Tunnelling system set for trial

Three new tunnel boring systems will undergo verification trials at the Northparkes copper and gold mine in 2012, Rio Tinto has announced.

The first of three underground excavation systems, developed in conjunction with Aker Wirth, was completed last month.

The system is 64 m long, has a maximum boring diameter of six metres and has minimum tunnel dimensions of five metres by five metres.

Rio Tinto head of innovation John McGagh said the technology could lead to a step-change improvement of conventional drill and blast practices.

“Depending on rock conditions, this system should provide a capability to excavate at more than double the rate of conventional methods,” he said.

“For example, in a typical deep copper ore body, the rate of horizontal tunnelling could be as high as 10 to 13 m a day using this new system.

“Aker Wirth is one of three partners with whom Rio Tinto is working to develop new equipment and systems for the rapid construction of deep underground mines.”

This tunnelling boring system trial has been integrated into a previously announced $90 million prefeasibility expansion study at Northparkes.

McGagh said the trial will complete the final stage of the systems’ performance verifications.

Rio is developing the systems as part of its ‘Mine of the Future’ program, which aims to significantly improve the construction and operation of underground mines.

“This is about The Mine of the Future program going underground, as we promised we would at the start of 2010,” McGagh said.

“This system incorporates continuous mechanical rock excavation that will not damage new tunnel walls, while still providing the ability to mechanically install ground support in parallel with tunnel advance.

“Importantly for Rio, it provides an opportunity to introduce fundamentally safer processes into the underground mining industry.

“This announcement demonstrates Rio’s ongoing commitment to exploiting step-change technology to deliver superior shareholder value while improving both safety and environmental performance.”

The Northparkes mines are a joint venture between Rio Tinto and Japan’s Sumitomo Group.

The company is aiming to deliver the system to the mine by early 2012 and have the trials completed by the end of the year.

After the trial, this technology is destined for use in other Rio Tinto underground mining operations internationally, the company said.

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