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.”