Integra Gold Reports up to 97.8% Gold Recovery in Phase 3
Metallurgical Testing
VANCOUVER, BRITISH COLUMBIA--(Marketwired - Feb 25, 2014) -
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, Québec
- 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, Québec. 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) |
|
Clusters and Zones |
|
North Cluster |
|
|
South Cluster |
|
Metallurgical Process |
Parallel |
|
|
Fortune |
|
|
Triangle |
|
|
Plug No. 4 |
|
Process 1 |
97.8 |
% |
|
96.6 |
% |
|
93.1 |
% |
|
87.6 |
% |
Process 2 |
97.1 |
% |
|
95.6 |
% |
|
92.9 |
% |
|
83.2 |
% |
Process 3 |
96.6 |
% |
|
97.1 |
% |
|
93.4 |
% |
|
85.1 |
% |
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, Québec 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 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
Integra's Lamaque gold project is located in the heart of the
Val-d'Or gold camp in the Province of Québec, Canada, approximately
550 km northwest of Montréal. Québec 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 Hervé 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 Géologica Inc., and Michel Garon, Eng.,
M.A.Sc. of WSP Group in Val-d'Or, Québec, 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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Provider (as that term is defined in the policies of the TSX
Venture Exchange) accepts responsibility for the adequacy or
accuracy of this news release.
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 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.
Corporate Inquiries:Integra Gold Corp.Chris
Gordonchris@integragold.comwww.integragold.com
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