Confirms Gold Recovery Of +99%
Amex Exploration Inc. (TSXV:AMX) has reported additional metallurgical results from the High Grade Zone (HGZ), located in the Eastern Gold Zone (EGZ) on the 100% owned Perron property in northwestern Quebec, Canada.
The second phase of metallurgical testing was completed to determine the theoretical recoverability of the HGZ mineralisation using a simple gravity-cyanide circuit, commonly used in many gold milling operations throughout the Abitibi region.
All three composite samples, representing high, medium, and low grade mineralization characteristic of the HGZ, were found to be highly amenable to the simple gravity- cyanidation circuit, with overall gold recoveries greater than 99% and silver recoveries better than 89.5%.
Kelly Malcolm, VP of Exploration, said these results further confirm that a simple gravity-cyanidation flowsheet would be sufficient to achieve equivalent or better than industry average recoveries. Metallurgical work was completed by SGS Canada Inc., a leader in metallurgical and analytical studies.
“I am very pleased with our metallurgy program to date. Our previously announced Phase 1 results showed exceptional gold and silver recovery using a 3-stage processing technique (gravity, flotation, and cyanidation),” Mr Malcolm said.
“The Phase 2 metallurgy program determined that we are able to achieve very high gold and silver recoveries using a simplified 2 stage process that eliminates floatation, thereby lowering projected processing costs as well as capital costs.”
Three samples of full PQ (large diameter) drill core were individually stage crushed with a combination of jaw, cone, and roll crusher to passing ½ inch. One quarter of the sample was rotary split and further crushed to 100% passing 6 mesh.
Following sample homogenisation, a 10 kg sub-sample was rotary split for Bond mill work index testing (BWI) and the remainder was crushed to 100% passing 10 mesh. Following sample homogenization, each sample was further rotary split into a 10 kg test charge and a 1 kg head assay charge.
As announced by Amex on August 5, 2020, the head assay samples were submitted for gold analyses using the screened metallics procedure. The results returned composite gold grades ranging from 5.65 g/t Au to 27.7 g/t Au and indicated high gravity recoverable gold for all three samples.
Gravity separation tests were completed on each composite, evaluating the potential for gravity recoverable gold and silver at a coarse grind size of P80 ranging from 240-330 μm using a Knelson MD-3 concentrator. The Knelson concentrate represents the achievable gravity recovery and was able to recover 72.9% to 83.7% of the gold and 88.0% to 96.6% of the silver. As announced by Amex on August 27, these results exceeded predictions from the head screened metallic analyses, which indicated expected gold recoveries of between 35% and 65%.
Cyanide leaching was completed on a sub-sample of each gravity tailing reground to a P80 of ~90 μm to evaluate the recovery of the remaining gold in the sample by bottle roll cyanide leaching. Each sample was leached at a density of 50% solids, with 0.5 g/L cyanide and maintained for 48 hours at pH of 10.5 to 11.0.
The cyanidation test conditions returned excellent results, recovering 95.1% to 97.9% of the gold contained in the gravity tailings to the pregnant leach solution after 48 hours. Cyanide consumptions ranged from 0.21 to 0.26 kg/t and lime consumption ranged from 2.48 to 2.76 kg/t.
The results from the gravity and cyanidation processes were combined to produce an overall metallurgical balance with total gold recovery for each of the three composite samples returning between 99.2% and 99.4% while silver recovery ranges between 89.5% to 96.8%.