Keeping your distance

Underground mining technology in New Zealand will take a great leap forward in mid-2007 when six Sandvik tele-remote-controlled loader-hauler-dumpers start production mining in the country’s two newest underground gold projects.   BY HUGH DE LACY

Three loader-hauler-dumpers (LHDs) are expected to be operated in OceanaGold’s Frasers mine at Macraes, east Otago, and three more at Newmont Waihi’s Favona mine in the Eastern Bay of Plenty township. It will be the first time that remote-controlled LHDs are used in New Zealand and, while it’s not state-of-the-art technology, it sets the country on the road to eventual mine automation.

The machines are Sandvik Toro 1400s, a standard underground mining machine with a 14 tonne tramming capacity and the ability to be either manually or remotely controlled. They will be operated by HWE Mining at Favona and Byrnecut Mining at Frasers.

HWE presently has three jumbos making the 2100 metre drive into Favona, and by late March they had progressed 1690 metres and were 241 metres below the surface. Including crosscuts they had completed 5700 metres of the 11,000 metres planned. At Frasers, Byrnecut had three development drives totalling 1630 metres reaching the ore body by the end of last year, with initial stoping getting under way in March.

When the mines come into production the LHDs will be remotely operated from moveable underground offices not far from the faces, though out of line of sight. Byrnecut’s operators will work in an air-conditioned container on the same level as their LHDs, while down Favona HWE’s operators will work from the back of a Toyota Landcruiser.

Though both companies are using Sandvik LHDs costing up to $1.4 million each, the remote-control technology, costing around $200,000 for each machine, is being supplied by two Australian companies that are pretty much the Ford and Holden of the industry – Remote Control Technologies (RCT) in the case of Byrnecut, and Nautilus in the case of HWE.

Remote-controlled mining, as distinct from fully automated mining, has been on the global scene for about 20 years, but has been slow reaching here because of the relative smallness of

New Zealand operations.

A sign of how far it has advanced in the Australasian context is that the joint Australia-New Zealand standard, which first came out in 1994, has been recently revised. Although there were three New Zealanders on the committee that handled the revision – Andrew Murley of NZ Hazardous Areas Electrical Co-ordinating, Paul Nieuwoudt of Solid Energy and Richard Davenport of Crown Minerals – the work was mostly done in Australia under the chairmanship of Peter Meyers of Standards Australia.

The revision was driven by recent accidents in Australian mines where underground workers have been injured or killed by remotely controlled LHDs and dumpers.

Fully-automated surface-controlled mining remains the preserve of big overseas mines, though Mount Isa in Queensland is looking at fully-automated LHDs to load their crushers.

Caterpillar and Sandvik are the only two manufacturers of fully-automated mining machines, from jumbos at the face to LHDs, crushers and trucks to the surface. Sandvik and Atlas Copco dominate the automatic drilling market globally, and Sandvik is also developing a new line of low-profile automated equipment for a new type of operation called mechanised breast mining, whose aim is to maximise the ore grade by minimising dilution.

An example of this sort of machine is Sandvik’s reef dozer, a low profile bulldozer – it’s only 880mm high by 1.7 metres wide and 3.1 metres long – that is completely remote-controlled, making it able to work in tight narrow seams where conventional LHDs can’t. It operates in conjunction with low and extra-low profile drills, loaders and bolters as part of an integrated system. The reef dozer pushes blasted ore a short distance from the breast to low-profile LHDs waiting in a gully.

The prototype reef dozer was trialled in November 2005 in Lonmin Platinum’s Karee 1B mine in South Africa, with the first production model shipped out of Sandvik’s manufacturing plant at Burlington, Toronto, last June.

Sandvik NZ engineer Grant Morling told Q&M that such fully-automated operations as Lonmin Platinum’s are still relative rare.

“You’ve got to be big and have a whole lot of money to get into that,” Morling says. “We’re only just seeing the rolling out of fully-automated machinery world-wide. As well as LHDs and trucks, generally of a 50-60 tonne capacity, there are now fully-automated jumbos, as well as solos which are an underground version of a surface drill.”

The solo has a smaller mast than a surface drill and uses more but smaller rods, typically 20 1.8 metre rods giving it a similar capacity to the half a dozen 3.6 metre rods on surface machines. The solos are parked at the face and then left to work on their own, changing their own bits when drilling pressure and parameters tell them they’re blocked.

Jumbos too can now be fully programmed to drill their own field after being parked at the face.

Sandvik was the first manufacturer to introduce automation systems for underground hard-rock mining, after beginning

developments in the mid-1990s. Its state-of-the-art AutoMine product is a modular system equally adaptable to small-scale and massive block-caving operations, with the machinery driven by an operator sitting in the comfort and safety of an air-conditioned room on the surface.

Apart from operator safety, the advantages of fully-automated mining include greater fleet utilisation and production, and reduced maintenance from optimised tramming speeds and smoother equipment operation.

What may come as surprise is that fully-automated mining doesn’t necessarily imply any great of loss of underground mining jobs. Or, to put it another way, the reduction in labour costs is minimal – depending, of course, on the degree of sophistication that the fully-automated operation replaces.

“With loaders especially they still need the operator, and they still need to take the machine underground,” Morling says. “The operator drives the machine to the face and sets up infra-red beam barriers round its working space to shut it down if anyone gets too close. Then the operator returns to the surface and runs the machine from an office, so you’ve still got the same guy doing the job, but in a much healthier environment.”

The cost of the associated infrastructure and of running the cables all the way to the surface is presently prohibitive of fully-automated operations in New Zealand’s small mines, Morling says. However, the tele-remote systems going into Frasers and Favona are only one technological step behind the most advanced systems in the giant mines overseas.