Browsing by Author "Karunaratne, S"

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item: Conference-Full-text
2nd Annual Conference on Minerals for a Better Future - A Multidisciplinary Approach [Pre Text]
(Department of Earth Resources Engineering, 2007-11) Karunaratne, S
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Alternative for river sand
(Department of Earth Resources Engineering, 2007-11) Ekanayaka, EMTM; Jayawardene, MN; Kannangara, KKDM; Puswewala, UGA; Rathnayake, NP; Chaminda, SP; Vijitha, AVP; Karunaratne, S
The need of finding an alternative for river sand arises due to the over exploitation of river sand and its various harmful consequences. The focus of the current study was on offshore sand, which is clearly one of the most viable alternatives for river sand, with respect to availability, ease of extraction, environmental impact and cost. Offshore sand is already used in Sri Lanka mainly for road filling and it is also used for construction in all over the world. A sea survey was conducted in Kaluthara-Benthota sea area and a resource distribution map was plotted. Samples from Muthurajawela offshore sand stick piles were collected and CT content was checked. Offshore sand saturated with sea water has Cl' content around 0.3%, where as if the seawater is gravity drained; it reduced to around the acceptable 0.075%. The action of an average rain fall would be enough to reduce the CT contents to below acceptable levels. However, two other alternatives were also studied in a limited way, namely manufactured sand and quarry dust are quarry products. While quarry dust is merely a by product from the production of course aggregate and tends to be flaky in shape, manufacture sand is actually produced such that a more desirable "rounded cubic" shape is obtained.
item: Conference-Full-text
Analysis of effect on vibration and air blast in rock quarrying
(Department of Earth Resources Engineering, 2010-09) Senadeera, SMADSI; Erangika, MD; Herath, MHBCW; Wickramasmghe, WIUS; Chaminda, SP; Dharmaratne PGR; Ratnayake, NP; Abeysinghe, AMKB; Premasiri, HMR; Karunaratne, S
Blasting induced ground vibration occurring in the quarries has ecome a serious environmental issue in Sri Lanka. To achieve high production targets the number of blasts has increased in the quarries and, therefore, mitigate measures to minimize the detrimental effects of the vibrations have to be identified. This research project on rock blasting was carried out to design a suitable indicating system to predict the ground vibrations and air blasts. In order to assess the variation of intensity of the ground vibration and the air blast over pressure, ground vibrations and air blasts results from two different types of explosives on different types of rocks were monitored. Statistical analysis of the data sets found a high level of confidence on the best fitting empirical relationship between peak particle velocity and scaled distance. By that two site-specific factors were established. A comparison of the analytical work revealed that the level of ground vibration varies significantly with the changing of charge weight per delay, explosive type, rock type and the distance from blasting point to monitoring point.
item: Conference-Full-text
Application of simulation methods to understand tsunami processes around the coastal region of Sri Lanka
(Department of Earth Resources Engineering, 2007-11) Rathnayake, RMMT; Nilminie, WNRPN; Senanayake, DS; Rathnayake, NP; Karunaratne, S
Tsunami is one of the most devastating natural disasters which cannot be prevented or precisely predicted even with the modern advanced technology. One of the best solutions for prediction as well as for the risk analysis of this natural disaster is Numerical Modelling. Present study focuses on the generation of earthquake induced different Tsunami scenarios from the potentially high amplitude earthquake generation zones in the Indian Ocean using Tsunami numerical modelling. Simulation modelling for different scenarios was carried out for source, propagation and inundation using UNESCO/IOC recommended interfaces of AVI NAMI and ComMIT, which uses TUNAMI N2 model. Etopo 2, JEBCO (combine SRTM, ETOP2 and Sea Map data) were used for bathymetry analysis. Distribution of wave heights, run up heights for given locations and arrival times of the waves were simulated as output data. Different Tsunamis were simulated, taking Java Sumathra and Macrum zones as Tsunami sources. Wave heights and propagation of Tsunami waves around twelve locations of Sri Lanka were analysed and vulnerable areas for different scenarios were identified. Results further indicated that if a Tsunami is triggered at Java-Sumatra, Southern part of Sri- Lanka will be severely affected, and particularly the Yala region, because of the direct hit of the Tsunami waves. ComMIT simulation results showed strong coupling to Tsunami sediment data and actual tidal records for 26th December 2004 Tsunami. Therefore, ComMIT seems to be one of the best models for Tsunami warning and forecasting in Sri Lanka.
item: Conference-Full-text
Assessing 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, S
Usage 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-text
Calcite and dolomite mineralization in the area around Balangoda and critical analysis of mining methods and utilization of the deposits
(Department of Earth Resources Engineering, 2009-05) Jayatissa, MDCP; Urapola, MOA; Perera, PAAP; Manojh Kumar, M.; Chandrakumara, GAK; Weerawarnakula, S; Abeysinghe, AMKB; Karunaratne, S
Among the industrial minerals found in Sri Lanka Calcium and Magnesium Carbonate bearing minerals and rocks play a major role in local industry. Crystalline Dolomite and Calcite found in metamorphic terrains are used in ceramic industry, fertilizer industry and in local lime manufacturing plants. Major Calcite and Dolomite occurrences in the metamorphic Precambrian basement are found in Digana, Kekirawa, Polonnaruwa, Balangoda, Baddulla, and Okkampitiya. Studies carried out in the area around Balangoda showed the calcite and dolomite occurrences are located in the area of Hlukpeilessa, Rajawaka and Molamure. Legal and illegal small scale mining has been carried out in the area during last few decades. Studies also showed most of the mining is carried out haphazardly. No proper mining methods have been used for maximum utilization of the deposits. Furthermore, long term mining has not uplifted the socio-economic conditions of the people of the area and proper environmental protection methods have also not been used. Systematic mapping of the deposits, educating miners on proper mining methods, safety precautions and value of environment protection could lead for better utilization of the deposits. Proper financial guidance through possible co-operate system to obtain financial assistance for mining , transporting materials and finding systematic market for continuous material supply could also uplift the socio-economic condition of the community.
item: Conference-Full-text
Characterization of tsunami wave using texture & structure of sediments from South Western coast of Sri Lanka
(Department of Earth Resources Engineering, 2006-10) De Silva, RHSI; Jeyram, P; Perera, RSL; Thananchayan, A; Wickramanayake, NU; Rathnayake, NP; Premasiri, HMR; Abesinghe, AMKB; Puswewala, UGA; Karunaratne, S; Dissanayake, DMDOK; Ratnayake, N; Chaminda, SP
This research focuses on characterization of Tsunami waves by using tsunami sediments, as the only reliable source of information which a Tsunami leaves after strike are sediments. The sediments contain information about Tsunami waves which can be extracted by analyzing. The study focuses on evaluating wave height, flow velocity and wave energy by examining of the thickness, grain size distribution, sediment structures and texture of tsunami deposits. These findings can be used for the prediction of Tsunami threats and in the formulation of precautionary measurements.
item: Conference-Full-text
Cleaner production assessment of a quarry mine
(Department of Earth Resources Engineering, 2010) Wijegunawardana, DS; Sabesan, S; Karunagalage, KVS; Kumara, HMCR; Karunaratne, S; Rohitha, LPS; Kirunanayake, P; Ratnayake, NP; Abeysinghe, AMKB; Premasiri, HMR; Karunartne, S
Wastages, energy loses, low production and environmental impacts are the major problems associated with quarry mines and s. It is essential to minimize these problems to optimize profit and to make a better working place. A Cleaner Production (CP) assessment was performed in quarry and crusher plant located in Nochchiyagama, Sri Lanka. The objective of this project was to identify and provide suggestions to reduce wastages and energy losses, reduce environmental impacts, and provide optimum installation criteria of and to optimize the explosive usage of the quarry with enhanced profit/benefits. The whole operational process was divided in to five sections, i.e. material balancing, energy survey, chain survey for , assessment of environmental aspects and rearranging blasting parameters according to Uniaxial Compressive Strength of rock in quarry mine. After implementing the CP, the solutions / suggestions of turning off generator after starting the plant, introducing cone nozzles to the , covering the conveyor belts, reducing powder factor, etc, was made and they were given to client. The expected annual saving of the CP implementation was Rs.3, 168,895.89 with number of other intangible benefits.
item: Conference-Full-text
Coastal erosion in South Western part of Sri Lanka from December 2006 to June 2007
(Department of Earth Resources Engineering, 2007-11) Hansi, MKTN; Lokukankanamage, DMG; Ranasinghe, GP; Witharana, GH; Rathnayake, NP; Karunaratne, S
Coastal region is a very valuable area for developing countries like Sri Lanka, since a good protected coastal region will facilitate the tourism as well as fishing Industry. But the coastal erosion, especially in South Western parts of Sri Lanka has significantly destroyed the coastal land. Therefore, effective management of the coastal area has become a necessity. Present study is focussed on the variation of coastal profile at ten selected locations from Moratuwa to Balapitya and the monthly changes of beach width, profile and the grain size distribution of sediment at the mean sea level. The study was conducted from December 2006 to June 2007. Results showed that during North East monsoon, the beach face became wider and gentler whereas, during South West monsoon the beach face became narrower and steeper. Further, the mean grain size showed higher values during North East monsoon period than South Western monsoon. This variation of beach width, beach profile and the sediment grain size was strongly correlated with the rainfall changes and it was concluded that the coastal erosion in this area is directly controlled by monsoon changes.
item: Conference-Full-text
Contribution of thermal power plants to ambient air quality levels in Colombo metropolitan region, Sri Lanka
(IEEE, 2023-12-09) Nishajanthani, HBU; Premasiri, HDS; Karunaratne, S; Athapattu, BCL; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Air quality models (AQMs) are essential in complex air quality management studies. Due to data limitations, AQMs are occasionally used in developing countries. This study focuses on assessing the impact of thermal power plants on ambient air quality in the Colombo Metropolitan Area (CMA), Sri Lanka, using the AQM for the first ever in Sri Lanka. Concentrations of SO2 and NO2 were measured at 18 sampling locations for 1- and 8-hour periods, while PM10 was measured for 24 hours during the southwest and northeast monsoon periods. The Factor of Two Observations (FAC2), Fractional Bias (FB), correlation coefficient (R), and Normalized Mean Square Error (NMSE) were used to evaluate the model performance. According to the results, AERMOD simulations overestimated hourly SO2 concentrations while the northeast monsoon exhibited higher pollutant concentrations. The peak value for the 24-hour average period of NO2 exceeded the WHO air quality guideline limits of 25 μg/m3, reaching 46.43 μg/m3 in the southwest monsoon and 41.89 μg/m3 in the northeast monsoon period, respectively. NO2 had a significant impact on other criteria air pollutants. The study emphasized the urgent attention to studies on implications for public health due to thermal power plants, mitigatory measures and appropriate policy decisions for protecting public health.
item: Conference-Full-text
Cost estimation and development of cash flow on mining operation (IML/A) (category quarry operation)
(Department of Earth Resources Engineering, 2007-11) Amirthasothy, V; Arulvadivel, T; Fareez, MRM; Kommala, KD; Madanayake, TA; Walideniya, HS; Weerawarnakula, S; Karunaratne, S
More than 70 quarry operations are conducted under the IML/A Category licence all over the country. The high demand of metal aggregates for the construction industry (road and buildings constructions) has made industrial quarry operations one of the most profitable mining operations in Sri Lanka. However, present economic situation and increase the number of I ML/ A category quarries in Kaluthara District (13 quarries) causing problems in aggregate industry in this area. Manufactured sand produced in quarries has become a better solution for scarce sand resources as well as to increase the quarry operation revenue. During this study three quarry sites in Kaluthara District were studied in detail and cost benefit analysis was made. Among these TAMAC quarry site was the main source for the study. Selection of a quarry site with low operation cost with minimum damage to the environment plays the major role in success. Proper blasting techniques, crusher plant design, selection of machinery and friendly environmental could increase net profits and help to continue operations in a sustainable manner.
item: SRC-Report
Design and construction of a pilot scale waste water treatment plant to treat polluted mine water
(2013-11-06) Karunaratne, S
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Design 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, S
The 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-text
Design and fabrication of cable bolt for excavation in a fractured rock
(Department of Earth Resources Engineering, 2009-05) Dhanawardana, YLC; Siriwardana, HDPM; Henderson, SH; Kumara, HMCP; Indika, KAS; Dharmaratne, PGR; Welideniya, HS; Rohitha, LPS; Karunaratne, S
In fractured rock masses, large excavations have an unsupported stand-up times less than the minimum time required to support the roof after the excavation. Therefore, the principal objective in the design of a support system is to help the rock mass to support itself. The use of rock bolts is a very flexible supporting method that can be combined with wire mesh, shotcrete and concrete lining. During past years a wide variety of dowels and bolt types were developed but most of them failed within a short period and the cost were high. Advantages of cable strand supports have been well documented and include flexibility, strength, and ease of installation. Main objective of this project is to design rock bolts using discarded wire ropes or cables at a low cost. A detailed designing methodology was carried out to fabricate this bolt. The bolt consists of nearly 1.6m long cable and 16 cm of anchored part and cable tightening part. Outer diameter of bolt is 33 mm and inner diameter is 12 mm and used cable diameter is 5mm. Field data illustrated the amount of load measurements that the bolt can carry is 5 kN. Suggestions were made to improve the design, which will enhance bolt performance. Field tests carried out at Bogala Lanka Graphite Ltd proved that cable bolts are effective in Sri Lankan conditions.
item: Conference-Full-text
Design 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, S
Hydrocyclone 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-text
Designing 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, S
Mixing 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-text
Designing suitable mining method and processing plant for Kukurampola magnetite ore body
(Department of Earth Resources Engineering, 2006-10) Amarasekera, HM; Sajirupan, S; Senanayake, IP; Sirisoma, RHANC; Chaminda, SP; Rohitha, LPS; Welideniya, HS; Karunaratne, S; Dissanayake, DMDOK; Ratnayake, N; Chaminda, SP
Evaluation of mining methods for the exploitation of Kukurampola ore body is considered in this report. Minerals take millions of years to form, but exploitation takes only few decades. Therefore, mineral deposit is a wealth which must be used for the maximum benefit of the country. Iron is one of the most important metals in the world for many industries. Therefore, exploitation of iron ore is essential for the industrial development of a country. The Magnetite deposit in Kukurampola contains high purity Magnetite; hence it is a valuable resource need rational exploitation. Mining methods evaluated include open pit and underground, and based on geological, engineering, environmental and economical factors combination of both open pit and underground mining are considered as the most suitable mining method. Consequent to open pit mining underground mining will commence for future ore body development and exploitation. A processing method is designed to produce feed material for palletizing those will include crushing, grinding and magnetic separation. If ample deposits are found in the future, there's a possibility of constructing a palletizing plant which need ore reserves for more than 25 years. Also, occurrences of magnetite in the neighborhoods are identified for further expansion of mining operations Special consideration is given to minimize environmental impacts. Remedial methods are proposed in this report to minimize adverse environmental impacts.
item: Conference-Full-text
Determination of soil overburden on Panirendawa iron ore deposit for selection of appropriate mining method/s
(Department of Earth Resources Engineering, 2010-09) Jayathilaka, BRPM; Perera, MSR; Jayasekara, DAIA; Liyanawaduge, CY; Abeysinghe, AMKB; Premasiri, HMR; Chaminda, SP; Ratnayake, NP; Abeysinghe, AMKB; Premasiri, HMR; Karunaratne, S
Panirendawa iron deposit consists of four isolated deposits namely A, B, C and D. The deposit D has potentially high magnetite concentration according to previous data. The main objective of the study is to carry out an electrical resistivity survey to determine the overburden thickness of the deposit D using the SAS 1000 Terrameter. Vertical Electrical Sounding (VES) was carried out at ten different locations around the deposit D. A single line parallel to strike was surveyed with six points of equal depth to the bed rock and the other two lines (west to east) were parallel to the dip as depth increases. The observed data were interpreted using the IX1D Interpex software in to ID and 2D formats to identify the underground layers/stratification with reference to the apparent resistivity values. The survey was preceded with mean depth about 6.5m of surface layer having about lOOOQm apparent resistivity overlying on a water baring surface with a mean thickness about 35m having about lOQm apparent resistivity; also about 41m below, the bed rock stood with an apparent resistivity about 44500m. According to present study, the most possible mining method would be underground mining.
item: Conference-Full-text
Determination of uniaxial compressive strength using point load index of high grade metamorphic rocks from western Sri Lanka
(Department of Earth Resources Engineering, 2009-05) Thushanthan, K; Udayantha, BVM; Chathuranga, SAKS; Dissanayaka, VAKA; Karunananthasivam, L; Jayasekara, JMEPK; Puswawela, UGA; Samaradivakara, GVI; Karunaratne, S
This research is focused on finding the correlation of unconfined compressive strength (UCS) with Point load Index (PLI) of gneissic rocks, and to propose proper correlating value, based on a study carried out for Sri Lankan Gneissic rocks. There has been an increasing use of the PLI as a measure of rock strength since its introduction in 1972. The small size and the simplicity of the point load tester have led to its use on site in many projects. The rock samples were obtained from three rock quarries in the Western Province. Using the results of laboratory testing of gneissic rocks under point loading as well as in Uniaxial Compression, and statistical analysis, different conversion factors relating UCS and PLI are determined for each quarry. The sample preparation and testing are conducted according to the A STM code. Exactly 206 individual test results, from 35 distinct rock units were used The conversion factor between UCS and PLI of the study is found to be between 9 and 14. The results of the study are useful to find the strength of rocks conveniently through point load testing.
item: Conference-Abstract
Develop a low cost and effective methodology to improve the physical properties of recycled aggregates with the use of rice husk ash- cement slurry
Kariapper, ABY; Karunaratne, S; Nanayakkara, D
This paper represents a surface treatment method for recycled coarse aggregates (RCA) based on a coating technique where different slurry ratios (i.e., Liquid: Solid) having varying proportions of rice husk ash (RHA) and cement was used. The different slurry ratios used in this research are 0.625, 0.750, 0.875 and 1.000. The solid compositions in the slurry were varied by varying the cement: RHA composition as followed 20%: 80%, 40%: 60%, 50%: 50%, 60%: 40%, 80%: 20% and 100%: 0%. By observing the results it can be seen that when the RHA replacement level in the solid composition of the slurry is increased the water absorption capacity of the treated RCA (TRCA) increases plus the strength factor of the coating decreases, hence it‟s suggested that RHA replacement should not exceed 40% in the slurry used to treat RCA. Furthermore it can be observed that when the slurry is thinner the water absorption capacity of the TRCA reduces. It can be further stated that there isn‟t an effect on the water absorption capacity of TRCA beyond 7 days of curing. Hence it‟s best to use a thin slurry that has a solid composition where the RHA replacement level does not exceed 40%.