Kootenay Silver (TSXV:KTN) is pleased to report results from preliminary metallurgical testing on its La Cigarra Silver Project in Chihuahua State, Mexico, applying the proprietary Silvox Technologies Inc. (âSILVOXâ) process which indicates a marked improvement in cyanide leaching for silver recoveries versus industry standard leaching processes previously applied to the deposit.
James McDonald, P.Geo, President and CEO stated, âAlthough additional metallurgical testing using standard and SILVOX processes will be required to further assess silver recoveries, results from preliminary testing utilizing the SILVOX process are highly encouraging. The ability to achieve enhanced silver recoveries could have a profound impact on the economic viability of La Cigarra and its potential near-term development as a low-cost, open-pit heap leach operation. Further detailed metallurgical testing using standard and SILVOX processes is expected to be completed in the near futureâ.
Initial bottle roll (âBRâ) testing using industry standards (âstandardâ) and SILVOX processes were recently completed using a typical 48 hour period at minus ¼ inch crush size from a bulk sample collected from La Cigarra. Standard cyanide leaching returned an estimated 38% silver recovery compared to a range of 44% to 52% from the SILVOX process, a 6% to 14% increase in silver recovery.
Additionally, two column tests using the SILVOX process were completed indicating potential for higher silver recovery than the BR test results. These tests were completed over a 120 day period at minus ¼ inch crush size with results suggesting at silver recovery of 52% to 58%. Column tests were not conducted to sufficient QA/QC but may suggest potentially higher recoveries than BR testing.
The results of 5 bottle rolls on a bulk sample composite are shown in the chart below. Four are labeled SILVOX 1 through 4 employing the SILVOX process while the one labeled Standard used industry standard cyanide leach methods. Reagent cost per tonne shows potential economic viability of the SILVOX process with both lower and higher costs compared to standard cyanide leaching.
Test Type | Standard | SILVOX 1 | SILVOX 2 | SILVOX 3 | SILVOX 4 |
Head Grade g/t Silver | 90.0 | 81.0 | 87.0 | 77.0 | 72.0 |
Silver Recovery | 38% | 44% | 45% | 51% | 52% |
Incremental Recovery Improvement | Base | 6% | 7% | 13% | 14% |
Total Reagent Cost per Tonne | $2.88 | $1.78 | $2.33 | $3.86 | $5.82 |
Note: La Cigarra bulk sample crushed to minus ¼ inch with 48 hour standard BR testing. Reagent cost assumes; $2.50/kg for CN, $0.12/kg for lime and $0.1 to $4.0/kg for SILVOX |
Metallurgical laboratory testing was conducted on composited samples from 10 representative core holes and 4 surface samples taken from outcrop, trenches and open cuts in the Las Carolinas and San Gregorio zones of the La Cigarra deposit. All BR testing was conducted by ALS Metallurgy in Kamloops, B.C. Column testing was completed by Laboratorio Metalurgico S.A. de C.V., a division of Sonora Naturals S.A. de C.V. in Hermosillo, Mexico.
A comprehensive metallurgical study will be undertaken using standard and SILVOX processes to assess variability across the La Cigarra deposit. Initially, additional BR tests will include two crush sizes of minus ¼ inch and minus 3/8 inch for both oxide and sulfide material. Further column testing to qualified standards will also be conducted.
Upon confirmation of the detailed test work and ongoing resource re-modelling, a Preliminary Economic Assessment (âPEAâ) will be considered for La Cigarra. The PEA would focus on the development of La Cigarra as an open pit heap leach operation transitioning into a milling operation with higher grade sulfides. Heap leach operations typically have much lower capital requirements and lower operational costs over milling.