Arizona Sonoran Copper Company Inc. , an emerging US-based copper developer and near-term producer, today announces interim results from its ongoing metallurgical testing programs, in the form of sequential assaying, bottle roll testing and column testing for the mineral resources at the Cactus Mine, that demonstrates improved overall recoveries of ~1% total soluble copper (“CuSol”) and a decreased net acid consumption of ~2 lb per ton of material.
TABLE 1: Updated Metallurgical Recoveries and Net Acid Consumption
| |
Preliminary Column Tests (PEA) |
Updated Column Tests |
Resource
Component |
Net
Copper
Recovery
(% CuAS) |
Net
Copper
Recovery
(% CuCN) |
Gross Acid
Consumption
(lb/ton) |
Net Acid
Consumption
(lb/ton) |
Net
Copper
Recovery
(% CuAS) |
Net
Copper
Recovery
(% CuCN) |
Gross Acid
Consumption
(lb/ton) |
Net Acid
Consumption
(lb/ton) |
| Stockpile |
| Oxide |
90% |
40% |
22 |
18 |
90% |
40% |
22 |
16 (-) |
| Open Pit & Underground |
| Oxide |
90% |
72% |
22 |
18 |
92% (+) |
73% (+) |
22 |
16 (-) |
| Enriched |
90% |
72% |
22 |
1 |
92% (+) |
73% (+) |
22 |
0 (-) |
The Cactus Mine project envisages a heap leach oxide and enriched sulfide (chalcocite/covellite dominant) recoveries and a solvent extraction/electrowinning (SX/EW) plant for producing LME Grade A Copper Cathodes.
Ian McMullan, Arizona Sonoran COO stated, “Within mineral resource, and from the PEA, we have identified an initial 1 billion pound copper soluble leachable material. These results, now track over 2 years of metallurgical observations and provide us with additional clarity and confidence towards future copper oxide and enriched leaching opportunities. The results further de-risk the technical assumptions used in the Cactus PEA as we move towards increasing levels of confidence for inputs into the PFS due later this year.”
A copper heap leach column testing program to delineate the metallurgical performance characteristics of the existing stockpile and remaining unmined copper resources at the Cactus mine has been ongoing since 2020. Results have been progressively reported in PEA, commensurate with Canadian National Instrument NI 43-101 reporting requirements. The PEA has an effective date of August 31, 2021 and is authored by Stantec Consulting Services (“Stantec”).
Copper recovery is estimated for acid soluble copper (“CuAS”) and cyanide soluble copper (“CuCN”) content as determined by a standard sequential copper assaying methodology developed at the Skyline Laboratory facility in Tucson, Arizona. The CuCN assay fraction is classified as enriched secondary copper sulfide mineralization (e.g. chalcocite, covellite, digenite). The combined CuAS + CuCN content of the materials represents potentially soluble copper that is recoverable using heap leaching techniques (“CuSol”). Projected copper recovery estimates previously reported have been derived based on this leachable copper content and continues to be validated in the ongoing Prefeasibility Study (“PFS”) testing program.
Primary copper in mineralization that is not readily acid or cyanide copper soluble per the assay methods (e.g. native copper, chalcopyrite, bornite) reports in the total copper assay (“CuT”). Copper assayed that does not report in the soluble copper assay methodologies is not expected to provide meaningful recoverable copper contributions with the commercial methodologies anticipated.
Oxide Materials
Recoveries
- No material changes to the Stockpile recoveries vs the PEA, thus leaching and recoveries expected to be similar;
- Opportunity to increase heap lift heights, resulting from comparable 20-foot-tall and 10-foot-tall column results; and
- An economic opportunity to crush and/or blast larger material in the oxide ROM feed will be evaluated in conjunction with the ongoing PFS work;
Net Acid Consumption
- 12% reduction of net acid consumption to 16 lbs per ton, based on the current mine plan tonnages, grades and expected copper recovery.
Enriched Materials
Recoveries
- Improved CuSol recoveries by 3% over the PEA basis to 75% for a two-year leach cycle.
Net Acid Consumption
- Consumption is expected to be negligible or generating up to 2 lbs of acid per ton leached at PEA average grades, representing a small reduction from the 2021 PEA basis.
- As envisioned with the PEA basis, the separate enriched leaching pad will benefit the bioleaching scheme. Tails assaying and size fractional recovery data is still pending for the enriched materials tested. There may also be an economic incentive to crush and agglomerate the higher-grade materials, which will be reviewed.
Quality Assurance / Quality Control
Metallurgical characterization testing continues at the McClelland Analytical Service Laboratory, a well-established Mineral Processing research and development firm in Reno, Nevada, under the direction of Mr. Jim Sorensen, Samuel Engineering. A summary of the interim results obtained since the Cactus Mine Project Preliminary Economic Assessment (“PEA”) with an effective date of August 31, 2021, through January 2022 is discussed in this release. Testing continues and results from future work may affect this interim analysis.
Drilling completed on the project in 2020 and 2021 was supervised by on-site ASCU personnel who prepared core samples for assay and implemented a full QA/QC program using blanks, standards and duplicates to monitor analytical accuracy and precision. The samples were sealed on site and shipped to Skyline Laboratories in Tucson AZ for analysis. Skyline’s quality control system complies with global certifications for Quality ISO9001:2008.
Technical aspects of this news release have been reviewed and verified by Dr. Martin Kuhn, who is a qualified person as defined by National Instrument 43-101– Standards of Disclosure for Mineral Projects.