Examining of rock drilling properties in underground metal mine excavation

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.

A New SJ* Value Based on Sievers’ J-Miniature Drill Tests to Determine the Drillability of Limestones

“…A higher penetration rate in Zone 1 (Figure 9) is attributed to two simultaneous factors: (i) the time it takes for the drill bit to adjust and settle into the rock surface and (ii) increased thermal damage to the surface of the thermally treated samples. A rapid penetration of the drill bit in the first seconds of the test, followed by stabilisation or a rapid decrease in drilling rate, was described in previous research and related to accelerated cutting edge wear [21]. Rocks with a significant quartzite content show a "breaking point" in the penetration-time curves, which is related to accelerated drill bit wear.…”

“…To do this, the authors tested quartzites to identify a "breaking point" after only a few seconds of drilling, at which point, the cutting edge of the drill bit was worn down and unable to produce any further indentation. This way of studying cutting tool wear from depth-time curves has been addressed in very few investigations, such as in the drilling performance in metal mine excavation in Turkey [21] or to assess the efficiency of TBM cutter heads in soft ground in central Dublin [22]. Despite its potential as an alternative method to study rock drillability, the use of the depth-time curve and its derivative, the penetration rate-time curve, have not been sufficiently investigated subsequently.…”

Numerical and Preliminary In Situ Investigation on Roadway Excavation Using Static Expansion Mechanical Fracturing

“…At present, the drilling-blasting method is still the most common roadway excavation method in underground metal mines all over the world, as a relatively mature technology [1][2][3]. However, the drilling-blasting construction is a labor-and timeconsuming operation [4], and it will produce a great many fractures in the surrounding rock of roadway and stope [5][6][7]. As the rock blasting within the excavation, it is bad for roadway supporting [8,9].…”