Earthwork at a Eureka County gold mine continues into the winter season as McEwen Mining Inc. builds one of Nevada’s newest greenfield open pit heap leach operations.
“It’s a great experience to be involved all the way along a project, to be able to participate on the permitting side the environmental work that needs to be done to get a project improved,” said Jeff Snyder, Gold Bar general manager.
The company, operating as the subsidiary McEwen Mining Nevada Inc., began construction of the Gold Bar Project on the Battle Mountain-Eureka-Cortez Trend in the fourth quarter after the Bureau of Land Management approved the mine’s proposed action by signing the record of decision Nov. 7.
“We’ve been lucky,” said Simon Quick, McEwen Mining’s vice president of projects. “We didn’t expect to work this far into the season.”
Developing the mine — at a total capital cost of $80 million — involves a process with a timeline dependent on north-central Nevada’s weather. In early December, contractors Highmark Construction, Brahma Group Inc. and N.A. Degerstrom were taking advantage of the cold yet dry conditions to clear the land and prepare the site.
“Our contractors are just part of our team,” said Ron Jensen, McEwen Mining safety manager, who described the company’s attitude toward safety as encompassing everyone who sets foot on the site.
The plan is to build out the leach pad in spring after a thaw, install mechanics and equipment in summer and begin operation in late 2018. Electricity will be generated on-site using natural gas to meet the 2-megawatt demand, and water will come from wells drilled with permission on the private land of a historic ranch.
Once in production, Gold Bar is expected to produce about 65,000 ounces of gold a year — 8,000 tons of ore a day — for a seven-year mine life. Design for the site on mostly BLM and some private lands, calls for four open pits. Two pits already exist from former workings, developed between 1988 and 1994. The resource totals about 500,000 ounces.
As with a typical heap leach operation, Gold Bar will use cyanide to extract the gold. However, the makeup of the host rock presents a challenge that requires an additional step.
“The clay content of the ore requires an agglomerate process to ensure we have good permeability on the leach pad,” said Jeff Gibby, Gold Bar project manager.
After blasting in the pits and scooping up the ore with loaders into haul trucks, the material will be sent to a crusher then delivered on a conveyer to an agglomerate drum. The 10-foot diameter, 60-foot drum adds solution and cement, and a tumbling action creates rock-like particles. Now like concrete balls, the particles go to the leach pad, where the cyanide solution flows over them.
“The agglomeration step is something that historically mines used to do, and it kind of grew out of favor with the advent of larger mining operations moving toward run-of-mine. [At] larger operations, you can make up for losses in lower recovery with volume,” Snyder said. “By putting in the agglomeration step and making sure you bind the clays, you get a much better opportunity for recovery once you put it on the leach pad.”
Industry standards suggest that the process of extracting gold from when cyanide is applied typically takes 90 days to obtain 65-75 percent of the gold. At Gold Bar, the so-called leach kinetics take 60 days to recover 80 percent.
“The great advantage is that the leach kinetics are comparatively rapid,” Snyder said.
The chemistry of the site might thrill scientists and investors, but earthworks owner representative Frank Sanchez had another view.
“The exciting part for me is starting a new project,” he said, reflecting on a full career of mining all over the world.
In early December, Sanchez drove to the top of a more than 8,000-foot mountain on a winding, juniper-lined mine road. Turning to look over the process area about 1,500 feet below and the distant valley, Sanchez shared the landscape he admires at sunrise almost every morning.
“We have the best view in the county,” Sanchez said. “Now tell me that isn’t a great view.”
McEwen Mining operates mines in Mexico and Argentina, and recently acquired the producing Black Fox Project in Timmins, Canada, as a capital investment. Gold Bar is the company’s only site now in development and is the company’s only U.S. operation. McEwen Mining is incorporated in Colorado but headquartered in Canada.
“Gold Bar is starting from nothing both on the buildup side and the staff side,” Quick said, explaining that presents an opportunity to create a beneficial culture among members of a close team.
Once in operation, the mine is expected to create about 120 full-time jobs, including contractors. Quick estimated that McEwen will employs about 150 people during peak of construction through next year. The company contracted M3 Engineering & Technology Corp. out of Arizona and NewFields based in Colorado with an office in Elko for engineering work.
“What we have been trying to do philosophically is try to employ as many locals as possible,” Quick said.
Eureka residents would have an approximately 30-mile drive northwest to reach the mine off of Highway 50.
From the highway, the previous operation can be seen on the Southern Roberts Mountains, but McEwen Mining’s environmental approach includes plans to minimize Gold Bar’s presence and impact, and reclaim the lands including the former mine. The company has about $15 million in an adjudicated bond for reclamation.
“We live here,” Snyder said. “We have as big a stake in preserving the environment as anyone does.”
The mine will use paint on buildings that blends into the landscape and lights that do not interfere with the desert’s dark skies. Additional environmental considerations include proponent-driven mitigation, carpooling and drive-time restrictions to reduce risk to sage-grouse; fencing to keep wildlife out; “bird balls” on ponds keep birds from the water; and using removed and burned pinion junipers in continuous mitigation.
“It’s those little things that matter,” Quick said.
Forming relationships with the locals also matters, and the company strives to maintain a presence in the community by keeping a Eureka office and getting involved with local events, such as the Christmas parade.
Additionally, the county maintains Roberts Creek and Three Bars roads that lead to the mine, and the county assistance preserves local employment.
“We are visitors to their town,” Quick said. “It’s important to take that into consideration in how you operate your business.”
If construction progress continues into the winter and stays on schedule for next year, Gold Bar might celebrate its first gold pour in the first quarter of 2019.