Abstract
In underground metal mines, drilling and blasting is widely used production method. Drilling holes is especially a time consuming operation. The aim of this study is to examine and analyze drilling operation and its duration in underground ore and dead rock. Drillability experiments are carried out on samples taken from the field. In core sampling two different types of core samples are taken whether it is parallel or perpendicular to ore bedding and dead rock. Results of drillability experiments are compared between the two types of core samples. DRI values are found to be 51 and 47 for the parallel and perpendicular core samples to ore bedding, respectively. DRI values for the parallel and perpendicular core samples to dead rock bedding are found to be 57 and 55 for the, respectively. In addition, graphs of drilling speed and drilling depth belonging to ore and dead rock are analyzed. It is examined that drilling speed increases steadily to maximum point in the first 5sec. and stays stable after that point. Therefore, it is concluded that production galleries and holes which are formed parallel to bedding would increase production efficiency.
Highlights
The main objectives in drilling blasting operations, excavation operations of mines and tunnel excavations are achieving the best efficiency, keeping the excavation equipments in good shape and reduced wearing
Rock mechanics tests are performed on samples taken from an underground lead-zinc ore mine near Bayindir
It can be seen that the uniaxial compressive strength values of the specimens are between 38.52 MPa and 106.18 MPa, the unit weight values are between 2.74 gr/cm3 and 3.26 gr/cm3, and the Schmidt hardness values are between 33.51 and 47.11, compactness ratio values are between 94.10 and 99.98, porosity values are between 0.02 and 5.90
Summary
The main objectives in drilling blasting operations, excavation operations of mines and tunnel excavations are achieving the best efficiency, keeping the excavation equipments in good shape and reduced wearing. When designing an excavation system, in order to achieve a good excavation performance, rock mass properties, physical and mechanical properties, drillability and properties of rock formation should be identified. As well as geological formation, physical and mechanical properties, drillability and corrosion of rock formation should be considered in detail. Drillability is defined as the advance depth of drilling bit in rock formation. In other words, it is the degree of easiness/hardness in drilling the rock. Drilling speed is measured centimeters moved in the rock formation per minute. Controllable factors are machinery, drilling equipment, energy transfer in drilling equipment and selection of drilling bit. Uncontrollable factors are geological variables, geomechanical properties of rock and rock mass properties. Most researchers have studied on drilling rate index for selection of the most proper excavation or drilling machine and investigated the relationship between rock
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