Paramount Gold Nevada has announced the results of a preliminary economic assessment (PEA) of its 100% owned Sleeper gold project in northwest Nevada. The project includes the historic Sleeper open-pit mine, which operated from 1986 to 1996 and produced 1.66 million oz of gold and 2.3 million oz of silver.
Metal Mining Consultants (MMC) conducted the Sleeper PEA. The study’s base-case scenario assumes open-pit mining and a 30,000-mt/d heap-leach facility having throughput capacity of about 11 million mt/y. Production would average 102,000 oz/y of gold and 105,000 oz/y of silver for seven years, with an additional 37,850 oz of gold and 30,500 oz of silver recovered during final leaching.
The gold grade would average 0.47 g/mt over the first three years and 0.41 g/mt over the life of the mine. Initial capital is estimated at $175 million, with a payback period of 2.7 years. Projected life-of-mine all-in capital, operating, and sustaining costs are estimated at $869/gold equivalent oz.
The PEA assumed $1,250/oz gold and $16/oz silver prices.
Processing facilities would be based on standard cyanide heap leaching, with a carbon-in-column and adsorption-desorption recovery plant. The plant would produce a doré product for direct sale to a regional refinery.
Existing infrastructure at the Sleeper mine site would require upgrades; however, the basic components remain in place. The site is currently connected to the regional electrical grid; however, a substantial capacity upgrade would be required. Existing shop and office buildings are located on top of mineable material and would require removal and reconstruction.
In addition to the base-case scenario, MCC also evaluated a combined heap-leach and bio-oxidation scenario to test its economic viability and to guide future metallurgical testing and trade-off analysis during prefeasibility. This opportunity would result in a 14-year operation incorporating a much larger pit supplying 50,000 mt/d to a standard heap-leach processing operation for 11 years. A 10,000-mt/d bio-oxidation plant would commence operation in year nine followed by standard heap leaching of this mineralized material. Life-of-mine production would total 1.7 million oz of gold and 3.2 million oz of silver. Total capital and sustaining costs would increase to $373 million.
