Bulk Tonnage Metallurgical Tests Return Significantly Higher Silver Head Grade of 91 g Ag/t Compared with the 31 g Ag/t Average Grade from the Original Twinned Holes in the Polymetallic Domain at Iska Iska, Potosi Department, Southwestern Bolivia
• Metallurgical tests from a 6.3 tonne PQ drill core bulk sample representative of the higher grade Polymetallic (Ag-Zn-Pb) Domain returned a significantly higher average silver value of 91 g Ag/t compared to the weighted average grade of the original twinned holes at 31 g Ag/t strongly suggesting that the average silver grade is likely significantly underreported in the original twinned holes due to the much smaller sample size
• The metallurgical tests confirm the viability of “Ore-Sorting” and Dense Media Separation at Iska Iska Project.
• Excellent pre-concentration results from the higher grade Polymetallic (Ag-Zn-Pb) Domain are now proven in a bulk sample. The 91.9% recovery of silver and lead with 76.0% recovery of zinc into a high grade (176g/t Ag, 1.88%Pb, 2.86%Zn = 299.15 g Ag eq/t) potential mill feed stream that contains only 46.6% of the Run of Mine Tonnage.
• The introduction of the pre-concentration stage allows Eloro to have more operational flexibility based upon conducting economic trade off scenarios between reducing downstream capital-operating costs and optimizing overall metal recoveries.
• XRT Ore Sorting is proposed for the coarser size fractions and Dense Media Separation (“DMS”) for treatment of the finer fractions so as to pull on the strengths of both technologies. The size split between the two technologies is unoptimized and the current results support the ability to potentially “ore sort” slightly coarser rocks than tested which would further increase the overall benefits of pre-concentration.
• Tin (Sn), although not included in the 132 million tonnes higher-grade starter pit area (MRE), is expected to potentially contribute to the enhanced values in the initial Preliminary Economic Assessment (“PEA”) with additional metallurgical testing and infill drilling.
Eloro Resources Ltd. (TSX: ELO; OTCQX: ELRRF; FSE: P2QM) (“Eloro”, or the “Company”) is pleased to announce the final results of its bulk metallurgical test program on the Iska Iska silver-tin polymetallic project in the Potosi Department of southwestern Bolivia.
Tom Larsen, CEO of Eloro commented: “The substantive difference in average silver grade in the bulk sample compared to the twinned holes strongly suggests that the silver grade in the two original twinned holes is likely significantly underreported due to the much smaller sample size. The recently released results from the definition drill program in the same general area within the initial MRE (see Eloro press releases dated December 18, 2023 and January 11, 2024) which yielded a number of higher-grade Ag intersections, also reflected in the improved silver grade equivalent values, further supports this underreported silver grade conclusion. These results highlight the fact that tighter spaced drilling is required to have a more representative sampling of high-grade areas in the Iska Iska deposit to obtain a more accurate estimate of the likely true overall grade.
Mr. Larsen continued: “While the initial test program focussed on the higher-grade part of the Polymetallic Domain as this is where the bulk of the current mineral resource is, further testwork is planned on the Tin Domain which is very under-drilled. The recent definition drilling reported significant Sn results and it is expected that additional definition drilling will expand and upgrade the tin resource so that it can potentially be included in the preliminary economic assessment (“PEA”) in progress.”
Mike Hallewell, newly appointed as Eloro’s Senior VP Engineering Projects/Metallurgy said: “The results indicate that 91.9% of the Silver and Lead, and 76.0% of the zinc can be pre-concentrated into a relatively high-grade mill feed product constituting only 46.6% of the original tonnage. The upgraded product results in higher flotation plant feed grades that will assist flotation stage recoveries. Both XRT “Ore Sorting” and DMS are well known, low risk separation technologies that provide Eloro with a great opportunity to significantly reduce operating and capital costs, reduce the mine cut-off grade and enhance flotation stage recoveries. The small differences in the -60mm+25 mm and -25mm+9.5 mm size fractions suggests that the top size could be increased above 60 mm. This would increase the percentage of Run-of-Mine (“ROM”) secondary crushed material that would report for pre-concentration, which would enhance the overall benefit of pre-concentration. The much higher Ag grades of 91 g Ag/t in the bulk metallurgical sample as compared to the twinned holes grade of 31g Ag/t is very encouraging. This along with the very high test recoveries for Ag, will have a major positive effect on potential project economics.”
METALLURGICAL TEST PROGRAM
As previously reported (see Eloro press release dated November 1, 2023), three metallurgical drill holes totalling 940 m were completed at the Iska Iska project. Two holes targeted the higher-grade Polymetallic (Ag-Pb-Zn) Domain while the third hole sampled the higher-grade Tin Polymetallic (Sn-Ag-Pb) Domain. These metallurgical holes were drilled using PQ core (~85mm Ø) and were designed to twin previous HQ core drill holes which contained representative mineralization with values for the predominant higher grade Polymetallic (Ag-Zn-Pb) outlined in Table 1. As shown in Figure 1, these metallurgical holes were targeted in the potential higher-grade starter pit area at Santa Barbara which contains an estimated mineral resource at a cutoff of NSR US$25/t of 132 million tonnes at 24.3 g Ag/t, 1.11% Zn and 0.50% Pb (72.06 g Ag eq/t) (see Eloro press release dated October 17, 2023). The drill core selected for testing from these holes, which totaled 7.9 tonnes from 519 m of drill core, was shipped to Wardell Armstrong International (“WAI”) in Cornwall, England, for crushing to 60mm and sizing into five different size fractions. The -60 mm+9.5 mm crushed and sized product was sent to TOMRA GmbH based in Wedel, Germany, for separate cascade “ore-sorting” tests on -60 mm+25 mm and -25mm+9.5 mm.
The testing program reported in this release focussed on the two PQ drill holes in the Polymetallic Domain which contain the majority of the tonnage and metal, namely MET-DSBU-10 and MET-DSB-30. The sample size tested was 6.3 tonnes from 418m of the overall drill core sent to WAI. Further PQ diamond drilling is planned to obtain a bulk metallurgical sample from the sulphide Tin Domain, in addition to testing MET-DSB-32 which is in the oxide zone of the Tin Domain. The Tin Domain, although it contains an inferred mineral resource of 110 million tonnes grading 0.12% Sn, 14.2 g Ag/t and 0.14% Pb (38.02 g Ag eq/t) (see Eloro press release of October 17, 2023), is very under-drilled especially to the west. The recent definition drilling reported significant Sn results and it is expected that additional definition drilling will expand and upgrade the Sn resource so that it can potentially be included in the PEA in progress.
The -9.5 mm+0.85 mm size fractions were subject to heavy liquid analysis performed on two separate size fractions (-9.5mm+5mm and -5mm+0.85 mm) to identify the amenability of the finer size fractions to Dense Media Separation (“DMS”). The -0.85 mm material and the pre-concentrated products from the “ore sorting” and heavy liquid tests will provide testwork material for further PEA level grinding and flotation metallurgical testwork at WAI. This work builds on previous metallurgical test work using representative Iska Iska samples, as summarized in the Company’s National Instrument 43-101 (“NI 43-101”) Technical Report filed on Sedar+ (see Eloro press release dated October 17, 2023).
These metallurgical drill holes also provided an important comparative bulk sample test of mineralization grade relative to the weighted average grade of the twinned holes.
Figure 1: Cross Section of MRE Block Model showing Locations of Metallurgical PQ Holes and Original Holes Twinned
Notes: OP = Open Pit defining mineral resource estimate (MRE), NSR – Net Smelter Revenue, HG = Higher Grade, LG= Lower Grade. Block model from Micon International Limited MRE (see Eloro press release dated October 17, 2023)
SUMMARY HIGHLIGHTS
1. Overall Summary Tests
The main focus of this testwork phase has been on the predominant Ag-Pb-Zn Sulphide Domain which accounts for the majority of the mineral resource tonnage and metal values. Table 1 below shows the compelling results from this preliminary study on the full bulk PQ sample representative of the higher grade Polymetallic (Ag-Zn-Pb) Sulphide domain. The results indicate that 91.9% of the silver and lead, and 76.0% of the zinc can be pre-concentrated into a relatively high-grade mill feed product constituting only 46.6% of the original tonnage. The upgraded product results in higher flotation plant feed grades that will assist flotation stage recoveries. While 91.1% of the bulk sample (-60mm+0.85mm) reports to pre-concentration the remaining 8.9% of the material by-passes pre-concentration and can be blended directly with the pre-concentrated feed ahead of grinding.
Table 1: Overall Pre-concentration Results
Table 2 below compares the individual back calculated head assays coming from the PEA preconcentration test work program with the assays from the 1/2 HQ twinned exploration holes. The overall weighted average Ag assay was significantly higher in the bulk PQ metallurgical hole sample at 91 g/t Ag as compared with the two original HQ geological twinned holes at 31 g/t Ag. This substantive difference in average Ag grade strongly suggests that the silver grade in the two original twinned holes is likely to be significantly underreported due to the much smaller sample size. The recently released results from the definition drill program in the same general area (see Eloro press releases dated December 18, 2023, and January 11, 2024) which yielded a number of higher-grade Ag intersections, further supports this conclusion. These results highlight the fact that tighter spaced drilling is required to have a more representative sampling of high-grade areas in the Iska Iska deposit to obtain a more accurate estimate of the likely true overall grade.
Table 2: Back Calculated Head Assay
2. Ag-Zn-Pb Sulphide Domain -60 mm+25 mm XRT Ore Sorter Result
In test 4.4, metal recoveries of 77.8%, 89.2% and 91.0% of zinc, lead and silver, respectively, were achieved into a pre-concentrate that comprised 38.1% of the feed weight. The pre-concentrate assayed 2.91% Zn, 2.05% Pb and 180g/t Ag (308.37 g Ag eq/t). These “ore” sorter results are presented in Table 3 and Figure 2 below.
Table 3: -60mm+25mm XRT “Ore” Sorter Cascade Results
Figure 2: -60mm+25mm Weight Yield Vs Metal Recovery to product
3. Ag-Pb-Zn Sulphide Domain -25 mm+9.5 mm XRT “Ore” Sorter Result
In test 1.4, metal recoveries of 81.9%, 89.5% and 89.6% for zinc, lead and silver, respectively, were achieved into a pre-concentrate that comprised 41.6% of the sample feed weight. The pre-concentrate assayed 2.96%Zn, 1.72%Pb and 183g/t Ag (305.13 g Ag eq/t). These “ore sorter” results are presented in Table 4 and Figure 3 below.
Table 4: -25mm+9.5mm XRT Ore Sorter Cascade Results
Figure 3 -25mm+9.5mm Weight Yield Vs Metal Recovery to product
4. Ag-Zn-Pb Sulphide Domain -9.5 mm+5.0 mm DMS Heavy Liquid Results
In 2.65 Specific Gravity (“SG”) sinks, metal recoveries of 85.3%, 92.7% and 92.3% of zinc, lead and silver, respectively, were achieved into a pre-concentrate that consisted of 45.9% of the feed weight. The 2.65 SG Sink product assayed 3.47% Zn, 2.38% Pb and 156 g/t Ag (314.61 g Ag eq/t). These heavy liquid test results are presented in Table 5 and Figure 4 below.
Table 5: -9.5mm+5.0mm DMS Heavy Liquid Results
Figure 4: -9.5mm+5.0mm Weight Yield Vs Metal Recovery to product
5. Ag-Zn-Pb Sulphide Domain -5.0 mm+0.85 mm DMS Heavy Liquid Results
In the 2.65 SG sinks, metal recoveries of 91.4%, 95.5% and 92.1% of zinc, lead and silver, respectively, were achieved into a pre-concentrate that comprised 49.5% of the feed weight. The 2.65 SG Sink product assayed 3.68%Zn, 2.37%Pb and 196g/t Ag (356.98 g Ag eq/t). These heavy liquid test results are presented in Table 6 and Figure 5 below.
Table 6: -5.0mm+0.85mm DMS Heavy Liquid Results
Figure 5: -5.0mm+0.85mm Weight Yield Vs Metal Recovery to product
Qualified Person (“QP”)
The metallurgical test program was directed by Mike Hallewell, B.Sc., F.I.M.M.M., F.S,A.I.M.M., F.M.E.S., C.Eng, Senior VP Engineering Projects/Metallurgy, and a Qualified Person (QP) as defined by NI 43-101 in consultation with Richard Gowans, P.Eng., an independent QP as defining by NI 43-101. Previous metallurgical work completed on Iska Iska is summarized in the NI 43-101 Technical Report (see Eloro press release dated October 17, 2023) prepared by Micon International Limited. Independent QPs for the Technical Report are Charley Murahwi, P.Geo., FAusIMM, Richard Gowans, P.Eng., Ing. Alan J. San Martin, MAusIMM (CP) and Abdul Aziz, Drame, P.Eng., all of whom are independent QP’s as defined by NI 43-101. Mr. Murahwi completed site visits in January 2020 and November 2022.
Wardell Armstrong International, based in Cornwall, UK, an internationally respected minerals processing laboratory, carried out the crushing of the bulk sample for shipment to TOMRA and completed metallurgical tests and assays on resulting products.
As part of the Tomra Group, TOMRA Mining, headquartered in Wedel, Germany, is a leading provider of ore sorting technologies, particularly specializing in X-ray Transmission (XRT) sorting. Among the latest advancements to enhance and improve finer particle separation, Tomra introduced a cutting-edge ejection module. This innovative module is specifically designed to increase separation accuracy and significantly reduce air consumption, thereby positively impacting operational expenditures (OPEX). Tomra’s extensive global reach has a proven track record in handling large-scale projects.
Dr. Bill Pearson, P.Geo., Vice President Exploration, Eloro and a QP as defined by NI 43-101 has reviewed and approved the technical content of this news release. Dr. Pearson who has more than 49 years of worldwide mining exploration, development and production experience, including extensive work in South America, manages the overall technical program, working closely with Dr. Osvaldo Arce, P.Geo. General Manager of Eloro’s Bolivian subsidiary, Minera Tupiza S.R.L., and a Qualified Person in the context of NI 43-101, who has supervised all field work carried out at Iska Iska. Dr. Arce supervised the on-site drilling and collection of the PQ core. Shipping to Wardell Armstrong in Cornwall for sample crushing was done through the facilities of Alfred H. Knight (AHK). Crushed material was shipped to Tomra in Germany for the cascade test on the ore-sorter then the concentrates were shipped to WAI for final metallurgical testing and assaying.
Silver equivalent (Ag eq) grades are calculated using 3-year average metal prices of Ag = US$22.52/oz, Zn = US$1.33/lb , Pb = 0.95/lb and Sn = US$12.20/lb, and preliminary metallurgical recoveries of Ag = 88%, Zn = 87%, Pb= 80% and Sn = 50%.
About Iska Iska
Iska Iska silver-tin polymetallic project is a road accessible, royalty-free property, wholly controlled by the Title Holder, Empresa Minera Villegas S.R.L. and is located 48 km north of Tupiza city, in the Sud Chichas Province of the Department of Potosi in southern Bolivia. Eloro has an option to earn a 100% interest in Iska Iska.
Iska Iska is a major silver-tin polymetallic porphyry-epithermal complex associated with a Miocene possibly collapsed/resurgent caldera, emplaced on Ordovician age rocks with major breccia pipes, dacitic domes and hydrothermal breccias. The caldera is 1.6km by 1.8km in dimension with a vertical extent of at least 1km. Mineralization age is similar to Cerro Rico de Potosí and other major deposits such as San Vicente, Chorolque, Tasna and Tatasi located in the same geological trend.
Eloro began underground diamond drilling from the Huayra Kasa underground workings at Iska Iska on September 13, 2020. On November 18, 2020, Eloro announced the discovery of a significant breccia pipe with extensive silver polymetallic mineralization just east of the Huayra Kasa underground workings and a high-grade gold-bismuth zone in the underground workings. On November 24, 2020, Eloro announced the discovery of the SBBP approximately 150m southwest of the Huayra Kasa underground workings.
Subsequently, on January 26, 2021, Eloro announced significant results from the first drilling at the SBBP including the discovery hole from 0.0m to 257.5m. Subsequent drilling has confirmed significant values of Ag-Sn polymetallic mineralization in the SBBP and the adjacent CBP. A substantive mineralized envelope which is open along strike and down-dip extends around both major breccia pipes. Continuous channel sampling of the Santa Barbara Adit located to the east of SBBP returned 164.96 g Ag/t, 0.46%Sn, 3.46% Pb and 0.14% Cu over 166m including 446 g Ag/t, 9.03% Pb and 1.16% Sn over 56.19m. The west end of the adit intersects the end of the SBBP.
Since the initial discovery hole DHK-15 which returned 29.53g Ag/t, 0.078g Au/t, 1.45%Zn, 0.59%Pb, 0.080%Cu and 0.056%Sn over 257.5m, Eloro has released a number of significant drill results in the SBBP and the surrounding mineralized envelope which along with geophysical data has defined an extensive target zone. On October 17, 2023, Eloro filed the NI 43-101 Technical Report outlining the initial inferred MRE for Iska Iska, prepared by Micon International Limited. The MRE was reported in two domains, the Polymetallic (Ag-Zn-Pb) Domain which is primarily in the east and south of the Santa Barbara deposit and the Tin (Sn-Ag-Pb) Domain which is primarily in the west and north. The Polymetallic Domain is estimated to contain 560Mt at 13.8 g Ag/t, 0.73% Zn & 0.28% Pb at an NSR cutoff of US$9.20 for potential open pit and an NSR cutoff of US$34.40 for potential underground. The majority of the mineral resource is contained in the constraining pit which has a stripping ratio of 1:1.
The Polymetallic Domain contains a higher-grade mineral resource at a NSR cutoff of $US25/t of 132 million tonnes at 1.11% Zn, 0.50% Pb and 24.3 g Ag/t which has a net NSR value of US$34.40/t which is 3.75 the estimated operating cost of US$9.20/t. The Tin Domain which is adjacent the Polymetallic Domain and does not overlap, is estimated to contain a mineral resource of 110Mt at 0.12% Sn, 14.2 g Ag/t and 0.14% Pb but is very under drilled.
The Company has completed a 5,267.7m definition drill program to upgrade and expand the higher-grade mineral resource in the Polymetallic Domain and has commenced a PEA led by Lycopodium.
About Eloro Resources Ltd.
Eloro is an exploration and mine development company with a portfolio of gold and base-metal properties in Bolivia, Peru and Quebec. Eloro has an option to acquire a 100% interest in the highly prospective Iska Iska Property, which can be classified as a polymetallic epithermal-porphyry complex, a significant mineral deposit type in the Potosi Department, in southern Bolivia. A recent NI 43-101 Technical Report on Iska Iska, which was completed by Micon International Limited, is available on Eloro’s website and under its filings on SEDAR. Iska Iska is a road-accessible, royalty-free property. Eloro also owns an 82% interest in the La Victoria Gold/Silver Project, located in the North-Central Mineral Belt of Peru some 50 km south of the Lagunas Norte Gold Mine and the La Arena Gold Mine.
For further information please contact either Thomas G. Larsen, Chairman and CEO or Jorge Estepa, Vice-President at (416) 868-9168.
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