Zephyr releases metallurgical results for Dawson
HALIFAX, NS, Feb. 26, 2015 /CNW/ - Zephyr Minerals Ltd. ("Zephyr" or the "Company") (TSX-V: ZFR) is pleased to announce metallurgical test results on the Dawson Gold Project in Colorado, USA. The project is comprised of 5 separate gold mineralized segments over a length of 2.6 kilometers, two of which have undergone metallurgical test work, the Dawson zone, and the Windy Gulch zone. Highlights include test results that indicate approximately 50% of the gold contained in the samples tested is recoverable using conventional gravity processing techniques and approximately 90% by flotation processing techniques.There were two metallurgical test programs conducted on samples from the Dawson Gold Project. The first program was conducted by Hazen Research Inc. ("Hazen") in Golden, Colorado in 1991. The second was by Bureau Veritas Commodities Canada Ltd., Inspectorate Metallurgical Division ("Inspectorate") completed in 2015. The Hazen test program tested two composite samples (altered and unaltered) from the Dawson zone while the Inspectorate study tested a composite sample (predominately highly altered) from the Windy Gulch zone. Approximately 85% of the current resource is in the Dawson zone while the remaining 15% of the resource is in the Windy Gulch zone.
The Hazen metallurgical test work samples are representative of about 80% to 90% of the Dawson zone. The Windy Gulch zone samples are from near surface, predominantly highly altered and are representative of approximately 70% of the currently delineated resource at Windy Gulch.
Gravity Tests:
Hazen test work: Preliminary gravity concentration tests were conducted to investigate the potential for gold recovery as a function of grind and were conducted on both the altered and unaltered composites. The results for the altered material show that approximately 50% of the gold values were recovered to the shaking table concentrate with grind size having no significant effect, up to 129 microns. Comparably, results for the unaltered material show gold recoveries to the concentrate to be about 60%. More importantly, the data show that 31% of the gold values for the altered and 49% for the unaltered materials were recovered to very high-grade free gold concentrates grading 222 kg/t (~6,500 oz/st) and 105 kg/t (3,062 oz/st), respectively.
Inspectorate test work: Preliminary gravity concentration tests were conducted using a centrifugal gravity concentrator at primary grind size ranges of 74 microns and 110 microns. A double pass through the centrifugal concentrator was followed by one upgrading stage on each primary gravity concentrate using panning. The results indicate that gold recoveries up to 50% may be projected. The results of the two tests showed that the first pan concentrates recovered 24% and 31% of the gold into products assaying 2,113 g/t (62 oz/st) and 2,930 g/t (85 oz/st) respectively.
Flotation Tests:
Hazen test work: Preliminary rougher flotation tests were conducted using conventional reagents and a nominal 74 micron primary grind size on altered and unaltered samples. Nearly 86% of the total gold was recovered to a flotation concentrate assaying 169 g/t and at 5.4 weight percent of the feed for the altered sample, and over 94% of the gold was recovered to a flotation concentrate assaying 135 g/t and at 7.8 weight percent of the feed for the unaltered sample.
Inspectorate test work: Three rougher flotation kinetics tests were conducted on the composite at primary grind sizes of 167, 109, and 75 microns to investigate the effect of grind size and particle liberation on gold grade and recovery. All tests were run at a natural pH and using conventional reagents. Metallurgical results are detailed in table below.
| Test | Grind | Mass | Assays | % Rougher Recovery | ||||
| No | P80 (µm) | Pull, % | Au g/t | Ag g/t | % S | Au | Ag | S |
| F 1 | 167 | 13.1 | 41.9 | 17.4 | 3.2 | 77.1 | 56.9 | 87.5 |
| F 2 | 109 | 16.2 | 35.8 | 16.4 | 2.6 | 82.4 | 68.0 | 89.4 |
| F 3 | 75 | 26.9 | 22.0 | 10.4 | 1.5 | 87.8 | 71.9 | 90.0 |
A combined centrifugal gravity separation plus rougher-cleaner flotation test was conducted at 110 micron primary grind size. The pan 1 concentrate recovered 24.2% of the gold at a grade of 2,113 g/t while total gravity concentrate recovery was 59.9% at a cumulative gold grade of 126.6 g/t. When combined with flotation 1st concentrate, recovery increases to 78.3% at a cumulative gold grade of 55.9 g/t.
It is apparent from these results that the Windy Gulch samples respond less favourably to flotation in particular and gravity separation in general than the Dawson samples tested at Hazen. This is highly likely due to the predominately highly altered (oxidized) nature of the Windy Gulch samples.
In conclusion, the results of gravity and flotation tests indicate a technically viable process option with excellent gold recoveries of over 90% for the unaltered resource. This unaltered resource comprises the majority of the deposit on the Dawson Gold Project.
About Zephyr Minerals Ltd.
Zephyr Minerals Ltd. is a gold exploration and development company focused on advancing its flagship Dawson Gold Project in Colorado, USA. Dawson is an advanced stage high-grade gold property with excellent blue sky potential. In the fall of 2013, Zephyr announced filing on SEDAR a technical report, prepared in accordance with National Instrument -- Standards of Disclosure for Mineral Projects ("NI 43-101") on Dawson. Zephyr has commenced base line environmental studies as part of its efforts to advance the Dawson Project with the ultimate goal of production, subject in part to a positive economic study.
Qualified Persons (QPs), as defined under National Instrument 43-101 regulations, who are responsible for the technical content of this press release are as follows:
Metallurgical Content: Mr. H.M. Matt Bolu, Principal Metallurgical Engineer of BOMENCO Inc., and the Company's metallurgical consultant, who is a P.Eng. registered with the Association of Professional Engineers and Geoscientists of BC (APEGBC). Geological Content: Mr. Mark Graves who is a P.Geo. registered with the Association of Professional Geoscientists of Nova Scotia (APNS)
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
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Contact
David H. Felderhof, Executive Vice President
Zephyr Minerals Ltd.
T: 902 446-4189
F: 866 941-4715
E: info@zephyrminerals.com
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