According to the tests, using proprietary cyanide free recovery technologies, up to 87.6% of silver was returned from samples grading 56 grams of silver per metric ton (g/t).
Three leach tests were conducted using the company’s mixed acid leach process. Roasting was conducted on the sample for two of the leach tests, producing higher recoveries, although the un-roasted sample still produced a 71% recovery rate.
87.6% silver recoveries resulted from a 4 hour leach time at 95°C, with the standard feed grind size of D80 175 micron of roasted material, while 84.3% recoveries resulted from a 4 hour leach at 95°C with the standard feed grind size of D80 175 micron with roasted material at a lower acid concentration.
71% recoveries resulted from a 4 hour leach at 95°C from received material, with the standard feed grind size of D80 175 micron with an altered acid mix concentration.
The average recovery for the roasted samples was 86% across the two leach tests performed using the proprietary process.
Patenting process
"These results further underpin the effectiveness of our processing technology,” said Bundeep Singh Rangar, interim CEO and Chairman of the board. “With our patented process we are achieving excellent recoveries in not only silver tailings, but also gold tailings as well, both of which have vast global markets for us.”
The proprietary process combines a mixed acid leach with a solvent extraction stage, utilizing specific organic compounds. No cyanide is used in this environmentally friendly process. The flow sheet design is for a closed loop, sealed unit in which all chemicals are then recycled.
Previous test work undertaken on other gold mine tailings utilizing the proprietary process resulted in a maximum 96.1% recovery of gold. Previous test work undertaken on other silver tailings resulted in a maximum 86.4% recovery of silver.
