ERE - 2008
Permanent URI for this collectionhttp://192.248.9.226/handle/123/18288
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- item: Conference-Full-textProceedings 3rd Annual Conference on Mining for Sustainable Development - A Multidisciplinary Approach [Pre Text](Department of Earth Resources Engineering, 2008-05) Karunaratne, S
- item: Conference-Full-textDesigning an underground ventilation system and fan selection(Department of Earth Resources Engineering, 2008-05) Widisinghe, SD; Silva, WJMPGS; Jayakody, JASP; Konsal, J; Rasika, WGP; WeIideniya, HS; Ekanayake, K; Karunaratne, SMixing of stale air with fresh air (short-circuiting of airflows) is a critical issue in any underground ventilation system. This study was done at Bogala mines owned by Bogala Graphite Lanka Ltd, where this type of mixing takes place in certain levels leading to a cyclic movement of stale air. The main objective of the research project is to design an underground ventilation system and to select fans to overcome these adverse effects and making ventilation more effective and efficient. As die mine is of complex nature, two particular levels at 205 and 240 fathoms were selected for the analysis, where the short circuiting of air is predominant. A detailed survey was carried out to measure the variations of airflow and frictional pressure drop along cross cuts, development drives and winzes in selected levels. The corresponding values of mine air resistance for airways were determined to generate a solution followed by suitable fan selection. Suggestions were made to improve the present ventilation system, which will enhance mine air quality increasing health and safety aspects of underground environment.
- item: Conference-Full-textDevelopment of a methodology for selection of industrial grade-a quarry site for coarser and finer aggregates(Department of Earth Resources Engineering, 2008-05) Maduranga, HGS; Sinthuja, S; Soundararajan, P; Kumara, MHCM; Amadoru, T; Wimal, MD; Abeysinghe, AMKB; Karunaratne, SRecent history has revealed that the identification of prospective mineral resources is essential to sustain mineral based industry to full fill the demand required in future. Aggregate industry also has the same risk of sustaining due increased demand and the lack of available sites. Therefore this study assists to identify prospective sites which can be developed to IML-A grade quarry sites and this develops a methodology which can be applied to all over the country to recognize such locations. The applicability of designed methodology is ensured by applying it to Kalutara District - Dodangoda AGA Division and potential sites are identified. Local authorities like Geological Survey and Mines Bureau will be able to reserve the potential locations which will be identified by the study for future development without urbanizing those areas. This will facilitate establishing new quarries at a lower cost.
- item: Conference-Full-textTunnel design for fractured rocks and suitable support selection(Department of Earth Resources Engineering, 2008-05) Senthilkumar, M; Senadhira, AMADM; Giriwaksan, S; Welideniya, HS; Dharmaratne, PGR; Karunaratne, SThis research focused on design of a tunnel in highly fractured rocks, and to propose suitable support classes, based on the study carried out at the Upper Kotmale Hydro Power project location. The necessity arises in order to cope up the unpredictable changes in geological patterns which highly influence the continuity of tunnel works. Present tunnelling method in fractured rocks need to be further evaluated to suit the engineering geological patterns and rock types of the area. The rock strength and the fracture intensity are assessed through field and laboratory works, including tunnel mapping and joint intensity surveys. The suitable support class selected based on Q-value system formulated by Nick Barton (Norway) in mid 70's.The data and the borehole samples obtained from site location facilitated to propose a proper support design, suitable to Sri Lankan geotechnical conditions. The variation in the rock mass from unweathered to highly weathered, sound to heavily fractured along a tunnel was accounted in selecting a suitable supporting method to avoid disastrous consequences and to provide a secure working environment. The results of the study were used to develop a model for tunnel design, and to propose modifications to the existing support classes in fractured rocks at Upper Kotmale Hydro Power Project. And it was understood Q-value evaluation could be more suitable than RMR, for Sri Lankan terrain.
- item: Conference-Full-textDesign and fabrication of hydrocyclones using Krebs mathematical model(Department of Earth Resources Engineering, 2008-05) Hettiarachchi, RNDS; Liyanaarachchi, KR; Lokubalasooriya, LBAM; Merza, AAMIMA; Thinesh, S; Femando, WLW; Karunaratne, SHydrocyclone is one of the most important devices used in mineral processing industry. It is a continuously operating classifying device that utilizes centrifugal, gravitational and inertial forces to classify particles. The cut point (dso) of a Hydrocyclone is the particle size at which 50% of particles in the feed of that size report to the underflow. There are a number of empirical relationships which are used for designing Hydrocyclones and in this research a parallel circuit of four Hydrocyclones were designed and fabricated by using Mular and JulTs Krebs mathematical model. In practice, the cut point is mainly controlled by Hydrocyclone design variables such as cyclone diameter, inlet diameter, vortex finder diameter and apex diameter. Krebs model provides relationships among these design variables. Disordered Kaolinite (Ball day) suspensions of 7% and 5% solids concentration were prepared and subjected to classification in the fabricated battery of Hydrocyclones. The resulting Hydrocyclone overflows were evaluated by Andreasen Pipette Method against predetermined dso values, which were calculated by using the Krebs equation for dso. The average recovery of less than 14 and 13 micron fractions were 98.96% and 94.28% respectively for the ball clay suspensions of 7% and 5% solid concentrations.
- item: Conference-Full-textFragmentation modelling for an 'A' grade quarry(Department of Earth Resources Engineering, 2008-05) Brahmanage, IR; Thusharana, SD; Wanniarachchi, WAAC; Anjana, PMN; WeIideniya, HS; Dharmarathne, PGR; Karunaratne, SThis research focuses on the degree of fragmentation resulting from a blast in an 'A' grade quarry. Two blast geometries were tested and verified in this research study. Quarrying industry has a quite long history in Sri Lanka; however it has not achieved significant technical development in comparison with other countries. Still the major concern of this industry is getting the maximum quantity of rock volume from a particular blast. Efficiency of subsequent unit operations such as loading, transportation, especially crushing is neglected. This research aims at achieving higher safety (i.e. fly rocks, air blast) and best fragmentation while minimizing production cost. It is widely accepted that Software tools could be used to improve blast performance, if it is used as a critical evaluation tool for fragmentation quality against any blasting geometries. In this study, software called "Split-Desktop" was used as a tool to estimate blast quality or particle size distribution in a stockpile. Then two blast geometry models such as "decked charging" and "slab hole" models were proposed with the intention of improving fragmentation.
- item: Conference-Full-textDesign and fabrication of a spiral classifier for off-shore sand washing(Department of Earth Resources Engineering, 2008-05) Udawatte, NBB; Siriwardene, HP; Samaratunga, SPND; Udayanga, WAC; Rupasinghe, SN; Theeparuban, B; Fernando, WLW; Karunaratne, SThe rapid growth of construction industry has created a significant demand for sand. Consequently, it has increased the exploitation rate of river sand giving rise to adverse environmental impacts. Therefore, the tendency now is to find alternatives for river sand avoiding massive environmental damages. Among the potential alternatives, offshore sand could be the best alternative, because of particle size distribution and availability. However, the demand on offshore sand is low, due to its soluble Cl- content which could influence badly on the structural properties of concrete. As a solution, sea sand could be stored in open air until the Cl- content is decreased to acceptable limits (<0.075% by weight) under the influence of rain water. However, considering the increasing demand and changing weather patterns, the above method appears to be inappropriate to meet the demand. In this research, a spiral classifier was designed and fabricated in order to wash offshore sand from salts and other suspended materials. The separation is done on sea sand by optimizing critical parameters of the spiral classifier such as feed rate, rotational speed of spiral, inclination angle of the spiral and weir height.
- item: Conference-Full-textInvestigation of salt water intrusion along the Bolgoda estuary(Department of Earth Resources Engineering, 2008-05) Jayamali, KVSD; Wijayawardhana, HMJT; Rajakaruna, RMCM; Indika, JPR; Rambukwella, UDP; Ratnayake, NP; Karunaratne, SSaltwater intrusion is a natural process that occurs in virtually all coastal water bodies. It causes various effects resulting high breeding of fish, prawns, water hyacinths and drinking water problems due to contamination of fresh water with saline water. Present study, focuses on the intrusion of saltwater along Bolgoda estuary. Objectives of this research are to determine the evidence of saltwater intrusion along the Bolgoda estuary and identify the social and ecological problems related thereto, such as the effects on riparian plants and aquatic life and the adoption of mitigatory measures. Investigation was carried out by measuring water quality parameters (Conductivity, pH, Dissolved-Oxygen, Temperature and Oxidation- Reduction Potential) along the estuary water in vertical profiles as well as water in nearby monitoring wells. Observations were made on different tidal periods to study the rate and extent of saltwater intrusion along the river. These vertical profiles of water quality parameters were taken along the river approximately around 50m intervals, starting from Panadura estuary towards the North direction of the estuary up to about 12 km. Results shows salt water intrusion is a prominent feature during the neap tide period than the spring tide period. Therefore, tidal variation does not control salt water intrusion for our sampling periods. However, salt water intrusion is lower in the periods with higher rainfall period. Therefore rainfall and possibly evaporation is the main controlling factor of the salt water intrusion at Bolgoda Estuary. Salt water intrusion in this estuary is an advantage to the surrounding community since salt water removes water hyacinth, and promotes prone farming.
- item: Conference-Full-textAssessing different methods of salt removal techniques from offshore sand(Department of Earth Resources Engineering, 2008-05) Ilankoon, IMSK; Jayarathne, LGR; Karunanayake, KDP; Thamilinpamalar, N; Wimalarathna, WMNJ; Vijitha, AVP; Ratnayake, NP; Karunaratne, SUsage of offshore sand as an alternative to inland river sand is beneficial due to the various environmental impacts of river sand mining in Sri Lanka. However, higher amount of chloride ions in the sea sand can corrode the reinforcements of the concrete. Therefore it's necessary to identify suitable, low cost and efficient method to remove cl* ions from the sea sand. In this study, three different salt removal techniques; mechanical washing, natural washing and recently introduced grain to grain collision were evaluated using samples from beach sand, river sand, offshore sand and old stock piled offshore sand. Relative salt content and absolute cl* content were measured using conductivity measurements and titration, respectively. Mean grain size and other textural parameters were calculated using sieve analysis. Results indicate lOOg of sand soaked in 200ml of water, required approximately 10 minuets to remove salt from sea sand. Natural removal of chloride by rainwater shows one year of Monsoon rain is more than sufficient to remove salt from even 10 m thick piles of sea sand. However, grain to grain collision does not show significant capacity to remove salt.
- item: Conference-Full-textFeasibility studies of a constructed wetland to treat contaminated water(Department of Earth Resources Engineering, 2008-05) Weerasooriya, UK; Dilrukshi, RAN; Adikari, AMHW; Rajeeth, A; Achchuthan, P; Karunarathne, S; Karunaratne, SAmong the vast number of methods that can be applied for the treatment of contaminated water, mine water was identified one of the best methods of treating of abandoned as the subsurface flow constructed wetlands through pytoextraction. Therefore further research was carried out to the applicability of constructed wetland to treat polluted water at abandoned quarry in Ragama (Prison Quarry). The main objective of the study was to measure the removal efficiencies of BOD, COD, NH3, NO3", PO43" using Thypha Latifolia (Cattail). The hydraulic retention time was 8 days. The concentration of Nitrate, Orthophosphate and Ammonia was monitored twice a week and BOD and COD were monitored once a week in order to determine their removal rates. While monitoring the removal efficiencies, the mechanisms of N, P and COD removals were identified. The mechanisms are based on the principle of mass conservation. The main nitrogen removal mechanisms identified were plant uptake and denitrification. It is assumed that ammonia and nitrate removal from wetlands by macropytes depended on the biomass of the roots. Average Nitrate and Ammonia removal from the planted cell was 42.9% and 27.8%, respectively, whereas the removal efficiency of Ortho Phosphate was 17.5% in the planted tank. Typha latifolia was identified as a suitable wetland plant which can remove nitrogen compounds in contaminated water.
- item: Conference-Full-textSeasonal changes and coastal erosion in the South Western part of Sri Lanka(2008-05) Subramaniam, DN; Amarakoon, GGNN; Gunathunga, SGAS; Pathinayaka, RC; Indeewara, VGD; Vijitha, AVP; Rathnayake, NP; Karunaratne, SSri Lanka is an Island, the economy of which relies very much on the developments of the coastal region, which supports tourism and fisheries. In addition, especially in the South-Western part of the country, the infrastructure lays in the proximity to the coast and the land is more precious and valuable. Further, the constructions around the coastal expanse, alter the sand dynamics of the coastal belt, increasing erosion and deposition at specific points. The erosion cannot be identified at a glance in one day, but when considering long-term sustainable developments, the loss of expanse due to erosion becomes vital. Hence, in this study we analysed the erosion pattern and gross land loss along South-Western part of Sri Lanka, considering duration of 6 months (Jun/07 till Jan/08). The variations of beach profile were determined from leveling perpendicular to the beach at 10 predetermined locations at one month interval. Grain size variations were also analysed from the samples collected from the mean sea level from each sampling locations. A strong correlation was observed at this location between the monsoon and erosion, while at Egodauyana, Panadura Moya, kani Lanka hotel and Payagala revealed rapid changes in erosion/deposition. Although the rainfall influences the beach variation, longshore currents, tides and coastal features (natural and artificial) are found to be dominating at these locations.