Tag Archives: cyanide-free

EnviroLeach test results bode well for gold market take-up

EnviroLeach Technologies has announced the successful completion of what it says is a comprehensive lab and bulk sample program using its patented cyanide-free formula on high-grade gravity table tailings material from a mid-tier gold producer.

Estimated gold recoveries from the bulk sample (2.7 t of material) averaged 97% and produced 277.8 oz of gold using the EnviroLeach process, which 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.

Following extensive lab and bench scale test programs, a locked cycle, bulk test program (leaching, filtering and electrowinning) was carried out on this 2.7 t bulk sample of table tails from the gold mining operation. The objective of the bulk test program was to determine the efficacy and recovery rates of gold from the host material using EnviroLeach’s proprietary formula and to collect key operational data such as leach kinetics, chemical reusability, reagent consumption and costs, the company said. The bulk test produced no tailings effluent, as all filtrate/liquids were reused in the process.

The test results report an overall average estimated gold recovery of 97% and three gold bars were produced having a combined gold content of 277.8 oz.

Duane Nelson, EnviroLeach CEO, said: “This successful bulk test on these high-grade gravity tails clearly validates the proficiency of our patented formula to offer a cost-effective, sustainable and environmentally friendly extraction alternative to the gold mining sector.

“Thousands of gold mines around the world rely on gravity-based concentration. This bulk test demonstrates that many of these mine operations could benefit from our eco-friendly extraction alternative.

“The adoption of the EnviroLeach process could reduce the industry’s reliance on the conventional cyanide and smelting methods used today and contribute to environmental sustainability across the gold mining sector.”

Golden Predator, EnviroLeach hit on the right gold extraction and recovery formula

Golden Predator Mining says tests have successfully confirmed that EnviroLeach Technologies’ environmentally friendly technology can effectively extract and recover more than 95% of the gold from sulphide concentrates produced at the 3 Aces gold project, in the Yukon of Canada.

The concentrate is produced using Golden Predator’s Secondary Recovery Unit (SRU™).

With this environmentally friendly technology confirmed in successive tests both in the EnviroLeach facility and at the Golden Predator bulk sample processing plant (pictured), the companies have initiated a larger material test run to process up to 5 t of gold-bearing sulphide concentrates to be completed onsite at Golden Predator’s plant in the Yukon, they said.

This testing follows an earlier agreement between the two companies to use EnviroLeach’s proprietary cyanide-free hydrometallurgical technology to extract gold from gravity concentrate produced at 3 Aces.

As part of this testing, a sample of gold-bearing sulphide concentrate recovered in 2018 was shipped from Golden Predator’s plant to the EnviroLeach facility in Surrey, British Columbia, in August of 2019.

Some 55.9 kg of the material was processed using EnviroLeach solution and 96.5% of contained gold was leached in six hours; and gold in solution was extracted by electrowinning and poured into a 91.3 g bar.

A sample of gold-bearing sulphide concentrate recovered in 2019 was also sent to and processed by EnviroLeach at the facility, with 30.4 kg of the material processed using EnviroLeach solution with 96.7% gold recovery in 29 hours; and gold in solution extracted by electrowinning in four hours and poured into a 77.8 g bar.

Following completion of test work in the EnviroLeach facility in Surrey, on-site testing was initiated to leach material at the plant during the week of September 23, 2019. This saw 121 kg of gold-bearing sulphide concentrates produced during 2019 processed in 21 hours with a 96.2% gold recovery; and electrowinning completed in 14 hours, with 255 g of gold recovered from the electrowinning cell and poured into a bar.

Janet Lee-Sheriff, Chief Executive Officer of Golden Predator, said: “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 which has immediate value on our 3 Aces project as well opening up other commercial opportunities.”

The Golden Predator-EnviroLeach working relationship has enabled the companies to successfully demonstrate the first “in the field” recovery of gold from gold-bearing sulphide concentrates, using EnviroLeach’s environmentally friendly formula and Golden Predator’s SRU processing equipment, according to the companies.