Kennecott Copper Mine
By their nature, even small mines disturb the environment. But operations as large as Bingham Canyon permanently alter it. At Bingham Canyon, environmental alteration is apparent not only in the enormous pit, but also in a 23-kilometer-squared (9-square-mile) tailings containment area that now holds 1.36 billion metric tons (1.5 billion tons) of mill tailings.
"There's no question that the Bingham Canyon Mine has permanently altered the local environment," says Bill Williams, Kennecott Utah Copper's director of technical services. "Our challenge is to manage that alteration in a responsible manner.
"In just the last decade, we've spent more than $200 million on work directly related to reclamation and minimizing environmental impact," explains Williams. "We've built a low-maintenance, high-efficiency water collection system that captures and recycles all groundwater. It's a gravity-feed system that requires no pumps and utilizes solar-powered monitors."
Kennecott's old copper smelter managed to stay within Utah state emission limits of 1,485 kilograms (3,300 pounds) of sulfur dioxide per hour. But the new smelter, which went on-line in 1995 as the world's cleanest, cuts sulfur dioxide emissions to 200 pounds per hour. "That means we're capturing 99.9 percent of the sulfur dioxide," points out Williams.
Kennecott Utah Copper also relies on power cogeneration, utilizing excess smelter heat to generate 65 percent of the smelter's power requirements, thus minimizing the burning of fossil fuels. Another system recovers valuable metals from flue dust, virtually eliminating that potential form of hazardous waste.
Finally, officials have begun planning for the eventual closing of the mine.
"Our master reclamation plan will be implemented after the mine finally closes, whenever that will be," says Williams. "But it's not a firm plan. It will be modified as applicable new technologies evolve.
"The open pit will remain as it is," continues Williams. "But the much larger tailings impoundment will be reclaimed. Remember, Bingham Canyon was a grazing area before mining began, and when we're finally through with mining, much of it will be a grazing area again."