Operation

As the second-largest copper producer in the United States, Rio Tinto Kennecott provides nearly a quarter of the country’s copper needs. Throughout its history, the Bingham Canyon Mine has produced more copper than any other mine — more than 19 million tons.

In addition to producing about 300,000 tons of copper a year, the Bingham Canyon Mine also produces approximately 400,000 ounces of gold; 4 million ounces of silver; 30 million pounds of molybdenum; and 1 million tons of sulfuric acid annually.

The Bingham Canyon Mine is the largest man-made excavation on Earth. It measures two and three-quarter miles across at the top and three-quarters of a mile deep. If you stacked two Willis Towers (formerly the Sears Tower) on top of each other, they still would not reach the top of the mine. You could lay the soccer field at Rio Tinto Stadium in Sandy, Utah, end-to-end more than 38 times across the top of the Bingham Canyon Mine before it would reach both sides.


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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Mining Info !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Mining

Copper production begins at the Bingham Canyon Mine, which is nearly two and three-quarter miles across and three-quarters of a mile deep. We carry out a sequence of drilling, blasting, loading, hauling, crushing and conveying 24 hours a day, seven days a week, 52 weeks a year.

Drilling and blasting

We detonate 1,200 pounds of explosives in holes 55 feet deep to break up the rock and explode the ore out of the ground.

Loading and hauling

Our electric shovels and haulage trucks move into the blasted areas. After the shovels load the ore and waste, the fleet of 70 haulage trucks transports the material to the in-pit crusher or waste rock repositories.

Crushing and conveying

At the gyratory crusher, we reduce approximately 150,000 tons of ore per day to pieces about 10 inches in diameter. We then transport the crushed ore by a five-mile conveyer system: three miles through a tunnel in the mountain and two miles above ground to the Copperton Concentrator. The conveyor moves at a speed of 900 feet per minute. Ore arrives from the mine at the Copperton Concentrator in about 28 minutes, where we temporarily store it in a 500,000-ton coarse ore stockpile.


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Concentrating

In the second step of the production process, we concentrate the ore, which separates valuable minerals from the ore into a concentrated liquid.

We turn the crushed ore into a slurry and transport it to flotation cells. We mix it with reagents to produce a bubbly froth. Ore particles containing most of the valuable minerals adhere to the bubbles, which float over the sides of the flotation cells. We then collect and filter this material, called concentrate.

The concentrate, which contains about 26 percent copper and by-products such as gold and silver, moves through a pipeline to Kennecott’s smelter, located about 17 miles to the north, for further processing.


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Smelting

The next stage, smelting, is a process of heating and melting the copper concentrates to cause a chemical reaction, which removes the copper from other elements in the ore. At the smelter, we produce large 750-pound anodes and transport them by rail to the Refinery. The copper is 99 percent pure at this stage.

The smelter at Kennecott captures 99.9 percent of the sulfur in the feed, making it one of the cleanest in the world. The smelter also recovers heat from the furnaces, which generates 60 percent of the facility’s total electricity.


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Refining

Refining is the final step in the copper production cycle and is the stage in which we separate precious metals from copper and recover them. Refining takes place at Kennecott's Refinery.

At the refining stage, the copper is in anode form. We subject 750-pound copper anode plates to an electric current for ten days and turn them into two 300-pound copper cathodes. This further separates the copper from other metals – the result is copper that is 99.99 percent pure.

At the refinery, all the other impurities — including silver and gold particles — drop off into the solution and settle to the bottom. The residue from that solution goes to the precious metals plant, where we put it through a series of chemical processes to separate out the gold and silver.

The last step in the production process is to stamp each bar with Kennecott's brand, the lot number, the weight and the fineness of the metal — that is, the percentage of gold or silver in the bar.

Kennecott produces about 400,000 troy ounces of gold per year, with a purity of 99.99 percent.

We also produce about 4 million troy ounces of silver every year, with a purity of 99.9 percent.