CARLIN — An autonomous drill rises and tilts in a lighted heading of Newmont Mining Corp.’s Northwest Exodus underground mine as the operator leaves the machine alone to work.
No one is in the cab. No one is actively monitoring its movements. Behind it, a rope blocks off the area with caution signs hanging from it to warn onlookers of “Autonomous Stope Drilling in Progress.”
“See, it’s drilling now, and he’s walking past us,” says general foreman John “JJ” Stefanic.
Driller Daniel Dorohov, known as “Double D,” previously preprogrammed the Epiroc Simba drill to insert a series of holes into the end of a tunnel, or drift. The holes will later be filled with explosives to loosen more gold-bearing ore.
“He came in. He set everything up. He programmed into the drill the holes, the angles and the depth it needed to go,” says Sam Marich, mine manager. “Then he set it up, made sure it started to run, hit a button and walked away.”
In January, Newmont drilled 1,102 feet using the Simba at Northwest Exodus.
“We’d like to say we go full automation, but there’s the human touch,” Marich says, explaining that autonomous equipment still needs people to operate.
Built for automation
Exodus, a portal mine, is one of four underground operations in Newmont’s Carlin integrated operations, where the senior gold mining company has been in production since 1965.
The company recently completed an expansion of Exodus — reaching the Northwest Exodus area by tunneling 2.5 miles and adding 5 miles of drift among levels — ahead of schedule and on budget for $69 million in July 2018. The expansion added 10 years of mine life and maintained the approximately 124 jobs at the site.
“That’s what’s great about the Northwest Exodus expansion,” says Will Newman, chief engineer for Carlin’s portal mines. “It allowed us to continue to mine an existing operation, and put a good number of years of added life on the project.”
In 2018, Newmont mined 430,000 tons from Northwest Exodus, and the mine contained 128,000 ounces of gold. The deposit’s overall average grade has been 0.26 ounces of gold per ton.
Northwest Exodus was developed with autonomous machines in mind. Newmont purchased the Simba and two autonomous Cat R1700G model, 9-yard loaders for the project, and trialed the systems before going 100 percent semiautonomous in late 2018.
“We were able to design Northwest Exodus the way we wanted,” Newman says, including “being able to set the mine up to use those machines.”
Because the Northwest Exodus ore body trends vertically down to about 1,800 feet below the surface, the operation lends itself to using a backfill transfer system and ore passes for moving material. An ore pass is a chute that allows ore to be dropped from the levels to a loading point, where a haul truck picks up loads and drives them about 3 miles to the surface. Ore from Northwest Exodus is then processed at the Mill 6 roaster about 20 miles away.
“[Ore passes and the backfill transfer system] help keep the trucks off the levels, which allows us to run our autonomous loaders on levels because we have to create exclusion zones,” Newman says. “That allows those loaders to work and be isolated so we can continue hauling ore and working in other areas.”
With the Simba, an operator can do two functions at once.
“I can let it drill while I do some other job,” Dorohov says, adding that he likes the chance “to experiment with it and run with it. … The Simba is one of the best instruments I have run here.”
Switching to autonomous drills like the Simba also helps keep personnel out of potentially hazardous situations. Whereas a manual drill requires the operator to do everything from aligning the drill to changing out steels, the autonomous drill allows the operator to work in a covered cab to teach the machine its movements.
“The more we can do to remove people from the condition, the better off we are,” Marich says.
The machine has human and engineered controls to help ensure safety. In addition to safety protocols that personnel must follow, the Simba has sensors that cause operations to stop if a person gets too close to the drill.
“They have quite a bit of advantage because you can run them and not have to worry about any industrial hygiene issues [such as exposure to diesel particulates] for the employees, and there is the potential of running them through shift change, which results in more productivity,” Marich says. “It’s two-prong: safety first and then production.”
The autonomous drill also adds a couple extra hours of drilling per day, as it continues working during shift changes. Previously, drilling would stop between shifts because operators had to be hands-on.
In addition to fine-tuning autonomous systems and installing a second ore pass, the team at Northwest Exodus plans on enhancing operational efficiencies — such as through materials management, stope performance, and better checks and balances — to increase production going forward.
The goal is to ramp up production from 1,180 tons per day to 1,350 tons per day by the second half of 2019 at Northwest Exodus.
Just as the company concurrently mined laybacks in the Lantern Pit while exploring underground through the early 2010s, considering an extension of the Northwest Exodus deposit could extend mine life beyond the 2027 target.
“Our objective with it is to maintain relatively steady production so as mining at Northwest Exodus begins to slow down, we’ll develop into [the next project],” Newman says.