A 3,100-tonne dragline has been successfully relocated 27 kilometres across BHP Mitsubishi Alliance’s (BMA) Peak Downs coal mine in Queensland, setting a new benchmark for such moves in Australia.
Draglines are among the largest and heaviest machines in open-pit mining. Designed to operate on a single site, they are slow to travel under their own power – covering just 1km in about 12 hours – and require extensive auxiliary equipment for long-distance relocations.
With a tight deadline and the need to cross a critical Aurizon rail line, BMA engaged heavy-lift specialist Mammoet to move the Marion 8050 dragline by jacking it up and transporting it on Self-Propelled Modular Transporters (SPMTs), which can travel up to 5km per hour.
This was only the second time Mammoet had used this method in Australia, following a similar project with BMA in 2017. This time, however, failure to meet the rail crossing window would have caused months of delays and significant costs.
Eight JS500 jacking towers were positioned under the dragline, lifting it 2.5 metres so that a configuration of 5×28 lines of SPMT could be placed underneath. Engineers worked from data on similar machines due to the dragline’s age and limited technical records. Once lifted, its weight was evenly spread across 560 tyres, keeping ground pressure below 9 tonnes per square metre.
“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,” said Jack Whittaker, Project Manager at Mammoet. “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 prepared a new route for the relocation, laying steel mats over softer ground to prevent the SPMTs from sinking. Given the intense Queensland heat and long travel distance, Mammoet also installed a canopy and mounted control box on the front SPMT to shield the operator.
The most time-critical stage was the rail crossing. Mammoet had a 72-hour shutdown window to build a temporary ramp over the tracks, move the dragline across, and restore the crossing.
“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,” said Laura Ewen, Branch Manager at Mammoet. “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.”
By using SPMTs, Mammoet avoided the need for the usual ancillary relocation equipment, portable substations and power cables, as the move was self-powered.
The result was a record-breaking relocation – covering the 27km in just 10 days at an average of 8km per day – compared to the month or more such moves usually require. The approach minimised downtime, reduced wear and tear on the dragline and delivered the machine to its new site safely, on time and without incident.