral in Godakawela Gem Field, Rathnapura in Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Kuruppu, K.A.D.D.N.; Hewathilake, H.P.T.S.; Illangasinghe, I.K.M.S.C.K.; Ranasinghe, R.A.N.C.; Jayasinghe, N.; Dharmaratne, T. S.Sri Lanka is well known for high-quality gemstones and 25% of the total land area is liable for potential gem fields. However, the identification of new gem bearing areas in Sri Lanka is mostly conducted by the sedimentological and geochemical analysis. Notably, most of the gem bearing areas have been associated with radioactive minerals (RAMs). Hence, the in-situ radioactivity survey is an important tool that has not been carried out intensively in Sri Lanka. Recent studies have revealed that the Godakawela gem field (GGF) in Rathnapura has an interesting radioactiveness. Therefore, the present study has conducted to investigate the type of the origin of the RAMs in GGF. The ambient gamma dose rate was measured by the plastic scintillation detector from 40 points in random walk mode and gamma energy was recorded in the NaI scintillation detector. Further, field observations, associated minerals, and surrounding geology were also considered together with the anomaly results. Anomaly results have proved that the GGF has high radioactiveness of 1305 nSv h-1 gamma radiation, which is ten times greater than the average baseline value in Sri Lanka. Peak anomaly observed in the base of the valley has shown a decrement in gamma dosage of 476 nSv h-1 compared to the mid-region of the slope. Hence, if it is a secondary deposit, a considerable amount of the RAMs must be settled to the low altitude area of the valley and given high peak anomaly. Godakawela is located in the Highland-Vijayan boundary which is also known to be fluoride-rich, and well-formed crystals of tourmaline have been associated in the area. Similarly, a large pegmatitic origin of the vein quartz deposit has been identified in this region. Therefore, depending on the distribution of radioactive anomaly patterns and the presence of associated minerals such as well-formed crystals of zircon, tourmaline together with the surrounded geological aspects has identified that the RAMs have primary origin in GGF. Keywords: Radioactiveness, Radioactivity survey, Gamma dose, Primary originItem Magnetometer Characterization of Iron Ore Deposit in Buttala, Sri Lanka(Uva Wellassa University of Sri Lanka, 2012) Hewathilake, H.P.T.S.Sri Lanka is endowed with mineral resources though many mineral occurrences were not fully assessed and quantified identifying the true potential. Mostly the geological formations of the valuable mineral engage with complex structures such that a detailed exploration program is essential to assess the grade, recovery, characteristics and quantity of the ore(s). The occurrence of the magnetite in Palawatte area was first discovered by the GSMB during the geological field mapping of the Buttala sheet (1:50,000) in 1999. Based on some sporadic studies as regards this iron ore were reveal that, the deposit containing considerably higher amount of magnetite but the significant factor is in the reserve estimations, most of the previous studies considered the total interesting area (the ridge of the Horakagodakanda hill) as the deposit. Since the underneath geological settings of the deposit is unknown, such an evaluation can be misled the future investigations and development of the deposit. Magnetic method is a very successful approach for exploring of minerals deposits with magnetic signature. As the one of the material that poses magnetic properties naturally, ferrous containing rocks and minerals provide anomalous signatures than of the background magnetic field that enabling to screen the same. A Proton Precession Magnetometer was used for the data acquisition (model - GSM-19TW). Based on the geomorphological and terrain conditions field data acquisition was continued randomly with an integrating GPS antenna to the magnetometer. Acquired raw data files were processed integrate with the Gem Link (version 5.2) and Geosoft.Oasis.Montaj (version 6.4.2 HJ) software. The processed total field magnetic intensity map and the anomaly map show the intensity of the positive anomalies is higher than the negative anomalies and a systematical stretch of positive and negative anomalies. Furthermore the anomaly map conspicuously illustrates the dipole behavior of the magnetic source beneath the interested area and confirms the geological configuration of the source body is a dike which dipping along the south-east direction.Item Synthesis of Aragonite Phase Calcium Carbonate Nanoparticles from Sri Lankan Beach Cockle Shells(Uva Wellassa University of Sri Lanka, 2020) Rashad, M.S.M.; Hewathilake, H.P.T.S.Cockle Shells (CSs) are very rich natural resource for Calcium Carbonate (CC). Synthesis of Aragonite Nano Particles (ANPs) is one of the prime targets of researchers in the biomedical field, since the biodegradability, biocompatibility, and porous nature of ANPs. Further, it is denser than calcite and can be integrated, resolved, and replaced by bone and also has the potential to develop as anticancer drugs, drug delivery systems, and for bone repairing. Highly purified aragonite phase CC hard to obtain by synthesizing. Sri Lanka comprises of a fairly huge amount of naturally formed CSs along the sea-coast without adding any industrial value, other than the beauty. Therefore, the present study has been forced to synthesize ANPs from CSs. The CSs collected from the beach were thoroughly washed, dried, and pulverized. 5.0 g of 63µm powdered CSs sample was stirred with 50.0 mL of deionized water and then 2.0 mL of Coco Diethyl Betaine (CDEB) surfactant has added continue the stirring. Nine different series were tested by varying the stirring speed and time with deionized water before adding CDEB. Raw CSs samples and prepared ANPs were characterized with X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectrometry, and Particle size analysis (PSA). XRD analysis has confirmed both raw CS and ANPs consist of aragonite phases and the applied mechano-chemical method (MCM) was able to preserve crystallinity of the Aragonite phase in ANPs. FTIR spectroscopic analysis has shown aragonite phase CC and confirmed that the CDEB does not affect the vibration frequencies of carbonate ions. PSA has shown that the average particle size below 100 nm, ANPs were able to obtain by stirring 63 µm powder under 1400 rpm for one hour before adding the surfactant. Hence the MCM was very effective in producing ANPs which is a promising material in biomedical applications. Keywords: Cockle shells, Aragonite, Biomaterial, Mechano-chemical, NanoparticlesItem Synthesis of Thermally Stable Silicone Based Novel Electro - Conductive Grease using Sri Lankan Natural Vein Graphite(Uva Wellassa University of Sri Lanka, 2021) Bandara, M.A.G.S.P.; Hewathilake, H.P.T.S.Grease is a solid or semi-solid product which contains three main components such as base oil, thickener and an additive package. While reducing the contact resistance, repelling moisture and inhibiting the corrosion, the Electro-Conductive Grease (ECG) can prevent static buildup. Hence, they can be used as a gap filler in the moving parts of the electrical circuits. However, electric and electronic apparatus with moving parts generate heat and it is necessary to maintain ambient conditions for the normal operation. Therefore, to overcome such issues thermally stable ECG has been taken more attention recently. Most widely used silicone grease has dimethyl silicone oil as the base oil and can be performed -50 °C – 170 °C temperature range but unable to serve as conductors. Graphite is anisotropic, being a good electrical and thermal conductor within the layers. Further, the carbon layers can slide with respect to one another quite easily, thus making graphite a good lubricant. Therefore, mixing graphite and silicone grease would preferably combine the electro- conductive nature of graphite and thermal stability of silicone grease. Powdered natural vein graphite and the silicone grease were mixed at different weight ratios and stirred well. Three sample series were prepared based on different graphite powder sample sizes such as 75μm, 63μm and below 63μm. Each sample was tested with DC electrical conductivity and thermal stability. X-ray diffraction pattern of raw graphite was exhibited that availability of impurities such as pyrite which help to improve electrical conductance nature. Carbon content analysis showed that highest grade of graphite was used to develop the grease. The FTIR spectra were exhibited that characteristic stretching vibrations of functional groups attached to the samples. Out of the 3 sample series, the sample with 35% of 75μm size graphite powder with 65% of silicone grease shows the highest electrical conductivity of 2.86 x 10-7 Scm-1 and able to show the wide service temperature range of 10°C to 120°C. Keywords: Electro-conductive grease; Sri Lankan vein graphite; Silicone grease