NON-TOXIC, CYANIDE-FREE TECHNOLOGY CAN POTENTIALLY DOUBLE SILVER RECOVERIES AND SIGNIFICANTLY CUT LEACHING TIMES
Highlights
- Preliminary metallurgical testing using EPS' proprietary solutions have significantly increased Candelaria's leach pad silver recoveries, exceeding 100% in comparison to previous testing using cyanide leaching (see Company's news release of
May 21 , 2019). - The sample tested consists of leached oxides from LP1, crushed to <1 inch (<25.4 mm) by previous operators, and has an average silver grade of 48.1 g/t. Crushing the leach pad material to ≤2 mm (2000 microns) has returned an average silver recovery of 49% in comparison to the cyanide leach test recoveries of 21% to 29% from past tests commissioned by the Company (see Company's news releases of
April 19, 2018 andMay 21, 2019 , and figure 1 for the location of LP1). - Additional short-term (5-15 minutes) milling to 550 and 110 microns (0.55 and 0.11 mm) increases the leach pad recoveries to 59.9% and 64.4%, respectively.
- The use of the trademarked TNS technology has positive ESG implications, notably because it reduces environmental impact. Unlike cyanide use, this process consumes minimal water, and no toxic effluents are produced. Furthermore, the residues (tailings) are inert and non-acid generating.
- Additional testing on material from both the existing leach pads and fresh ore is planned for the second half of 2024.
Background
EPS has developed a novel solid-liquids separation technology (TNS™) and leach processes to recover metals. EPS extensive research and development has resulted in constant improvements and adaptations that have accumulated 40 patents, producing, in the process, formulations suitable to separate metals from complex oxide and refractory mineralized materials. TNS™ technology was designed for the application of liquid solids separation in dewatering of mine waste and is also very effective in separating hydrocarbons in oil-sands. The TNS™ process, combined with its unique cyanide-free leach technology especially formulated to extract metals, has demonstrated to recover more silver and gold than traditional leaching methods.
The traditional silver cyanide leaching typically takes several hours to several days using agitated leaching techniques. However, EPS' innovative technology uses patented chemistry to extract metals in less time than an agitated leaching system. It also separates liquids from solids, enabling dry-stacked tailings; it works with coarse particles (≤2 mm or 2000 microns material in Candelaria' s case) and is not inhibited by the presence of clays. Thus, the process potentially reduces capital and operating costs while increasing metal recovery.
The TNS technology has been tested on materials from mine sites from various parts of the world and piloted successfully in dewatering oil-sand tailings in
Testing and Leach Results
A bulk sample representative of leach pad 1 (LP1) weighing 228 kg and entirely crushed to ≤2 mm (<2000 microns) with a Vertical Shaft Impact crusher at
A representative portion of the bulk sample was weighed and sieved to separate two fractions. Material smaller than 2 millimeters was used for testing. The tests were conducted on 1 to 2 kg splits of the sieved (<2 mm) material. Splits tested were prepared according to acceptable industry standard practices (homogenized, coned and quartered several times). The minus 2 mm size was selected because of economic reasons, as it is a size fraction that can be achieved with one single stage of HPGR crushing. This is inexpensive relative to milling and yields better silver recoveries than those obtained by leaching the coarser (1 inch = 25.4 mm) material existing in Candelaria's leach pads.
The current silver recoveries using EPS' proprietary solutions average 49% on samples as received at the lab (<2 mm = 2000 microns), which significantly exceed the 20.9% and 29% silver recoveries achieved with cyanide leaching from bottle roll tests using material of similar size respectively (See the Company's news release dated
Further milling for short periods (5 to 13 minutes) yields finer material (550 to 110 microns = 0.55 to 0.11 mm), increasing silver recoveries to between 59.9% to 64.4% (see details in Table 1). These recoveries far exceed the silver recoveries by traditional cyanide leach methods. Historic cyanide heap-leach silver recoveries of fresh ore, as reported by Kinross and its predecessors, averaged 51% during the open-pit life of the mine in the 1980's and 90's. Subsequent testing by Silver One using cyanide on partially leached material yielded recoveries in the 21-29% range for LP1 (see Company's news releases of
Final results from Extrakt are anticipated in the latter part of 2024. These results will be used in an anticipated economic study on the Candelaria project.
Analytical and QA/QC
Samples were assayed both by the
Qualified Person
The technical content of this news release has been reviewed and approved by
About Silver One
Silver One is focused on the exploration and development of quality silver projects. The Company owns a 100%-interest in its flagship project, the past-producing
The Company owns 636 lode claims and five patented claims on its Cherokee project located in
Silver One also owns a 100% interest in the
About Extrakt
Extrakt Process Solutions is a technology company that is focused on separation technologies for recovering precious metals, hydrocarbon separation as well as dewatering of mine waste and other related processes. The company has a global patent portfolio and continues to develop new processes and technologies.
See www.extraktps.com
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Forward-Looking Statements
Information set forth in this news release contains forward-looking statements that are based on assumptions as of the date of this news release. These statements reflect management's current estimates, beliefs, intentions and expectations. They are not guarantees of future performance.
things: risks and uncertainties relating to Silver One's limited operating history, ability to obtain sufficient financing to carry out its exploration and development objectives on the
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