Hellyer Gold Mine
EnviroGold Global plans to start precious and base metal production in Hellyer, Tasmania, in late 2022
|At a Glance|
|Geological Setting||Polymetallic Volcanic Massive Sulfide|
|Planned Plant Capacity||1.2 million tpa|
|Estimated Tonnage||9.0 million tonnes|
The Hellyer Project is in north-western Tasmania, Australia, approximately 60 km south-southwest of Burnie.
During its life, the Hellyer Mine produced 15 million tonnes of ore and yielded 601,000 tonnes of bulk concentrate, 2.7 million tonnes of zinc concentrate, and 728,000 tonnes of lead concentrate.
EnviroGold Global is partnered with Hellyer Gold Mines (HGM), which holds the rights for current and proposed mineral recovery operations. The current tailings recovery and retreatment operation started in October 2018.
Prior to commissioning retreatment, a total JORC Mineral Resource Estimate from 2012 indicated 9.25 million tonnes at 2.35% Zn, 2.99% Pb, 92 g/t Ag, 2.57 g/t Au, and 0.19% Cu.
EnviroGold Global’s reprocessing project will advance in two phases. The Phase One facilities are expected to process up to 500 tonnes-per-day of tailings, representing approximately 14% of the expected 3,500 tonnes-per-day nameplate production in Phase Two.
Phase One production is expected to optimize implementation of EnviroGold Global’s proprietary process at scale and demonstrate regulatory compliance (water and air).
Due to the refractory nature of the precious metals within the volcanogenic massive sulfide (VMS) ore, initial data indicate that 95% of the gold and 67% of the silver remains unrecovered within the tailings after the current flotation process.
The initial stages of EnviroGold Global’s reprocessing will target these gold- and silver-rich tailings as feed stock—approximately 9.02 million tonnes—without the need for additional energy- and carbon-intensive milling.
These tailings are estimated to contain an unrecovered gold grade of 2.46 g/t and silver grade of 59.6 g/t.
Working with Core Resources as our flowsheet development partner, EnviroGold Global has developed a proprietary two-stage chemical oxidation process to liberate metal from refractory ore, adding essential innovations to long-proven techniques.
Using this independently-verified process, EnviroGold Global will vastly enhance precious metal recoveries at Hellyer. Test work completed to date has demonstrated gold recovery rates of 83.5% and silver recovery rates of 94.6%.
Pre-treatment oxidation techniques, such as roasting, have been common for making refractory material amenable to conventional cyanidation. But they are carbon- and energy-intensive, and come at considerable—and ever increasing—financial and environmental costs.
Pre-treatment technologies have also been limited by the need to process at high pressures, high temperatures, with long reaction times and high reagent consumption—which means they are extremely corrosive to plant equipment.
Our innovations solve these problems. EnviroGold Global’s two-stage process exposes ground ore typically encountered in tailings streams to a series of weak acid solutions that progressively oxidize pyritic sulfide structures and breaks ultra-fine amounts of precious metals from their surrounding minerals, making them amenable to recovery.
This two-stage leach is achieved at atmospheric pressure, low temperatures with no additional energy requirements, and with extremely fast reaction times compared to alternative technologies.
With low rates of reagent consumption, modern reagent recycling and recovery circuits, and 21st century corrosion-resistant materials, EnviroGold Global’s process is a cost-effective method of recovering the precious metal component of refractory ores at commercial scale.
Tailings from refractory ores typically have acid-forming potential, which will leach numerous heavy metals into the environment over time.
EnviroGold Global’s proprietary two-stage oxidation process eliminates the potential for these tailings to produce acid, remediates the previously hazardous waste, and greatly reduces the balance sheet liabilities attached to mine remediation and closure.
EnviroGold Global’s technical assessments of the Hellyer Tailings Project indicate that the new reprocessing project’s tailings do not require underwater storage as there is limited, if any, acid forming potential.
EnviroGold Global anticipates its on-site management, laboratory, and operational staffing requirements will directly employ around 40 people, with most sourced from the local Tasmanian community, expanding the significant economic activity from the existing operations under HGM.
- 94.6% Silver Recovery Demonstrated by EnviroGold Global for Hellyer Refractory Tailings with 634k oz Gold, 22.9M oz Silver and 419k tonnes Copper-Lead-Zinc with grades of 2.60 g/t Au, 94 g/t Ag, 2.33% Zn, 3.01% Pb and 0.19% Cu Contained in 6.37Mt of Measured & Indicated and 1.21Mt of Inferred Resources detailed in a 2020 JORC Historical Estimate
Graphical illustrations are for informational purposes only. Geographic features and boundaries may not be to scale or reflect regulatory official boundaries. This information contains forward looking statements. Please refer to our disclaimer statement here.
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