Master of Science in Mining and Mineral Exploration

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Browsing Master of Science in Mining and Mineral Exploration by Subject "METAMORPHIC ROCKS-Sri Lanka"

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    Effectiveness of emulsion explosives in quarrying in high grade metamorphic rocks in Sri Lanka
    (2017-06) Pathirana, KPR; Weerawarnakula, S; Hemalal, PVA
    In mining, blasting is the predominant method adopted for breaking consolidated rocks with the main objectives being extraction of minerals at minimum cost with minimum damage to the environment. Explosive is a compound or a mixture of compound which is capable of undergoing extremely rapid decomposition with deflagration or detonation. When the explosive reaction takes place radial cracks are form by as a result of detonation pressure with fragmentations followed by gas pressure. The optimization of explosive usage in Sri Lankan metamorphic rock is the main objective of this research. The detonation velocity of the explosive should match, as closely as possible, the sonic velocity of the rock to be blasted of rock. The rock's sonic velocity is a reliable indicator of its structural integrity and resistance to fragmentation. With varying rock types, sonic velocities vary with varying structural formations. Aggregate impact value is one parameter of hardness of rock. This study is conducted by considering the aggregate impact value as the indicator of hardness of rock. Test is planned, keeping blasting parameters constant namely hole diameter, explosives charge, burden, spacing and stemming against the different rock types with different aggregate impact values. The efficient use of explosives, along with the proper selection, will be the key to a successful blasting program. After comparison of the results of production rock volume and fragmentation formulate the explosives usage to get the optimum results that how explosives behave with the different rock types with different aggregate impact values or hardness. Dautrich method is the first time practically used in Sri Lankan field to determine the velocity of detonation of emulsion explosives in this research. This method is indirect field test method for suggesting VOD of explosives and the determination of the VOD is based on the fact that processes that propagate at different linear velocities travel different distance, in the same time interval. According to the blast results harder rocks fragmented with emulsion explosives, higher production volume were obtained than less hardness rocks. Increasing the hardness, increasing the production rock volume. Therefore, the relationship with hardness of rock and emulsion explosives usage is observed. Fly rock throw is more important to safety of blasting. This research indicates that fly rock distance is higher with AIV values more than 27. This result clearly indicates that emulsion explosives is very suitable for Sri Lankan metamorphic hard rocks.
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    item: Thesis-Full-text
    Relationship between los angeles abrasion value and mineralogy of rocks
    Dayarathna, IWTP; Puawawala, UGA; Rohitha, LPS; Abeysinghe, AMKB
    This research includes study of the relationship between Los Angeles Abrasion Value and the mineralogy of rock aggregates narrowed down to the commonly found high grade metamorphic rocks in Sabaragamuwa Province. The study was carried out minimizing the effect of other factors as much as possible. Los Angeles Abrasion Test and Mineral content of each rock sample selected was determined at the laboratory. Thin section analysis was carried out to determine the mineral content with the help of electronic microscope equipped with a digital camera and the AutoCAD software. Most of the rock quarries in the study area consist of biotite gneisses. Two samples are selected to represent them. Most of the other samples were selected from waste rock piles of quarries to have samples with varying content of minerals.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. The best regression line fit for the test results is a third order polynomial line between Quartz Content and Los Angeles Abrasion Value which shows coefficient of determination as 0.7952. Another important achievement of this study was developing a field guide to assist the personnel at the field work. 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.