Promising Metallurgical Testwork Undertaken On Three Composite HGZ Samples
Amex Exploration Inc. (TSXV:AMX)(FRA:MX0)(OTCQX:AMXEF) has achieved promising metallurgical results from the High Grade Zone (HGZ), located in the Eastern Gold Zone (EGZ) on its 100% owned Perron property in northwestern Quebec, Canada.
Vice President Exploration, Kelly Malcolm, said all three composite samples, representing high, medium, and low grade mineralisation characteristic of the HGZ, were found to be amenable to gravity, flotation, and cyanidation, with overall gold and silver recoveries greater than 99%.
Mr Malcolm said it is likely, based on these results, that a simple gravity-cyanidation flowsheet would be sufficient to achieve very high recoveries.
“As we continue to rapidly advance the Perron project towards a future maiden resource, we wanted to confirm the amenability of the mineralisation to conventional milling operations with a particular interest in the gravity recoverability of the gold and silver in the system,” Mr Malcolm said.
“Results exceeded our expectations, confirming the simple nature of the coarse gold in the High Grade Zone. These initial results indicate that not only would most conventional milling operations result in very high metal recoveries, but also that mineralisation at Perron is suitable for the majority of nearby active mills in the Abitibi region of Quebec and Ontario.
“The company plans to complete additional metallurgical work in the future on the Denise, Grey Cat, and Gratien zones as well, with all of those zones sharing similar visible gold and low sulfide mineralization.”
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 six 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.
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.
Bond ball mill grindability (BWI) testing was completed on each of the three samples. With BWI values ranging from 16.5 to 17.2 kWh/t, the samples were determined to be moderately hard to hard compared with the SGS database.
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. These results exceeded predictions from the head screened metallic analyses, which indicated expected gold recoveries of between 35% and 65%.
Flotation testing was completed on a 2 kg sub-sample of each of the gravity tailings to evaluate the potential for additional gold recovery. Flotation conditions used recovered 74.1% to 83.9% of the gold. Although the recoveries are quite good, the gold and silver recovered by the flotation circuit would likely be recoverable by direct cyanidation of the gravity tails.
Cyanide leaching was completed on a sub-sample of each flotation 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 92.1% to 94.1% of the gold contained in the flotation tailings to the pregnant leach solution after 48 hours.
Total gold recovery for each of the three composite samples returned between 99.6 % and 99.9% while silver recovery ranges between 99.8% to 100%.