Integra Gold Reports up to 97.8 Gold Recovery in Phase 3 Metallurgical Testing
February 26, 2014 --
Press release highlights:
• Test work completed by ALS Metallurgy (ALS”) in Kamloops, British Columbia, with supervision by WSP Group (WSP”) from Val-dOr, Qubec
• Phase 3 focused on applying recovery processes consistent with existing milling infrastructure in the region
Integra Gold Corp. (TSX-V: ICG) ("Integra" or the "Company") is pleased to announce it has completed its Phase 3 metallurgical testing program at its Lamaque Gold Project in Val-dOr, Qubec. The Phase 3 program was designed to individually assess the metallurgical response of samples from the projects four gold deposits using flowsheets that replicated the processes used by various mills in the immediate vicinity of the Lamaque Project. The Company is currently assessing the viability and availability of each of the mills and will incorporate these results into its future plans.
Results of this program confirm that gold at the Lamaque Project can be efficiently recovered utilizing the same processing methodologies and flowsheets used in existing milling facilities in the immediate vicinity. We will use this positive metallurgical data to guide the next phase of our development plan, which is to assess all options and determine the best fit for the Companys needs moving forward. The fact that there are six potentially available mills included as part of this study speaks volumes about the infrastructure advantages this project has,” commented Company President and CEO, Stephen de Jong. The recent test work indicates that metallurgical gold recoveries can be optimized to over 95% which is consistent with what was achieved historically on similar types of mineralization at the neighbouring Lamaque and Sigma mines. Further metallurgical work is required for the Plug No. 4 material and we are confident there is significant room for optimization. We do not anticipate this will have a significant impact on our upcoming PEA as the initial phase of proposed production will focus on the Triangle and Parallel Zones.”
The following table give a summary of Phase 3 optimized recoveries using a 96 hour leach time:
Phase 3 Metallurgical Testing - Gold Recoveries versus Metallurgical Process
(96 hour retention time)
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Process 1 - Gravity concentration with CIL cyanide leach
Process 2 - Whole ore cyanide leach
Process 3 - Whole ore CIL cyanide leach
Process 4 - Flotation separation with cyanide leach of concentrate (excluding leach of tails)
Summary of Phase 3 Metallurgical Testing
The metallurgical test program was completed by ALS on samples from the Lamaque deposits in Val-dOr, Qubec on behalf of Integra, with supervision by WSP from Val-dOr. The focus of this program was to test and compare four possible flowsheets, mirroring existing milling infrastructure in the region, on composites from four separate gold mineralized zones.
Four separate composites from the Parallel, Triangle, Fortune and No. 4 Plug zones were prepared from crushed drill core. The four composites were prepared to be at a median range of gold grade respective to each zone. Gold head assays were conducted using a screened metallic assaying method due to the coarse nugget effect of the gold in these deposits. The composites assayed 9.1, 8.8, 6.2 and 4.4 grams/tonne gold (g/t Au”) for the Parallel, Triangle, Fortune and No. 4 Plug composites, respectively.
Four flowsheets were tested on each sample. The first involved a gravity concentration followed by a Carbon-in-Leach (CIL”) cyanide leach of the gravity tails. The second was a whole ore cyanide leach and the third was a whole ore CIL. The fourth flowsheet involved a flotation separation (rougher and cleaner) followed by a separate cyanide leach of the flotation concentrate. Gold recoveries from the first three flowsheets were similar. Using these three flowsheets, and a 96 hour leach time, gold recoveries were as followed:
Parallel Zone Composite: 96.6% to 97.8%
Triangle Zone Composite: 92.9% to 93.4%
Fortune Zone Composite: 95.6% to 97.1%
Plug No. 4 Zone Composite: 83.2% to 87.6%
Using these same three flowsheets but with a 48 hour leach time, gold recoveries were as followed:
Parallel Zone Composite: 94.1% to 96.7%
Triangle Zone Composite: 89.3% to 90.2%
Fortune Zone Composite: 92.8% to 95.0%
Plug No. 4 Zone Composite: 82.7% to 86.1%
The main difference between flowsheet performances was related to reagent consumption, with the CIL extractions consuming approximately twice as much sodium cyanide. In comparing the first three flowsheets, recovery differences were small enough that reagent consumptions and other economic factors relating to the use of the different processing facilities would likely be more significant than the metallurgical recovery differences.
The fourth flowsheet which involved gold recovery utilizing the flotation and cyanide leaching flowsheet produced significantly lower recoveries. This flowsheet, when not including the cyanide leach of the flotation tailings, had gold recovery substantially lower than the other flowsheets tested. Reagent consumptions for this flowsheet were also lower.
All flowsheets were tested with a primary grind sizing of 75μm K80. Further testing with various grind sizes may be used in the future to further optimize test work.
The first flowsheet tested utilized a batch Knelson gravity concentrator with a hand panning of the gravity concentrate. Tailings from this gravity concentration underwent a 96 hour CIL cyanide test. The leaches were conducted at a pH of 11.0, with a sodium cyanide concentration of 1,000 ppm and with 30 grams per liter of carbon added to the leach slurry.
The second and third flowsheets were similar. The second flowsheet involved a 96 hour whole ore leach using 1,000 ppm sodium cyanide and a pH of 11.0. The third flowsheet used the same conditions as the second with the 96 hour leaches being CIL tests with 30 grams per liter of carbon added to the leach slurry.
The fourth flowsheet utilized flotation separation with a rougher separation followed by one stage of dilution cleaning. The flotation cleaner concentrate was subjected to a cyanide leach at 2,000 ppm sodium cyanide at pH of 11.0 for 96 hours. The flotation separations were conducted at natural pH with Potassium Amyl Xanthate (PAX) as a sulphide collector and Methyl Isobutyl Carbonyl (MIBC) as the frother.
No. 4 Plug Composites Future Testing
The No. 4 Plug composite has shown slightly lower overall gold recoveries when compared to material from other zones in all of the metallurgical processes tested. Before additional metallurgical testing is performed, and in order to fine-tune metallurgical recoveries for this zone, a mineralogical analysis of this ore type will be conducted. In previous testing work (see press release dated May 01, 2013 and July 25, 2013 on Phase 1 and 2 testing), finer grinding and more intense leach conditions had shown to optimize and improve performance significantly.
Project and Company Profile
Integras Lamaque gold project is located in the heart of the Val-dOr gold camp in the Province of Qubec, Canada, approximately 550 km northwest of Montral. Qubec is rated one of the best mining jurisdictions in the world. Infrastructure, human resources and mining expertise are readily available.
The Companys primary objective is to continue to prove up additional resources while advancing the existing resource towards production. The project is divided into three main clusters of mineralization, the North, South and West Cluster. The North Cluster consists of the Parallel, Fortune, No. 5 Plug, and No. 3 Mine zones and is located approximately 1 km from the South Cluster, which includes the No. 4 Plug, Triangle and Triangle South zones. The Sixteen Zone and No. 6 Vein form the West Cluster.
The Lamaque exploration project is under the direct supervision of Herv Thiboutot, Eng. and Senior Vice-President of the company, and Francois Chabot, Eng. and Operations and Engineering Manager of the Company, both Qualified Person (QP”) as defined by National Instrument 43-101, and Alain-Jean Beauregard, P.Geo., Daniel Gaudreault, Eng., Geo. of Gologica Inc., and Michel Garon, Eng., M.A.Sc. of WSP Group in Val-dOr, Qubec, all three independent QP as defined by National Instrument 43-101. The Companys QPs have reviewed the technical content of this release.
Quality Assurance - Quality Control (QA/QC”)
Thorough QA/QC protocols are followed on the project including insertion of duplicate, blank and standard samples in all drill holes. The core samples are submitted directly to ALS Laboratory Group and Bourlamaque Labs in Val-d'Or for preparation and analysis. Analysis is conducted on 1 assay-ton aliquots. Analysis of Au is performed using fire assay method with atomic absorption finish, with a gravimetric finish completed for samples exceeding 5 g/t Au, or a metallic sieve assay for samples containing visible gold. When available the gravimetric or metallic sieve assay results are used for the reported composite intervals.
ON BEHALF OF THE BOARD OF DIRECTORS
Stephen de Jong
CEO & President
Corporate Inquiries: Chris Gordon firstname.lastname@example.org
Or visit the company website: www.integragold.com
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Cautionary Note Regarding Forward Looking Statements:
No stock exchange, securities commission or other regulatory authority has approved or disapproved the information contained on this presentation. This presentation contains "forward-looking information" concerning Integra Gold Corp.s (Integra or the Company”) future financial or operating performance and other statements that express management's expectations or estimates of future developments, circumstances or results. Generally, forward-looking information can be identified by the use of forward-looking terminology such as seeks”, "believes", "anticipates", "plans", continues”, "budget", "scheduled", "estimates", "expects", "forecasts", "intends", projects”, predicts”, proposes”, "potential", targets” and variations of such words and phrases, or by statements that certain actions, events or results "may", "will", "could", "would", should” or "might" "be taken", "occur" or "be achieved". Forward-looking statements included in this presentation include statements regarding potential mineralization and mineral resources, the proposed mining scenario for the South Lamaque Gold Project, including information with respect to the supporting infrastructure, the potential life of mine, rates of employment and the effects of steps taken to mitigate local impacts and the expected completion dates of exploration and drilling, exploration results, estimated and future exploration and administration expenditures, the completion of scoping studies, preliminary economic assessment, pre-feasibility or feasibility studies, and future plans and objectives of Integra. While all forward-looking statements involve various risks and uncertainties, these statements are based on certain assumptions that management of Integra believes are reasonable, including that it will be able to obtain financing and on reasonable terms, that its current exploration and other objectives can be achieved, that its exploration and other activities will proceed as expected, that its community and environmental impact procedures will work as anticipated, that general business and economic conditions will not change in a material adverse manner, that Integra will not experience any material accident, labour dispute or failure or shortage of equipment, and that all necessary government approvals for its planned exploration and potential development activities will be obtained in a timely manner and on acceptable terms. There can be no assurance that the forward-looking statements will prove to be accurate and actual results and future events could differ materially from those anticipated in such statements. Important factors that could cause actual results to differ materially from the Integras expectations include, among others, the actual results of current exploration activities being different than those anticipated by Integra, changes in project parameters as plans continue to be refined, changes in estimated mineral resources, future prices of metals, increased costs of labor, equipment or materials, availability of equipment, failure of equipment to operate as anticipated, accidents, effects of weather and other natural phenomena, risks related to community relations and activities of stakeholders, and delays in obtaining governmental approvals or financing. Although Integra has attempted to identify important factors that could cause actual results to differ materially, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that such statements will prove to be accurate as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. Integra does not intend, and expressly disclaims any intention or obligation to, update or revise any forward-looking statements whether as a result of new information, future events or otherwise, except as required by law.
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