Most of the mineral resources are buried deep underground. When the open pit or surface minerals are mined out, and you want to continue digging, you need to go deep underground and do underground mining. At this time, it is necessary to drill various pathways between the surface and the ore body for ore transportation, ventilation, drainage, and pedestrian. These access roads are widely known as mine tunnels. Mine roadway excavation is an important part of mining resource exploitation. With the mining of mineral resources deeper and deeper, mine roadways need to be continuously excavated. Naturally, the use of rock drilling tools is indispensable in the excavation. So, what are the requirements of mine tunnel excavation for rock drilling tools?
1. High-speed drilling characteristics
Modern hydraulic rock drills provide powerful power for rock drilling tools. During the working, rock drilling tools are subjected to strong compressive stress, tensile stress, thread wear, friction and heat, and scouring from rocks.
2. Rock drilling tools materials demand characteristics
① Sturdiness. To achieve minimum energy loss and ideal drilling straightness, good robustness and reasonable rock drilling tools size are required.
② Fatigue resistance. Rock drilling tools are subjected to great compressive and tensile stresses at very high frequencies during the working, so they require extremely high fatigue resistance.
③High strength. Working with a high-power rock drill, it requires a very high strength for rock drilling tools to minimize the possibility of breakage of rock drill tools.
④ High wear resistance. For rock drilling tools, high wear resistance ensures a higher service life for thread. It is especially true for carbide part of rock drill bit.
3. Drilling characteristics
In underground rock drilling, the important drilling characteristics mainly includes three main aspects.
①Drilling diameter. The selection of hole diameter needs to comprehensively consider the size of roadway, the specification of drilling jumbo, the power of rock drill, the depth of hole, the blasting method, and the hardness of rock. To sum up, the selection of hole diameter mainly needs to consider the number of holes in the working face, the number of blasting, the drilling accuracy and the size of rock-breaking particles, the requirements for roadway support, and the requirements for the number of shotcretes.
② Hole depth. Before designing and laying holes, the depth of drilling needs to be considered comprehensively. To realize the ideal balance of drilling depth and rock drilling shifts, it is also necessary to comprehensively consider rock conditions, work plans, and shift arrangements. In roadway operations, one of the most important objectives is to achieve maximum single roadway feed.
③Verticality of the hole. Many factors affect the straightness of a hole, and drilling accuracy and drilling speed are important factors to achieve higher productivity. Therefore, good quality of drilling is as important as the number of holes per hour. An ideal vertical hole allows for better blasting efficiency.
Effective slagging is indispensable for efficient drilling speed. On the contrary, it will reduce service life of rock drilling tools, accelerate the wear of rock drilling equipment, and reduce drilling speed and drilling accuracy. In short, if effective slagging cannot be achieved, the economy of whole operation will be greatly reduced.
During roadway drilling and blasting operations, a 64-127 mm diameter slotted hole is used in the center. Smaller holes of 35-45 mm are drilled before the operation to ensure the accuracy of trenching holes and to reduce the consumption of rock drilling tools. The main objective is to obtain space for blast expansion in advance to achieve better blasting results and effective depth.
In short, rock drilling tools play an important role in realizing rock drilling. Precise machining processes and ideal process tolerances are required to produce good-quality rock drilling tools with good drilling performance. Likewise, the whole system, including drill jumbo, rock drill, and rock drilling tools, needs to be adapted to the specific rock drilling conditions and applications. Only in this way can the rock drilling process be more efficient.