Integra Gold Reports up to 97.8% Gold Recovery in Phase 3 Metallurgical Testing
February 25 2014 - 9:25AM
Marketwired Canada
Press release highlights:
-- Gold recovery of up to 97.8% for the Parallel Zone composite samples
using a combination of gravity and Carbon-in-Leach ("CIL") cyanidation.
-- Test work completed by ALS Metallurgy ("ALS") in Kamloops, British
Columbia, with supervision by WSP Group ("WSP") from Val-d'Or, Quebec
-- Phase 3 focused on applying recovery processes consistent with existing
milling infrastructure in the region
Integra Gold Corp. (TSX VENTURE: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-d'Or, Quebec. The Phase 3 program was designed to
individually assess the metallurgical response of samples from the project's
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 Company's
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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Clusters and Zones
----------------------------------------------
North Cluster South Cluster
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Metallurgical Process Parallel Fortune Triangle Plug No. 4
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Process 1 97.8% 96.6% 93.1% 87.6%
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Process 2 97.1% 95.6% 92.9% 83.2%
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Process 3 96.6% 97.1% 93.4% 85.1%
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Process 4 85.8% 82.0% 71.1% 58.4%
-----------------------------------------------------------------------
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-d'Or, Quebec on behalf of Integra, with supervision by WSP from
Val-d'Or. 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.
Testing Parameters
All flowsheets were tested with a primary grind sizing of 75um 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
Integra's Lamaque gold project is located in the heart of the Val-d'Or gold camp
in the Province of Quebec, Canada, approximately 550 km northwest of Montreal.
Quebec is rated one of the best mining jurisdictions in the world.
Infrastructure, human resources and mining expertise are readily available.
The Company's 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.
Qualified Persons
The Lamaque exploration project is under the direct supervision of Herve
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 Geologica Inc., and Michel
Garon, Eng., M.A.Sc. of WSP Group in Val-d'Or, Quebec, all three independent QP
as defined by National Instrument 43-101. The Company's 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
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term is defined in the policies of the TSX Venture Exchange) accepts
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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",
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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 Integra's 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.
FOR FURTHER INFORMATION PLEASE CONTACT:
Corporate Inquiries:
Integra Gold Corp.
Chris Gordon
chris@integragold.com
www.integragold.com