BHP Billiton Mitsubishi Alliance (BMA) entrusted Mammoet with the relocation of the 3,100-tonne dragline across its Peak Downs coal mine.
Up against a deadline, allowing the dragline to travel the 27km under its own steam would have taken too long – two weeks non-stop driving, in fact, as it takes it 12 hours just to crawl one kilometre.
Instead it was jacked up onto self-propelled modular transporters (SPMTs), which can travel up to 5km per hour.
Eight JS500 towers were set up underneath the dragline for the jacking operation. Once it was elevated to 2.5 metres, a configuration of 5x28 lines of SPMT were positioned underneath the load to transport it.
Mammoet’s SPMTs achieved a speed of 8km per day and completed the trip in 10 days, setting a new benchmark for dragline transportation.
“In the past, dragline jacking in Australia has been performed using climbing jacks, which require manual handling of timber stacks to gradually lift the load,” explains Mammoet project manager Jack Whittaker.
“The JS500 system requires fewer jacking towers and uses cassettes, which are inserted at its base. This saved a lot of time, resulted in less equipment and removed the need for manual handling”.
BMA constructed a new route for the dragline to take. Where there were soft areas in the soil, steel mats were used to prevent the SPMTs from digging in and getting stuck.
Due to the distance and heat, a canopied seat was installed on the deck of the front SPMT. This meant the control box could be mounted instead of carried, and the driver could be shielded from the sun.
The team had a 72-hour window for the closure of a railway line en route. In that time they had to construct the temporary ramp over the track, make the crossing and return everything back to its original state.
“One of the key reasons that BMA reached out to us was because the Aurizon rail crossing is a critical line – transporting coal from different mines in the region to the coast for exporting,” says Mammoet branch manager Laura Ewen.
“Peak Downs had competing projects in the area at the time, and the shutdown crossing window wouldn’t align again for another three months. The dragline was required for coal extraction in the southern pits for production.”
Using SPMTs not only got the dragline to site safely, on time and without incident, it also reduced wear and tear on the machine and its mechanical parts.
The other benefit of this method was logistical – the ancillary equipment required to move a dragline, along with a portable substation connected via a long ‘umbilical’ cable linked directly to overhead power cables on site, was not needed because everything was powered by the SPMTs.
