- Preliminary tests at TOMRA in Germany indicate the mineralization at Iska Iska is amenable to “ore-sorting” with removal of at least 40% of the waste in the Polymetallic Domain and up to 80% in the Tin Domain which would substantially increase concentrator feed grades as well as reduce future operating costs and significantly lower the cut off grades (COG) for the pending mineral resource estimate (MRE).
- Positive “ore-sorting” results were obtained from composite samples of both the tin (Sn) and polymetallic (Ag-Zn-Pb) mineralization domains in the Santa Barbara deposit indicating its wide applicability throughout the entire deposit.
- Further metallurgical studies conducted by Wardell Armstrong International on a composite sample of the tin mineralization has improved tin concentrator recovery to 50%. This recovery is un-optimised and has been achieved using a mixture of Multi Gravity and tin flotation techniques which are specifically designed to recover the finer grained cassiterite.
- The concentrator could produce an approximately 5%Sn concentrate grade amenable to the tin fuming process that ultimately could produce a 60-70%Sn concentrate for smelting.
- The level of metallurgical and pyrometallurgical work that has been conducted is exceptionally high for an inaugural MRE but is justifiable due to the significance of this large potentially open pittable tin and polymetallic resource.
- The additional metallurgical/mineralogical knowledge will enable Eloro to rapidly move towards a preliminary economic assessment (PEA).
TORONTO, July 26, 2023 (GLOBE NEWSWIRE) -- Eloro Resources Ltd. (TSX: ELO; OTCQX: ELRRF; FSE: P2QM) (“Eloro”, or the “Company”) is pleased to announce major advances on metallurgy for the Iska Iska silver-tin polymetallic project in the Potosi Department of southern Bolivia. These tests were directed by Mike Hallewell, C.Eng., Eloro’s Senior Strategic Metallurgist and a qualified person (QP) as defined by National Instrument 43-101 (NI 43-101). in consultation with Micon International Limited Principal Metallurgist, Richard Gowans, P.Eng., an independent QP.
Work by the Eloro geological team at Iska Iska led by Dr. Bill Pearson, P.Geo., Executive Vice President of Exploration and Dr. Osvaldo Arce, P.Geo., Manager of Minera Tupiza, indicates that Santa Barbara is essentially two major deposits in one as shown in Figure 1. Tin (Sn) mineralization with silver (Ag) dominates in the western and deeper portions of the deposit (Tin Domain) while in the eastern and southern shallower parts of the deposit, polymetallic silver-zinc-lead (Ag-Zn-Pb) mineralization predominates (Polymetallic Domain). The overall deposit as presently drilled extends more than 1,200m along strike, is up to 800m wide and extends to a depth of at least 1,000m with mineralization open in all directions.
Tom Larsen, CEO of Eloro, said: “These positive metallurgical tests, particularly the “Ore-sorting” tests at TOMRA, have a major positive impact on the potential future production at Iska Iska. For this reason, and in consultation with our independent consultants, Micon International, we deferred completion of the inaugural MRE until these tests were completed and the results could be fully incorporated into the final MRE which is now expected to be released in latter August.”
Mike Hallewell, C.Eng, Eloro’s Senior Strategic Metallurgist commented: “The level of metallurgical and pyrometallurgical work that has been conducted thus far at Iska Iska is exceptionally high for an inaugural MRE but is justifiable due to the significance of this large potentially open pittable tin and polymetallic resource. This additional metallurgical/mineralogical knowledge will enable Eloro to rapidly move towards a preliminary economic assessment (PEA).”
Metallurgically the two different domains require different approaches to optimize recoveries. As much of the mineralization in both domains occurs in veins and vein breccias, it was felt that “ore-sorting” technology developed by TOMRA could have a significant impact by selectively removing waste material resulting in a significant reduction in operating costs while at the same time producing a major increase in grades of feed to the grinding circuit.
256 rocks representing five different lithological groups within the Polymetallic Domain and five different lithological and tin grade groups within the Tin Domain were scanned using the on-site GeologicAI core scanner and then subsequently sent for amenability testing at TOMRA in Wedel, Germany. The preliminary images and assays indicate a positive response to XRT Ore sorting.
Based upon these results, the preliminary indications are at least 40% of the run-of-mine (ROM) polymetallic mineralization could be rejected as waste while for the Tin Domain, as much as 80% of the weight can be rejected as sub – cutoff grade (COG) waste. Ore sorting will significantly increase concentrator feed grades which will enhance concentrator recovery in both domains. In addition, bulk mining techniques can be employed without resultant dilution issues and this will reduce downstream processing costs.
The positive results obtained justify the diamond drilling of larger size diameter holes to produce bulk samples of both Polymetallic and Tin Domains for “Cascade” testing at TOMRA, Germany. The resultant XRT pre-concentrated product will be used for the downstream PEA studies.
Optimizing Tin Recovery
Wardell Armstrong International, based at the old Wheal Jane tin mine site in Cornwall, England have conducted further tin optimisation testing on a composite sample from the tin domain, drawing on their strong historical background with tin studies. The main thrust of this work was to identify ways of increasing the tin recovery in the concentrator and consisted of Falcon Continuous Roughing followed by multi-gravity separators (MGS) and cleaning of Falcon Rougher Concentrates. These multi-gravity technologies can recover the bulk of the recovered tin in as coarse a grain size possible. The Falcon tailings are then reground prior to a tin flotation rougher stage where much finer cassiterite is recovered using MGS cleaning of the resultant tin flotation rougher concentrates. The combined multi gravity concentrator and tin float concentrator tin recovery was increased to 50% using this flowsheet and further optimisation studies of this flowsheet have been identified which will form part of the PEA study using the XRT pre-concentrated products as mentioned above.
The University of Oruro has also tested other pre-concentration techniques including Dense Media Separation (“DMS”) using heavy liquids. The DMS testwork results for the three different grade samples tested were positive, matching the XRT “Ore sorting” mentioned above where as much as80% of the weight can be rejected as floats at sub-COG waste in the Tin Domain. This is a positive result and provides further options to increase the quantity of waste rejected by using DMS as a potential further stage of pre-concentration on XRT products and/or the nominal -10mm that is too fine to be XRT “Ore Sorted”. This provides further confidence that the low-grade tin domain can be effectively upgraded.
Figure 1 – Plan Map Showing Major Tin and Polymetallic Domains in the Santa Barbara Deposit, Iska Iska
Dr. Osvaldo Arce, P. Geo., General Manager of Eloro’s Bolivian subsidiary, Minera Tupiza S.R.L., and a Qualified Person (QP) in the context of NI 43-101, has reviewed and approved the technical content of this news release. Dr. Bill Pearson, P.Geo., Executive Vice President Exploration Eloro, and who has more than 45 years of worldwide mining exploration experience, including extensive work in South America, manages the overall technical program, working closely with Dr. Osvaldo Arce, P.Geo. Dr. Quinton Hennigh, P.Geo., Senior Technical Advisor to Eloro and Independent Technical Advisor, Mr. Charley Murahwi P. Geo., FAusIMM of Micon are regularly consulted on technical aspects of the project.
Metallurgical work was directed by Mike Hallewell, B.Sc, F.S.A.I.M.M., F.I.M.M.M., C.Eng., Eloro’s Senior Strategic Metallurgist, a QP as defined by NI 43-101, in consultation with Micon International’s Principal Metallurgist, Richard Gowans, P.Eng., an independent QP as defined by NI 43-101. “Ore-sorting” tests were completed at TOMRA’s facilities in Wedel, Germany. TOMRA GmbH are a leading technical authority in XRT Ore sorting. Note that the term “Ore” is part of the registered product name of TOMRA and the use of the term “ore” in this press release does not imply that the mineralization at Iska Iska is “ore” as defined by NI 43-101.
Tin optimization tests were completed at the facilities of Wardell Armstrong International in Cornwall, England. Wardell Armstrong International are an internationally recognised consulting group. The metallurgical testwork carried out at the University of Oruro, Bolivia facility has been found to yield accurate results in comparison to similar analysis at internationally accredited laboratories hence the results are considered reliable for preliminary analysis.
Eloro utilized both ALS and AHK for drill core analysis, both of whom are major international accredited laboratories. Drill samples sent to ALS are prepared in both ALS Bolivia Ltda’s preparation facility in Oruro, Bolivia and the preparation facility operated by AHK in Tupiza with pulps sent to the main ALS Global laboratory in Lima for analysis. More recently Eloro has had ALS send pulps to their laboratory at Galway in Ireland. Eloro employs an industry standard QA/QC program with standards, blanks and duplicates inserted into each batch of samples analyzed with selected check samples sent to a separate accredited laboratory.
Drill core samples sent to AHK Laboratories are prepared in a preparation facility installed and managed by AHK in Tupiza with pulps sent to the AHK laboratory in Lima, Peru. Au and Sn analysis on these samples is done by ALS Bolivia Ltda in Lima. Check samples between ALS and AHK are regularly done as a QA/QC check. AHK is following the same analytical protocols used as with ALS and with the same QA/QC protocols.
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 DHK-15 which returned 129.60 g Ag eq/t over 257.5m (29.53g Ag/t, 0.078g Au/t, 1.45%Zn, 0.59%Pb, 0.080%Cu, 0.056%Sn, 0.0022%In and 0.0064% Bi 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 442 g Ag eq/t (164.96 g Ag/t, 0.46%Sn, 3.46% Pb and 0.14% Cu) over 166m including 1,092 g Ag eq/t (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, 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. In its September 20, 2022 press release, the Company reported that new downhole geophysical data has significantly extended the strike length of the high-grade feeder zone at Santa Barbara a further 250m along strike to the south-southeast from existing drilling. The 3D inverse magnetic model which correlates very strongly with the conductive zone suggested that the high-grade feeder zone may extend across the entire caldera for as much as a further 1 km along strike for a total potential strike length of at least 2 km. As reported, the definition drill program was modified to sectionally drill this potential extension with the intention of defining a major open pittable deposit in the valley of the caldera.
The Company completed 84,495m of drilling in 122 holes from the definition drill program in the Santa Barbara target area.
On November 22, 2022, Eloro announced the acquisition of the Mina Casiterita and Mina Hoyada properties covering 14.75 km2 southwest and west of Iska Iska. These properties connect with the TUP-3 and TUP-6 claims previously staked by Eloro. Eloro has also staked additional land in the area. Following the acquisition, the total land package in the Iska Iska area to be controlled by Eloro will total 1,935 quadrants covering 483.75 km2.
Artisanal mining in the 1960’s identified high grade tin (Sn) veins on the Mina Casiterita property that are hosted in an intrusive dacite. Production from 1962 to 1964 is reported by the Departamento Nacional de Geología in Bolivia to be 69.85 tonnes grading 50.60% Sn.
Recently completed magnetic surveys by Eloro has outlined an extensive, near surface, magnetic intrusive body on the Mina Casiterita property immediately southwest of Iska Iska. This intrusive hosts the previously mined high-grade tin veins and is very likely the continuation of the porphyry tin intrusion projected to be below the epithermal Ag-Sn-Zn-Pb mineralization at Iska Iska.
Work by the Eloro geological team at Iska Iska indicates that Santa Barbara is essentially two major deposits in one. Tin (Sn) mineralization with silver (Ag) dominates in the western and deeper portions of the deposit (Tin Domain) while in the eastern and southern shallower parts of the deposit, polymetallic silver-zinc-lead (Ag-Zn-Pb) mineralization predominates (Polymetallic Domain). The overall deposit as presently drilled extends more than 1,200m along strike, is up to 800m wide and extends to a depth of at least 1,000m with mineralization open in all directions.
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 Barrick’s Lagunas Norte Gold Mine and Pan American Silver’s 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.
Information in this news release may contain forward-looking information. Statements containing forward-looking information express, as at the date of this news release, the Company’s plans, estimates, forecasts, projections, expectations, or beliefs as to future events or results and are believed to be reasonable based on information currently available to the Company. There can be no assurance that forward-looking statements will prove to be accurate. Actual results and future events could differ materially from those anticipated in such statements. Readers should not place undue reliance on forward-looking information.
Neither the TSX nor its Regulation Services Provider (as that term is defined in the policies of the TSX) accepts responsibility for the adequacy or accuracy of this release.
A photo accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/42ba87ae-c709-4ffe-9ef2-971c74dab8df