Northparkes driverless trucks head deep underground
It’s one thing to have driverless dump trucks hurtling around open-cut mining operations beneath the bright Australian sun.
It’s another when the automation of a mining operation occurs almost 600m below ground, as is the case at the Chinese-Japanese owned Northparkes copper-gold mine near Parkes in NSW’s central west.
And despite the challenges compared with its open-cut cousins on the surface, Northparkes has managed to achieve a world first — 100 per cent underground automation, something previously only achieved in demonstration mines.
Northparkes was the first in Australia to use the block cave mining method in which a block of rock mass is prompted to cave in after being undercut and blasted.
The broken rock works its way down funnel-shaped “drawbells’’ with the help of gravity to an extraction level below the block cave. It is on the extraction level that load-haul dumpers — essentially flat trucks designed to operate in tight tunnels — scoop up the broken ore from drawpoints and take it to a collection point for underground crushing and hoisting to the surface.
Load-haul dumpers, or LHDs, are brutes of machines, armed with 12 tonne buckets. Northparkes has a fleet of eight which are now driverless, some 580m below surface. They work in the E48 mine, the third block cave development since production started in 1994.
Absent drivers, the load-haul-dumpers automatically move up to a drawpoint and signal to one of three operators on the surface that it is ready to pick up a bucket of ore. The operator takes control of the loader for no more than 20 seconds, directing it to scoop up the ore, and then sending it off to the underground collection point. The load-haul dumper then runs back, and gets ready again. It happens over and over, 1600 times every 24 hours, all by themselves.
“We are pretty proud of that,’’ Northparkes managing director Stefanie Loader tellsThe Australian.
“It has been a long journey. The technology is only part of it, it is actually getting the operators to buy in, and the mining team to say: ‘This is actually going to work. A machine can do this better than people.’
“We have separated machines and people, creating the best safety environment.
“The No 1 risk across all mining operations is people and vehicles. So not only do we get the efficiency gains, we also get the safety benefit of not having people exposed to that risk.
“It is orders of magnitude different in terms of the levels of safety.
“The big advantage is that you are taking people out of the load-haul dumpers itself. Think of a 12-hour shift in the loader from an overall occupational health perspective. There are better places for the people to be sitting than in a LHD.
“No one should be doing the same task for 12 hours. We know that doing the same task repeatedly is not the best way of engaging people and getting the best performance out of them in terms of interest in their job, their ability to contribute. So from a motivational and job satisfaction point of view, it is the sort of thing that we absolutely as a mining industry can automate.’’
But Loader hints at reluctance by the industry to fully embrace automation. “We have actually made it happen. Others are dabbling around in it and see the potential. But our story really says you have to jump in with both feet, and it is going to take time. Once you get there, the results are incredible,’’ Loader says.
Apart from the safety dividend, the automated load-haul dumpers have delivered an efficiency dividend.
“Over a 24 hour period we get 20-25 per cent more out of an automated LHD than we do out of a manual LHD,’’ Loader says.
“That is pretty much down to the fact that an automated LHD can run 24/7. It doesn’t need to have lunch breaks, or change over drivers.
“It operates at the efficiency that a first-class manual operator can achieve but with the benefits of lower maintenance costs because it is operated the same way, every single time, by the automated system.’’
She says the uptake of the technology was not about employing fewer people. “What it has done is shift the task that our operators are engaged in. Previously they might have been in a LHD for the bulk of their shift, but now they are doing a wider variety of tasks, and we need people to support that automated system.’’
Northparkes is an 80:20 per cent joint venture between China Molybdenum (CMOC) and Sumitomo group companies, with CMOC the manager after buying its interest from Rio Tinto in 2013 for $US820 million.
Loader says the automation journey for Northparkes started about 10 years ago when the operation began to work with Sweden’s high-technology engineering group Sandvik, which developed the “AutoMine’’ loading and haulage automated system for underground mines.
“And we know from talking to Sandvik that we are the only people doing this across an entire operational level in an underground mine anywhere in the world,’’ Loader.
While the fixed layout of a block cave mine lends itself to automation, Loader says it was not necessarily a critical success factor for automation.
“We started playing automation in the second block cave mine (E26). And when we saw the opportunity, we actually built automation into the design for E48.’’
Annual production at Northparkes is running at 50,000 tonnes of copper and 46,000 ounces of gold, with the gold revenue helping to deliver one of the lowest cash costs in the business (US68c a pound in the last quarter).
Approvals are in place for the mine to continue to 2032 but it has reserves good until 2034, and resources that exceed that again. “We have started talking about a long-term goal of being here for 100 years,’’ Loader says.
“You might say that is a pipedream, but I don’t think it is. We have a mineral field here at Northparkes. And we have explored and evaluated only a handful of the deposits that sit within that mineral field.’
“Just line up the ones we know about and I can see us mining beyond 2050. We don’t know what technology we will be using, or what the next level of automation will be. But we have got time,’’ Loader says.