On the last weekend in April, Kennecott Utah Copper reported it had resumed mining ore from its Bingham Canyon mine in Utah, less than a month after a massive landslide. Some 129,000 tons of ore were delivered to a crusher over a two-day period, a company spokesman said. The normal processing rate is 150,000 tons a day.
Slightly two weeks after a landslide sent 165 million tons of earth down into the world’s largest open-pit copper mine and covered portions of the floor up to 300 ft deep, mine officials have been able to take a closer look at the damage. The slide caused no injuries. Earlier in April, the Mine Safety and Health Administration cleared geologists and engineers from Kennecott Utah Copper, a subsidiary of London-based Rio Tinto, to enter the massive slide area that was created on April 10 in the Bingham Canyon mine, located west of Salt Lake City.
Kennecott spokesman Kyle Bennett says earlier reviews of the mine floor showed that the in-pit crusher and five-mile conveyor, which moves crushed rock to the facility’s concentrator, were undamaged.
“We have had damage to three of our 13 shovels and 14 of our 100 hauling trucks,” Bennett says. “We don’t know yet whether any of them will be recoverable. We also have damage to a few of our graders and dozers that were in the pit. Some of the equipment has been buried by the slide, and some has been damaged and moved out of the area.”
Cementation, a global mine-building contractor whose U.S. operations are based in nearby Sandy, Utah, was at work on two exploratory tunnels in the mine. Those tunnels have been covered by the slide, says Willie Finch, a Cementation spokesman. “The portals we had were at the bottom of the mine on the south wall, and they are now buried,” Finch says. “We had two bolters and two drillers there. We know where they are—we just can’t get to them. Our assumption is that equipment will be lost, but we are hopeful it will not be. I’m not sure of its value at this time.”
Finch says Kennecott has suspended Cementation’s contract, and the company laid off its 70 people working at the site.
Mining operations continue on the unaffected upper-southeast side of the pit, Bennett says. The company also has been using trucks to haul stockpiled material to the concentrator while regular operations are scaled back.
In an April 25 press conference, Kennecott President Kelly Sanders announced a plan for returning the mine to productivity. The program schedule was scaled back from Rio Tinto’s initial estimates. “In the next 30 days, we will complete an assessment of the pit to ensure safe work conditions, and once those are satisfied, we’ll begin moving ore to the crusher again,” Sanders said. “As we resume operations, we expect … our production to be about 50% of what our plan for 2013 was.”
Bennett said the slide destroyed an access road into the pit, and officials will develop plans for reconstructing it as soon as possible.
The slide occurred on the mine’s northeast slope and was anticipated by Kennecott engineers. Days before it occurred, crews moved equipment away from the rim, along with the modular visitors-center building.
Sanders says, in the coming months, the company will be looking at ways to contain costs, which may include layoffs. Since the slide, the company has shifted workers to other parts of the operation and asked some to take voluntary furloughs.
The Bingham Canyon mine has operated for more than 100 years and is the second-largest copper mine in the U.S. In addition to producing 300,000 tons of copper a year, the mine annually produces 400,000 ounces of gold, four million ounces of silver, 30 million lb of molybdenum and one million tons of sulfuric acid.