Golden Sunlight Secures Customer For Tailings Reprocessing Project

Editor's Note: The following release was issued Tuesday by Golden Sunlight Mine officials.

Nevada Gold Mine's (NGM) processing operations cover the full gambit of processing routes using heap leach, oxide milling with CIL, pressure oxidation of single refractory ores, and roasting and pressure oxidation of double refractory ores. As such, NGM is a leader in refractory ore processing globally.

In the refractory processes, high temperatures are required to ensure sulfide oxidation for optimal gold extraction. Naturally occurring sulfur contained in gold ores acts as a fuel source to raise temperatures but the sulfur content of NGM's ores is below required levels. This means that we need to supply additional energy to achieve the required conditions.

In our process development we've managed to substitute steam for additional fuel in the autoclaves to achieve optimal temperatures, but only additional sulfide will satisfy the roasters. The Goldstrike roaster operation has successfully managed this through purchasing elemental sulfur to add to the processing circuit but it is subject to the wildly swinging market prices of sulfur. Gold Quarry (Mill 6) makes use of Newmont's Cripple Creek & Victor (CC&V) concentrate. However, CC&V concentrate volumes are insufficient to consistently supply the roaster at Mill 6 or the other NGM facilities in the longer term.

This led the NGM team to seek an alternative long-term solution that would provide a reliable, low cost, bulk source of sulfur that could meet NGM's long term needs. At the same time, Barrick's Golden Sunlight Mine had been looking at reprocessing tailings from historic workings that contain significant quantities of sulfur as part of the environmental rehabilitation of the site.

Barrick's Golden Sunlight Mine in Whitehall, Montana has been in operation since 1982, producing 3.3 million ounces through both open pit and underground operations. Mining ceased in 2019 and the operation has moved into care and maintenance. The tailings at Golden Sunlight represent a significant sulfide resource. Recent testwork has shown that a sulfur concentrate can be produced economically via flotation, leaving a more stable flotation tailing with low sulfur content that would be thickened and used to back-fill the open pit.

This benefits the site through stabilizing the walls of the old open pit, as well as removing a potential pollutant to ground water thereby eliminating the need for perpetual water treatment. It reduces the overall environmental liability associated with the mine while providing local employment and tax revenue. At Barrick, sustainability is at the heart of our business and this is an opportunity to close Golden Sunlight in a sustainable manner.

Barrick's Golden Sunlight Mine has begun the permitting process for a tailings retreatment project that will produce up to 200kt of sulfide concentrate per year, with first production expected in 2022. In what is a win-win situation for Nevada Gold Mines and Golden Sunlight, NGM is entering a concentrate off-take agreement with Barrick's Golden Sunlight Mine. Golden Sunlight receives a long-term stable price for its concentrate, while NGM achieves a high quality, bulk source of sulfur with gold price upside. Combined supply from Newmont's Cripple Creek and Victor Mine and Barrick's Golden Sunlight Mine will provide NGM a stable fuel supply for the next ten years with potential to extend as required.