TORONTO (miningweekly.com) – Dundee Sustainable Technologies (DST), a division of Dundee Corporation, announced on Friday that it had received an independent certification of the performance of its cyanide-free gold extraction process from Environment Canada, through the Canadian Environmental Technology Verification Programme (ETV).

The certification confirmed that the DST gold process successfully extracted an average of 81%, with a maximum of 90%, of the gold content from a total of 170 t of refractory gold-bearing pyrite concentrate, while the cyanide extraction process achieved an average of 71% on the same material.

"We consider this an important endorsement of the DST gold process; demonstrating its potential as an interesting alternative to cyanide,” stated DST president and CEO John Mercer.

The tests were conducted on material sourced from a jurisdiction that had restricted the use of cyanide within its territory. This refractory concentrate was chosen owing to the difficulty of extracting its gold using conventional processes, demonstrating the effectiveness of the DST gold process, the company said.

According to DST, the performance test sampling was conducted at its demonstration plant according to test protocol developed by STS Canada, which also supervised the process. Samples were submitted for analysis to an accredited laboratory owned by SGS Canada.

DST advised that all solid residues meet environmental norms and that its chlorination circuit delivered the expected gold recoveries, which were higher on average than cyanide yields on the same samples. Further, the process successfully demonstrated its closed-circuit operation with the recycling and regeneration of the reagents.

DST was currently working on projects for the commercialisation of its technologies in Canada, Argentina, Bulgaria, Chile, Ireland, Namibia and Peru.