ISERME - 2017

Permanent URI for this collectionhttp://192.248.9.226/handle/123/14733

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    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.
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    Applicability of ground penetration radar (GPR) technique to optimize soil Nail Wall designs
    Lasan, HLI; Weerasekara, MN; Prashanth, S; Abeysinghe, AMKB; Premasiri, HMR; Samaradivakara, GVI; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Soil nailing is used to stabilize existing natural slopes or excavations using soil reinforcement technique. Due to lack of information on ground profiles and thickness of soil layers, the required soil nail lengths cannot be determined in advance, for most of the steep slopes. Furthermore, the cost of drilling in fresh rock is much higher than the cost of drilling in soft soil and weathered rock. Without proper information on the depth at which the fresh rock is found, a cost-effective soil nail wall design cannot be finalized. This research was focused on studying the methods that can be used for soil nail wall design optimization by applying Ground Penetration Radar (GPR). The study was carried out on an unstable slope near Nursing Training School located in Kandy in the central part of Sri Lanka.The physical properties of soil were determined by direct shear tests, and stability analysis was done by means of “Slope-W” software. GPR techniques were also used in this study. The investigation results showed that the existing slope is unstable, and necessary to be protected. Further, it was identified that the basement rock cannot be encountered at already designed depths of the soil nails, which was subcequently proven as correctbased on data from ongoing drilling for soil nail installations. With the precise knowledge about the underground geological structure using GPR technique, the drilling cost, nail transporting cost, nail off cutting time to complete the total work can be reduced.
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    Geochemical aspects of Calcite and Dolomite deposits around Rajawaka off Balangoda, Sri Lanka, and suitability for industry
    Liyanage, WLDNK; Ranasinghe, GHPGKM; Yapa, SKSP; Weerawarnakula, S; Premasiri, HMR; Abeysinghe, AMKB; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Major calcite and dolomite occurrences are found in Rajawaka off Balangoda in Sri Lanka. The area is undertaken by Precambrian marble rock which is one of the most common sources of calcite and dolomite in Sri Lanka. Field investigation, locating sample points, analytical work using AAS, ETDA titration, colorimetric methods and microscopic analysis were carried out in different phases to obtain chemical and mineralogical composition of calcite and dolomite. Results revealed that the marble samples contain major proportion of calcite mineral, calcitic marble with minor amount of dolomite. Quartz, graphite, pyrite, diopside, apatite, muscovite, phlogopite and biotite occur as accessory minerals. Also, analytical data showed an average acid insoluble of 5.73% and SiO2 of 4.71%, moderately high CaO content` of 81.71%, with low MgO content of 4.91% and very low iron oxide content of 0.37% and aluminum oxide content of 1.62%. These characteristics make this deposit suitable for major industrial uses especially the production of high quality lime and fertilizer manufacturing industries, and it is not suitable for the high-quality glass industry due to high content of silica and other accessories.
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    Influence of mechanical and aggregate properties of rock on powder factor in rock blasting
    Karunanayake, KDP; Dharmaratne, PGR; Rohitha, LPS; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Profit margins in metal quarrying have drastically reduced in Sri Lanka due to high powder factors recorded in recent rock blasting activities. Importance of analysing the influence of mechanical and aggregate rock properties on the powder factor arises in this context to determine suitable rocks in which expenditure on blasting is minimal during the production stage. Eight quarries operated under the close supervision of qualified Mining Engineers were selected for this study to ensure that a proper blasting geometry and configurations have been properly managed during the period of study. Random core samples were obtained from each quarry site and tested for Density, Uniaxial Compressive Strength (UCS), Tensile Strength and Aggregate Impact Value (AIV) and Rock Mass Rating (RMR). Explosive consumption and drilling records for the past six months were obtained from each quarry for the calculation of powder factor. Powder factor was plotted against each selected rock property and regression analysis was performed to understand their standalone influence. Results of the analysis concluded that the aggregate rock properties, especially Aggregate Impact Value (AIV) have a greater influence on the powder factor. Relationship established in this research can be used to predict powder factor of a fresh rock before conducting any blasting activity.
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    Effectiveness of emulsion explosives in quarrying in high grade metamorphic rocks in Sri Lanka
    Weerawarnkula, S; Hemalal, PVA; Pathirana, KPR; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    The optimization of explosive usage in Sri Lankan metamorphic rock is the main objective of this research. Sonic velocity of the rock is a reliable indicator of its structural integrity and resistance to fragmentation. Aggregate impact value is a one parameter of hardness of rock. This study has been conducted on the assumption that the aggregate impact value is an indicator of hardness of the rock. Tests have been planned keeping blasting parameters constant against different rock types having different aggregate impact values. Comparison of the results shows the behaviour of explosives with different rock types having different aggregate impact values or hardness. D'Autriche method has been used to determine the velocity of detonation of emulsion explosives. According to the results of blasting using emulsion explosives on hard rocks produced a greater blast volume and a higher production with a lower fly rock throw, compared with that of softer rocks. Therefore, it is established that the concrete relationship with higher blast efficiencies exist with the hardness of rock and emulsion explosive usage.
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    Processing vein quartz in Badulla area to suit manufacturing chemically reinforced glasses
    Pathirage, SS; Hemalal, PVA; Rohitha, LPS; Siriwardhana, YPS; Ratnayake, NP; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Chemically reinforced glass, commercially known as tempered glass has a high global demand with the rapid increase in the usage of touch-screen type mobile phones and tablets. To maintain a high quality and to enable improvements of these devices the resolution, clarity and durability of tempered glass has to be improved and therefore, the selection of quality raw silica for tempered glass has become critical. Sri Lanka is one of the main exporters of silica to the world market and currently, Sri Lankan supplies mainly consist of crushed and powdered bulk unprocessed raw material. In this background, it would be prudent to export semiprocessed quartz as raw material for chemically reinforced glass. The requirements for chemically reinforced glass is a minimum value of 99.8 %, SiO2 and the maximum impurity levels of 9 ppm of Fe2O3 and 350 ppm of Al2O3 with the size requirement being 75-300 microns. In this study, sources for the production of raw material for the production of chemically reinforced glass was investigated using various types of vein quartz originating from quarries situated at Badulla in Sri Lanka. Milky, Smokey, Transparent, Rose, Mica associated and Feldspar associated quartz obtained from 7 quarries were investigated. Samples were analyzed using Atomic Absorption Spectrophotometer (AAS) and Inductively Coupled Plasma (ICP) techniques for trace elements. Results of the chemical analysis showed a markedly low iron content with less than 15 ppm in transparent quartz, less than 25 ppm in milky quartz, less than 30 ppm in smokey quartz, less than 35 ppm in rose quartz, less than 30 ppm in mica associated quartz and less than 300 ppm in feldspar associated quartz. More than 700ppm of Al2O3 content was observed in feldspar associated quartz. Cr content in rose quartz was more than 700 ppb and more than 800 ppb in mica associated quartz. Smokey quartz showed a high Ni and Al2O3 contents. Milky and transparent quartz in the observed quarries showed the lowest trace element contents and their natural quality close to the requirements of chemically reinforced glass and SiO2 levels are higher than 99.8%. Further results obtained using an industrial scale pilot plant show a significant reduction of Fe content, less than 5 ppm occurring in milky quartz with size reduction carried out followed by magnetic separation and removal of fraction less than 75 micron. Processed transparent quartz and milky quartz in Badulla area can directly be exported as raw material for chemically reinforced glass.
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    Relationship between Los Angeles abrasion value and mineral content of metamorphic rocks
    Dayarathna, IWTP; Puswewala, UGA; Abeysinghe, AMKB; Rohitha, LPS; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    This research includes study of the relationship between Los Angeles Abrasion Value and the mineral content of rock aggregates narrowed down to the commonly found high grade metamorphic rocks in Sabaragamuwa Province. Los Angeles Abrasion Test and mineral content of each rock sample was determined at the laboratory. Thin section analysis was carried out to determine the mineral content with the help of petrological microscope equipped with a digital camera and AutoCAD software. The regression analysis was carried out to develop a relationship between Los Angeles Abrasion Value with engineering and mineralogical properties such as relative dry density, Quartz content, Feldspar content as well as Mica content. Another important achievement of this study was developing a field guide to assist the personnel at the field. It was completed with the photograph of each rock sample, microscopic view of the sample and their respective engineering and mineralogical properties such as Los Angeles Abrasion Value, dry density, Quartz content, Feldspar content and Mica content.
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    Applicability of pre-heating techniques for recovery of garnet from garnet biotite gneiss
    Jayakodi, JDSU; Weliwita, BY; Nishanthan, SS; Samaradivakara, GVI; Abeysinghe, AMKB; Rohitha, LPS; Vijitha, AVP; ; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    In mineral processing industry, the highest energy is consumed by crushing and grinding operations. However, if we can initiate micro cracks in the hard rock pieces in advance, we should be able to reduce the crushing energy and liberate useful minerals economically. Various pre-heating techniques have been tried by the scientists around the world to liberate minerals from rocks. In this investigation, pre-heating techniques were used to liberate Garnet from Garnet Biotite Gneiss. The market price of Garnet varies with the particle size. Hence, the samples were crushed and sized into industry needed three size fractions: (+250-850) μm, (+180-250) μm and (-180) μm. Afterwards, by means of Wilfley Table, Garnet was separated from rocks. Final Garnet recovery percentage was recorded for different temperatures. Furthermore, energy calculation was done for each sample to get an idea about the power consumption. It was observed that the crushing strength decreases with the temperature increment and it has been proven by identifying propagation of micro cracks in thin sections, prepared from rock samples pre-heat treated in Muffle Furnace and Microwave Oven. The analysis reveals that the preheat treated and quenched samples give higher Garnet recovery than Garnet recovered from as-received samples of Garnet rich Biotite Gneiss.
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    Dynamics of the Madu-Ganga Estuary
    De Silva, UHNH; Somasiri, RBHP; Jayasekara, NNL; Ratnayake, AS; Dushyantha, N; Weththasinghe, SM; Samaradivakara, GVI; Vijitha, AVP; Ratnayake, NP; Abeysinghe, AMKB; Dassanayake ABN; Elakneswaran, Y;
    Among the estuaries in Sri Lanka, Madu-Ganga Estuary plays a significant role to generate a massive income through tourism. The existing tropical ecosystem attracts the tourists. However, this ecosystem faces problems of environmental deterioration problems which affect the tourism industry and income of the local community. Therefore, this research is mainly focused for understanding hydro dynamics and sediment dynamics process in Madu-Ganga Estuary. The four field visits were carried out to cover southwest and northeast monsoon periods. In situ and laboratory tests were conducted for surface and bottom water samples of Madu-Ganga Estuary to analyse the quality of the water. In addition, grab and core samples and sub-bottom profile data were used to identify sediment distribution patterns of the estuary. Moreover, time series satellite images were used to identify nearshore sediment dynamics along the western coast of Sri Lanka. Results show that a significant variation of water quality parameters under the estuary mouth opened and closed conditions. The spatial variation of chloride content also indicates that estuary mouth opened condition plays a major role to control seawater invasion in this aquatic system. Sub-bottom profile data shows cyclic/seasonal changes in accumulation of sediments in Madu-Ganga Estuary. Time series satellite images indicate that sand can probably receive from the southern region by predominant longshore currents during the southwest monsoon. Further studies are recommended to identify lake ecosystem responses to physicochemical changes and to design seasonal mining capability.
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    Nearshore sediment dynamics in Sri Lanka
    Ratnayake, AS; Weththasinghe, SM; Dushyantha, N; Premasiri, HMR; Ratnayake, NP; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Coastal environment is a unique morphodynamic system for diverse changes. The present study estimated coastal morphodynamic changes and sediment transportation directions at locations of Uswetakeiyawa beach nourishment and Colombo harbour expansion project areas. In addition, heavy mineral occurrences were studied in beach sediments altogether parameters of mineralogical and geochemical compositions to identify depositional environments. Moreover, time series satellite images were used to identify seasonal coastal sediment accretion and depositional trends. Uswetakeiyawa beach nourishment project area indicates complex sand accretion or erosion, and a net reduction of overall beach widths with reference to the initial field visit. This site records bi-directional sediment transportations by longshore currents during the monsoon periods. Similarly, Colombo harbour expansion project area shows that the cumulative beach erosion has increased after the construction of the breakwater (rate = 0.7 m/year from May 2000 to April 2011 and rate = 28.2 m/year from April 2011 to June 2012). The cumulative and site-specific sand accretion and erosion patterns show clear influence with the monsoon seasonality. Beaches were wider during the stormy south-western monsoon, whereas beaches were narrower during fair weather of north-east monsoon. In contrast, ilmenite, zircon, garnet, monazite and rutile were identified as main heavy minerals in beach sediments. The heavy mineral potential of the north-eastern coast was high (average about 45-50% in the Verugal and 70-85% in the Pulmoddai deposits and 3.5-5.0% in the offshore samples from Nilaveli to Kokkilai), compared to the south-western sediments (average about 10% in onshore and 2% in offshore Gin River mouth). Observed high concentrated heavy minerals in beach and low concentrated offshore sediments suggest the panning system in the surf zone to form enriched placer deposits. The whole rock major and trace compositions of beach sediments were marked enrichment of TiO2, Fe2O3, Ce, Cr, Nb, Th and V compared to the average upper continental crust values. The analysis of prominent coastal longshore transport patterns shows that clockwise flows in the eastern and north-western coasts. In the south-western coast, transport directions were divided into two branches of anti-clockwise and clockwise. Therefore, the schematic representation of monsoon-derived longshore currents suggests that the sources of heavy minerals in the Pulmoddai and Verugal deposits may have probably influenced by clastic sediment supply in eastern India and Sri Lanka (the Mahaweli River), respectively. Heavy minerals in the western coast can probably derive from Precambrian metamorphic rocks, and supplied to coast through river systems in Sri Lanka.
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    Structures of water column and sediment sub-bottom in the Tangalle Bay, Sri Lanka
    Weththasinghe, SM; Ratnayake, AS; Dushyantha, N; Ratnayake, NP; Samaradivakara, GVI; Vijitha, AVP; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Water quality parameters and local morphology are important for monitoring aquatic life, and for planning any coastal development project. So far, few studies have been carried out in Sri Lanka for identifying water column structure and subbottom lithology in coastal zones. Tangalle Bay is situated in lowlands in the intermediate zone of southern Sri Lanka. Tangalle Bay replenish freshwater by minor tributaries (e.g., Kirama Oya) and Rekawa Lagoon. Field excursion in Tangalle Bay was carried out during the northeastern monsoon which is relatively less influenced by high wave-energy compared to the southwest monsoon. In this study, water quality parameters were measured using Valeport Midas CTD instrument. In addition, sub-bottom morphology was identified using Bathy 2010PCTM CHIRP sub-bottom profiler. Pre-decided systematic sampling locations were identified for covering three cross-shore and six long-shore survey lines. Water quality parameters of cross-shore and long-shore survey lines are represented separately. In cross-shore survey lines, temperature variations show warm pool in shallow water (depth < 3 m), up to a distance of 4 km from the shore. In addition, temperature variations in deep and distance (> 4 km) water can probably indicate well-mixed nature, perhaps due to upwelling. Less dense water can be observed in shallow water (depth < 3 m). Density variations also indicate upwelling of dense water at a distance of 4 km. The lowest salinity was detected close to the nearshore area due to freshwater supply by tributaries. Salinity variations also indicate possible vertical zonation of upwelling beyond 4 km distance from the shore. Dissolved oxygen values are high up to a 3 km distance in surface and bottom water, due to well mixing in the nearshore area. However, dissolved oxygen values are decreased in bottom water at distance of 3-4 km from the shore. In long-shore survey lines, temperature and density variations show strong stratifications same as that of cross-shore survey lines. High salinity on the bottom and low salinity on the surface water in the nearshore area can probably indicate freshwater supply from terrestrial margins. Sub-bottom profile data indicate the attached coral reef on the bed rock. This attached coral reef creates two depositional features such as layered sedimentary features on the landward side and homogeneous sediments on the seaward side of the bay.
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    Fluctuations in groundwater level and corresponding earth resistivity changes
    Chandrasena, RTPIU; Madushanka, GHSP; Amalan, K; Samaradivakara, GVI; Chaminda, SP; Jayawardena, CL; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    The earth resistivity at a known location was frequently measured, through resistivity sounding. Resistivity of subsurface layers could be influenced by the permeability, porosity, transmissivity, composition etc., where moisture content was the concern of this study. ABEM-Terrameter SAS 1000 instrument was used for surveying and data were interpreted using “IPI2-win” software. A borehole was established to reveal accurate subsurface stratification information and monitor the groundwater level, at the surveying location. Groundwater level was recorded through a datalogger in the borehole, at each 12 hour interval. The precipitation data of the area were obtained from the meteorological department to understand the wet & dry seasonal characteristics. Attempts were made to identify the changes in apperant resistivity data in response to the changing groundwater levels/moisture content and the accuracy of corresponding layer thicknesses, computed through resistivity data.
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    Effect of organic bio-polymer on bio-mineralization of CaCO3
    Nawarathna, THK; Nakashima, K; Kawasaki, S; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Organic matrix in the biogenic CaCO3 has a significant influence on the CaCO3 crystal growth, its polymorphs and morphology. In this research, effect of the cationic and anionic organic bio-polymers on the crystallization of CaCO3 was investigated in microbial induced carbonate precipitation (MICP) process. In the current study, poly-L-lysine and poly-glutamate were used as cationic and anionic biopolymers, respectively. Urea hydrolysis by ureolytic bacteria Pararhodobacter sp. led to CaCO3 formation in the presence of Ca2+ ions. The reaction was conducted with the addition of the polymers under different conditions. After oven-drying precipitation, the amount of precipitate was measured and morphology of the precipitate was analyzed by using scanning electron microscope. Bell-shaped curve was obtained in the relationship between the amount of the precipitate and the poly-L-lysine concentration. However, amount of precipitate remained approximately constant with the increase of the poly-glutamate concentration. In the presence of poly-L-lysine, morphology of the crystals changed from well-developed rhombohedral crystals to ellipsoidal shaped aggregates. But in poly-glutamate addition, polyhedral and spherical crystals are predominant.
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    Diamond core drilling for narrow vein graphite exploration - as practiced at Bogala Mines, Sri Lanka (A Case Study)
    Ekanayake, EMKB; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    The vein type graphite deposits which are rich in carbon found in Sri Lanka occur in metamorphic rocks as narrow steeply dipping veins. In Sri Lanka, generally these graphite deposits are explored by diamond core drilling technique. This technique has revolutionized the mining industry and directly resulted in the discovery of many minable ore bodies that would otherwise have gone untapped. Generally in this technique, possible ore bodies (veins) are explored by drilling a series of exploratory drill holes according to a pattern of drill holes designed by a competent geologist. After receiving core samples and related data sheets, core logging activity is carried out by the geologist for each and every bore hole. It is usually one of the last stages of exploration, and with data taken from core logging can be used to interpret 3-dimentional view with the support of software like Surpac. Finally it would be possible to determine whether the prospect is economically viable or not for mining. This paper looks at the suitability of diamond core drilling technique practiced in exploring narrow graphite veins in Bogala Graphite Mines of Sri Lanka and will discuss in detail pros and cons of the applying method.
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    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.
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    Effects of metal ions on flotation of Sulfide minerals
    Mayumi, I; Atsuhiro, T; Tatsuya, S; Tsuyoshi, H; Carlito, BT; Naoki, H; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Flotation is a mineral processing method that using deference of Hydrophilicity/hydrophobicity. In flotation, air bubbles are induced to the slurry that contains ground ore and water. Hydrophobic minerals are attached to air bubbles and floated to the surface of the slurry, and hydrophilic minerals remains in the slurry. Hydrophilic/hydrophobic property of minerals can be controlled by chemical reagents: Collectors like xanthate adsorbs on Cu and Pb sulfide minerals and make the mineral surface hydrophobic. If ore contains several minerals, interaction of the minerals on the floatation is observed: Sphalerite has less affinity to xanthate and low floatability. When anglesite exists with sphalerite, however, Pb2+ released from anglesite react with sphalerite and PbS-like compounds is formed on the surface, which has a high affinity to xanthate, resulting in the high floatability of sphalerite. Using a model sample containing galena, sphalerite, pyrite, anglesite, pyrrhotite and barite, the effects of Zn2+ on the flotation of the minerals was investigated with DOW#250 as frother, potassium amyl xanthate as collector, Na2SO3 as depressant, H2SO4 and NaOH as pH adjuster. When 500 ppm of Zn2+ was added, floatability of sphalerite was suppressed. The suppression mechanism of sphalerite by Zn2+ is discussed based on the experimental results.
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    Assessment of seasonal impacts on groundwater quantity and quality in upstream of Malwathu Oya Basin
    Madhushankha, JML; Madhuwan, ARB; Menan, P; Chaminda, SP; Abeysinghe, AMKB; Jayawardena, CL; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    Malwathu Oya Basin which covers 2350km2 located in Anuradhapura district is considerably populated and the safety and the available quantity of water is crucial for the people. Water samples were collected from selected locations during South- West monsoon period, Second Inter monsoon period and North-East monsoon period from September 2016 to March 2017. The samples were analysed for pH, turbidity, conductivity, fluoride, chloride, magnesium and calcium as basic drinking water quality parameters. Only the shallow regolith aquifers are considered for the study. The groundwater quality variation of the area shows a considerable variation from dry season to rainy season in general water quality of the area, and is in acceptable limit for most of the basic parameters. With the seasonal changes Fluoride and Chloride content is higher than permissible limits in some areas.
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    Bioremediation of lead-contaminated mine waste using microbially Induced carbonate precipitation
    Mwandira, W; Nakashima, K; Kawasaki, S; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
    The aim of this study was to use microbially induced calcium carbonate precipitation (MICP) technique to bioremediate lead using bacterium Pararhodobacter sp. Laboratory scale experiments conducted, achieved complete removal of lead. This result was further confirmed by SEM and XRD analysis that indicated coprecipitation of calcium carbonate (CaCO3) and cerussite (PbCO3). Furthermore, syringe test demonstrated that MICP based sequestration of heavy metals via coprecipitation with calcium carbonate may be useful for lead bioremediation. Very few low-cost in situ heavy metal treatment processes for lead bioremediation are available; therefore, bioimmobilization of lead by MICP has the potential for application as a low-cost and eco-friendly method for heavy metal remediation.
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    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.