EnviroGold Global Limited (CSE: NVRO | OTCQB: ESGLF |FSE: YGK), a Clean Technology Company accelerating the world’s transition to a circular-resource economy, announces it has filed a patent for its proprietary process to efficiently recover precious and critical metals from refractory ores while completely neutralizing the acid-forming potential of waste (the “NVRO Process”). The Company plans to apply this technology to tailings as well as primary production streams worldwide.
There are over 280 billion metric tonnes of mine tailings on the earth’s surface with a contained metal value that exceeds US$3.4T. McKinsey & Company reports that refractory ore represents 24% of current gold reserves and 22% of all gold resources globally, most of which are in jurisdictions with low mining-regulatory and political risk. Moreover, gold reserve grades from refractory ore are 86% higher than non-refractory materials, and gold production from refractory sources is expected to grow at almost five-times the pace of non-refractory sources over the next several years (link). Refractory ores will also be of growing importance in the recovery of strategic and critical metals such as copper, lead, and zinc.
See related articles: EnviroGold Global Announces Closing of First Tranche of Private Placement Led by Management & Insiders, Social factors and geopolitical tensions are the major cause of disruption in the mining sector, with ESG the top focus
Costs are historically higher in refractory ore projects, but the NVRO Process addresses the key technical problems preventing the recovery of trillions of dollars of trapped resources, lowering both CAPEX and OPEX over existing processes designed to address refractory ore, with better environmental outcomes.
NVRO Process Highlights
- Low, exothermic temperatures of <100°C (compare to energy-consuming roasting at 500°-700°C)
- Operates at atmospheric pressure (14.7 PSI, compare to 510 PSI)
- No need for specialized high pressure/high heat equipment or the large footprint of Bio-Oxidation
- Lower energy, less corrosion means less downtime and cheaper materials
- Mild acid as a catalyst, not a consumable, and a self-sustaining chain reaction
- Eliminates acid-forming potential of waste, removing key environmental liabilities
- Saves on energy, emissions, and enhances ESG project profile
- Byproduct (magnetite) can close the loop on localized steel recycling
Refractory ores are complex and particularly difficult to process for the recovery of metals, which are entrained as sub-microscopic particles inside the lattice of pyrite and arsenopyrite, primarily. Other processes used to recover metals in refractory ores utilize high heat (roasting), high pressure, long acid residency times, ultrafine grinding, or expensive, specialized equipment. These parameters contribute to high energy consumption and high CAPEX/OPEX, often making many refractory ore projects uneconomical. Moreover, the waste generated from pyritic ores is potentially acid-forming and represents environmental liabilities both for companies’ balance sheets and for communities.
EnviroGold Global’s NVRO Process operates at atmospheric pressure, relatively low heat using an exothermic reaction, and does not necessarily require fine grinds to optimize gold and silver recovery. It uses a two-stage acid leach with short, one-hour acid residency times in which the acid is a catalyst, and therefore little of the acid is consumed in the reaction. An acid recycling circuit serves to help further minimize costs.
The process also completely neutralizes the acid-forming potential of the pyrites in refractory ore. This eliminates significant legacy environmental liabilities from existing tailings as well as new ore streams, offering owners with potentially acid-forming projects and waste stores an ESG and cost-savings opportunity. Following the completion of our proprietary leach, almost 99% of the original pyrite is oxidized and can then be neutralized to ferric oxyhydroxide—mineralogically goethite—which is inert and non-acid generating.
In addition to its economic and environmental benefits for the mining industry, the NVRO Process can also close the loop on steel recycling. The NVRO Process can convert the goethite to hematite, then maghemite, and finally magnetite, for separation into a product suited to pelletizing. These pellets are distributed steel mini-mills using electric arc furnaces, which significantly improves the economics and allows operators to effectively compete with large, high-emission conventional steel mills.
The NVRO Process was developed by EnviroGold Global’s Chief Technology Officer (“CTO”), Brock Hill. It enhances the Company’s growing intellectual property portfolio, adding to its suite of twenty filed patents and designs. Commenting on the patent filing, Mr. Hill said, “this patent is a hugely significant milestone for the company, and for the metals processing industry, really. It will greatly reduce the geological risk in developing an underutilized store of resources in refractory ore—not just gold and silver, but also strategic metals, which is absolutely required for the green energy revolution. It will also make the mining industry a safer partner for resource development—a win for the environment and a win for society.”
EnviroGold Global will first apply the NVRO Process to refractory material at the Company’s Hellyer Tailings Project, where independent analysis from the Company’s flowsheet development partner, Core Resources, has demonstrated gold recovery rates >80% and silver recovery rates >90% for total project after-tax free cash flows of US$ 350M (link) . The application of the Company’s proprietary technology to the Hellyer Tailings is expected result in the production of ~965,000 gold-equivalent ounces over an ~8yr project life through the liberation of precious metals, including gold and silver, and critical metals, including copper, lead and zinc. The Hellyer Tailings resource is well-studied with multiple JORC technical resource reports and an updated NI 43-101 mineral resource estimate (2022) on file.
EnviroGold Global is in advanced commercial negotiations with other owners of refractory mine tailings to apply the NVRO Process to the liberation of additional resources worldwide, and expects to announce at least one more definitive tailings reprocessing contract in 2022.
Source: EnviroGold Global