First Out of The Box

OPERATOR DAYTON GRAY trams mining’s largest battery-electric loader into a charge bay in the Lift 1 haulage loop at New Gold’s New Afton block cave. There are no overhead cranes or forklifts in the converted re-muck, where the loader’s self-swapping system disconnects and lowers a depleted battery, trams to pick up a fully charged battery and automatically connects it. Gray doesn’t leave the cabin throughout the process, controlling the swap by following prompts on a touchscreen. Less than six minutes later he trams out of the charge bay and speeds up an incline.

New Afton mine manager Peter Prochotsky sees this process as the potential future of “refueling” for underground mobile equipment.

“It’s a huge step change for our industry to move from diesel to electric, and I’m happy to take part in it,” he says.

The loader, the first Sandvik LH518B 18-tonne battery-electric vehicle (BEV), is the first major piece of BEV infrastructure at New Afton. The gold mine, which blasted its first drawbell in 2011 and entered production in 2012, has a history of pioneering innovative new technologies that help ensure the safety and health of its employees while also improving productivity. New Afton was an early adopter of automation and is proud to be a first-mover in battery-electric mining.

In 2016, New Afton completed a feasibility study to determine the viability of its C-Zone ore body. The C-Zone, which contains approximately 29 million tonnes, is expected to begin production in the second half of 2023 and extend New Afton’s mine life to 2030. New Afton considered electrification from the beginning due to the new ore body’s depth 1,150 metres below surface, and mine superintendent Jeff LaMarsh said New Afton recognized a number of potential benefits of battery-electrification during the study.

What stood out most for Prochotsky the first time he saw the loader operating underground was the lack of heat.

“Sandvik LH518B produces approximately 10 percent of the heat of a comparable diesel loader,” says Prochotsky. “It’s astounding how much less heat it produces, so it’s been great for our underground workplace and environment. Battery-electric equipment has been seen to create a large occupational health and hygiene benefit for our employees. Ventilation to dilute heat, diesel particulate and dust in enclosed underground spaces is at a premium, and BEVs help us reduce these workplace contaminants.”

THE BATTERY-ELECTRIC LOADER is also much quieter than its diesel equivalent.

“You can have a one-on-one conversation next to the operating piece of equipment, which you could never do with a diesel,” says LaMarsh.

The biggest surprise for LaMarsh, though, was the loader’s sheer power.

“Sandvik LH518B has significantly more mucking power,” he says. “In a traditional diesel, you have to rev the engine to get all your hydraulic power, whereas in the BEV it’s the maximum amount of hydraulic power, right from the get-go. The instant torque is beneficial, both for mucking and for starting on a ramp. From a productivity and efficiency standpoint, it’s miles ahead of the competition in terms of the diesel equivalent, in our experience.”

Starting, stopping and tramming short distances have had the biggest impact on the battery-electric loader’s reduced cycle time, but Prochotsky says the biggest productivity driver is horsepower density.

“We have roughly four times the amount of wheel motor power in Sandvik LH518B than its diesel equivalent, so the up-ramp time is proportionately faster,” he says. “Tramming up ramp, on grade, we typically estimate our diesel LHDs to move at about seven to eight kilometres per hour, whereas we’re seeing speeds of 12 to 14 kilometres per hour with the battery LHD.”

New Afton’s data on Sandvik LH518B shows that replacing one diesel loader with a comparable BEV is expected to reduce the mine’s total greenhouse gas emissions by as much as 2 percent in a year, assuming full production.

“That’s a really large number which, among other things, depends on how much we use the equipment and how much diesel we’re offsetting, but for an underground mine even replacing one piece of diesel equipment with battery-electric can have a major impact on your total GHG reduction.”

The energy consumption of Sandvik LH518B has been significantly less than New Afton’s diesel equivalent loader. “The overall energy cost compared to diesel is about 10.9 percent while operating,” says Prochotsky.

Sandvik LH518B is equipped with Auto- Swap, a patented self-swapping system for the Artisan battery pack. The loader is also the first Sandvik BEV featuring AutoConnect technology, enabling an operator to swap batteries even quicker without exiting the cabin.

“The AutoSwap, AutoConnect technology has been smooth and seamless,” says Prochotsky. “It’s been a nice benefit for the operators, both in safety and efficiency, not having to exit the cab to unplug the battery.”

NEW AFTON EVALUATED different charging methodologies. LaMarsh said the ability to swap batteries quickly is an advantage of Sandvik BEVs, as the loader doesn’t need to be parked for an extended period.

“Sandvik LH518B was an attractive option for us because it has the battery swap technology as opposed to the quick-charging, and that really bodes well in a block caving operation,” says LaMarsh. “Battery swapping helps ensure a lot more utilization of the equipment, whereas with a fast charge, you do need to have downtime to facilitate that charging. For us here in a block caving application, a battery swap is the leading technology in our minds. When you’re relying on quick charge technology, every minute affects the equipment’s utilization.”

BATTERY SWAPPING ALSO enables New Afton to spread charging load over longer periods of time, helping to mitigate the aggressive power draw quick-charge solutions can place on a mine’s grid.

“Battery swapping technology is a great option for us because we only need to charge the batteries to just under the discharge rate,” says LaMarsh.

As New Afton expands down towards C-Zone, the mine is constrained by its original Lift 1 power supply of approximately 5 megawatts.

“We’re going to carry that same cable diameter down deeper, so when we talk about electrifying C-Zone, we do need to ensure that the power demand stays within our cable capacity,” says Prochotsky. “We see the best way to do that is to spread the load over a longer time period. We’re still using the same amount of energy by electrifying our production fleet, but we don’t have a peak power demand that exceeds the amount of power our cables can supply. Ultimately for C-Zone, we want to spread our power demand over the largest time possible.”

New Afton currently uses Sandvik LH518B in the mine’s Lift 1 haulage loop to load trucks and tram ore to the gyratory crusher. By 2023, the mine anticipates transitioning the loader to the new B3 cave to continue truck loading. B3 is essentially an intermediate zone that will take New Afton from its current Lift 1 mining area down to the future C-Zone.

THE C-ZONE BLOCK cave is about 550 metres below Lift 1 and 1,150 metres below surface. Mining at the future production area’s depth presents ventilation and operating cost challenges that Prochotsky expects BEVs and electrification can help mitigate.

“Mining economically at such depth can be complex, and we see battery electrification as one of the potential solutions to the challenge,” says Prochotsky. “The virgin rock temperature increases the heat of the level while in production, so that and ventilation constraints both favour battery-electric equipment.”

New Afton will take delivery of two Sandvik Z50 battery-electric trucks during 2022, enabling the mine to benefit from its existing battery infrastructure and growing battery knowledge. Although the mine purchased the 50-tonne trucks as a production solution for its B3 mining area, New Afton mine managers anticipate using them to help accelerate C-Zone decline development until B3 production ramps up in the fourth quarter of 2022.

“It’s always a challenge to get enough ventilation down to the face until we’ve established our permanent ventilation infrastructure,” says Prochotsky. “By utilizing battery trucks, we expect we’ll reduce the heat generated upstream of the development face and eliminate diesel particulate.”

SANDVIK FACTORY PERSONNEL have supported New Afton with projected discharge rates and duty cycle modelling for Sandvik LH518B that Prochotsky said have been accurate.

“Sandvik is helping us understand the best staging for pieces of equipment, the best loop spacing, location of passing bays and charging stations, those sorts of design criteria that we can then implement prior to actually getting down to C-Zone,” says Prochotsky. “We’ve always had a very good relationship with Sandvik. For a long time we’ve been using Sandvik drills and bolters underground, and to continue our relationship and move into automation and now battery-electric vehicles has been a natural progression.”

“I personally believe electrification is the way of the future.” LaMarsh says. “Being part of a group that gets to pioneer BEV technology in underground mining is really exciting.

“Every mine likely has a capital purchase or a maintenance replacement coming up in the next few years, and I think they would be missing out if they decided not to investigate or pursue battery-electric technology,” he says.