10 juillet 2014
Columbus Gold's Eastside Project in Nevada Yields 95% Gold Recoveries from Metallurgical Testing
|Vancouver, BC, Canada, July 10, 2014. Columbus Gold Corporation (CGT: TSX-V) ("Columbus Gold")Columbus Gold Corp. (CGT) is pleased to report the results of initial metallurgical tests on gold and silver mineralization at its Eastside gold project in Esmeralda County, Nevada. |
Fourteen samples of rotary drill cuttings were selected for the initial metallurgical tests using 92 hour, cyanide-leach, bottle roll tests. Testwork was performed by Kappes,Cassiday, and Associates (KCA) in Reno, Nevada. The samples were selected to represent a wide range of gold and silver grade, differing depths below the surface, differing areas of the deposit, and differing oxidation.
One split of each of the fourteen samples was ground to 80%passing 200 mesh. The average recovery from cyanide leaching of this ground material was 95% for gold and 52% for silver. The gold recoveries ranged from 85% to 99%and the silver recoveries ranged from 27% to 79%. The entire KCA report is available for review at the following link:
Almost all gold mineralization drilled at Eastside is oxidized with the exception of only one deep intercept in Hole ES-32 which was unoxidized and sulfide-bearing, but is amenable to leaching with cyanide as shown by the KCA leach results of the sample taken from the 965-970 ft(294-296meters) deep interceptin vertical hole ES-32. The gold recovery from this unoxidized sample was 95% and the silver recovery was 79%.
In addition a second split of each of the 14 drill samples was processed "as is", or exactly as collected at the drill, with no grinding or crushing. These samples varied greatly from sample to sample in the amount of coarse and fine material present. The largest fragments of solid rock ranged up to ¾ of an inch (19 mm) in size. On the other hand, some of the samples had little rock above ½ inch in size (12 mm). A visual estimate of the amount of coarse versus fine material in each sample, and the maximum fragment sizes present, is contained in the KCA report linked above.
The recoveries from the 14 "as is" samples by cyanide leaching for 92 hours averaged 57% for gold and 18% for silver. The range ofrecoveries from the "as is" samples was extreme, ranging from 20% to 85 % for gold, and from 6% to 52% for silver. The wide range in results does not seem to be due to grade, depth, oxidation, or alteration type, but rather to the variation in the amount of coarse material in the samples. Further testing is in progress, beginning with screen analysis of raw samples.
The purpose of metallurgical tests on "as is" materials is to begin to understand if Eastside gold mineralizationmight be processed by heap leach techniques, although it is impossible to predict actual recoveries from such preliminary testing.Much larger samples, usually obtained by core drilling, and metallurgical testing of that core, including column leach tests, will be necessary before one can more accurately predict heap leach recoveries and properly evaluate crushing. Columbus management believes that these results are sufficiently encouraging to proceed with further testing. Core drilling is planned as part of the next drilling program currently being permitted.
Andy Wallace is a Certified Professional Geologist (CPG) with the American Institute of Professional Geologists and is the Qualified Person under NI 43-101 who has reviewed and approved the technical content of this press release. Mr. Wallace is a director of Columbus Gold and the principal of Cordilleran Exploration Company (Cordex), which is conducting exploration and project generation activities for Columbus Gold on an exclusive basis.
ON BEHALF OF THE BOARD,
Robert F. Giustra
Chairman & CEO
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This release contains forward-looking information and statements, as defined by law including without limitation Canadian securities laws and the "safe harbor" provisions of the US Private Securities Litigation Reform Act of 1995 ("forward-looking statements"), respecting drilling, testing, sampling, metallurgical studies, potential mining methods, permitting, the apparent reason for a wide range of recoveries and Columbus Gold's general exploration plans. Forward-looking statements involve risks, uncertainties and other factors that may cause actual results to be materially different from those expressed or implied by the forward-looking statements, including without limitation the ability to acquire necessary permits and other authorizations; environmental compliance; cost increases; availability of qualified workers and drill equipment; competition for mining properties; risks associated with exploration projects, mineral reserve and resource estimates (including the risk of assumption and methodology errors); dependence on third parties for services; non-performance by contractual counterparties; title risks; and general business and economic conditions. Forward-looking statements are based on a number of assumptions that may prove to be incorrect, including without limitation assumptions about: general business and economic conditions; the timing and receipt of required approvals; availability of financing; power prices; ability to procure equipment and supplies including without limitation drill rigs; and ongoing relations with employees, partners and joint venturers. The foregoing list is not exhaustive Columbus Gold undertakes no obligation to update any of the foregoing except as required by law.