Engineering & Mining Journal

FEB 2019

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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GREAT BASIN DEVELOPMENT FEBRUARY 2019 • E&MJ 45 www.e-mj.com the project and, 800 holes later, we had 1.2 million ft of drilling data." The underground mine will access a 23.9-million-ton mineral reserve with a 1.74% copper equivalent grade. For the first five years, Nevada Copper expects the mine to produce on average 60 million lb of copper, 9,000 oz of gold, and 173,000 oz of silver. A future open-pit mine will access a mineral resource of 4.2 billion lb of cop- per with significant precious metals credits. The company is currently conducting a pre- feasibility study (PFS) on it, which should be available in the first quarter of 2019. It includes an additional mill that can handle 35,000 t/d. The main shaft for the underground mine has been sunk to the 2770 lev- el. The 2850 shaft station is complete and lateral development is proceeding on schedule. Crews are now sinking the East-North ventilation shaft. The pre-sink has been completed to 125 ft, the Gal- loway has been erected and lowered into the shaft. The hoist buildings have been completed and the headframe is being in- stalled. The ventilation shaft will be sunk conventionally from the surface until it meets a fault at about 1,300 ft and then the miners will approach it from the bot- tom with an Alimak. "We have an EPC contract with Sedg- man to build and operate the mill and Cementation will operate the under- ground mine for the first two years and then we will transition," French said. "We are leasing the equipment from Cat/ Cashman and Epiroc. With an EPC, we do not expect any creep in costs. We have also hired Mining Plus to assist with overseeing the Cementation contractors. Many of the Cementation miners worked on this project four years ago and they are familiar with the geology and rock conditions." Nevada Copper also worked with Q&DE Construction out of Reno on the earth- works for the mill and the dry-stack tail- ings excavation, both of which have been completed. "Why did we do dry stack?" French asked. "Three reasons: water availability, permitting and land space. Nevada is now requiring more long-term monitoring of saturated tailings. Dry stack tailings use one-third to one-quarter of the land space of a traditional tailings storage facility, and one-third of the water. Yes, it's more expensive, but the deltas come together over time." The concrete work on the mill started in January. When the Pumpkin Hollow mill comes online, it will have about 150,000 tons of ore (high and low grade) stockpiled. It will be a typical crush-grind-float op- eration with ball and SAG mills, flotation and thickening. A transload facility will al- low Nevada Copper to ship concentrate to Europe and Asia from a West Coast Port. Premier's Nevada Growth Program Recent Nevada development projects are not just limited to the Walker Lane. In northeast Nevada, Premier Gold Mines Ltd., a Canadian company with producing mines in Mexico and a few projects in On- tario, has been experiencing considerable growth. Reviewing a timeline that used the average gold price as a backdrop, Tim George, manager of engineering services, Premier Gold Mines, described how activ- ity in Nevada has grown for them despite the swings in gold prices. "Our involvement in Nevada started in June 2012 when we acquired the Cove property lease from Victoria Resources," George said. "A little more than 2.2-2.3 million oz of gold were mined from the Cove pit. Production ended in 2001 and we have started an exploration program there. In August 2014, Premier acquired the other half of the property, the Cove Pit, from Newmont and put the entire land package back together." In April 2015, Premier purchased Goldcorp's 40% interest in the South Ar- turo mine, making the company a joint venture partner (JV) with Barrick Gold. In August 2016, South Arturo poured its first gold pour. "That's currently our only producing mine in Nevada," George said. In October 2016, the company signed an earn-in agreement with Kinross for the Goldbanks property. They produced a re- source on Cove in March 2017. By the third quarter of 2017, Phase 2 mining was completed at South Arturo. In Janu- ary 2018, they entered into a JV with Bar- rick Gold on the Rye property, and in Feb- ruary 2018, they released a revised set of reserves and resources for South Arturo. In May, Premier completed a Preliminary Economic Assessment (PEA) on the Cove property. By the third quarter, they initi- ated development on the Phase 1 pit and El Nino underground operations at South Arturo. Most recently (November 2018), they acquired the Rodeo Creek property. "Despite the gold prices throughout this period, Premier's growth in Nevada has really accelerated," George said. Turning his attention toward South Arturo, he described development on the Phase 1 pit as a pushback on the old Dee pit. "The pits are being mined out of order," George said. "Phase 2 was com- pleted first and we have now moved to the Phase 1 pit. We will mine the Phase 3 pit last." "When we picked [South Arturo] up in 2015, the proven and probable reserves were 161,000 oz of gold and no pro- duction had taken place," George said. "Since the beginning of this year, we have produced 146,000 oz and the prov- The polymetallic deposits on both sides of Yerington contain more than 33 billion lb of copper.

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