Southern Silver Exploration Corp (TSX-V:SSV, OTCQX:SSVFF) reported that metallurgical scoping test work confirmed the viability of recovering gold as a by-product at its Cerro Las Minitas project in Mexico.
The Vancouver-based company confirmed the technical feasibility of recovering both free cyanide leachable gold and refractory gold from pyritic material through a process of fine grinding and hot atmospheric pressure oxidation followed by cyanide leaching.
Southern Silver described the results as “significant” as it now allows new gold revenue in future economic modelling of the CLM project. This is one of several engineering initiatives the company is pursuing to de-risk and boost the value of the CLM project.
Earlier work on the CLM project didn't consider the potential contribution of gold in the financial modelling mainly due to low gold grades in the Skarn Front mineralization which made up the majority of the mineral resources on the project.
However, post-2020 drilling in the La Bocona, South Skarn and North Felsite regions encountered significantly higher gold grades which represented untapped value, noted the company.
Similarly, oxide mineralization which was identified in the 2021 Mineral Resource update on the project was never incorporated into economic modelling. As a result, Southern Silver initiated a metallurgical test program to understand gold deportment in both the sulphide and oxide resources.
Both sulphide and oxide composites were tested as part of the metallurgical program. Mass balance reconciliations on the sulphide composite test work indicate that 50% of the total gold is recoverable by hot atmospheric pressure oxidation prior to cyanide leaching at an overall 83.9% recovery. An additional 21.5% of gold is recovered into a copper concentrate at payable grades for a total of 71.5% recovery of gold.
The oxide composite was treated with standard cyanide-leach over a 48-hour period at increasingly finer grinds. Leach extraction successfully returned 70.2% recovery at a p80 of 75 microns grain size, 74.0% recovery at p80 of 53 microns; and 75.1% recovery at a p80 of 38 microns.
“Southern is very encouraged by the results from the recent metallurgical test program on the CLM project which will allow the incorporation of +70% recoveries of gold from both oxide and sulphide mineralization into the process flowsheet,” said Rob Macdonald, vice president exploration at Southern Silver.
“Of the three commercially proven oxidation techniques, the atmospheric leach has demonstrated what is likely the most cost-effective gold extraction technique which can be easily incorporated into future financial modelling of the project.”
Southern Silver said mineralization remains open at depth on the eastern side of the Cerro, which with further exploration can add high-margin mineralization early in the production scenario.
The company also provided details about the test program and bench-scale flotation tests which were done by Canada's BaseMet Labs.
Contact the author Uttara Choudhury at uttara@proactiveinvestors.com
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