Anglo American has started running its innovative tunnel boring machine at the Grosvenor coal mine in Moranbah.
The miner is working with Redpath on what is a first for the mining industry, by using a tunnel boring machine (TBM) for drift excavation.
Officially launching the project yesterday, Anglo American’s head of underground excellence, Dieter Haage, said this development was an important milestone in the overall delivery of Grosvenor, which is located next to Anglo’s existing North longwall mine.
“It is exciting to reach this milestone today after almost 1.5 years of construction activity,” Haage said.
“The $40 million earth pressure balance machine will allow us to reach the coal seam early next year, bringing us that step closer to longwall production in late 2016,” he added.
The eight metre diameter Earth Pressure Balance (EPB) TBM was manufactured by Robbins and will be used on the coal mine to excavate two drifts instead of the traditional method of using a road header.
One drift will be used for transporting the coal from the longwall to the stockpile on the surface, while the other will be used for personnel and vehicle access.
According to Redpath’s general manager of coal Gavin Ramage, TBM offers a safer, quicker and more stable excavation option.
“The tunnel boring machine is expected to excavate drifts at least three times faster than a road header, which provides much quicker access to coal,” Ramage said.
“There are also a number of safety benefits associated with using the TBM, mainly from the highly stable and durable ground support required, which has a 50 year life expectancy, as opposed to the less stable support used for a road header.”
The TBM will pass beneath a steel archway roof that has been installed at the drift’s entrance and begin drilling into the ground to build the seven metre diameter tunnel, descending at an angle of one in eight until it reaches the depth of the coal seam approximately 160 metres below.
As it advances forward Anglo will use pre-cast concrete rings segments to line the inside of the drift.
Using the TBM removes the need to rehabilitate the drift support every 10 years as the TBM support has a life expectancy five times that which is laid for the road header.
“Similar to the tunnel borers that have been used to construct the road tunnels in Brisbane, the TBM tunnelling method will deliver advances in safety, higher quality drifts and faster project development,” Anglo American’s Grosvenor project director Glenn Tonkin added.
There are currently 700 people on site during the construction phase, and once in production employee levels will stabilise at around 350 staff.