Arizona Gold & Silver Inc (TSX-V:AZS, OTCQB:AZASF) announced promising results from its metallurgical tests at the Philadelphia gold-silver project in Arizona, achieving over 90% gold extraction through agitation leaching and 61% to 73% extraction via column leaching.
The final metallurgy report from McClelland Laboratories focused on two bulk samples of oxidized material sourced from underground and surface workings.
The program aimed to assess the viability of heap leaching for gold recovery from material with 1 to 2 grams of gold per tonne.
Column leach tests, which simulate heap leaching conditions, indicated both bulk samples were readily amendable to simulated heap leach at all three of the crush sizes tested.
It showed that finer crush sizes improved extraction rates, with the best results occurring at -1/4 inch (6.3 mm).
After 177 days of testing, gold extraction ranged from 60.6% to 72.7%, with the potential for additional recoveries projected up to 80% if the leaching period extends to 360 days.
Agitation leach tests revealed that both samples were highly amenable to cyanidation at all grind sizes, with gold extractions from both samples exceeding 90% at a grind size of -425 microns.
Silver recovery ranged from 10% to 55% depending on the sample and grind size.
Arizona Gold & Silver highlighted the report's conclusion that “the Philadelphia deposit is very amenable to agitation cyanidation with excellent gold extractions and low reagent consumption.”
Greg Hahn, vice president of exploration, welcomed the test work results. “We are very pleased with the results of test work on what I see as potentially large volumes of oxide material,” he commented.
“The program demonstrated excellent gold extractions and modest silver extractions (as expected). Importantly, the column leach work demonstrates that our metal extractions at Philadelphia are in line with other heap leach operations in the region.”
He added: “The trade-off between higher capital and operating costs in a milling operation versus lower capital and operating costs for heap leaching would be the subject for an economic trade-off study down the road.”
The company plans to conduct further column and agitation leach tests on specific drill core samples and coarse rejects from reverse circulation cuttings, targeting both the high-grade veins and stockwork mineralized zones across the entire deposit.
This additional work will help characterize the leaching properties and kinetics throughout the deposit's full strike length.
Additionally, the company announced the retirement of board member Eugene Spiering.