Greener gold leaching tested at 3 Aces

Golden Predator Mining Corp. Nov. 12 announced that tests have confirmed that EnviroLeach Technologies Inc.'s formula effectively extracts and recovers more than 95 percent of the gold from sulfide concentrates produced at the company's 3 Aces project in eastern Yukon.

EnviroLeach Technologies has developed a proprietary non-cyanide, water-based, neutral pH treatment solution for recovering precious metals from ores, concentrates and recycled electronics.

The solution can effectively dissolve gold into aqueous solution with similar leach kinetics and economics to that of cyanide but is sustainable, safe and environmentally friendly. This water-based process has a broad applicability spectrum and is effective on most gold ores and concentrates.

The EnviroLeach process delivers numerous benefits over current leaching techniques and has the potential to unlock the value of many deposits located in environmentally sensitive areas that cannot be developed using current extraction methods.

At 3 Aces, Golden Predator is testing this process to recover the gold from the No. 2 concentrate produced from bulk sampling of the high-grade gold mineralization at the project.

The gravity processing plant captures roughly 85 percent recovery of the contained gold without the use of chemicals. This gold reports to two concentrates. The No. 1 concentrate is poured into doré bars and shipped to a refinery for further processing. The No. 2 concentrate, which contains heavy mineral sands with some gold, has been set aside for further processing.

A sample of this gold-bearing sulfide concentrate recovered during bulk sampling in 2018 was shipped to the EnviroLeach facility in Surrey, British Columbia in August.

Using the EnviroLeach solution, 96.5 percent of the gold was recovered from a 55.9-kilogram sample of the material in just six hours.

Electrowinning was used to pull the gold out of solution and a 91.3-gram (2.9 ounces) bar was poured. Electrowinning is the process of recovering metals from a solution by passing a current though that solution.

A sample of gold-bearing sulfide concentrate recovered in 2019 was also sent to and processed by EnviroLeach at the Surrey facility.

A 30.4-kilogram sample of the material was processed using EnviroLeach solution with 96.7 percent of the gold recovery in 29 hours; and a 77.8-gram (2.5 oz) bar was recovered from the electrowinning cell and poured into a bar.

Following completion of test work in the EnviroLeach facility in Surrey, testing was initiated on the 3 Aces property in September.

During this on-site test, a 121-kilogram sample of the sulfide concentrates produced during 2019 was processed in 21 hours with a 96.2 percent gold recovery; and a 255-gram (8.2 oz) of gold was recovered from the electrowinning cell and poured into a bar.

Using Golden Predator's Secondary Recovery Unit (SRU), a trademarked name for the processing equipment that is being tested using the EnviroLeach process, an initial five metric ton bulk test will be conducted in phases at the site of the company's gravity recovery plant on the 3 Aces property in the Yukon.

"The plant and SRU are examples of the continuing ways that Golden Predator works to be innovative, testing new methods that have the ability to change how we operate at projects like 3 Aces," said Golden Predator Mining CEO Janet Lee-Sheriff. "Working with EnviroLeach provides us a unique opportunity to lead the way for safe and responsible new cyanide-free extraction methods in processing gold bearing concentrates which has immediate value on our 3 Aces project, as well opening up other commercial opportunities."

–SHANE LASLEY