Browsing by Author "Samarakkody, SATI"

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item: Conference Full-text
Effect of trenching on bast-Induced ground vibration in Sri Lankan metal quarries
Samarakkody, SATI; Dharmaratne, PGR; Hemalal, PVA; Premasiri, HMR; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Problems due to ground vibration are a matter of serious concern for the users of explosives, as it is not possible to eliminate vibration totally or to contain them at the source. Efforts need to be made in controlling the vibration to fall within the safe level, without affecting the production schedules and economic viability of the project. If ground vibrations predicted or monitored exceed the statutory limit, control measures are taken by modifying the blast design parameters. In the research, digging a trench between the vibration source and the point of observation has been studied as a technique to reduce the transmission of the Rayleigh waves. The extent to which ground vibration could be reduced has been examined by field experiments carried out at an open cast quarry situated at Arankele, Sri Lanka. Blast vibration measurements have been carried out for active isolation, where the trench is excavated closer to the blasting point. An average of ten single shot hole blasts carried out correspondingly for four different depths of shot holes namely 1 m, 1.5 m, 2 m and 2.5 m with varying depths of trench shows ground vibration reduction percentages of 6.3%, 1.2%, 7.0% and 18.3% at a point immediately after the trench keeping the depth of the trench greater than that of the shot hole in each blast, and reduction percentages at a point closer to the observation point under the same conditions for the four shot hole depths were 72.2%, 54.4%, 55.1% and 45.1% respectively. The corresponding values after digging the trench show ground vibration reduction percentages as 57.8%, 53.9%, 40.5% and 36.7% at the point immediately after the trench location and vibration reduction percentages of 55.5%, 64.7%, 56.8% and 42.3% at the point closer to the point of observation for the corresponding four shot hole depths. Results indicate that after digging the trench, ground vibration reduction levels recorded were much higher, compared to those obtained before digging the trench. However, results obtained closer to the point of observation do not indicate a reduction for each shot hole depth. This leads to the conclusion that active isolation results in a considerable reduction in ground vibration level under given geological conditions.
item: Thesis-Full-text
Effect of trenching on blast-induced ground vibration in sri lankan metal quarries
Samarakkody, SATI; Dharmarathne, PGR; Premasiri, HMR
Problems due to ground vibration are a matter of serious concern for the users of explosives. It is not possible to eliminate vibration completely or to contain them at the source. Effort need to be made in controlling them within safe level, without effecting the production schedules and economic viability of the project. When predicted or monitored vibration exceeded the statutory limit, ground vibrations are generally controlled by modifying the blast design parameters. In critical situation, digging a trench has reduced ground vibration. The extent to which it can reduce ground vibration has been examined by field experiments at a open cast quarry mine located at Arankele in Sri Lanka. After selecting a suitable quarry site at Arankale off Kurunagala in North-Western province of Sri Lanka. Suitable place for blasting face, digging a trench and observation point have been identified. Vibration measurement were carried out after single shot hole blasting method prior to digging a trench and after digging the trench with variation of depth of drill holes and depth ofthe trench, at points located just before the trench(A), just after the trench (B) and approximate observation point away from the trench (C). Average often single shot hole blast carried prior to digging trench show ground vibration reduction percentage are 6.326% ,1.23%, 7.023% and 18.309% at B, and 72.262%, 54.474%, 55.183%, and 45.191% at C. Results after digging the trench show ground vibration reduction percentages are 57.878%, 53.946%, 40.514% and 36.757% at B and 55.509%, 64.787%, 56.848% and 42.382% at C. Such results indicate, just after the dug trench, ground vibration reduction level is very much higher compared to the results obtained before digging the trench. However considerable deferences have not been observed at the observation point under same condition. The results also show that the percentage of the reduction depend on the trench depth to blast hole depth ratio.
item: Conference-Full-text
Recovery enhancement of graphite tub-dust to 99+ carbon using a mill modification
(Department of Earth Resources Engineering, 2007-10) Samarakkody, SATI; Rohitha, LPS; Fernando, WLW; Karunaratne, S
There are many mineral processing methods that are being used in mining and mineral processing industries. One such method very widely used in the graphite industry is froth flotation. During the present study, graphite having a 82- 85% C, with a low market, has been up- graded to Carbon 99% + grade by using flotation. It has been observed that the rod weight in the grinding operation has a major role to play. If the rod weight is increased over and above the critical weight, over grinding takes place. Further, it has been found that pH and the type of collector also play major roles in the graphite processing. Laboratory trials indicate that by using the rod weight of 625kg to 725kg in the rod mill and the particle size range of 75 to 150 microns, maximum recovery of 85% could be achieved at 99% + C grade.