VANCOUVER, British Columbia, April 15, 2019 (GLOBE NEWSWIRE) -- Otis Gold Corp. (“Otis” or the “Company”) (TSX-V: OOO) (OTC: OGLDF) is pleased to announce that metallurgical work conducted at Kilgore on the lower volcanic stratigraphy, referred to as the “Sill Domain”, has returned favourable simulated heap leach gold recovery results of 83.5% on 38mm (1.5”) crush material. Additionally, final gold grades from column leach tests on crushed core show a 59% increase in gold grade. The results continue to demonstrate very favourable metallurgy at Kilgore, and the increase in recovered gold grade confirm that gold grades in the existing resource are potentially under-reported.
Highlights of the metallurgical testing results are as follows:
- Bottle roll leach tests on Sill Domain material achieved gold extractions averaging 86.4% at 10 mesh, and 93.0% at 200 mesh;
- Column leach test results from Sill Domain material show 74.8% gold recovery from 12.5mm (0.5”) crushed core, and 83.5% gold recovery from 38mm (1.5”) crushed core. The 38mm crushed core leached slower but has higher overall gold extraction; and
- Final gold test grades from Sill Domain material show a 59% increase, with calculated final grades returning up to 1.42 g/t Au from initial head assay test grades of 0.89 g/t Au.
Metallurgical Testing - 2019
Otis submitted approximately 1,400 kg of whole PQ core from drill hole 17OKC-379 for metallurgical testing; the hole is a twin of 17OKC-356 that returned 129.6 metres(m) averaging 1.66 g/t Au from 155.4 to 285.0m, including 24.4m averaging 3.45 g/t Au from 157.0 to 181.4m (true widths are estimated between 80% and 100% of the drilled interval). These drill results come from a package of lithologies including Tertiary volcanic and Cretaceous sedimentary rocks. Further details of the metallurgical test work can be found on the Otis website under the Kilgore metallurgy tab at www.otisgold.com.
Results from the metallurgical testing are summarized as follows:
- Bottle roll leach tests on Sill Domain material achieved gold extractions averaging 86.4% at 10 mesh, and 93.0% at 200 mesh; silver extraction during bottle roll leach tests average 57%;
- Column leach test results from Sill Domain material gave 74.8% gold recovery from 12.5mm (0.5”) crushed core, and 83.5% recovery from 38mm (1.5”) crushed core;
- Final gold test grades from Sill Domain material show a 59% increase, with calculated final grades of up to 1.42 g/t Au returned from initial head assay test grades of 0.89 g/t Au;
- Optical mineralogy combined with whole rock and rare earth element analysis confirms that the Sill Domain material are porphyritic andesite flows; and
- Aspen formation rocks have been confirmed as quartz-adularia altered, arkosic, turbidite sediments.
Metallurgical testing at Kilgore is ongoing, with current work comprising a suite of tests on PQ core from near surface volcanic rocks. Testing will include the addition of 76mm (3”) column leach tests to better simulate run-of-mine open pit heap leaching (ROM-OPHL).
Throughout the history of the Kilgore project, metallurgical studies have been ongoing. The following represents a summary of this metallurgical testing. It is important to note that tests conducted before the introduction of NI 43-101 do not meet current reporting requirements and are provided for reference only. For full details on metallurgical testing, please refer to NI 43-101 Technical reports dated August 14, 2018 and July 31, 2012; which can be found on SEDAR or the Otis website.
Echo Bay – 1995/1996 Metallurgical Testing
Echo Bay Mines submitted drill core and reverse circulation cuttings for metallurgical testing in 1995 and 1996, in anticipation of starting up a small-scale open pit heap leach mining operation on the Kilgore deposit. The material submitted was divided into three classes: oxide, sulfide and mixed material.
Highlights of 1995 and 1996 metallurgical testing were:
- Bottle roll test gold extractions varied from 82.9% to 94.8% for the three material types;
- Column leach tests on oxide material of 12.5mm (0.5”) crushed core returned gold extraction up to 94.3%;
- Column leach tests on mixed material of 25mm (1”) crushed core returned gold extraction up to 85.5% after 75 days; and
- An independent study in 1996 concluded that there is no sulfide mineralization and that variation in gold extractions over time is due to porosity, therefore longer leach times would favor increased gold extractions.
Further details of the Echo Bay’s metallurgical test work can be found on the Otis website under the Kilgore metallurgy tab at www.otisgold.com.
Otis Gold – 2010/2011 Metallurgical Testing
In 2010, Otis Gold submitted four composite samples to McClelland Laboratories Inc. of Reno, Nevada. The composites comprised three principal host rock types identified at that time from the Kilgore deposit: Aspen sandstone, lithic tuff, and felsic dike and were derived from four drill holes: 09OKC-195, -197, -205 and -206. The calculated head grades are illustrated in the table below.
|Rock type||Gold grade g/t||Silver Grade g/t|
McClelland stated in conclusion that:
- The Kilgore drill core composites were amenable to simulated heap leach cyanidation treatment, at an 80% passing 12.5mm (0.5”) feed size;
- Gold recovery rates generally were fairly slow. Column test gold extractions ranged from 70% to 85%, after 80 to 109 days of leaching; and
- Gold recoveries from bottle roll tests obtained after 96 hours ranged from 50.0% to 78.9%.
Otis Gold - 2012 Metallurgical Testing
Three drill core composites were submitted to McClelland Laboratories Inc. for metallurgical testing with the objective of determining heap leach amenability of the composites to comparative feed sizes. The three composites came from whole PQ core from drill holes 11OKC-285 and -287, twin holes of 11OKC-258 and 10OKC-228 respectively. The composites comprised 38m (124.5 ft) of oxidized lithic tuff with an average grade of 0.46 g/t Au; 38.1 m (125.0 ft) of oxidized felsic dike, and 32.9m (108 ft) of unoxidized felsic dike with an average grade of 1.15 g/t Au (true widths are estimated between 80% - 100% of the drilled interval).
McClelland stated in conclusion that:
- All three core composites were amenable to simulated heap leach cyanidation treatment at 80% passing both -38mm (1.5”) and 12.5mm (0.5”) feed sizes;
- 38mm (1.5”) feed size gave gold extractions from 71% to 85%; 12.5mm (0.5”) feed size gave gold extractions ranging from 74.5% to 85.5%;
- Oxidized lithic tuff did not show feed size sensitivity to gold extraction;
- Oxidized felsic dike gold extraction increased with decreasing feed size; and
- Unoxidized felsic dike required a longer leach cycle than the other two composites.
Alan Roberts, MSc, CPG, Vice President of Exploration, serves as the Qualified Person for this news release and has reviewed and approved the technical content contained herein.
About the Kilgore Project
The Kilgore project lies on the north-eastern margin of the Miocene-Pliocene Kilgore Caldera complex in the Eastern Snake River Plain, Idaho. The Kilgore project includes the Kilgore deposit with a current NI 43-101 resource comprising: Indicated Resource of 825,000 ounces Au in 44.6 million tonnes at a grade of 0.58 g/t Au and an Inferred Resource of 136,000 ounces Au in 9.4 million tonnes at a grade of 0.45 g/t Au (see 2018 Kilgore Project NI 43-101 Technical Report and Mineral Resource Estimate dated August 14, 2018). The Kilgore deposit is a low-sulphidation, gold bearing, quartz-adularia epithermal system hosted in Tertiary volcanic rocks, local Tertiary intrusive rocks, and basement Late Cretaceous, Aspen Formation sedimentary rocks.
About the Company
Otis is a resource company focused on the acquisition, exploration, and development of precious metal deposits in Idaho, USA. Otis is currently developing its flagship property, the Kilgore project, located in Clark County, Idaho and the Oakley project, located in Cassia County, Idaho.
ON BEHALF OF THE BOARD
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President & CEO
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|Forward Looking Statements|
|Certain information in this news release contains forward-looking statements and forward-looking information within the meaning of applicable securities laws. All statements, other than statements of historical fact are forward-looking statements. Forward-looking statements are based on the beliefs and expectations of Otis as well as assumptions made by and information currently available to Otis's management. Such statements reflect the current risks, uncertainties and assumptions related to certain factors including, without limitations, drilling results, the Company's expectations regarding mineral resource calculations, capital and other costs varying significantly from estimates, production rates varying from estimates, changes in world metal markets, changes in equity markets, uncertainties relating to the availability and costs of financing needed in the future, equipment failure, unexpected geological conditions, imprecision in resource estimates or metal recoveries, success of future development initiatives, competition, operating performance, environmental and safety risks, delays in obtaining or failure to obtain necessary permits and approvals from local authorities, community agreements and relations, and other development and operating risks. Should any one or more of these risks or uncertainties materialize, or should any underlying assumptions prove incorrect, actual results may vary materially from those described herein. Although Otis believes that assumptions inherent in the forward-looking statements are reasonable, forward-looking statements are not guarantees of future performance and accordingly undue reliance should not be put on such statements due to the inherent uncertainty therein. Except as may be required by applicable securities laws, Otis disclaims any intent or obligation to update any forward-looking statement.|