By Big Al
Corvus Gold Receives Sulfide Gold Recovery of +90% Using AAO Process at the North Bullfrog Project, Nevada
Corvus Gold Receives Sulfide Gold Recovery of +90% Using AAO Process at the North Bullfrog Project, Nevada
April 27, 2017
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Vancouver, B.C… Corvus Gold Inc. (“Corvus” or the “Company”) – (TSX: KOR, OTCQX: CORVF) announces the initial results from testing the Atmospheric Alkaline Oxidation (“AAO”) method of oxidizing sulfide mineralization for low cost cyanide gold extraction (Figure 1). Initial results of the AAO method for oxidizing sulfide material resulted in overall gold recoveries of approximately 93% from milled material in the Sierra Blanca tuff (largest host unit), which is comparable to oxidized milled material recoveries in the current production plan. Results for the remaining three units are pending. Estimated additional operational cost to the mill material for the AAO process would raise the mill cutoff grade to approximately 0.65 g/t.
The current North Bullfrog model has several areas below the current designed pit bottom that could be mined at above the projected sulfide mill cutoff grade. Further test work is on going for both mill material as well as heap leach testing of lower grade material using the AAO process.
Figure 1 Comparing original sulfide floatation concentrate to post AAO process oxidized concentrate that is readily leachable with standard CIL gold extraction.
The AAO process has been extensively tested at the Hycroft project in northern Nevada where a pilot scale demonstration plant has been operated as well as test heap leach pads confirming the effectiveness of the processing technique. The AAO process has been included in the recent feasibility study done for the Hycroft project for commercial application.
Jeff Pontius, President and CEO of Corvus said, “The encouraging results from the application of the AAO process to North Bullfrog sulfide material could be a bonus to the project which already hosts a large oxide resource. In addition to the higher-grade, millable sulfide material, Corvus is conducting heap leach applications of AAO similar to the test work conducted at the Hycroft Mine which if positive, could amplify its impact on the project. The current oxide deposit in our PEA study is underlain by an extensive sulfide zone that if amenable to this new low-cost method of extraction could change the way we approach exploration and expansion of the North Bullfrog project and district.”
AAO Sulfide Oxidation Process Test work
The test work conducted by Hazen Research, Inc. on North Bullfrog sulfide material is testing the four rock types which host nearly all of the known sulfide mineralization on the project (Table 1). The current test results are from the Sierra Blanca unit, which hosts about 50% of the currently known sulfide mineralization on the North Bullfrog property. The test work conducted standard flotation concentration of the sulfide material which produced a high-quality concentrate that averaged 92% gold in just 12% of the original materials (9:1 concentration ratio) for the Sierra Blanca rock unit. That concentrate was then mixed with …read more
Source:: The Korelin Economics Report
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