As the new editor of the Mining Quarterly, in early May I took my first mine tour, traveling to Newmont Goldcorp’s Phoenix mine about 12 miles southwest of Battle Mountain.
“Usually folks save the best for last, but in this case, you get to experience the best first,” said Phoenix General Manager Mark Evatz.
People at other mines might argue that their mine is the best, but like all the mines around the state that each have several unique features, Phoenix does have several aspects that stand out. It has a big mill which is the largest semi-autogenous grinding (SAG) mill in the United States and the second largest in North America (there is one larger SAG mill in Canada). And along with producing gold and silver, Phoenix also produces copper cathode sheets that are ready to send straight to market.
Copper is an important player in the Phoenix production portfolio. Along with the copper sheets, the mine also produces a copper concentrate. The copper production totals about 40 million pounds a year. Phoenix is the only mine with major copper production in the new Nevada Gold Mines joint venture.
The copper production supplements the mine’s gold production of about 180,000 ounces per year.
The mine produces several metal product streams. About half the gold that goes through the mill is captured in a precipitate and that goes to the Twin Creeks mine to be made into dorè bars. The other half of the gold is captured in the copper concentrate that goes to third party smelters at various locations around the world. And there are the copper cathode sheets produced at the solvent extraction/electrowinning (SX/EW) plant.
The tour of Phoenix in early May took place a little while before the mine makes a transition from being a Newmont mine to being part of the Nevada Gold Mines joint venture between Newmont and Barrick. Evatz will be leaving Phoenix to continue working for Newmont, and Detlev Van Der Veen, who has been the mine manager at Phoenix, will become the new general manager for Phoenix/Lone Tree.
Mining in the area of the Phoenix mine dates back to 1864, when copper and silver were discovered in Copper Canyon. Copper Canyon Mining Company acquired property in the area in 1916. On the walls of a conference room in the Phoenix office building there are pictures of a floating dredge that looks like a big houseboat. The dredge was used in the area in the 1940s and ‘50s.
Duvall Corporation acquired the mining properties and began mining copper at today’s Phoenix mine site in 1964. Duvall’s Battle Mountain open pit mines were Nevada’s third largest copper producer until depressed copper prices in the 1970s led to a gradual conversion to gold production. Duval spun off Battle Mountain Gold, which operated the gold mill through 1993.
Newmont merged with Battle Mountain Gold in 2001, and Newmont’s Phoenix operation was commissioned in 2006.
With the long history of mining at Battle Mountain and Phoenix, there are some miners who have a long history with the mine.
“We’ve had two or three guys who started with Duvall and the group that had it before, and they worked around the region and then came back and finished their careers exactly where they started,” said Phoenix Process Maintenance Superintendent Bob Tucker. “We had one guy who had 33 years in the industry. He started his career on this mountain and finished it on this mountain.”
“We’ve got guys working here right now whose fathers worked here, who began careers here years and years ago,” said Phoenix Process Operations Superintendent Galen Hope.
There have been many years of mining at the Phoenix site, but there is still a lot of life left in the mine. In September 2018 the Bureau of Land Management approved a proposed expansion of the Phoenix mine which provides for the potential to extend the life of the mine from 2040 to 2063. The proposed expansion, with enhanced operational efficiencies, would increase the surface disturbance at the mine by 3,497 acres, from 8,374 to 11,871 acres.
A mid-size mine
Phoenix today has about 450 employees, and there are about another 30 at the Lone Tree mine to the north.
“Everything you see today fundamentally comes down to the fact that we have a great team,” Evatz said. “Everyone knows their roles and responsibilities on the team, they show up extremely dedicated, and that’s what drives success here at Phoenix.”
“The beauty of our site here is the teamwork,” Phoenix Process Manager Megan Tibbals agreed. “It’s a pretty close-knit group here working efficiently as a team. No job is too big or small for any of us to pitch in and help out.”
Evatz said there are three core values at Phoenix. Safety is the foundation, and after that, the two top priorities are environmental compliance and being good stewards in the community.
About half the workforce lives in Battle Mountain, Evatz said, and the other half lives in Winnemucca, which is about another 50 miles down the interstate.
Newmont started operations at Phoenix in 2006, and the following year plans began for a new copper processing project at the mine. The construction of a copper SX/EW facility was approved in April 2012. Construction was completed in Oct. 2013, and the first copper cathode sheet was produced on Oct. 14, 2013. Commercial production began on Oct. 31, 2013.
The process is designed to produce around two million pounds of copper each month.
Now, ore that would have been dumped out as waste is used to create a steady supply of copper cathode sheets that are shipped to market.
“The ore that we’re processing out here, before we built the SX/EW facility and the copper leach pad, this would have all been considered waste,” Hope said. “Because its grade is so low, or the composition isn’t correct for the mill, it would have just been wasted. But now we have the ability to make a revenue stream out of what was once considered a waste stream.”
Waste ore that had been stockpiled years ago has also been hauled to the leach pads to make copper.
The leach pads for the copper are currently about eight miles from the pit that the ore comes from, so it’s about a 45 minute round trip for the haul trucks. Up to around 50,000 tons a day is hauled to the copper leach pads.
A phase 2 copper leach pad next to the original pad was commissioned in Oct. 2018. They are not quite through the second lift on the phase 2 leach pad.
The leach pad is irrigated with a dilute sulfuric acid solution. The leached copper goes to a nearby pond, and the pregnant leach solution and is then piped to the solvent extraction plant. There, the pregnant leach solution is first mixed with “organic,” and an extractant absorbs the copper and settles in the extraction settlers. The copper-loaded organic then proceeds to the adjacent stripping settler, where the copper is stripped from the “organic,” creating a rich electrolyte. Looking down into that tank you see a blue solution and turquoise-colored residue on the equipment and around the edges.
The electrolyte is piped to the nearby tank house where more magic happens. The electrolyte is fed into electrowinning cells which each have 61 anodes and 60 cathode stainless steel blanks. Electricity causes the copper to plate onto the blanks, and when the new copper sheets are about a quarter of an inch thick, a large overhead crane pulls the cathodes out of the solution. The copper sheets are then stripped off as they go though some automated stripping equipment, and they are bundled for shipment.
The copper is also given a grade before it goes out. The copper sheets produced at Phoenix are grade A, although a few sheets get assigned a lower grade.
Each copper sheet weighs about 95 to 105 pounds. Around 40,000 pounds of copper is shipped out in each truckload.
“It’s a fun little operation over here,” said Joel Sherbondy, a process control specialist who works in a control room that looks out over the electrowinning process. “It’s a little different from my days back in the mill. It’s clean. It comes in a nice, pretty blue and it turns into copper. It’s forgiving — if you have an upset it cleans up real quick. In my mill days you could spend a lot of time cleaning up … this is a lot different. It’s pretty sweet.”
“The best part of the job is you see the end result,” Sherbondy said. “When I made gold, I didn’t see any gold. Here, you see your end result every day. It’s kind of rewarding.”
The big mill
The big SAG mill at Phoenix is larger than any other in the United States, and it is an impressive sight.
The mill processes 30,000 to 40,000 tons each day, depending on the rock type.
“This is a low-grade deposit, so volume is what makes up the difference,” Evatz said. “High tonnage and quality recovery of the low grade ore is what allows us to keep profitable.”
The SAG mill is 18,500 horsepower.
“The motor on our SAG mill is the fascinating part for me,” Hope said.
“The mill is its own motor,” Tucker explained. “The mill is what would be considered the rotor in a motor. It’s a gearless drive. So you don’t have a motor and a gear.
“Traditionally what you’ll see is a geared drive, a big ring gear and pinions. A mill of this size would take two motors and pinions, one on each side,” Tucker said.
He said there have been debates about the mill over the years, but that overall the mill has worked out well, and it offers some flexibility you don’t get with more traditional mills. It can run in either direction, and most importantly, it is easy to change the speed.
“I think for this facility it was a good choice because you can run slow or fast,” Tucker said. “You want to slow it down based on hardness of ore. If the ore is fairly soft, you want to be able to slow the mill down, but if the ore is fairly hard, you have to run it at a higher speed.”
“And we’re mining out of two different ore bodies that are completely different from each other,” Hope said. “So having that flexibility for speed is really critical for these ore bodies.”
Some of the rock in the Fortitude section of the mine is extremely hard.
“In other mines you can drill a hole in 10 minutes,” Phoenix Drill and Blast Analyst Arturo Trevizo said during the mine tour. “It can take us an hour to drill one hole.”
The hard rock is mixed with softer rock to create blends that the mill can process.
The mine tour made a stop in the shop, which has four haul truck bays, and Nash Johnson explained the new locking station system that had been instituted just a couple weeks earlier. It’s a safety measure designed to keep unauthorized people out of the work areas.
“It is a change for the guys, it’s a big change,” Johnson said. “They seem to be taking it pretty well. I have to remind them, we don’t just change for the sake of change. There’s always something behind it.”
“We’re really on the cutting edge of using technology to leverage up and expand our operations in terms of profitability,” Evatz said, “and also to make the work more safe and efficient from the workers’ standpoint.”
Evatz said that labor is about 45 percent of the costs at the mine, and technology helps the miners “be more efficient and effective in how they go about doing their jobs.”
“So we’re really excited about the technology that we’re utilizing, and also the technology that we think is coming up that will be put to work for us.”
Two of the recent advances in technology that the mine is making use of are autonomous drilling and drones. This mine tour included a drone demonstration.
The Phoenix mine has been using drones for a few years. Recently they have made increasing use of drones for various applications.
Drones are used for surveying and engineering the mine site. They check out the high walls and slopes. They are also used to keep everyone updated on day-to-day operations.
“With drill perspectives, shovel headings, loaders, or on the dumps, we can see those areas changing and we can enhance our operations,” Phoenix Mine Operations Foreman Trent Ingle said.
“We can give an image to our shovel operator, and they have a good visual aid, especially after coming back from their days off,” Ingle said. “They see right away what they can anticipate.”
“That’s a big help that we’ve seen with the drone application.”
The drone images also give guidance to the haul truck operators.
“We assess and evaluate our haul roads and intersections, and see where there are areas for improvement,” Ingle explained.
“It’s quite a bit of a visual aid,” Ingle said. “And we also utilize it for month-end surveys. That’s a big one, that’s helped us out. From a safety perspective, instead of walking the perimeters of stockpiles, we can eliminate having individuals on the ground. We use the drones to get the images and the accurate volumes.”
Nick Ingwers, a Phoenix senior engineer tech who operates drones, said that when they are out on the mine site with drones they have a Wi-Fi connection so they can use a laptop or tablet to send images to the engineers right away.
“It’s really helped us out quite a bit,” Ingwers said. “It gives us some pretty immediate feedback on the stuff out there, and it gives them, if it’s good, the immediate results they’re looking for.”