Agnew Mine

Agnew Mine

The Challenge

The Agnew Mine Gold Mine is located in Western Australia in the northern Goldfields region and is operated by Gold Fields. Gold Fields is a geographically diversified producer of gold with multiple operations in Australia, and mines in Ghana, Peru, Chile and South Africa. 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. MDA was able to provide a drill rig and drill string capable of completing the reaming requirements.

Our Solution

MDA addressed the client’s requirement with a series of innovative strategies. The RD6-123R rig was mobilised to the mine due to its ability to meet the project’s unique operational and safety expectations. To mitigate the risks associated with the traditional cutter changing method, a thermal lancing method was developed, enabling all maintenance activities on the reamer head to occur in a safer location. To address the potential for any hole closure of the existing pilot hole, a 16″ tricone bit was utilised, chosen specifically for its efficiency and compatibility with the geological conditions.

The Result

The project falls under the Construction Model status and is set to be successfully completed through effective collaboration with partners and the principal. A newly developed thermal lancing method was utilised to detach the reamer head from drill string, thereby allowing the reamer head to be successfully removed from beneath the open hole to a safe location away from the hole where the worn cutters were successfully changed out.

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.

Project highlights

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

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