Robbins TBM launched to bore Australian coal mine

The machine was built using Onsite First Time Assembly (OFTA) in order to fit within a tight project schedule, the company stated. Assembly at the remote jobsite near Moranbah, Australia took some four and a half months, and then the machine was walked down into a launch tunnel.

Two decline tunnels, at grades of 1:6 and 1:8, will be used for mine access to new coal seams. The hybrid machine is tackling mixed ground conditions ranging from sand and clay to varying types of sedimentary hard rock up to 120 MPa UCS, as well as coal seams. Methane gas is expected to be present throughout the tunnel, so the machine has been designed as Explosion Proof Compliant to ERZ-1.

"Grosvenor is the first underground coal mine in Queensland to use a TBM for drift construction," said Glenn Tonkin, Grosvenor project director. "We are proud to be pioneering this technology."

Roughly 300m of ground in each decline tunnel are expected to require EPB mode, while the rest of the tunnel will be bored in hard rock mode.

"The machine essentially uses its EPB technology to deal with methane gas safely," said Doug Harding, Robbins vice president. If any methane leakage is detected, an evacuation system called a "snuffing box" will draw methane out of the end of the screw conveyor and directly into the ventilation system.

Tonkin added: ""We commenced tunnelling last month and the machine has advanced more than 100m so far. We are on track to reach pit bottom in the next couple of months. The first few weeks were largely spent commissioning the machine in compliance with the mine standards. We expect the machine will perform well and we will achieve the planned cutting rates."

The machine is expected to complete the first decline tunnel in April 2014.