EnviroLeach Technologies and Golden Predator Mining have entered into an agreement that will see EnviroLeach’s proprietary cyanide-free hydrometallurgical technology extract gold from gravity concentrate produced at Golden Predator’s 3 Aces project in the Yukon of Canada.

This working relationship provides both companies with the first on-site bulk test of EnviroLeach’s new cyanide-free technology, they said.

Initial laboratory, pilot scale and production scale testing was successfully conducted at EnviroLeach’s facility in Surrey, British Columbia, prior to on-site testing at Golden Predator’s processing plant in the Yukon. All tests were conducted under the supervision of EnviroLeach and Golden Predator personnel with results to be released shortly, they said.

The initial 5 t bulk test will be conducted in phases and completed at the plant, they added.

Golden Predator operates the plant for the purposes of bulk sample testing of gold concentrate from its 3 Aces project. As part of its processing plant, Golden Predator developed a mobile batch recovery unit (Secondary Recovery Unit or SRU™) for the recovery of gold from its sulphide concentrate. Golden Predator intends to use the EnviroLeach proprietary cyanide-free technology in the SRU, it said.

Duane Nelson, President and Chief Executive Officer of EnviroLeach, said: “The gold recovery from Golden Predator’s arsenopyrite concentrate confirms the ability of our new eco-friendly formula to extract gold into solution from sulphide ores and recover it using conventional technologies.

“EnviroLeach is the only commercial-scale, economically viable and safe hydrometallurgical gold extraction process in the world. Our unique and eco-friendly process will change the way the world produces and recycles gold.”

Janet Lee-Sheriff, Chief Executive Officer of Golden Predator, added: “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.

“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.”

The EnviroLeach process can effectively dissolve gold into aqueous solution with similar leach kinetics and economics to that of cyanide but is sustainable, safe and environmentally friendly, according to the company. This water-based process has a broad applicability spectrum and is effective on most gold ores and concentrates, the company said, potentially unlocking the value of many deposits located in environmentally sensitive areas that cannot be developed using current extraction methods.

Golden Predator’s test processing plant (pictured), the first of its kind in Yukon, Canada, commenced operations in 2016 providing increased metallurgical and geological understanding of its 3 Aces project. The plant is a relatively simple gravity circuit using a closed-circuit water system with no added chemicals due to the free-milling nature of 3 Aces gold.

The 50 t/d closed circuit plant recovers gold from #1 concentrates realising over 85% recovery of contained gold with doré bars sent to a commercial refinery for final processing. Golden Predator is currently testing EnviroLeach’s patent pending technology in it’s SRU for the extraction of gold from their #2 concentrates.

The 3 Aces Project is an orogenic gold project in southeast Yukon which provides the testing material for the processing plant. Golden Predator has to date focused exploration on a broad gold-in-soil anomaly, where numerous orogenic gold-bearing quartz veins have been discovered.

Golden Predator made an early decision to bulk sample at its 3 Aces project when it realised that much of the gold contained in its veins is high grade (not uncommonly over 30 g/t gold) and nuggety. The best way to determine the true gold value of a nuggety gold system is to conduct large scale bulk sampling which also allows Golden Predator the opportunity and ability to conduct on-site bulk metallurgical and processing tests.