Mine surveying works for the purpose of excavating the remaining reserves of bauxite in the deposit of “Podbracan”
Mining projects for mineral resource mining contain in certain cases specific technical and technological solutions, these being the result of the mine’s characteristic spatial position and the geometry of the ore deposit, existing mining works, structures, and terrain relief etc. For the purpose of completion of the mining project, it is necessary to carry out a series of mining and surveying tasks during the pre-project and project stage of mining, as well as during the construction of mining facilities and excavation of mineral resources. Specific features of the project concerning excavation of the remaining reserves of bauxite in the deposit of “Podbracan”, and in this way the forthcoming mining and surveying works, are displayed by the integration of the underground mining project into the existing mine chambers, infrastructure structures on the terrain surface and into the open pit. Large number of mining and surveying works will follow the completion of this project, but in the meantime, this paper shows the a priory accuracy assessment of the spatial position of the point, it being the exit point to the existing bench of the open pit at the elevation +420m.
The applied mining method, named the sublevel caving excavation method in crosswise direction, was chosen based on the relevant mining-geological parameters, mining conditions and other technical-technological factors influencing the mining. Basically, the ore body is made of separate mining fields divided by height to levels with the height difference of 10m. By this method, mining starts at the end of bench drift (EH) and generally progresses toward the opening location of the level, i.e. the haulage drift (TH). Excavation dimensions of the bench drift (EH) are 3.5m×3.5m. The stope is made of the over pit part with overall height at 6.5m and the pillar next to the excavation drift, 4.0m wide. The mining of bauxite is performed backwards, in retreat towards the level gallery, by rock drilling of mining holes in the shape of semi-fan and blasting (“semi-fan”). Angle of blasting surface is 60°, while the internal distance between the semi-fans is 1.8m, which is the least resistance line at the same time. The transport and hauling of the ore is realized by the diesel-powered loading-hauling and dump (LHD) equipment and pit truck. The loading and transport of the blasted ore from the stope to the appropriate loading place to the pit truck is realized by the LHD machine. The ore is transported by the pit truck through the main haulage adit (GIP) to the surface, and afterwards with the same truck to the ore dump location.
A special feature of this project requires an analytical and systematic approach when defining the existing spatial position and geometry, and setting out structures designed at and under the terrain surface (Kessler et alli. 2008). The tasks set shall be completed by mining and surveying works, whose extent, type and special positioning must observe the progress of the project.
Mine surveying works
Mining and surveying works are present at the pre-extraction and extraction stage of the underground deposit mining project.
Pre-extraction activity in view of mine surveying includes:
– Analysis of the existing geometric base on the terrain surface, stabilization of new geodetic points and determination of their spatial coordinates;
– Connection of geometric grid on the terrain surface with mine traverses and determination of spatial coordinates of points in the pit;
– Detailed scanning of the open pit levels which are interactive with the designed bench drifts for the purposes of geomechanical analysis of the stability;