Features

Intelligent technology assists tailings dam construction

 

A civil works contractor has taken advantage of intelligent machine control systems in an OEM’s earthmoving equipment to construct tailings storage facilities in a WA extractive operation.

When long-time friends Joe Riccardo, Mike Heddon and Mark Tyler set up RHT Contracting in mid-2018, they knew they needed a winning edge when bidding for contracts – so they went for the most innovative and technically advanced construction equipment available.

That saw them choose Komatsu’s intelligent Machine Control (iMC) dozer and excavator technology when bidding for a large contract to construct tailings storage facilities (TSFs) for a major mining operation in Western Australia.

Currently RHT runs four Komatsu iMC machines: two D65PXi-18 swamp dozers, a D155AXi-8 dozer, and a PC360LCi-11, as well as Komatsu wheel loaders, dump trucks, graders, and other excavators on the one site.

Not only does the iMC technology give RHT significant safety, productivity, efficiency and accuracy advantages in TSF construction, it also provides the company’s mining clients with the security and peace of mind that their critical facilities have been built to the highest and most exacting standards.

Today, that’s essential for any extractive operation, following catastrophic failures of tailings dams in South America in the past five years, which have killed many people and caused widespread environmental devastation.

To ensure their integrity and long-term performance, it is essential that TSFs are constructed to an established process, which involves placing the dam material in 300mm thick layers, that are then compacted, and the top 100mm scarified to ensure a strong lock with the subsequent 300mm layer.

Using Komatsu iMC machines in this application, each 300mm layer can be placed quickly and efficiently, within tight tolerances, ready for compaction.

And unlike conventional “bolt-on” machine control systems, the iMC system prevents dozer blades or excavator buckets from “over-digging” into the already compacted and scarified layers, ensuring they are not compromised during placing of the next layer.

When RHT was formed, Riccardo, Heddon and Mark Tyler (the company’s name comes from their surname initials) saw the opportunity to use Komatsu’s iMC technology to give them a real competitive advantage.

“These days, you’ve really got to innovate,” Heddon said. “Clients want to see that you are innovative and you’re not a dinosaur.

“I’ve been going to shows like CONEXPO and BAUMA for years, and I see all the latest stuff, and I was wondering how good it actually was. Then we spent some time with Dean Jones and Colin Brindle (from Komatsu Perth), to find out what their iMC technology could do.

“We were convinced enough to buy a D65PXi-18 swampy and a PC360LCi-11 excavator, plus a Topcon base station, which were delivered in February 2019, and took them to the site.

“We also put on Fraser Mead, a young surveyor, who’s passionate about technology, plus he’s really into drones and how they can really help with the whole mine infrastructure construction process.”

When it comes to efficiency, the D155AXi-8 is still a ‘work in progress’ for RHT.

SUPER-FAST DELIVERY

As of June 2020, Mead and RHT trialled Komatsu’s EDD (EveryDay Drone) technology, a high precision UAV (drone) survey system providing super-fast on-site processing with Komatsu SMARTCONSTRUCTION’s Edge technology.

“Initially the operators weren’t convinced about the iMC machines,” Heddon said. ”They said ‘Stuff this, I’m an operator, I don’t need that’, but then after a few days of seeing what the technology could do, they were going ‘Wow!’

“On the first dam we built, we never put a grader on it, did the whole batter with just our first D65EXi dozer and the PC360LCi excavator. I have never, ever done that before, so they are exceptionally good. The dams look great, the batters look great, we’re never having to do rework, we get it right – from the start to the end. It’s always spot on.”

Following the success of the first D65PXi-18, RHT bought a second D65PXi-18 in September 2019, and the D155AXi-8 in February 2020.

“At the moment, we’ve got all these machines working on-site, building up to three dams at one time,” Heddon said. “With the dozers, we are using them for winning material from borrow pits, while the excavator is pulling up batters.”

Building tailings dams for larger mines requires large amounts of earthworks – with dam walls up to four to six kilometres around, along with haul roads, so there is a lot of earth to be moved.

RHT’s two smaller iMC machines, with their swamp tracks, are proving ideal for the precision final trim work to millimetre level accuracy, while the larger D155AXi-8 is being used for the bulk earthworks on the dams and haul roads.

“On the newer dams we are building, we are using clay oxide materials, which are heavier to work with, which is why we brought in the D155AXi,” Heddon said. “Plus we can also use it for building haul roads. We can just map in a haul road route and design, and the machine can go out and build it, even in rock and clay.”

One thing RHT has found is that the D155AXi-8 hasn’t so far been giving quite the final trim accuracy of the D65PXi-18s.

“Certainly it’s extremely accurate compared with any conventional dozer next to it, but because we’ve seen how precise the D65s are to a few millimetres, we were expecting that with the D155. However, because it’s bigger, it corrects slightly differently,” Heddon says.

“It’s still good, still within ‘coo-ee’ of what we need, but we know at the moment it’s giving a slightly rougher surface, so you’ve got to take things a bit slower, use a lower gear to get there.

“On the bulk side, Komatsu’s intelligent Machine Control works really well, absolutely on this bigger dozer. You can just set it, and it does exactly what we need. It’s on the fine control, where I think we can get it going even better.

“Because this is all so new, it’s something we are working with Komatsu to perfect.”

On the first dam it built, RHT found that a D65PX8-18 was even more effective on the batter than a regular grader.

ON THE LEVEL

Heddon added the iMC ensures that rework and over-excavation never occurs, thereby eliminating overruns and field survey work.

“With Komatsu’s intelligent Machine Control acting as a rover, we know we are always building to the exact specs. We are never over-building, and everything is always exactly level and ready for rolling.

“We don’t require anyone to go out there with a dumpy level, checking levels and all that stuff,” he said.

The other advantage of the iMC is having all the works designs already in the machines, ready for the operators as soon as they need them.

“That’s a big saving because the operators have everything at hand in the machines to do the work,” Heddon explained. “In the old days, we’d have two teams out there pegging the site, one for the day shift, and another for the night shift.

“Now we just put in a couple of reference pegs, then once the operator has the levels, it’s all good to go.”

And as each part of the job is completed, it can be immediately checked and audited – and the records remain readily available at any time in the future for RHT Planning’s clients or geotechnical engineers.

“This technology means that the as-built track mapping is all there from the start,” Heddon said. “When you’re building a tailings dam, it’s essential that layers go down in 300mm lifts, before the next one goes on top.

“We can see all this on the computer and know that it was done precisely. So, in future if there is ever a question with a dam, we can go back in there and show that it was done exactly right. There’s no need for anyone to go in and micromanage. It’s a great system.”

Another benefit of the iMC machines, Heddon said, is “essentially they act as a mobile rover, because everything is done within the machine. So the surveyor can be away on another mine site, and if the operator finishes a job, the surveyor can jump in remotely, and work together with the operator to set things up for the next job. So people are not sitting around waiting for someone to get back after lunch to start up again”.

Heddon added the iMC also helps to increase site safety. “Safety is paramount for us. And not having people working on the ground around dump trucks, excavators, wheel loaders, dozers and other machines, is a major safety component. It’s just unreal,” he said.

Heddon also observed some interesting reactions from operators using the iMC systems, and RHT’s clients.

“When these machines first came to site, people said it was just more shit to go wrong. But then after a few days, they all agreed the benefits are countless. And our clients have been really impressed with the quality, efficiency and technology the iMC machines offer.

“With this technology, we have the trucks deliver to the site, the dozers push it out – and it’s so level that the trucks can keep working, whereas before we’d have to call in a grader to give the trucks access.

“Everyone is stoked with it, the whole concept,” Heddon said. “We’ve since bought a second base station, and we’re putting that in our second site.”

INTO THE FUTURE

Heddon sees tremendous potential for Komatsu’s iMC technology in future projects. “This is really moving into the future, that’s the only direction we want to go now. And particularly after those catastrophic dam failures in Brazil, the more you can prove the quality of your work and show that to the geotechs and the clients, the more successful we can be.

“They really need the confidence that these dams are getting built correctly at all times, not just some of the time.

“It’s giving the mining companies that security and peace of mind that their dams are built right, so they know they have their dams constructed to world’s best practice.

“We’re very committed to this technology,” Heddon concluded. “We want to see it on all our earthmoving machines, and we are very keen to see it on the larger excavators, at least up to PC490 size.”

Source: Komatsu Australia