In underground applications, a minute saved can be a drill-foot earned.
By Joe Bradfield
Major Drilling Group International is a global expert in just about any drilling application, but in Flin Flon, Manitoba, they specialize in underground exploration. All of their underground coring rigs are Atlas Copco Diamec. They run five U8 rigs currently and have eight U6s, including a new Diamec U6 MCR model. Six more U6s are on order.
Shorter Takes Longer
For orebody definition, Major Drilling uses the U6 exclusively. It’s a powerful drill that has earned a reputation as one of the most competent drills in the underground exploration market, capable of drilling beyond 900 m. However, shallower definition drilling as specified by their client may involve holes only 20 to 200 m deep.
Major Drilling Area Manager D.J. Wilson explained that moving the U6 and its ancillary equipment, and then resetting it to make a series of these shallower holes, entails disproportionately long accumulations of downtime.
“If our targets are 400 to 500 m, then we would have our crews continue to use the skid-mounted U6s,” Wilson said.
Consider how shallower holes cost more. Making two 500-m holes provides 1,000 m of coring in two moves. Total downtime on skid-mounted equipment is six to eight hours. By comparison, drilling 10 50-m holes achieves the same drill-feet but requires 10 moves totaling 30 to 40 hours of downtime. It’s 500% more time and labor cost for the same amount of coring.
After trying various solutions, Major Drilling put the Diamec U6 MCR (Mobile Carrier Rig) to the test. They are the first North American company to try the combination of the U6 and Simba 1257 multipurpose carrier after successful trials in Australia.
Underground exploration rigs in general are specialty drill rigs used in confined areas. The drill rig and its ancillary equipment are not integrated in one bulky vehicle but kept separate.
Matthew Bullee, who has been with Major for seven years, detailed the steps of a move: Crews have to call for a tractor or lift to move not only the rig but the steel sloop, stage scaffolding, helper’s equipment and safety stations. The crew must disassemble the drill rig from its power plant and water supply and move each one separately. Setting up at the next pillar could take half a shift. Setting up at another mine level could take more than one shift. Each move exposes disassembled part connections, such as the rig’s hydraulics, to contamination.
In recent years, Major has been exploring ways to make the U6 more mobile. Mounting the U6 to a carrier as is done for almost all surface rigs was an obvious solution, but each attempt brought a mix of advantages and disadvantages.
When Major mounted the U6 to a crawler frame, it cut transportation and setup to just a couple hours. It allowed the driller good flexibility for drilling descending angles. It didn’t have much range above, though. The driller and helper had to build up cribbing to drill upward, and there were certain approaches to the wall it just couldn’t reach. But its mobility meant the drilling crew didn’t have to wait for another piece of equipment to move the drill—it moved itself.
The crawler-U6 combination was a successful concept, at least on level terrain. Wilson said it didn’t provide much advantage when they moved from level to level and was awkward up and down the ramps in general mine traffic. One of Major’s clients challenged the company to investigate wheeled mounts to cut transportation and reset time even further. The first attempt was a six-wheeled carrier.
A wheeled carrier enabled the U6 to travel much quicker up and down the ramps and take less of a beating than a crawler during the move. The drawback of this first wheeled design was its height. The carrier was so tall that the helper had to build and work from staging. Though it could certainly drill down, the drill itself couldn’t be positioned lower than the carrier deck. During each move, this staging was an additional item to disassemble, transport and re-erect.
The Diamec U6 MCR surpasses the benefits of earlier attempts without any of the drawbacks. The rig is leveled and stabilized with four jacks. The water pump and 80 m of trailing cable are mounted right on the carrier. And the carrier’s articulated body and sturdy boom allow the operator completely flexible positioning.
“I’ve drilled plus 90 and minus 90 holes in the same place,” Bullee said.
Quick on its Feet
“It is quick,” Wilson said of the U6 MCR rig. “Move time is down to 40% to 50%.”
Bullee reported similar gains, saying they are making moves in an hour to hour and a half now, while moving skid-mounted U6s requires three to four hours. “You can make a level-to-level move and still get 40 to 60 m yet on a single shift, depending on rock conditions, of course.”
The wheeled carrier they had tried before, said Bullee, had allowed them 20 to 40 m after a level-to-level move.
“It might not seem like much difference, just 10 m or so more a move over another carrier system,” Bullee said. “But if you get even that 10 m a shift or a little more in a year of shifts, that can be as much 1,000 m more drilled.”
Bullee also commented on ramp speed. The wheel-mounted Simba 1257 carrier was actually determined to be too fast, so they keep it in first gear.
Bullee made sure to point out Major Drilling is a safety-conscious company, taking measures beyond federal requirements and even the requirements of their hosts. For instance, part of the time they spend in a move involves transferring and resetting safety equipment—fire extinguisher, eyewash station, descalers, lighting—which Major requires to be highly visible and accessible at every drill site.
“But safety is better in a move now. The most serious injuries happen usually when people are moving things. Less time spent moving, and having less stuff to move, all equals less risk of serious injury.”
Brief Learning Curve
Darian Woods has been drilling with Bullee for years, but this is his first shift on the U6. “Basically, drilling
is no different than any other U6, but what’s new is learning knuckle points and the boom, and driving it,” Woods said.
Easy to learn, spending more time spent drilling and less moving, and all this with increased safety—it’s no stretch to conclude that Canada’s first U6 MCR is a major improvement.
Joe Bradfield is senior writer for Ellenbecker Communications, an international communications firm specializing in the drilling, mining and construction industries.
Atlas Copco DTH Rig Goes On-line
Atlas Copco has upgraded its SmartROC D65 surface drill rig to enable direct communication with its Rig Control System (RCS) through a computer network.
The SmartROC D65, first introduced in 2010, offered enhanced communications capabilities provided by Atlas Copco’s computer-based RCS. The 2010 model allowed drill plans from the office to be loaded into the rig’s control system from a USB memory stick. Now the SmartROC can download data directly from the office computer from the worksite’s own local area network (LAN) or wireless network (WLAN).
“This is an Ethernet application module for SmartROC D65 rigs working in a fixed installation in mines and larger stone quarries,” said Olav Kvist, product line manager for Atlas Copco Surface Drilling Equipment.
According to the company, the new interface not only makes data transfer simpler and faster; it is also more user-friendly since planners are able to make changes and last-minute adjustments.
In addition, Kvist points out, the new communication capability paves the way for mines and quarries to install wireless systems and also offers SmartROC D65 owner-contractors a competitive advantage in that they can “plug” in to their customers’ networks.
The application was developed in 2011 and has been tested in Australia with excellent results, according to Atlas Copco.
The SmartROC D65 is designed for down-the-hole drilling in the 110– to 203-mm hole diameter range. It uses Secoroc COP 44, 54 or 64 DTH hammers to a maximum depth of 175 ft (54 m) in the long-feed version. Drilling air is provided by an onboard Atlas Copco XRX10 compressor that supplies 435 psi (30 bar) pressure; a Caterpillar C15 539-hp (402-kW) engine powers the rig.
SmartROC D65 shares its intelligent platform with all rigs in the SmartROC family and the Pit Viper blasthole drill series. The rig communication standard is based on the International Rock Excavation Data Exchange Standard enabling total management and operation control.