One of the biggest issues miners face is processing the material they extract in an efficient and effective manner. For Golden Predator’s (V.GPY) 3 Aces project, bulk sampling has yielded a great deal of knowledge and with it three distinct concentrates. All are high grade, but each presents a different processing challenge.
The #1 concentrate is very straight forward. This is free milling gold and Golden Predator has built a very simple, gravity and water test processing plant in Watson Lake, Yukon to test bulk sample material which separates the gold. Essentially, this is akin to placer mining and, by recycling the water used, GPY, is able to minimize the environmental impact of this test facility while achieving 85+% total recovery in an entirely chemical free process, 2/3 of this in the #1 concentrate. Gold – and a little silver – from this concentrate is poured into the doré bars Golden Predator delivers for further refining, then some is used by the Yukon Mint to make gold coins and bars.
This leaves the #2 and #3 concentrates. The #3 is essentially intermediate material, not waste or tailings, with a moderate grade of economic value and work is underway on how to continue to extract gold from the material. But a big focus of Golden Predator’s efforts in 2019 has been the #2 concentrate. This is non-refractory gold particles, just as with the number one con, but with particle sizes too small to be separated from the sulfide material by gravity alone. The challenge here is to separate the gold from the sulfide. Following standard practice, Golden Predator sent its first #2 concentrate to a US smelter.
The ever diplomatic Golden Predator CEO Janet Sheriff told me, “We questioned the results reported by the smelter and began work on alternatives to shipping to an out-of-country smelter.”
Many miners are resigned to smelter “inaccuracies” as a cost of doing business. Not Golden Predator. “What if we had our own alternative to a smelter?” asked Sheriff.
As it happened, Golden Predator Chairman Bill Sheriff had been looking at alternatives to commercial smelters for years. “I’ve invested in some and looked at lots,” said Sheriff. “I ran into Duane Nelson at a conference three or four years ago. He’s the CEO of EnviroLeach (C.ETI) who was working on some new technology for extraction. We decided to send some samples to EnviroLeach. I wasn’t sure it would work but worth a try. None of the others worked.”
EnviroLeach is an interesting story in itself. Its CEO was the CEO and co-founder of SilverMex and the founder of Quotemedia – the data services company which provides stock quotes for TSX and TSX-V companies as well as companies on other exchanges. Nelson is thoroughly familiar with mining and smelting. When Sheriff got in touch, EnviroLeach was primarily recovering gold from E-Waste – old computers, modems, phones and so on. The company claims that a tonne of E-Waste yields between 50 and 2400 grams of gold, far more than most run of mine material in the gold sector.
On the mining side, EnviroLeach claimed that it had a cyanide free way to dissolve gold into solution. Plus, it had a way of using electricity to get the gold out of that solution. The question was, would it work?
Initially, Golden Predator shipped samples of its #2 concentrate to EnviroLeach. “We were pretty scientific,” said Janet Sheriff. “Different crush sizes, different years, supervised testing supported by independent assays.”
The initial results were reported in a Golden Predator Mining Corp press release on November 12, 2019. The material shipped to EnviroLeach in Surrey was processed with the 55.9 kg of 2018 material yielding 96.5% of the contained gold and a “button” of 91.3 grams. The 30.4 kg of 2019 material yielded 96.7% and a button of gold weighing 77.8 grams. And in reasonable timelines of 6 and 29 hours respectively.
Excellent results but, realistically, shipping tonnes of material from the Yukon to Surrey BC would be very expensive. So, the second test used Golden Predator’s mobile batch recovery system at the test plant. “It looks like it should be a brewery,” said Bill Sheriff.
The mobile test was conducted at Golden Predator’s bulk sample processing facility in Watson Lake, Yukon and 121 kg of gold-bearing sulfide concentrates produced during 2019 were processed in 21 hours with a 96.2% gold recovery. 255 g of gold was recovered from the electrowinning cell and poured into a button.
The next step is a 5-tonne bulk test which will be conducted in phases and completed at Golden Predator’s bulk sampling plant or even offsite as the batch plant is mobile. The results of this test will be reported as they happen but the Sheriffs are more than a bit pleased with these early results.
“This is a good solution for free-milling gold,” said Bill Sheriff. “And it seems to work for a variety of polymetallic mines including copper/gold deposits which can produce gold-bearing concentrate.”
The end result is high purity, green gold from a mobile batch unit.
“At 3 Aces the EnviroLeach formula appears to work better and faster than cyanide,” said Janet Sheriff. “and it’s environmentally benign.”
There are a lot of gold and gold/copper deposits in Canada and Golden Predator is well aware of potential commercial applications of their mobile batch unit utilizing EnviroLeach’s recipe. Right now, the 5-tonne bulk test will be watched with interest by Golden Predator shareholders and colleagues in the mining community. A new, environmentally friendly, non-smelting, process would actually be a game changer for mining in Canada as well as the world.