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CORTEZ HILLS PROMISES BIG BOOST TO BARRICK PRODUCTION
Domestic Mine Article by Harold Hough Dec/Jan 2010
.jpg) After buying out Rio Tinto’s share of the Cortez Mine last year, Barrick is poised to make the Cortez Mine a major part of the company’s gold production for the next few years. If all goes well, 2010 will see Cortez producing one million ounces of the 7.7 to 8.1 million ounces of gold produced by Barrick, the world’s largest gold producer.
Cortez has been a successful gold mining district for nearly 150 years. It began in 1862, when a horse kicked up a piece of quartz laced with gold. The owner of the horse was W. H. Talbott and he sent the specimen to Virginia City for assay. Finding that there was silver as well as gold in it, he staked out his claim and the rush was on. Within a year, the City of Austin had a population of 10,000. But within 20 years, the gold and silver had started to peter out and miners left for new, more promising fields. The Great Depression ended mining – or so people thought.
Ironically, the future of gold mining for the district had already been found. In 1922, a new gold deposit was located by Lee Lakin eight miles northwest of Cortez Gold Mines in the Bullion Mining district. During the next few decades, gold mining continued sporadically. The Gold Acres operation included open pit and underground mines in the 1930s and 1940s. Cortez Gold opened in 1968 and production ended in 1976.
The area also had its part in the heap leaching revolution. The United States Bureau of Mines built a heap leaching pilot plant nearby in 1969. This pilot proved the heap leaching technology that would revolutionize Nevada gold mining.
The current operation is a result of the discovery of the Pipeline orebody by Placer Dome and Kennecott. The Pipeline deposit was responsible for an annual output between 1998 and 2005 of over one million ounces of gold per year. The Cortez Hills deposit was discovered in 2002 and was a result of Placer Dome’s exploration philosophy of carrying out extensive exploration in the area of current operations. In 2006, Barrick Gold acquired 60% in Cortez when it purchased Placer Dome. It acquired the remaining 40% from Rio Tinto in March 2008.
CORTEZ HILLS KEY TO BARRICK FUTURE
While the Pipeline deposits are open pit mined, the Cortez Hills operation will be a combination of underground and open pit mining. Low grade ore from the open pit at the Cortez Hills deposit will be heap leached at dedicated heap leach pads at the Cortez Hills site, while ore from the underground mine will be mixed with higher grade open pit material and sent 10 miles to the Pipeline mill via the largest overland conveyor in Nevada.
The operation, which cost about half a billion dollars, is nearly complete and is on track to begin production in the first quarter of 2010. It’s expected to produce over one million ounces per year, for the next five years, at a cash cost of $350 - $400 per ounce.
Although radical environmentalists opposed the Cortez Hills operation, Barrick was able to prevail because they were able to show that they had been a strong advocate of environmental restoration in Nevada. Nevada is home to a large game fish called the Lahontan Trout. Unfortunately, commercial fishing 100 years ago, dams, and water diversion had reduced the Lahontan’s range to three percent of its former habitat.
Barrick helped to reverse that trend. Not only did the company donate thousands of dollars to preserve the trout, it also provided engineering skills for making Mary’s River an interconnected habitat for the fish. The mine replaced culverts that restricted trout migration, engineered a bridge to replace a culvert, and provided money for its construction. Meantime, volunteer groups of miners restored the river’s banks. While some of the efforts like placing rocks to create pools created rapid results, much of the miners’ work was aimed at improving the fish’s chances for the long term. These volunteers planted willows, which shade and cool the water. They also installed fences to keep the cattle out and stabilize the bank. The result is that Lahontan Trout populations are growing in the Mary’s River for the first time in decades.
Barrick has also teamed up with the Nature Conservancy to restore fish and bird habitat along a five mile stretch of the Truckee River in Nevada. Through the support of Barrick the Conservancy has been able to buy 20 river miles and 20,000 acres of flood plains, wetlands, and forest.
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