GOLD PROCESSING
Ripe for recovery
EnviroGold Global estimates the addressable market for metal extraction from tailings at more than $ 3.4 trillion
If there was ever a time to back innovation, it is today in the gold mining sector, Dan Gleeson says
With gold now hovering around the $ 4,000 / oz mark, yellow metal miners have run out of excuses to not back mining innovation.
The junior mining community is abuzz with‘ new’ projects looking at different ways of tackling orebodies previously considered unviable at lower prices, mid-tier miners are reformulating pit shells to extract material that might have previously been below cutoff grades and the majors are evaluating M & A as well as pushing the button on the odd brownfield project within their portfolios.
On the other side are a host of start-ups and innovators waiting for the community to tap their solutions – whether that is in the existing brownfield processing stage, those processing solutions geared towards greenfields, or technologies looking to recover gold from waste or tailings streams.
NVRO: Metal recoveries and‘ giveaways’
Having spent the last four years pushing patent applications and refining the economics behind an environmentally conscious strategy for recovering metals from tailings deposits, EnviroGold Global is now a matter of months away from moving into commercial territory with its NVRO PROCESS™.
NVRO is designed as a closed loop process for treating tailings. It‘ excites’ existing reagents within these deposits while providing minimal reagent make-up through a low temperature, low atmospheric pressure process to produce a pregnant leach solution( PLS) where metals can be recovered economically.
David Cam, CEO of EnviroGold, told IM:“ Our brief when it comes to gold isn’ t to make doré; that’ s a downstream process where there are existing solutions from the rest of the industry. What we do is process tailings using a two-stage oxidative leach that breaks down the sulphide bond in these sulphidic, refractory or pyritic tailings so that it no longer exists. This frees up the PLS for recovery of the valuable metal or metals.” The company claims it can reduce sulphides in tailings deposits by up to 97 %, coming close to eradicating potential acid mine drainage problems while providing huge economical benefits for customers through its cost-effective process.
Cam added:“ One of our customers has $ 650 / t in-situ metal value sitting in their tailings that they have not been able to extract – that’ s as good or better than many‘ mines’ today. Our aim is to extract this value for them with very low cost, as well as remove a toxic liability from their portfolio.”
The process Cam talks about has hallmarks of both fine grinding and oxidative leaching, plus the NITROX Process to pretreat refractory gold ores, with a“ couple of nuggets of secret sauce”, Cam says.
“ We’ ve taken the best of those two technologies and folded them into ours,” he explained.“ Some of the reactions that were suppressed in the other two processes have been encouraged in ours to produce a faster process that does not require excess heat or pressure and can occur without oxygen. It brings the two existing processes to a new level.”
EnviroGold isn’ t about to give up that secret sauce, but the granting of 22 patents( another two are pending) indicates the extent of this proprietary technology.
“ Yet, all the hardware is off-the-shelf,” Cam says.“ There’ s nothing at all bespoke about the hardware – it’ s tanks, pipes, pumps and valves in a closed loop.”
While the metal value is enticing enough, NVRO also provides environmental benefits that can extend tailings storage facility life and provide new process water options for an operation.
Cam explained:“ Following our process,
you can take your tailings to a dry stackable form if you want, providing more‘ real estate’ in the tailings storage facility. The water that is removed is then‘ agricultural grade’, which can be used internally or within the wider mine community.”
These are important benefits that, Cam admits, are not currently factored into the licence pricing model for NVRO.“ These are effectively‘ giveaways’ at the moment,” he said.
EnviroGold is not on its own in looking to transform tailings deposits from liabilities to profitable metals streams with reduced environmental burdens. Even in its precommercial state, it has encouraged three major companies to engage with the NVRO philosophy.
It has entered a strategic alliance with Fraser Alexander to provide turnkey, on-site deployment, from tailings reprocessing to safe tailings emplacement, supported by early-stage joint engagement with prospective customers. Hatch has been appointed to deliver a high-level process review and engineering study in support of the commercialisation of NVRO. And ANDRITZ has been engaged to simulate the NVRO Process using its IDEAS Simulation software to accelerate client-specific process optimisation, engineering and rightsizing for end-to-end processing of sulphidic mine tailings.
AI-backed ore blending opportunities
Declining grades and rising processing costs are reshaping the economics of gold mining. Management across the industry faces a pressing question: how can operations ensure maximum recovery without driving up energy consumption or overextending margins? Traditional methods of mine planning and grade control help, but when it comes to ore blending and stockpile management – the processes that directly affect plant performance – most operations still lack real-time optimisation tools.
Ore blending isn’ t just a logistical
18 International Mining | NOVEMBER / DECEMBER 2025