The Bingham Canyon porphyry copper-gold-molybdenum deposit is one of the largest and highest-grade porphyry orebodies in the world.

Porphyry dikes, faults, and quartz veins are steeply dipping and have two dominant orientations; north-northeast– and northwest-striking. Dikes have a north-northeast strike but they thicken and develop northwest-trending apophyses and host high-grade copper-gold zones at intersections with northwest-faults, indicating that magmatic-hydrothermal fluids were focused by these structural intersections.

Vein truncation relationships coupled with abrupt changes in copper-gold grades, sulfide ratios, and potassic alteration intensity at porphyry intrusive contacts indicate that the mass of introduced copper and gold decreased significantly during successive porphyry intrusive-hydrothermal cycles, presumably due to depletion of metals and volatiles in the underlying magma chamber.

There are 11 giant electric shovels and one hydraulic shovel operating in the mine.
• The largest electric shovel has a 56-cubic-yard dipper that scoops up approximately 98 tons of material in a single bite, a weight equivalent to about 50 automobiles.
• The newest electric shovel costs more than $20 million and weighs 3.2 million pounds.
• There are about 70 gigantic haulage trucks operating in the mine. These trucks carry from 255 to 320 tons of material in a single trip.
• The mine has eight large drills that stand between 75 and 100 feet tall and drill blast holes 55 feet deep. On average, 200 holes are drilled in a typical day and packed with 1,200 pounds of special blasting agents.
• The in-pit crusher reduces ore to less than 10 inches in diameter or about the size of a basketball. Very fine dust particles are captured in an air pollution control device called a bag house — similar to a very large vacuum cleaner.

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.

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.

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.

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.