Browsing by Author "Cooray, J.T."
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Item Characterizing of Vein Quartz Occurrences in Sri Lanka(Uva Wellassa University of Sri Lanka, 2012) Piumalee, W.D.H.; Cooray, J.T.; De Silva, S.N.Sri Lanka endowed with vast potential and exquisite varieties of industrial minerals. Unique physical and chemical properties of high grade quartz as a raw material for high-tech products. The characteristics of vein quartz vary with the geological environment, and although it is primarily composed of silicon dioxide, gaseous, liquid, solid trace elements can occur within crystals or between crystal boundaries. In Sri Lanka, silica is available in two forms as free silica and combined with other elements and compounds. Quartz with extreme purity over 99 percent of Si02 is found in many parts of Sri Lanka as discordant veins and they are mainly confined to the central Highlands. Highland/Vijayan complexes boundary zone. Contain vein quartz apart of the deposits within Highland complex. The origin and provenance of vein quartz in Sri Lanka is highly a debatable aspect.Item Defluoridation of Groundwater by Electrocoagulation: Performance Evaluation of Electrodes(Uva Wellassa University of Sri Lanka, 2021) Yathushan, R.; Cooray, J.T.Fluoride dissolves in groundwater due to water-rock interaction and human activities. Drinking water with a low or high level of fluoride can cause adverse health effects to humans. Sri Lankan drinking water standard for fluoride is 1.0 ppm but, most of the groundwater from dry zone areas of the country exceeds this level while some even exceed 5.0 ppm. Electrocoagulation is one of the best methods that can be used to remove excess fluoride from drinking water. During this study, the performance of different metal electrode pairs, the dependence of initial pH, the retention time of process, the effect of pH variation, applied voltage and conductivity were studied concerning the removal of fluoride. Al-Al, Fe-Fe and Al-Fe were chosen for performance evaluation of electrodes. At the same time, initial pH was varied from 6.5 to 8.0 by 0.5 uniform intervals, and samples were taken in each 30 minutes intervals up to 4 hours in all experiments to determine the removal efficiency. The fluoride concentration of samples, were determined by UV Spectroscopy. DI water with 10 ppm fluoride was used for all experiments and during this process voltage, conductivity, current density, electrode separation distance and effective area of electrodes were maintained at constant. Al-Al electrodes showed better performance at 7.0 pH in a low retention time of 90 minutes and Fe-Fe electrodes were effective at 8.0 pH in a high retention time of 120 minutes. Natural groundwater with a higher concentration of fluoride (5.36 ppm and pH 7.98) was tested using Al-Al electrodes. After 2 hours of process, fluoride concentration was reduced to less than 1.0 ppm level, for Fe-Fe electrodes more time was required than Al-Al electrodes. During the procedure, pH was stable for Fe-Fe electrodes, but for Al-Al electrodes, pH value was increased more than 8. Al-Al electrodes can be effectively used for defluoridation of groundwater in Sri Lankan arid zones. Keywords: Defluoridation; Groundwater; ElectrocoagulationItem Delineating Vein Quartz and Bedrock with the aid of 2D Resistivity Technique Compared with Ground Truths(Uva Wellassa University of Sri Lanka, 2012) Zufra, M.H.; Cooray, J.T.; De Silva, S.NSri Lanka consists of four major lithotectonic divisions. And nine-tenths of the island is underlain by Precambrian crystalline rocks, the rest being made up mainly of Miocene Limestone and Quaternary deposits along the north-western and northern regions. Principally, mineral resources are highly confined to the Highland/Vijayan boundary zone. One of the main mineral resources along this zone is vein quartz, predominantly south and southeastern part of the island. Mahagama and Randeniya are two major occurrences which were investigated in detail including ID resistivity survey and 2D resistivity profiling by the Geological Survey and Mines Bureau (GSMB). Generally, vein quartz boulders are confined to elongated ridges along strike direction displaying a weather resistant nature. That is a key to delineate vein quartz from its associated bedrock. Otherwise, it is very difficult to isolate vein quartz from background material, particularly from the bedrock, due similar resistivity ranges.Item Development of Cost Effective Carrier Material for the Bio Fertilizer to Enhance Eppawala Phosphate Solubility(Uva Wellassa University of Sri Lanka, 2016) Rajhkumar, T.; Peries, C.M.; Cooray, J.T.Plants acquire phosphorus (P) from soil solution as phosphate anion. It is the least mobile element in plant and soil contrary to other macronutrients. Phosphorus solubilizing bacteria play role in phosphorus nutrition by enhancing its availability to plants. Bio fertilizers are inputs containing microorganisms which are capable of mobilizing, nutritive elements from non-usable form to usable form through biological processes. This study focused to develop a cost effective carrier material for the bio fertilizer to enhance the solubility of Eppawela phosphate. Eppawala Rock Phosphate samples were collected and microbial isolation was performed. Isolated microbial strains were inoculated on Pikovskaya's medium (PVK), a selective medium to screen Phosphorous Solubilizing Microorganisms. Thereafter, High-grade Eppawala Rock Phosphate (HERP) was mixed with carrier materials such as Kaolin, Fly ash and Glyceride were used because of containing high amount of plant nutrients and having the ability to increase the soil fertility. Kaolin and fly ash proportions were mixed in different proportions and apatite and gliricidia were maintained in constant in every treatment. Carrier material packets were prepared by mixing the broth cultures with sterile other ingredients. The P content was determined by the UV spectrophotometer at 400 nm. Two bacterial strains (B1 and B2) were selected as potential phosphate solubilizes on PVK agar medium. There was significant effect on carrier material type and the bacterial type for the P solubalization (p < 0.05). Both B1 and B2 bacterial types were shown high performance of the P solubalization with the addition of carrier material compare to the control. The most effective proportion of carrier material was Treatment 03 for the B1 bacterial types (Bacteria 1+ Rock Phosphate (40 g) + Gliricidia sepium (10 g) + Kaolin (30 g) + fly ash (20 g)) with the p value of 0.043 (p < 0.05). Both B1 and B2 bacterial types were shown highest P solubalization in 1S1 week.It can be concluded nutrient enriched carrier material can enhance the activity of phosphorous solubilizing bacteria for solubilizing phosphorus in HERP. Further, it can useful to develop the bio fertilizer with combining low water soluble HERP and the microbial population. Keywords: Bioleaching, Carrier material, Phosphorus solubilizing bacteriaItem Development of Glassy Hard Wearing Glaze for Floor Tiles(Uva Wellassa University of Sri Lanka, 2016) Gamage, S. L.; Medawela, S.; Cooray, J.T.Glaze is a decorative layer on the tile surface and mainly there are three types, gloss, matt and rough. In Sri Lanka, most of people would like to use gloss tiles than matt or rough. Gloss glazes easily bounce the light and render adorable surface of the tile. However, gloss glazes can be easily scratched and wearable. Therefore, hard wearing gloss glazes are very important in Sri Lankan tile industry. However, Sri Lankan ceramic industry is not producing any glazes and all raw materials for production of glazes are importing. The main problem is lack oftechnology and high production cost. In this work, we developed a new glaze with increasing the surface hardness using TiO2, ZrO„ V20, and Al203/corundum as suitable additives without change the composition of frit, glossiness and firing temperature. In addition, fast firing cycle with single firing system was use for this research. The study was carried out changing the composition of above materials and checked the surface abrasion. In our results, Al203 was shown positive results for increasing wear resistance among other materials. Further, dry glazes made here used to remove unwanted organic materials and other impurities, and also reduced the surface defects on the tiles. In addition, we show that the abrasion class was increased by glaze when it add as in particle form, since it helped to reduce the contact area on the tile surface. Keywords: Glaze, Frit, Alumina, corundum, surface abrasionItem Enhancement of solubility of Eppawala Rock Phosphate through Bioleaching(Uva Wellassa University of Sri Lanka, 2015) Senevirathna, T.C.; Peries, C.M.; Cooray, J.T.Phosphorus (P) plays an indispensable biochemical role in photosynthesis, respiration, cell division and several other processes in the living plant (Grover, 2003). An inadequate supply of phosphorus in the early stages of plant growth reduces most of these physiological functions and ultimately reduces the crop productivity. Therefore, external applications of P fertilizers is necessary in terms of better crop production. Locally available P resources like Eppawala Rock Phosphate (ERP) deposits are now highly concerned due to the environmental effects and the high cost of imported P fertilizers. However, the ERP is considered as less applicable local P resource for short term cultivations due to the low solubility. Although chemical treatments are highly available to solubilize ERP, the cost of application is fairly high. In that sense, the inoculation of naturally existing P-solubilizing microorganisms is considered as a promising technique to solubilize P sources due to the low application cost and giving a thrust to economic development without disturbing ecological balance (Reyes et al., 2002). Thus, this study was focused on screening the P solubilizing microorganisms (PSM) from ERP deposit and apply them to enhance the solubility of ERP and High-Grade Eppawala Rock Phosphate (HERP). Methodology Powdered Rock Phosphate samples were collected from the rock phosphate stockpile of phosphate mine of Lanka Phosphate Limited, Eppawala. Microbial isolation were performed from the obtained Phosphate samples using standard microbiological techniques. Isolated microbial strains were inoculated on PVK medium, a selective medium to screen PSM. Thereafter, screened microbial strains were inoculated in PVK broth media containing either ERP or HERP separately. P content in each sample was determined using UV spectrophotometric method after 1 , 2 and 7 Result and Discussion Four bacterial strains and four fungal strains were initially isolated using the rock phosphate samples obtained from phosphate mine of Lanka Phosphate Limited, Eppawala, Sri Lanka. Out of them, two bacterial strains (B1 and B2) were selected as potential phosphate solubilizers based on the development of clear halo zone on PVK agar medium due to the P solubilization in the surrounding medium (Fig. 1 a and b).Item Fabrication of an Abrasive Wheel using Garnet Sand(Uva Wellassa University of Sri Lanka, 2013) Dayananda, P.S.C.; Ekanayake, T.; Cooray, J.T.Economic sand accumulations are found along Eastern and Southern coastal belts of Sri Lanka These mineral sand deposits consist of ilmenite, rutile, zircon, garnet, magnetite, monazite, sillimanite and quartz. Mineral sand separation plants separate minerals using their physical properties such as specific gravity, magnetic properties and conductivity. Garnet is produced as a by-product of this separation process and is removed as a tailing. Southern coastal areas of Sri Lanka such as Tangalle, Ussangoda and Kirinda are known for large scale garnet sand accumulations. Garnet is a mineral with relatively high hardness value. Therefore it can be used as an abrasive material for various applications such as tool sharpening, wood polishing, and metal polishing. Water jet cutting machines use garnet in fine powder form as the abrasive material. There are two types of abrasive materials, namely coated abrasives and bonded abrasives which can be made out of garnet sand. Bonded abrasives are used mainly in abrasive wheels where a suitable bonding material binds the abrasive. These abrasive wheels can be used for removing very fine quantities of material from the work piece. Grinding is a process of removal of particles and surface generation used to shape and finish components made of metals, wood and other materials. Grinding process needs an abrasive product usually a rotating wheel in contact with a work surface. The grinding wheel is composed of abrasive grains held together in a binder. These abrasive grains act as cutting tools and remove very small chips of material from the work piece. Bonded abrasives are used for this sort of applications. Various bonding materials such as vitrified bond, rubber bond, shellac bond, metal bond are used in abrasive wheels. This research was carried out to produce an abrasive wheel using Sri Lankan garnet sands and different types of bonding agents. Performance of each combination was tested.Item Identification of Method to Minimize Glaze Pinhole in Porcelain Tableware(Uva Wellassa University of Sri Lanka, 2016) Weerakkody, W.A.S.H.; Hettiarachchi, P.; Cooray, J.T.Sri Lankan porcelain industry governs a vast reputation of producing high quality porcelain products. Among different companies Dankotuwa Porcelain PLC upholds a great demand as the world's whitest porcelain manufacturer. Porcelain refers to a wide range of ceramic materials heated at higher temperatures to acquire vitreous qualities. This study was focused on the reduction of the defects that are determined as the faults or failures in porcelain items which can be occurred at any stage of the manufacturing process. The main focused defect in this study is the defect Glaze Pinhole. It is defined as pin pricks or small cavities beneath the surface on the mould side of the article. Aiming a profit maximization through reducing extra processing cost due to repaired and damaged items efficient methodology was built up to reduce glaze pinholes. In our study root causes for glaze pinhole were identified with the aid of a causes and effect diagram. It was identified that the particle size of the ball milled glaze, glaze flow and the dust particles on the porcelain body critically affect the occurrence of glaze pinholes. It was noted that best method to minimize glaze pinhole is dust must be removed perfectly and glaze particle size is within 71-72% (below 8[Im particles). Glaze flow should be within 25 and 26mm. The cost efficiency was calculated as cost reduction due to decreasing of glaze pinholes and the reduction of ball mill grinding time. The energy saving due to the reduction of ball mill grinding time from 28-17 hours worth more than one thousand. As a result of this study it could be minimized the glaze pinhole percentage of porcelain tea cups from 8.21% to nearly 3%.Thus it showed a significant cost reduction worth nearly eighty two thousand rupees due to the 5% decrement of glaze pinhole percentage for nearly twenty thousand pieces. Keywords: Porcelain, Defects, Glaze pin-holingItem Improve the Green Tile Strength of the Tile Body by Using Montmorillonite(Uva Wellassa University of Sri Lanka, 2016) Ahamed, A.M.I.; Kumarasinga, W.H.; Cooray, J.T.Floor tiles are commonly made of ceramic, porcelain and stones due to their attractiveness, durability, and easiness to clean. The main components of a tile are tile body, glaze layer, and printed layer. The production cost lost is mainly depending on green and dry tile body. The tile body is very important for good quality and high strength finished products (fired tile). This research aims to manufacture high strength green and dry Tiles by using montmorillonite (MMT) because montmoillonite is consists of nano particles which will increase the density of the tile body. MMT sample was selected from Murunkan, Mannar for the investigation. First, silica test was carried out for clay samples (Ball clay and MMT clay). After the silica test; the tested clay sample were used for making base formula by adjusting silica percentage of the body composition because, MMT has high amount of silica. The green tile body was made using ball clay, MMT, feldspar, silica sand, dolomite, sodium triphosphate and sodium silicate. The raw materials were grind with 40% water in a pod mill about 13 minutes. The grind sample called slip. The slip was dried at 120 °C. Dried sample was crushed and sieved by 1000 ii.tm sieve. Then 6% of water was added to the sieved sample and mixed with hand. It's called moisture powder. Then 83g of moisture powder was weighted and green tile was pressed by using Laboratory press and flexural strength (modulus of rupture-MOR) was measured. Dried and fired tiles were made and finally tile strength (MOR), loss on ignition, shrinkage, water absorbance were measured and analyzed according to reference tile. MMT has nano particles; it was reducing the pore space and increases the packing fraction of the green tile body that's why prepared green tile, dried tile and fired tile strengths were increased. Keywords: Montmorillonite, Flexural strength, ShrinkageItem Magnetic Data Reduction of Basement Correction(Uva Wellassa University of Sri Lanka, 2013) Badugama, L.N.; Cooray, J.T.The magnetometer survey is a passive geophysical technique that measures the contrasts of magnetic properties between the feature of interest and its surrounding environment. This technique has wide applications in mineral and archeological investigations. Rocks and minerals with high ferrous content provide anomalous signatures than the background enabling to screen them. The magnetometer surveys are always disturbed by temporal variations: Diurnal variation, Magnetic storms and Micro-pulsation, which depend upon the time and space. Magnetic surveys are not done during magnetic storms. The diurnal variation cannot be avoided and the noise will disturb the data quality. To eliminate the diurnal variation from data a base station is used in magnetic surveys. In order to overcome the temporal variations, a base magnetometer is needed to correct these time dependent variations. . While the base records the temporal variation of the area the rowing magnetometer records both the temporal variation and the local anomaly. For a large-area survey, or an airborne survey, the magnetic field may be monitored at several locations, continuously, to identify the spatial variations of the time-varying field. If the rover is too far away from the base station, the time-varying fields measured at the rover will differ from those measured at the base station, resulting in increased error. The effective range of a single base station is generally considered to be less than 100 km for air-borne survey and for a ground survey it is about 200 m. This distance may vary according to the survey area and the expected accuracy. Owing to the large area covered by an aeromagnetic survey, a single magnetic base station would not have provided adequate coverage. Instead, several base station magnetometers are in operation during the survey (Hrouda et al, 2009). The base correction is conducted with the assumption that the environmental effects over the survey area are constant. The base magnetometer is synchronized with the rowing component and the environmental effect is removed according to the respective time stamps. However, if the survey area is large, the base station needs to be shifted as the assumption is no longer valid. As the crustal magnetic component of locations where the base station(s) establish during a survey is not a constant, a correction is needed to be applied for base stations. The present work attempts formulating a model for the basement correction. Methodology A mathematical model that completely describes the magnetic surveys, with two sub surveys was created. This method can be extended for many sub surveys, considering two sub surveys at a time. The variables were: IGRF value, local anomaly, environmental noise, local anomaly at the base station, and the location.Item Preparation and Characterization of Geopolymer Composites Containing Fly Ash, Bottom Ash and Rice Husk Ash(Uva Wellassa University of Sri Lanka, 2016) Kajanthan, K.; Premachandra, J.K.; Cooray, J.T.Geopolymers being the synthetic analogues of natural zeolitic materials possess excellent properties, including fire and acid resistance, and mechanical properties. As a result, geopolymers have become an alternative construction material in place of Portland cement. They find structural applications such as sculpture, building repairing and building restoration. In producing geopolymers, the raw materials containing mainly silica and alumina are converted through chemical reactions into aluminosilicate structures in alkali medium. These aluminosilicate structures are composed of a network of randomly arranged silicate and aluminate tetrahedra in conjunction with charge-balancing alkali metal cations. The compressive strength of this resulting inorganic polymer depends on both the ratio of Si/Al and the types of the raw materials utilized. This research focused on the use of fly ash (FA), bottom ash (BA) and Rice husk ash (RHA) as a value addition in the preparation of geopolymer composites and the characterization of composites prepared. The effects of relative amounts of raw materials and the curing time of geopolymers on their compressive strength and water absorptivity were investigated. In sample preparation, a series of samples was prepared by hand mixing of selected amounts of cement, fine FA, BA, fine RHA, prewashed and dried sand, water and NaOH. The other series of samples was prepared by hand mixing of selected amounts of the same raw materials with Ca(OH)2. Further, the cylindrical samples for characterization were prepared by molding using a hydraulic press and demolded samples were kept at 80 °C for 4 hrs. Compressive strength of both series of samples was measured after curing them for 7 days and 14 days. The results showed that the compressive strength of the samples increases with increasing the curing time. At high relative amounts of cement and low amounts of the mixture containing FA and RHA, the compressive strength increases with decreasing the amount of cement and increasing the amounts of the mixture containing FA and RHA with compared to that of the samples in the absence of FA and RHA, regardless of the curing time. The incorporation of Ca(OH)2, has resulted in increase of compressive strength of samples with high relative amounts of cement and low amounts of the mixture containing FA and RHA. Keywords: Geopolymers, Fly ash, Bottom ash, Cement, Compressive strengthItem Production of Lubricant using Sri Lankan Graphite(Uva Wellassa University of Sri Lanka, 2013) Dissanayake, V.N.W.W.; Cooray, J.T.; Attanayake, A.N.B.Graphite is a polymorph of carbon that possesses high electrical conductivity. Most of the industrial applications of graphite exploit this physical property. The loose coupling among the graphite sheets contributes to another industrially important property that enables it to be used as a dry lubricant (Jie, 2012). Graphite has advantages in situations where wet lubricants might not be practical and also in lubricating porous substances such as wood. Graphite has the natural ability to conduct heat and electricity and is chemically inert. So it can be used as a conductor while lubricating the surfaces. Graphite lubricant enhances load carrying capacity and solves sliding friction problems where conventional lubricants fail to perform and produces better bonding strength. Graphite, being naturally hydrophobic, resists rain, water, snow, and mud and aids in reducing the development of corrosion and rust on valuable equipment (Jie, 2012). Viscosity is the most important parameter in selecting a lubricant. It changes lubricating properties at different temperature ranges. Therefore it is important to define a temperature range in which the lubricant can be practicable. Sri Lanka has reputation for its high quality vein graphite. Bogala and Kahatagaha are the main graphite mines in Sri Lanka Kahatagaha graphite is said to be 99% pure crystalline vein graphite. This research focuses on producing a lubricant using Sri Lankan graphite at low cost particularly with the aim of productive utilization of graphite mill waste in future. It investigates the optimum composition of the lubricant compound by testing various materials combinations and concentrations that produce the best lubricity of graphite. Methodology Various weight ratios between finely-ground Kahatagaha graphite powder (75µm) and coconut oil, toluene and carbon tetrachloride were used (5% to 60%) as the testing compounds. Viscous graphite/organic liquid mixtures were stirred and blended in fast mill. Viscosity of each mixture was measured by Brookfield Viscometer. The best organic liquid used to produce graphite lubricant was identified based on higher viscosity and the optimum concentration of that compound suitable for industrial applications was determined.Item Purification of Meetiyagoda Kaolin for boron free glaze manufacturing(Uva Wellassa University of Sri Lanka, 2015) Hussain, M.H.S.; Cooray, J.T.; Medawela, S.A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass for covering of roofs, floors, walls, or other objects. Tiles are often made from ceramic with a hard glaze finish. But sometimes with other materials such as glass, marble, granite and slate are also used to produce tiles. Among them, floor tiles are commonly made of ceramic, porcelain and stones due to their attractiveness, durability, and easiness to clean. The main components of a tile are tile body, glaze layer, and printed layer. The raw materials used to form a tile consist of clay minerals, quartz, feldspar which is used to lower the firing temperature and chemical additives required for the shaping process. Tile decoration is mainly depending on the glaze layer. Sodium feldspar, potassium feldspar, quartz, wollastanite and kaolinite are abundantly used materials in glaze production. Even through Sri Lanka contains most of the above raw materials; at present all required glaze materials as imported to the country due to the cost, lack of technology and some quality problems of raw materials. So this research aims to manufacture a low cost glaze medium mainly using local mineral materials and few imported materials. Methodology The current study was carried out at Uva Wellassa University, Badulla, Sri Lanka and Lanka Tiles PLC, Jaltara, Sri Lanka. First, the raw materials were purified to make frit and glaze. The acid leach process was carried out for purification of kaolin and the magnetic process was carried out feldspar, wollastanite and quartz. The clay sample selected for investigation was kaolinite clay obtained from Meetiyagoda area. Then the clay sample was ground using a laboratory ball mill to –149 μm (100 meshes). The ground clay sample was placed on the sieve, and then mechanically shacken for 5 min. The oversize was further grounded followed by sieving with the same sieve. The procedures were repeated till the entire clay sample passed through the sieve. After that ground clay sample passing 100 mesh was subjected to calcination. The sample was heated at C ) to activate the clay before acid treatment (Al-Zaharani and Abdulmajid, 2009). Calcineated clay sample passing 100 mesh were leached using 3M hydrochloric acid for different periods of time (10-150 min) and at different leaching temperatures (25ºC to boiling temperature) using a constant temperature shaking water bath at a fixed shaking rate of 160 cycles/min and using boiling under reflux (Hulbert and Huff, 1970). At the end of leaching, the resulted slurry was filtered to separate undissolved materials and, washed in distilled water. The filtrate and washings were continued until ions were removed in the sample. The resulting sample was dried for 24 h in Laboratory oven. Likewise the feldspar and wollastanite were purified by magnets. The purity and quality of leached kaolinite were tested using common base (CS 100) in tile industry. After that the frit was made using 80g of sodium tetraborate pentahydrate (Na2B4O7.10H2O), 100g quartz, 160g of kaolin, 40g of wollastonite, 20g of zirconium silicate and 5g sodium chloride. The raw material was mixed in a pot mill. Water was added slowly step by step until the mixture forms in to a crumb. The crumb was heated at 100 C until it was completely dry. Then the dried product was transferred to porcelain cups and it was placed in a laboratory muffle kiln. The kiln was heated at a rate of 4 C per minute up to a 1050 C and kept at same temperature for 90 minutes (Simon et al, 2007). The furnace was switched off and the crucible was allowed to cool down to ambient temperature in the furnace. The product was removed, wrapped in a plastic film hammered to break in to small pieces. Then the base formula was generated by using it. Glass formation and formulation mechanisms (fluxes, vitrifying agent, opecifier), thermal expansion of the materials and melting point (softening temperature) were considered for base making. The materials in the base thermal expansion were adjusted according to frit thermal expansion. Frit (30g), kaolin (8g), sodium feldspar (30g), wollastanite (32g), zirconium silicate (10g), aluminium oxide (2.5g), zinc oxide(1.5g), C.M.C (0.2g) and S.T.P.P (0.2g) were added to the base formula and it was grind with 100 ml water in pot mill for about 20 minutes. Resulted base medium was sieved using a 100 µm sieve and it was sprayed by spray gun on to engobe green tile. Base density and base viscosity was measured before spraying. Based tile was fired in the kiln. Finally fired tile surface properties, thermal shock, abrasion, strain, cracking and acid resistance were checked to ensure the quality.Item Quality of Sea Sand vs. River Sand(Uva Wellassa University of Sri Lanka, 2012) Sripranavan, S.; Attanayake, A.N.B.; Cooray, J.T.Over the years, with increasing development activities of the country, demand for sand has reached to an exceptionally high level. Yet river sands and sea sands are virtually the main industry raw material source. Indiscriminate mining and extraction of river sand has led to severe environmental degradation. Therefore it is necessary to explore for alternative sources. The collected river and sea sand samples were tested for moisture content, organic matter content, pH value (acid demand), mechanical grain size analysis and specific gravity value. Comparison was made between the properties of the two sand varieties. The result that Specific gravity determination of samples value are between 2.62 — 2.74. This indicates that the Specific gravity determination of the tested dune sand sample is within that oft normal sands and therefore sands are suitable for construction purposes. From the Sieve analysis test, over 90% of the sand samples are between 1.18 mm to 0.15 mm sieve size, while some 1% is coarse particles, and 3% is very fines (silt and clay). With the majority sand samples consisting of sandy particles. Therefore sands are for suitable for construction purpose. All the engineering properties of the sea sand closely match with river sand used in construction. Therefore use of sea sand will help mitigate the environmental degradation caused by excessive river sand extraction.Item Removal of Heavy Metal Ions from Drinking Water by Using Rice Straw Method(Uva Wellassa University of Sri Lanka, 2016) Gowsiya, A.; Cooray, J.T.Adsorption of some common heavy metals ions from drinking water by rice straw method was investigated by using filtration method. The adsorption capacity was investigated by various concentrations of heavy metals ions solutions. The effect of initial metal ion concentration and binding capacity of rice straw for each heavy metal have been studied. Initial concentrations of water sample were selected according to the most available range of natural waters in Sri Lanka. The results showed that rice straw was not releasing anything undesirable to the water. When the initial concentration of heavy metal irons increased, removal percentage also increased. Manganese and lead were efficiently removed from drinking water by using rice straw method. But iron has showed less binding capacity in rice straw method. As the result rice straw method is not efficient for removing iron from drinking water. The order of efficiency of metal ion removal in rice straw method is Mn (II) > Pb (II) > Fe (III).Average removal percentage of heavy metal irons are Mn (II), Pb(II) and Fe(111) is 71.5%,51.18% 21.1% respectively. Keywords: Adsorption, Binding Capacity, Heavy metal, Rice straw methodItem Sedimentological and Mineralogical Investigations of Heavy Mineral Sand Deposits in Mahaweli River Alluvial Fan(Uva Wellassa University of Sri Lanka, 2013) Janajeewa, W.M.C.; Cooray, J.T.; Jayawardana, D.T.Most of the economically important offshore heavy mineral sand deposits in Sri Lanka including Koddiyar bay is not fully investigated and there are very limited studies available in literature. Koddiyar Bay is the Mahaweli River discharging area. Detailed investigation on heavy mineral sand deposits is vital before extracting them. This paper presents the results of a sedimentological and mineralogical investigation of Koddiyar Bay heavy mineral sands deposit with the view of identifying its economic potential. More than ninety percent of Sri Lankan terrain is underlain by metamorphic rocks with meta - sedimentary or meta-igneous origin. Meta-sediments consists of quartzites, quartz schists, fine to medium grained acidic gneisses and granulites, calc gneisses, crystalline limestones, dolomites, sillimanite gneisses and silimanite-garnet-graphite rocks (Fernando, 1986). During the ice age, the present inner harbor area of Koddiyar Bay might have had the normal ridge and valley topography as we find in present day inland. With the rise of the sea level the present inner harbor area has submerged gradually and it has opened up rapidly due to wave and current actions with time (Wijayananda, 1985). Rock fragments are flown to Mahaweli River mainly during rainy season from catchment areas. Heavy mineral particles are derived from these detrital materials. Heavy mineral grains are subjected to abrasion during this transportation. Grains with higher hardness like ilmenite, rutile and garnet do not change their shape during the course of transportation. Moderately hard grains like magnetite are changed slightly their shape and they tend to form round grains. Low hardness grains like monazite and zircon are changed slightly their size and shape also tend to well roundness. Then this heavy and light mineral grains move with combination of sea waves and tidal forces. Then sedimentation occurs along coastal stretch in Koddiyar bay. This processes are not continue throughout the year. During monsoon period deposition layer thickness is higher than dry season.Item Sri Lankan Vein Graphite Classification Using Image Processing and Neural Network(Uva Wellassa University of Sri Lanka, 2016) Wickramasinghe, E.M.C.G.; Cooray, J.T.; Wimaladharma, S.T.C.I.Image classification is an essential task in pattern recognition applications. Rock and mineral images are some of the typical examples for natural images, and their analysis is more important in rock and mineral industry. Ore mineral classification is based on specific visual descriptors extracted from the images. These textures are used to identify their visual similarity and categorise them accordingly. This research primarily addresses the problem of automatic measurement of graphite ore textures by image analysis in a way that it is relevant to mineral processing in Kahatagaha Graphite Lanka Limited, Sri Lanka. Specifically, it addresses three major hypotheses: Automatic separation of graphite ore by image analysis provides a feasible alternative to manual curing by mineralogists and labourers, Image analysis can quantify process mineralogy by physical parameters and Image analysis provides potential benefits to process mineralogy and better retains the information of manual logging. Traditionally, minerals are visually recognized and manually outlined prior to the digitizing and subsequent analysis. The preciseness of the outcomes is affected by the conventional methods. This limitation can be overcome by using multichannel methods of classification with Artificial Neural Network, in which the minerals in multichannel digital images are accurately recognized based on their unique spectral or elemental signatures, established by a training stage prior to classification. The technique is applied here for model analysis of images, which are digitized using a standard digital camera. In all case studies of the analysis of graphite lumps, the resulting mineral modes are sufficiently precise to identify significant compositional heterogeneities between groups of samples. This model can be readily applied to automated vein graphite ore classification in mineral processing industry. Keywords: Mineral classification, Image processing, Neural network, Vein graphite classificationItem Synthesizing Electro - conductive grease using graphite(Uva Wellassa University of Sri Lanka, 2015) Christopher, W.A.P.P.; Cooray, J.T.; Attanayake, A.N.B.Graphite as we all know is well renowned for its ability to conduct electricity as well as its lubricant nature. The carbon atoms in graphite are sp2 hybridized. Each carbon atom bonds with three other carbon atoms via the three sp2 hybridized atoms to form a sheet of carbon atoms lying in a hexagonal pattern or a honey comb structure and carbon atoms are bound together by strong covalent bonds. And each of these sheets of carbon is bound together by weak van der Waals bonds. The fourth electron in a p orbital is left free and its these electrons that contribute towards the electrical conductivity of graphite. Grease is a semi solid lubricant widely used in the industrial world to reduce ware and tare. Grease is made of three principal components known as a base oil, thickener and additives. Thus combining graphite with grease would preferably transfer the electro-conductive nature of graphite to grease forming an electro-conductive grease. Usage of such a product would be, grounding static discharges, providing electrical continuity between irregular or pitted surfaces, ensuring electrical contact between loose or vibrating parts and small gaps, application to ball bearings in computer equipment where it allows static discharge to pass through the bearing instead of building up and arcing. Synthesizing such a graphite based grease product was the main objective of this study. Materials and methodology Natural vein graphite was used to make graphite powder under 75 microns. Basic grade grease was used as the substrate. Different weight ratios of both graphite and grease were mixed by blending to generate the sample series. The samples were tested for electrical conductivity using the impedance analyzer. A standard cell was made to hold the sample. The conducting length was kept to a minimum assuming that in real world applications (12 millimeters). The cell electrodes were designed in such a manner that two over rings were placed to ensure that the effective conducting length was kept constant throughout the sample series tested. Three measurements were taken with each generating a graph of imaginary part of impedance versus the real part of it. And the resistance of the sample was determined by the point where the curve seemed to make contact with the x axis of the graph. And the capacity of the particular sample can be determined by finding out the frequency of the peak point of the semicircle.Item Toxic Metal Absorptivity to Agriculture Soil(Uva Wellassa University of Sri Lanka, 2015) Chamara, M.A.N.; Cooray, J.T.; Attanayake, A.N.B.Soil contamination has increased by several folds within the recent past due to various man made activities. Various types of toxics involve in the processes of making contaminated soil profiles. There are many toxic metals and chemical complexes which contaminate soils. When toxic agents contact with soils they may absorb or adsorb in to the soil structure depending on their structural and physical properties. One of the major sources of contaminant is agrochemicals. Due to expansion of agricultural practices and over use of agrochemicals (pesticides, weedicides, insecticides, fungicides and others) the effect has become adverse. Sri Lanka is covered with versatile range of soils with highly contrast physical properties. In this study, soil samples from different agricultural areas in Badulla district have been used to determine their quantity of toxic metal absorptivity quantitatively. Method Five areas were selected where there are many types of agricultural activities. Uncontaminated samples were collected from these farms (Mirigama, Passara, Badulla Bandarawela and Welimada). Soil properties like moisture content, soil pH, bulk density, hydraulic conductivity, soil porosity were studied in order to categorize the soil types. Soil columns were made for these samples and metal absorptivity was studied by adding Roundup pesticide (which is heavily used agrochemical in the area). Concentration of the agrochemical was kept at its normal dosage. Original agrochemical was fully studied with ASS to identify the containing metal ions and the obtained leachates were also measured for the same set of metal ions to confirm their soil absorptivity under specific time period. Obtained AAS results interpreted to identify the correlations between soil properties and toxic metal absorptivity.