The Moolarben Coal Operations joint venture, the operator of the Moolarben coal complex in the Hunter Valley region, in New South Wales, Australia, has invested about $3-million to buy six new Komatsu 830E haul dump trucks, with customised suspended dump bodies (SDBs) from SDB supplier Duratray.

The investment was prompted by an environmental noise-reduction trial at the mine, last year, during which a SDB was used.

In terms of the New South Wales Protection of the Environment Operations (PoEO) Act of 1997, which is enforced by the New South Wales Environment Protection Authority, some mines must establish a noise-management plan and be subject to the calibration and monitoring of acoustic sound levels.

Moolarben Coal realised that the noise during loading operations is intrusive to the surrounding community of the Hunter Valley region, near Mudgee, even when the noise level at the mine complied with the PoEO Act and, as a result, the possible benefits of using Duratray’s SDBs to reduce the noise were identified.

The SDB trial at the Moolarben coal complex, which started in early 2012, delivered a notable measurable reduction in noise during the loading of adverse hard-rock materials.

Some of the results showed that sound levels for a standard dump body ranged from 132 dB to 146 dB, while the criteria for a Duratray truck body ranged from 127 dB to 139 dB, which demonstrates a reduction in linear sound power levels of between 5 dB and 7 dB, surpassing government compliance requirements.

However, prior to the trial in 2012, a trial was also conducted in 2011, during which one Duratray SDB was used at Anglo American Australia’s Drayton opencut thermal coal mine, in the upper Hunter Valley region.

The SDB tray’s performance as a solution to environmental noise reduction, high operator loading impact levels and achieving consistent payload results were tested over six months.

Besides reducing environmental noise levels, the SDB provides a range of other benefits, including increased payloads, a reduction in carry back, reduced spills, lower maintenance and longer asset life, compared with traditional steel trays, as well as loading impact reduction, owing to the rubber wear floor and liner.

Unlike regular truck bodies, the design of Duratray’s SDB comprises a thick, yet flexible, rubber wear mat, which lines the wall and the floor of the dump body. The floor is supported by high-capacity synthetic suspension ropes, which are anchored and tensioned into the sides of the abrasion-resistant steel frame of the dump body.

These components act by dampening the noise when rock is dropped in the tray.

The Duratray SDB can carry between 40 t and 400 t.

About 1 000 SDBs are in use at mines worldwide, in locations as diverse as Argentina, Brazil, Canada, Chile, South Africa, the UK and the US.