September 28, 2022

Marigold seeks to extend mine life | Mining

ADELLA HARDING Mining Correspondent

With all the mining plans and exploration plans for SSR Mining Inc.’s Marigold mine, which has been in production in Nevada since 1989, mine general manager Don Dwyer said he sees “no reason to which we wouldn’t be here another 30 years.”

Marigold’s facilities are five kilometers south of Interstate 80 in Valmy, and current mining operations are nearby, but Marigold’s properties include Trenton Canyon and Buffalo Valley, where exploration is underway or planned. for potential future use.

SSR Mining plans to spend $24 million on exploration at Marigold this year.

“We secured the rigs earlier in the year,” Dwyer said.

Plans also include starting engineering studies at Trenton Canyon to “basically help us understand how big the pits would be,” as well as where the heap leach pads or a new waste rock dump would go and to from there to figure out how operations at Trenton Canyon would add to the life of the mine and start the permitting process, he said.

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Newmont Corp. operated Trenton Canyon years ago, and there is an old building on the site that houses the North Peak carbon columns and an office trailer, but Dwyer doubted they would be used in new operations. Newmont’s clearance could facilitate new licensing efforts for Trenton Canyon, he also said.

“We’re likely to build a new heap leach facility at Trenton Canyon and carbon columns and bring the carbon back to Marigold, which is about a 25-minute drive,” Dwyer said.

Buffalo Valley is still 20 minutes south of Trenton Canyon, so it would be an even longer return to Marigold. Buffalo Valley has a small open pit from a former production.

Stewart Beckman, executive vice president and chief operating officer of SSR Mining, said on the company’s first quarter earnings call that “we are getting new drilling at Buffalo Valley that we are excited about and also at Trenton Canyon. which is a bit different from what we had previously thought….

Exploration drilling at Trenton Canyon includes examining deep sulphide ores, “but the majority of what we drill is oxide ore that we can currently leach in heaps,” Dwyer said.

The Marigold mine life is now 2032, but this does not cover the potential of Trenton Canyon and Buffalo Valley, as well as the possibilities at the current mine site, where current mining is in the Mackay complex.

Dwyer said mining is ongoing in the complex at Mackay 4, 5 North 2 and H1 in the northern part of the pit, and all ore is trucked to a heap leach pad. without going through a crusher or going to a mill.

“Basically we blow it up, and it goes to the heap leach pad on its own,” he said, and the ore from the pads later goes to the carbon columns, and the gold from there goes through an electrowinning circuit, the retort system and then to the foundry to be cast into gold bars.

At the leach pads, Marigold has completed construction of Cell 19B and is “currently stockpiling ore on this cell, and this year we will begin construction of Cell 23A,” Dwyer said.

Meanwhile, the US Bureau of Land Management’s Winnemucca office is in the midst of an environmental assessment for the Valmy expansion, which covers a series of older pits that Marigold is seeking to expand. These include the Mud, Valley and New Millennium pits. New Millennium itself was an extension of the old Antler and Basalt pits.

“We will start in the Mud Pit in 2025, and the others will come later in the life of the mine,” Dwyer said, noting that there is ongoing exploration to expand New Millennium and add to the life of the mine. of Marigold.

According to Denver-based SSR Mining’s earnings report, Marigold produced 33,788 ounces of gold in the first quarter, compared to 67,936 ounces in the first quarter of 2021 due to mine scheduling and increased production. heap leach inventory that delayed some gold production. in the second quarter.

Heap leach inventory has increased due to when ore is placed on the leach pads and slower leach rates of finer ore from the northern pits, the report said.

SSR Mining also said Marigold remains on track for a production forecast of 215,000 to 245,000 ounces of gold in 2022, with most production coming in the second half. Beckman said the fourth quarter will be the best when higher grades are processed.

Dwyer said “we will be extracting higher grades from the H1 pit.”

All-in sustaining costs for Marigold averaged $1,564 per ounce in the first quarter, compared to $1,195 in the 2021 quarter, but the company said costs will improve in the second half.

Marigold has 450 employees, and “the goal is to get to just over 460,” Dwyer said, adding that two-thirds of employees come from Winnemucca and the rest from Battle Mountain, and many are long-term employees. .

Ralph Erquiga celebrated his 40th birthday at Marigold this year. He was a process manager, but he became a capital project manager.

“You don’t often find that people stick with a company for that long,” Dwyer said.

“Overall, at Marigold, we really try to embrace people and culture, and our turnover rate is lower than our peers because we’re focused on people,” he said.

Marigold’s fleet includes 25 Hitachi and Komatsu 320-ton haul trucks, a P&H electric shovel that handles about two-thirds of the mining, and four hydraulic shovels. Dwyer said Marigold is slowly replacing Hitachi excavators with new Komatsu excavators.

Reclamation over the years has included backfilling the pits, and Marigold is currently backfilling the Mackay 3 pit and the 5 North 1 pit.

Marigold is also going dry for the first time in all its years of operation, with four active wells and three more wells to come. The current dewatering rate is less than 2,000 gallons per minute and Marigold will build rapid infiltration ponds this year, Dwyer said.

Currently, water is discharged into Cottonwood Creek under a temporary discharge permit.

Dwyer said the dewatering “allows us to access ores deeper in the Mackay pits in the Red Dot area on the west side.”

The BLM issued a decision record in October 2019 allowing dewatering up to 10,718 gallons per minute.

Marigold has also continued to work on improving safety at the mine since a double fatality in 2017 which was the first for the mine, and Dwyer said there has been a decline in injuries. In fact, the Nevada Mining Association awarded Marigold eight individual safety awards last year, the most of any mining company in the association, he said.

The Mackay complex is named after the Mackay School of Mines at the University of Nevada, Reno, and UNR is one of the major royalty holders in this area of ​​the Marigold mine. The university receives a royalty from mining at Mackay.

SSR Mining, which was called Silver Standard Resources before shortening its name to SSR Mining, bought 100% of Marigold in 2014, and the company merged with Alacer Gold Corp. in 2020. The Company’s other operations include the Seabee underground mine in Canada, the Copler mine in Turkey and the Puna silver mine in Argentina.

According to the technical report on Marigold prepared by OreWin and published in February, Marigold’s first recorded gold production dates back to 1938 from an underground mine, and approximately 9,000 tons of ore were processed before the shutdown. production by World War II.

Several unsuccessful attempts were made to reopen and operate the mine before exploration activities resumed in 1968, the report said. From 1968 to 1985, several companies explored the Marigold area, and in 1986 a joint venture was formed between a subsidiary of Santa Fe Pacific Railroad and the Cordex Group. They consolidated some land holdings.

A production decision was made in March 1988 on the 8S deposit, and in August 1989 the first gold bar was poured at the Marigold mill, the report said.

Rayrock Mines, Cordex’s operating company, bought two-thirds ownership of Marigold in 1992, and Homestake Mining Co. held the remaining stake until Barrick Gold Corp. absorbs Homestake, then owns one-third.