95% Gold Recoveries from Metallurgical Tests at Columbus Gold's Montagne d'Or Gold Deposit, French Guiana
Vancouver, BC, Canada, January 8, 2015. Columbus Gold Corporation (CGT: TSX-V, CBGDF: OTCQX) (“Columbus Gold”) is pleased to announce the results of comprehensive metallurgical test work from Columbus Gold’s 100 % controlled Montagne d’Or Gold Deposit, Paul Isnard Project, in French Guiana.
Three gold recovery process options were investigated on master composites: 1) whole-ore cyanidation, 2) a combination of gravity concentration followed by cyanidation of gravity tailing, and 3) gravity concentration followed by gold flotation from the gravity tailing. The test work indicates that the ore types of the principal Upper Felsic Zone (“UFZ”) and subsidiary Lower Favorable Zone (“LFZ”) are highly amenable to the three metallurgical processes tested, with recoveries of gold ranging from 95% to 97% as follows:
|Process||UFZ Master Composite||LFZ Master Composite|
|Whole Ore Cyanidation||94.7||0.08||97.0||0.06|
|Gravity + Cyanidation||96.7||0.06||97.2||0.05|
|Gravity + Rougher Flotation||96.8||0.09||96.6||0.08|
* at a grind size of 80% passing (P80) 75μm
The metallurgical tests were performed on two master composites prepared from 3.3 tonnes of whole core intervals from the UFZ and the LFZ. Triplicate fire assays for gold and silver showed that the UFZ master composite averaged 1.50 g/t Au and 3.33 g/t Ag and the LFZ composite averaged 1.56 g/t Au and 4.67 g/t Ag.
The response of test samples to different process methods are summarized as follows:
- Baseline leaching of ground whole ore for 72-hours in 0.5g/L sodium cyanide extracted 94.7% of the gold from the UFZ master composite and 97.0% of the gold from the LFZ master composite ore at a grind size of 80% passing (P80) 75μm.
- Gravity separation was able to recover up to 47.9% of the gold from the UFZ master composite and 40.2% of the gold from the LFZ master composite into gravity cleaner concentrates representing about 0.1 wt.% of the test material.
- Overall gold recoveries from the test flowsheet, which included gravity concentration followed by cyanidation of the gravity tailing, were slightly better than the recoveries achieved from whole-ore cyanidation at the same P80 75μm grind size.
- Gravity concentration followed by rougher flotation of the gravity tailings at a grind size of P80 75μm achieved 96.8% gold recovery from the UFZ master composite and 96.6% gold recovery from the LFZ master composite. This included 20.6-47.9% of the gold reporting to gravity concentrate and 48.8-72.8% of the gold reporting to the flotation rougher concentrate. Combined silver recovery into combined gravity and flotation concentrates ranged from 80 89%.
- Metallic screen assays indicate the presence of coarse gold in the Montagne d’Or test composites. The 30-50% gravity recoverable gold obtained from the gravity process also confirms this finding.
Pending metallurgical test results include additional flotation studies to evaluate the extent to which the flotation concentrates can be upgraded. In addition, confirmatory test work is being performed on ten variability composites under optimized test conditions to evaluate impact of spatial and grade variations throughout the deposit. The results from these additional tests are anticipated to be completed by the end of February 2015.
The metallurgical tests are being conducted by Bureau Veritas Commodities Canada Ltd., Inspectorate Metallurgical Division, under the direction and supervision of Eric Olin of SRK Consulting (U.S.) Inc. The metallurgical tests are an integral part of a Preliminary Economic Assessment (“PEA”) on the Montagne d’Or deposit to be completed in the spring of 2015, which will include an updated resource estimate incorporating the results of the Phase II diamond drilling program (126 holes, 25,570 m) and a preliminary environmental assessment.
The test work is being funded by Nord Gold N.V. (LSE: NORD LI) as part of a minimum US$30 million exploration and development program pursuant to which they can earn a 50.01% interest in Montagne d’Or and the Paul Isnard mineral claims, by completing a bankable feasibility study no later than March 2017.
Eric Olin, of SRK Consulting (U.S.), Inc., MSc, MBA, RM-SME and a Qualified Person under National Instrument 43-101 has reviewed the metallurgical information contained in this release.
ON BEHALF OF THE BOARD,
Robert F. Giustra
Chairman & CEO
Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
For more information contact:
Peter A. Ball
Senior Vice President
VP Communications & Technology
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 Columbus Gold’s: indications that ore types of the UFZ and LFZ are highly amenable to the three metallurgical processes tested; metallurgical tests; completion of new mineral resource estimate; completion of the PEA; projected funding of drilling programs by Nord Gold N.V. pursuant to the terms of the option agreement and the related completion of a bankable feasibility study (“BFS”); and 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: 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 including, without limitation, the accuracy of interpretations; mineral reserve and resource estimates (including the risk of assumption and methodology errors and ability to complete a new resource estimate by the proposed target date or at all)); whether the ore types of the UFZ and LFZ are highly amenable to the three metallurgical processes tested; the ability to meet proposed schedules for the shipment of samples and completion of metallurgical tests; the ability to complete the next phases of metallurgical tests by the proposed target date or at all; the ability to complete the PEA by the stated deadline or at all; dependence on third parties for services; non-performance by contractual counterparties; title risks; risks associated with Nord Gold N.V. electing not to exercise its option and make the related option payments and the ability to complete the BFS by the stated deadline or at all; 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: whether the planned metallurgical tests are appropriate for the site; 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, optionees and joint venturers. The foregoing list is not exhaustive and Columbus Gold undertakes no obligation to update any of the foregoing except as required by law.