CRCMining is developing a water-jet drilling tool capable of rapidly drilling 8 m+ holes to cable-bolt hole requirements, improving productivity and reducing manual handling associated with the existing cable bolt drilling methods. Current cable bolt or long tendon installation practice for roof support is considered to be a highly unproductive exercise, and presents a major bottleneck to roadway development in underground coal mining. The required manual handling of drill rods during the drilling process presents a hazard to cable bolting operators, as well as exposing them to unsupported rock mass.
An urgent need exists for an improved technique for mounted cable bolt drilling and installation systems, to increase safety and productivity.
A CRCMining-ACARP project investigated the potential of CRCMining’s water-jet technology in drilling holes for cable bolts in underground coal mines. Using a variety of drilling apparatus to assess the functional requirements for cable bolt drilling, the investigation has successfully demonstrated that good quality holes (tight diameter control, straight trajectory) for cable bolt installation can be drilled in sandstone at appropriate drilling speeds. The individual requirements and potential capability of a water-jet cable bolt drilling tool – relating to diameter control, spudding, drilling rate, tool thrust and power – have also been investigated and are now well understood.
The water-jet drilling technology uses a high-pressure water-jet cutting head for rapid and continuous drilling of holes of varying length, without the need for manual adding or removing of drill rods as part of the cable bolt installation process. Key benefits of applying the technology include:
•Increased productivity of the cable-bolt installation process
•Elimination of manual drill rod handling, leading to reduction in operator risks
•Step improvements in Underground Roadway Development productivity
•Strong potential for combining the waterjet technology with cable-bolting and automating the entire installation process.
A roadmap to take this project to technology transfer has been developed, and CRCMining is currently exploring opportunities for technology development and technology transfer.
A subsequent development program is required to engineer the capabilities demonstrated during this project into a single prototype tool and deployment system. This system will then be deployed into a mining environment for proof-of-concept demonstration and assessment trials to examine long-hole deviation and handling of actual strata conditions and variation.