Selection Requirements of Underground Mining and Tunneling Drill Rock Tools

With the continuous progress and development of mining, underground mining enterprises worldwide are trending towards large-scale, mechanized, digitized, and safer operations. When it comes to selecting large-scale, high-cost equipment, decision-makers typically conduct comprehensive assessments tailored to their specific mining conditions, investing considerable effort into equipment selection. However, the cost aspects related to the selection and application of drill rock tools are often overlooked by many mining enterprises.

Drill rock tools serve as a critical component in the entire rock drilling equipment arsenal. For the mining industry, the selection and application of these tools have a decisive impact, as choosing the right tools can significantly enhance drilling efficiency, hole quality, and tool lifespan. Simultaneously, this optimization greatly improves overall equipment performance and mining operation costs.

The drill rock tool chain constitutes the final link in the entire rock drilling system, encompassing the drill bit, coupling sleeve, drill rod, and adapter.

The entire drill tool system requires precise manufacturing processes and ideal tolerances to ensure superior quality and rock drilling performance. Similarly, adjustments must be made to the entire system, including the drill rig, rock drill, and tooling system, based on specific rock drilling conditions and applications. The drill rock tool system needs to meet the following requirements:

High-speed drilling characteristics

Modern hydraulic rock drills provide unparalleled power for drill rock tools. During operation, these tools endure significant compression stress, tensile stress, thread wear, frictional heating, and erosion from rocks.

Material requirements for drill tools

In such complex conditions, drill rock tools demand materials that exhibit four key characteristics: (1) Durability - to minimize energy loss and optimize drilling verticality, requiring robust materials and appropriate tool dimensions; (2) Fatigue resistance - due to high-frequency stress and tension, necessitating exceptional fatigue resistance; (3) High strength - essential under high-powered rock drills to minimize the risk of tool breakage; (4) High wear resistance - crucial for prolonged thread life, especially for the alloy parts of drill bits. These characteristics are often interdependent, requiring optimized material selection, product design, and advanced heat treatment processes to achieve optimal performance.

Drilling characteristics

Critical drilling characteristics during underground rock drilling include:

• Hole diameter - considering tunnel dimensions, drill rig specifications, rock hardness, and blasting requirements.

• Hole depth - balancing drilling depth with rock conditions, work plans, and shift schedules to maximize advance per drift in tunnel operations.

• Hole verticality - crucial for enhanced productivity, where drilling accuracy is equally vital as drilling speed. Ideal vertical holes improve blasting efficiency, minimizing deviations due to poor hole alignment and rock conditions.

Sludge removal

Efficient drilling rates hinge on effective sludge removal. Ineffective sludge removal can reduce tool lifespan, accelerate equipment wear, and lower drilling speed and accuracy, thus impacting operational economics negatively.

Hole expansion

During tunnel drilling and blasting operations, central slot holes with diameters ranging from 64-127 mm are typically used. Initial drilling of smaller holes (35-45 mm) ensures precision and reduces tool wear, providing adequate expansion space for effective blasting and achieving optimal depth.

These considerations underscore the critical importance of selecting and applying drill rock tools meticulously, aligning them with specific mining conditions and operational requirements to achieve superior drilling performance and operational efficiency underground.