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:: From Waste to Revenue: Newmont to Begin Processing Copper Plates at Phoenix
Newmont Mining Corp. will soon cut out the middle man in copper production. In August, Newmont employees and contractors were putting the finishing touches on the Phoenix Copper Leach Project. The copper processing plant construction is expected to be completed this month and should be producing copper sheets by October, said Scott Collins, Newmont project controls manager at the Phoenix Mine. “When fully ramped up, there will be a staff of about 50 to run the whole plant," Collins said.
Once the plant is completed, the mine will transport the finished product directly to manufacturers from the site. Collins said the plant will process about 2 million pounds of copper a month. The plant may produce 20 million to 25 million pounds of copper a year. It will produce about 200 million to 300 million pounds over the life of mine, which is estimated at about 30 years. The project is 12 miles southwest of Battle Mountain on private and public lands in Lander County. This plant is allowing the Phoenix Mine to turn what was originally classified as waste into revenue for Newmont, said Newmont Senior External Communications Representative Matt Murray.
Construction on the plant began in 2012, but the leach pad was built in 2011. The leach pad is 8 million square feet, said Joe Namlick, NewFields construction manager at Newmont’s Phoenix Mine. “There’s additional plans to expand the leach pad," he said. As each portion of the project is finished, the system is checked before it’s handed over, Namlick said. “We’ve taken a hybrid approach to the process, Joe has been here at the site for quite a while," Collins said. “Newmont employees work closely with the contractors." Despite the plant not being finished, leach was already underway in August, Collins said.
The copper leach project is a closed-loop process, which means the sulfuric acid solution used to extract the copper from the rock is used over and over again, Collins said. The plant has acid tanks, which are connected to the system to add more sulfuric acid solution when needed, he said. The tanks at the plant will hold 93 percent sulfuric acid in a solution. The sulfuric acid solution is gravity-fed through pipes to the leach pad. It is about 21/2 miles from the plant to the leach pad.
The facility and the trench holding the pipes are lined to protect the surrounding area from leaks. If a pipe leaks, the acid solution would still reach the leach pad because of the way the channel is constructed — downhill and lined. Once the sulfuric acid reaches the leach pad, it dissolves the copper in the dirt. This dissolved copper and sulfuric acid solution, then moves by piping into the pregnant leach solution or PLS pond. The pond is double lined and has bird balls covering the surface, so animals can’t land in the solution.
From the pond, the leach solution, which contains copper values, is sent back to the processing plant by 600-horse power pumps. Once the leach solution reaches the plant, it begins the process to become copper sheets. “We separate the copper from the acid by introducing an organic solution," Collins said. “Then we introduce the electrolyte solution in the tank farms. The electrolyte solution cleans the solution of the crud, then it’s sent on to the electrowinning process and copper plates are produced."
The electrowinning process makes the copper go from a liquid back to a solid. The electrolyte solution, containing the copper values, is sent into electrowinning cells.
Each of these 30 cells contains 60 cathode plates and 61 anode plates, Collins said. The cathode plates are made of stainless steel and the anode plates are made of lead. “The copper won’t stick to (the anode)," Collins said. “The anode is there to push the copper on to the cathode." Each sheet of copper produced will be about 120 pounds and will be 3 feet by 3 feet. The copper sheets will be transported directly from the mine to manufacturers.
While this is the first plant of its kind in Nevada, there are several facilities like Phoenix’s in Arizona, however those are much bigger, Collins said.
Safety and environmentally friendly
Every part of the project was constructed to make sure the acid and other solutions stay within the process. “Everything is set up for containment," Namlick said.
Every area is lined. The acid tanks are inset to help contain any leaks. The electrowinning cells have covers, so the fumes remain inside the system and workers do not have to wear ventilators while in the plant. “The blue pipes in the building are for the scrubber system," Namlick said. “It keeps the air cleaner and it gets filtered out." The buildings also have a fire suppression system that sprays 1,600 to 1,800 gallons of water per minute.
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