The Biggest Man-Made Hole in the World
A FRIEND had said to me: “If you go to Salt Lake City, be sure to visit the Kennecott copper mine at Bingham Canyon. You will be surprised at what you see.” My wife and I had that opportunity in August 1992. We discovered that our friend was not exaggerating.
We took a leisurely 26-mile [42 km] drive southwest out of Salt Lake City, in the blazing, dry heat of Utah. As we headed for the nearby Oquirrh mountain range, we soon saw our destination—a huge slash of pale yellow ocher on the horizon, contrasting with the darker color of the surrounding mountains. It was the massive diggings and terraces of the Kennecott copper mine. But even that view did not prepare us for what we were about to see.
We began to wind our way up a steep mountainside. On the way, we passed huge dump trucks, as big as a small house, the largest of which can carry up to 240 tons of rock on each trip. They are so big that their 12-foot[3.7 m]-diameter wheels tower above the tallest person. Eventually we reached the public observation area. And there it was—the biggest man-made hole we had ever seen!
As we looked over the edge to the bottom of the pit, those massive trucks seemed like dinky toys. We were staring into an excavation more than half a mile [0.8 km] deep and with a diameter of two and a half miles [4 km]. The pit bottom is over 5,000 feet [1,500 m] above sea level, and the upper edges of the pit reach 7,800 feet [2,400 m]. It is so deep that the world’s tallest building, the Sears Tower in Chicago, at 1,454 feet [440 m], would reach only half way up the side of the mine. The company aims to go down another 850 feet [260 m], which they calculate will give them work at least until the year 2020.
The mine looked like a giant amphitheater, with 50-foot-high [15 m] terraces, known as benches, stepping down to the depths of the abyss. We were told that this copper mine can be seen from the space shuttle. Yet, all of this had a very simple beginning 130 years ago, when the mountain was still over 8,000 feet [2,400 m] high.
Ridiculed for Mining
Mining first started in 1863, when Colonel Patrick Connor from Fort Douglas staked claims. However, it was small-scale mining and was unprofitable. The Bingham Canyon mine as such was first started in 1906 when Daniel Jackling’s Utah Copper Company and a rival company began hauling ore that contained only 2 percent copper. An official brochure explains that “they were ridiculed by mining men of the era who thought they could never make a profit mining such low-grade ore.” What would they say today, when the percentage of copper to ore is only 0.6 percent? Why, “more copper has been produced by Bingham Canyon than any mine in history. Five billion tons of rock have been moved since the open pit was first started.”
Copper is not the only product—gold, silver, and molybdenum (a metal used to strengthen steel) are also produced, as much as 500,000 ounces [14,000,000 g] of gold and over 4,000,000 ounces [110,000,000 g] of silver as by-products in one year! Little wonder this mine has been called the richest hole on earth.
And if you are wondering why copper is so important, imagine what would happen if all the copper was stripped out of all electrical wiring, out of all generators, transformers, and other current-carrying devices. The list could go on to include refrigerators, airplanes, cars, and so forth. Copper is fundamental to the processes of modern life, even as it was in ancient times. Copper is mentioned 166 times in the Bible.—Genesis 4:22; Exodus 27:1, 2.
Copper Extraction—No Easy Process
What we saw in that huge pit is only the beginning of the process that results in valuable copper. The mine is where the drilling, blasting, loading, and hauling take place. The ore is then taken to an in-pit ore crusher, from which a conveyor system transports the crushed ore to a concentrator and flotation plant five miles [8 km] away. The concentration system increases the copper content of the ore from 0.6 percent to 28 percent by removing unwanted materials.
Next comes the smelting process, which gets rid of impurities, such as iron and sulfur, yielding molten copper that is now 98 percent pure. This is poured into rectangular forms called anodes and then cooled. The last step is the refining process. A brochure explains: “The anodes are subjected to an electrolytic process where the copper is refined to a purity of 99.98%.” It is during this process that gold and silver are recovered as by-products. This transformation turns the copper into large cathodes, 330-pound [150 kg] plates of copper that are then sold to the manufacturers of copper, brass, and bronze products.
All of this sounds rather simple. But in fact, the whole operation is very complicated and occupies a lot of space. After all, it takes a ton of ore to produce just 11 pounds [5 kg] of copper. So the next time you see copper wiring or a copper pan or kettle, remember it may have come from the biggest hole that man has ever made.—Contributed.
[Pictures on page 24, 25]
Above: The pit is over half a mile [0.8 km] deep and two and a half miles [4 km] across
Top right: Smelter featuring one of the world’s tallest chimneys
Inset: A 330-pound copper cathode, marked to indicate how copper is used by percentage
Bottom right: A diesel truck that carries up to 240 tons of ore
Photos (above and page 25 top): courtesy Kennecott Utah Copper
[Picture Credit Line on page 23]
Photo courtesy Kennecott Utah Copper