Superior’s Copper Mine Idle, But Still Ready


SUPERIOR, Arizona – There is no copper mining at the Resolution Copper east plant, several miles beyond the town of Superior. But in Shafts 9 and 10, work continues to maintain the extensive underground network of pipes, corridors and control systems necessary to keep the mine in working order for its eventual use.

Shaft No.9 is a holdover from the original operation of the Magma mine, which closed in 1982 – the remaining eight original shafts are now abandoned and have been separated by thick concrete barriers of the new operation. Resolution drilled the 10th well itself and the two lift towers are on top of a hill overlooking Oak Flat. At the time of its completion in 2014, the No. 10 well was the deepest in the United States.

The latter descends to over 7,000 feet, well below sea level and to a layer where the Earth is so hot that water seeps into the hole at nearly 175 degrees Fahrenheit. Keeping the mine in working order requires an extensive network of pumps, fans, trains and electrical equipment that must be constantly maintained.

From a miners’ point of view, perhaps the most important are the air pumps and coolers, which not only provide breathable air, but keep the mine shaft to a minimum so that the heat and the humidity are kept at bay. When PinalCentral was shown around the lower level of the mine, it was about 80 degrees.

At this depth, water seeps through the walls and ceiling, accumulating in puddles at the bottom of the well. Despite the cooling system, the water is still warm to the touch. A series of pumps “drain” the mine at a rate of nearly 500 gallons per minute. Otherwise, the mine would quickly fill with water, and this excess is pumped to the West Resolution plant, closer to Superior, where it is processed for use in agriculture.

“The deeper you go, the deeper you sink into the water table,” said Bo Deen, construction superintendent at the West Resolution plant.

Deen said when Resolution took over, he had to remove water from the flooded remains of the Magma mine. Additionally, when Resolution began to sink the 10th well, it encountered more water than expected, resulting in a two-year delay as it sought to further increase the capacity of the pump. Another work stoppage occurred when they had to install air conditioning units underground due to the extreme heat.

Deep down, the mine is surprisingly bright through the warm haze, as the hallways are well lit and all the miners wear a beacon on their helmets. Despite a bit of corrosion and rust along the pipes and ironwork, which the mining team must deal with as part of regular maintenance, there isn’t much in the tunnels that draws the pay attention to the extreme depth. Even thousands of feet below sea level, there is still Wi-Fi.

In addition to the lower level, PinalCentral was guided through the “never sweated” level, “only” 1,100 feet below the surface. This level, much colder than the bottom, is where the train lines run with excess sludge that builds up for miles through the mountains until the tunnel opens onto the rolling hills. from the West Resolution plant, closer to Superior.

The train can also transport workers between the two sites. Deen calls the ride “pretty knotty” and the ceiling is low. Several workers say they will occasionally jog the road for fun.

“When most people think of underground mines, their reference is 100 years ago,” said Andrew Lye, Director of the Resolution Copper project. “Today’s underground mines contain modern technology and people are really surprised when they go underground to see something more like a factory. Even with modern technology and PLCs, we still need people to operate and maintain operations, and people to build. Developing these skills to operate and maintain modern mines is something I am proud of. “

800 meters from the twin wells is a copper deposit that has become a focal point of fierce feuds over the past decade. Going forward, Resolution Copper hopes to drill the ore and extract the copper using a boulder excavation process that will permanently damage the site directly above Oak Flat, which happens to be a popular campground and, more importantly, a site of religious significance to the local Apache tribe of San Carlos.

Currently, Resolution is conducting exploratory drilling to more accurately locate the location of the ore, which is deep underground but above the mine’s lowest level.

“In mining, if they don’t have the technology, or if it costs too much to operate, they won’t,” Deen said. “They calculated the profit to the nearest penny. “

Superior was the site of the world’s first mine shaft cooling towers, built in the 1930s. But technological advances in miner safety and ventilation, as well as environmental remediation, have kept pace. the ability to scale up projects so that their local impacts remain controversial.

According to the company’s website, sensors monitor workers and equipment at all times, comprehensive data systems provide up-to-the-minute analysis, and battery-powered vehicles in the mine reduce the need for cables or electrical connections. The data, along with the connectivity between mine shafts, means that in an emergency, miners have more time to escape danger.

The water consumption forecast once copper drilling begins – even assuming the company’s best-case scenario in terms of licensing, it’s still a decade away – could be huge. But even without mining, a 2019 report estimates that dewatering and refrigeration operations require 2,400 megawatts.

Lye noted that the company was purchasing renewable energy certificates, which offset 100% of their electricity consumption in 2020, and that the partnership with the utility of the Salt River project allowed them to provide 25% of their current consumption of energy. electricity directly from solar energy.


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