Effects of joint orientation in tunneling

This research is focused on the effects of joint orientation with respect to the direction of tunnel axis. It is expected that the stability of surrounding rock is affected by the strike and dip of the joints and the direction of the tunnel axis, whether it is with the dip or against dip etc. similarly the spacing of joints will also affect the stability. The orientation of joints in different directions can form blocks liable to fall. The objective of this research project is to determine the degree of influence of joints' strike and dip orientation in tunneling. Field works related to this project was carried out at the Bogala Graphite Lanka Ltd. Tunnel mapping and other observations related to the project were made at 489.6m level in Bogata mine. Models were made with joint spacing of 15mm with two joint sets (joint sets parallel to tunnel axis and joint sets perpendicular to tunnel axis). Tunnels were created with 90mm diameter with dip angles of joints are 00,300,600,and 900. The tunnels models are loaded using UCS machine and observed the behavior of rock mass around the tunnels during loading. From the results the most preferable dip angle for the joint strike perpendicular to the tunnel axis would be the 900 and for the joint strike parallel to the tunnel axis would be 00

Optimization of Sri Lankan underground graphite mining methods, from a view point of rock mechanics and cost

There are three main Graphite mining companies in Sri Lanka, namely, Bogala Graphite Lanka PLC (Bogala and Rangala mines), Kahatagaha Graphite Lanka Ltd (Kahatagaha mines) and Sakura Graphite PVT Ltd (Ragedara mines). Cut-and-Fill method is adopted at Bogala and Open Stoping is adopted at both Kahatagaha and Ragedara Mines respectively. Rangala mine is still in its exploration stage. In Sri Lanka Graphite occurrences are in the form of veins with a steep dip. Cut-and-Fill method is used as it is cheap and a good way of using as excess rock generated can be used for filling the voids. This is a traditional method of mining and no theoretical studies had been carried out. By achieving greater safety and reducing the cost, the local graphite industry will have a higher profit margin.Senate Research Gran

Removal of sulphur from graphite powder

Graphite is crystalline carbon identical in composition with charcol and diamond. There are three principle types of graphite viz. Vein, Flake and Amorphous. Sri Lankan graphite falls into the vein graphite category, which can be further subdivided into crystalline and amorphous forms. Graphite occurs in narrow, long and often irregular veins, general attitude conforms to the major rupture direction of rocks in the vicinity, but deviations are possible in both strike and dip. Graphite veins are extremely pure with relatively little Gangue is mainly lenses of wall rock or quartz. Occasionaly calcite, pyrite and chalcopyrite occur in small quantities

Minimization of fires in crushing graphite

Graphite is one of the naturally occuring crystalline forms of Its chief charateristics are its black colour, metallic luster,extreme softness, high conductivity of heat and electrici_ ty, high refractoryness and chemical inertness The mining of graphite in Sri Lanka and its export have continui_ ed since 1821, and in the early days the country enjoyed a virtual monopoly in the world markets. The graphite mining industry is one of the oldest mineral industries in the island

Influence of mechanical and aggregate properties of rock on powder factor in rock blasting

Profit margins in metal quarrying have drastically reduced in Sri Lanka due to high powder factors recorded in recent rock blasting activities. Importance of analysing the influence of mechanical and aggregate rock properties on the powder factor arises in this context to determine suitable rocks in which expenditure on blasting is minimal during the production stage. Eight quarries operated under the close supervision of qualified Mining Engineers were selected for this study to ensure that a proper blasting geometry and configurations have been properly managed during the period of study. Random core samples were obtained from each quarry site and tested for Density, Uniaxial Compressive Strength (UCS), Tensile Strength and Aggregate Impact Value (AIV) and Rock Mass Rating (RMR). Explosive consumption and drilling records for the past six months were obtained from each quarry for the calculation of powder factor. Powder factor was plotted against each selected rock property and regression analysis was performed to understand their standalone influence. Results of the analysis concluded that the aggregate rock properties, especially Aggregate Impact Value (AIV) have a greater influence on the powder factor. Relationship established in this research can be used to predict powder factor of a fresh rock before conducting any blasting activity

The key factors affecting the competency in value addition to gem and jewellery in Sri Lanka

Gem and jewellery industry in Sri Lanka plqys a vital role contributing immenselY toforeign exchange earning to the country's economy. The industrial value chain begins lvith gem mining and ends with retailing ofjewellery while, several stages are included amid. It is imperative to be discerned that every stage involves trading, resulting export of a larger amount if semi-finished products without adding the premium value which creates lack of competitiveness. S tatistical data illustrates a clear dispariry in terms of revenue generated through the gem exports as opposed to jewellery exports. Thus, the discrepanry between country's resource capaciry and its level of fabrication has inspired to conduct this research work