Underground » Mining Technology and Production
Cable bolt drilling remains a hazardous and labour-intensive task in underground roadway development, primarily due to the manual handling of drill rods and subsequent operator exposure to machinery and unsupported rock mass. A novel technique for continuously drilling cable bolt holes using a water jet drilling tool was recognised by the ACARP Roadway Development Task Group as having the potential to minimise manual involvement and operator exposure, as well as providing improvements to cable bolt installation productivity.
The main objective of this Water Jet Cable Bolt Drill Investigation project was to leverage CRCMining's extensive continuous water jet drilling expertise to assess the potential for such a system to be used for drilling cable bolt holes.
Technical risks and key functional requirements of a water jet cable bolt drilling tool were identified. The experimental program used different apparatus to assess each of the functional requirements. The drilling tools included a commercially-available jetting head, a CRCMining patented jetting head specifically designed for this project, and a reconfigured drilling tool from CRCMining's Tight Radius Drilling (TRD) system.
Drilling tests demonstrated the production of smooth and straight holes in sandstone samples. The drilling apparatus successfully simulated the drilling of horizontal 8m hole lengths while achieving diameter control that was consistent within a tolerance of +4mm of the design diameter (42mm). CRCMining's patented jetting head achieved maximum penetration rates of 1.8 m/min with injection pressure of 90 MPa and water consumption of 100 litres/min. During the course of the program, CRCMining researchers undertook a number of inventive steps to successfully manage diameter control when drilling through bedding layers and in spudding sections. The testing program has enabled identification of key design criteria for an effective water jet cable bolt drilling tool and deployment system.
Following the success of this project in addressing the fundamental risks and demonstrating key drilling capabilities, CRCMining proposes a subsequent developmental phase to build a water jet drilling tool prototype that integrates the key functionalities into a single tool. This would involve partnering with an OEM to initiate technology transfer and commercial development once performance of the drilling tool prototype has been verified in an underground field trial. Potential collaborative opportunities for site testing and further development are being explored through CRCMining's Member companies, which include BHP Billiton, Peabody Energy, Xstrata, Sandvik, Caterpillar, and Joy Global.