The Agnew Gold Mine, operated by Gold Fields, is in the northern Goldfields region of Western Australia. Gold Fields is a globally diversified gold producer with operations in Australia, Ghana, Peru, Chile, and South Africa. Furthermore, the Agnew Gold Mine consists of three underground operations and a processing plant and it employs various mining methods, including sub-level open stoping.
A situation arose at the operation whereby an existing pilot hole, drilled to a depth of 857m, was required to be reamed to a 4.5m diameter. As a result, MDA was able to provide a drill rig and drill string capable of completing the reaming requirements.
MDA addressed the client’s requirement with a series of innovative strategies. Subsequently, the RD6-123R rig was mobilised to the mine to meet the project’s unique operational and safety expectations.
Additionally, the team developed a thermal lancing method to mitigate risks associated with traditional cutter changing. This enabled safer maintenance of the reamer head. They also chose a 16″ tricone bit to prevent pilot hole closure due to its efficiency and geological compatibility.
The project, under the Construction Model status, is set to be completed through collaboration with partners and the principal.
A newly developed thermal lancing method was used to detach the reamer head from the drill string. This allowed the reamer head to be removed to a safe location, where the worn cutters were successfully changed out.
Moreover, this innovative approach aims to not only resolve the immediate issue but also reopen the pilot hole, thus maintaining the project momentum and ensuring continuity of operations.
Tram rig underground, rig-up on the pad, perfectly aligning with existing pilot hole
Trip drill pipes down existing 16″ pilot hole for a total length of 857m
Back reaming of raise bore hole to 4.5m dia
Thermal lanced and removed reamer from the open hole, enabling safe cutter change
Successfully reattached reamer head to drill string
Rig-down and tram rig to surface
