(via TheNewswire)
The metallurgical testing was conducted as part of the ongoing Pre-Feasibility Study ("PFS") for Diablillos, and further complements the positive metallurgical results achieved for the JAC and Fantasma deposits, which were announced on
Key takeaways from the PFS-level metallurgical test work include:
Recovery rates at the Oculto deposit are expected to range between82% - 86% for silverand84% - 89% for gold.These results represent a significant increaseover the average recovery rates of 73.5% for silver and 86% for gold used in the 2022 Preliminary Economic Assessment (“PEA”).
A substantial percentage of the silver and gold at Oculto can be recovered by gravity separationwhich results inhigher recovery rates and lower processing costs.
Importantly,fine grinding is not necessarywith the most efficient recoveries achieved at a grind size of 150 microns for both gravity and cyanidation and an optimal retention time of 36 hours.
Description of Metallurgical Test Work on Oculto Samples
The latest program involved metallurgical testing of four composites from the Oculto deposit, including gravity separation testing and cyanidation of the gravity tailings for the recovery of gold and silver. The composite samples were selected from prior samples used for metallurgical testing, which are representative of four distinct mineralogical regimes at the Oculto deposit. The campaign was designed to supplement and optimize the results from prior metallurgical test work programs, conducted between 1996 and 2021, which formed the basis of the 2022 PEA for the Diablillos project.
The latest test work demonstrated that gravity separation can be used before cyanide leaching to recover substantial amounts of silver and gold at Oculto. The overall gold and silver recoveries achieved by gravity separation followed by cyanidation of the gravity tailings are summarized in the table below, and will be incorporated in the upcoming Mineral Resource estimate (“MRE”) update and PFS for the Diablillos project.
Table 1 - Summary of Metallurgical Testwork Results at Oculto Deposit
Mineralogical Regimes | Total Silver Recoveries | Silver Head Grades | Gravity Recovery | Total Gold Recoveries | Gold Head Grades | Gravity Recovery |
% | g/t Ag | Ag % | % | g/t Au | Au % | |
Shallow gold zone | NM1 | NM1 | NM1 | 88% | 1.10 | 12.3% |
Silver enrichment zone | 86% | 151 | 16.4% | 86% | 1.45 | 16.2% |
Tesoro zone | 83% | 124 | 3.3% | 84% | 2.60 | 8.6% |
Northeast zone | 82% | 77 | 7.5% | 89% | 1.91 | 10.1% |
Note: 1There was very little silver present in the ‘shallow gold zone’ sample, and as a result no meaningful (‘NM’) results are available.
Process Design
The process design for the PFS will consist of a conventional silver/gold processing plant flowsheet incorporating crushing, grinding, gravity concentration and intense cyanidation circuit, cyanide leaching with oxygen addition, counter current decantation (“CCD”) washing thickeners and Merrill-Crowe precious metal recovery from solution followed by on-site smelting to doré bars.
A summary of the processing flow sheet for the Diablillos project is shown below.
Figure 1 - Process Flowsheet for the
Upcoming Milestones and Catalysts
Bottle roll and column testing is currently being conducted to evaluate the viability of heap leaching lower-grade mineralized material from the Oculto deposit, with results expected by the end of the year. It is anticipated that heap leaching some lower-grade material that is not otherwise expected to be incorporated in the mine plan, could result in increased mineral resources and a further reduction in the overall strip ratio at Diablillos.
The Company anticipates announcing several significant milestones over the next few months, including:
Announcing assay and geophysical survey results from regional exploration targets at JAC North, Alpaca and Fantasma (
October 2023 )Updated Mineral Resource estimate for the Diablillos project (late Oct. / early
Nov. 2023 )Bottle roll and column testing results for heap leach processing (Q4 2023)
Pre-Feasibility Study results for the Diablillos project (
January 2024 )
About Diablillos
The 80 km2Diablillos property is located in the Argentine Puna region - the southern extension of the Altiplano of southern
The most recent Mineral Resource estimate for the Oculto Deposit is shown in Table 2:
Table 2 -Oculto Mineral Resource Estimate – As of
Category | Tonnage (000 t) | Ag (g/t) | Au (g/t) | Contained Ag (000 oz Ag) | Contained Au (000 oz Au) |
Measured | 19,336 | 98 | 0.88 | 60,634 | 544 |
Indicated | 31,978 | 47 | 0.73 | 48,737 | 752 |
Measured & Indicated | 51,314 | 66 | 0.79 | 109,370 | 1,297 |
Inferred | 2,216 | 30 | 0.51 | 2,114 | 37 |
Notes: Effective
QA/QC and Core Sampling Protocols
AbraSilver applies industry standard exploration methodologies and techniques, and all drill core samples are collected under the supervision of the Company’s geologists in accordance with industry practices. Drill core is transported from the drill platform to the logging facility where drill data is compared and verified with the core in the trays. Thereafter, it is logged, photographed, and split bydiamond saw prior to being sampled. Samples are then bagged, and quality control materials are inserted at regular intervals; these include blanks and certified reference materials as well as duplicate core samples which are collected in order to measure sample representivity. Groups of samples are then placed in large bags which are sealed with numbered tags in order to maintain a chain-of-custody during the transport of the samples from the project site to the laboratory.
All samples are received by the SGS offices in Salta who then dispatch the samples to the SGS preparation facility in San Juan. From there, the prepared samples are sent to the SGS laboratory in
Qualified Persons
David O’Connor P.Geo., Chief Geologist for AbraSilver, is the Qualified Person as defined by National Instrument 43-101 Standards of Disclosure for Mineral Projects, and he has reviewed and approved the scientific and technical information in this news release.
About AbraSilver
AbraSilver is an advanced-stage exploration company focused on rapidly advancing its 100%-owned Diablillos silver-gold project in the mining-friendly Salta province of
For further information please visit the
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info@abrasilver.com
Tel: +1 416-306-8334
Cautionary Statements
This news release includes certain "forward-looking statements" under applicable Canadian securities legislation. Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable, are subject to known and unknown risks, uncertainties, and other factors which may cause the actual results and future events to differ materially from those expressed or implied by such forward-looking statements. All statements that address future plans, activities, events or developments that the Company believes, expects or anticipates will or may occur are forward-looking information. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. When considering this forward-looking information, readers should keep in mind the risk factors and other cautionary statements in the Company’s disclosure documents filed with the applicable Canadian securities regulatory authorities on SEDAR+ at www.sedarplus.ca. The risk factors and other factors noted in the disclosure documents could cause actual events or results to differ materially from those described in any forward-lookinginformation. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.
Neither the
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