Antares Reports Haquira East Sulphide Mineral Flotation Recovery Tests Show Positive Results
08 Aprile 2010 - 7:40PM
Marketwired Canada
-- Rougher concentrate recoveries up to 95% Cu
-- Project capable of delivering high-quality, clean concentrate
-- Estimated recovery of 89.3% copper, 72% gold and 57% molybdenite in
final concentrate
Antares Minerals Inc. ("Antares") (TSX VENTURE:ANM) is pleased to announce that
it has received results of a bench-scale scoping metallurgical study on two
composite samples of primary copper sulphide-bearing drill core from the Haquira
East mineralized zone at the Haquira copper project. The study was completed by
Resource Development Inc. (RDi), based in Golden, Colorado. The metallurgical
test work included sample preparation and characterization, mineralogical
examination, Bond's ball-mill work index determination, grind studies and
rougher flotation recovery tests. The highlights of the study are the following:
-- Rougher concentrate recovery of 95% and 92% of copper from Composite
No.1 and No.2, respectively.
-- The first two minutes of rougher flotation recovered over 85% of copper
at a concentrate grade of 29% to 30% Cu.
-- The rougher concentrate analysis showed very low levels of any
deleterious elements such as arsenic, lead, phosphorus etc.
-- The rougher flotation scoping tests indicated that a simple reagent
suite consisting of potassium amyl xanthate (PAX), diesel fuel and
methyl isobutyl carbonyl (MIBC) will float the majority of the copper
sulphides, gold, and molybdenite in the ore.
-- Bond's ball-mill work index was determined to be 12.76, which is within
the range of values reported for porphyry copper ores.
-- RDi projects that the sulphide-bearing material can be treated with a
standard process flow sheet, similar to conventional Cu/Mo ores being
processed in the U.S. The estimated overall recoveries for the two
composites tested are: 89.3% of copper, 72% of gold and 57% of
molybdenite,. Additional test work is required to confirm these recovery
values.
RDi emphasized that, while these are excellent results at this stage of the
project examination, additional test work is needed to confirm the mineral
recoveries, optimum reagent mix, and the full process flow-sheet recommendation.
John Black, President and CEO of Antares Minerals Inc. commented as follows:
"We are pleased with these highly encouraging test results regarding the
metallurgical characteristics of the Haquira East primary sulphide material.
These results demonstrate that a high-quality, clean concentrate can be produced
from Haquira East. While these metallurgical data are based on only two
composite samples, the intervals are representative in nature and point to
highly favourable processing recoveries using a conventional flow sheet and
standard reagents. These results continue to support Antares Minerals' primary
mission of adding value to its mineral discoveries."
"Additional test work will be organized to confirm these data and to progress
our understanding of the sulphide material at Haquira East. We look forward to
completing these studies in 2010."
Discussion of Results
SAMPLE ORIGINATION, PREPARATION AND ASSAY RESULTS: Two composite samples were
collected from Haquira East sulphide-bearing drill core and sent to RDi for
assay analysis and metallurgical testing. An attempt was made to identify
different grades of copper, molybdenum and gold for process testing. The samples
consisted of the following drill core intervals:
Composite No.1
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Drill Hole # From (m) To (m) Interval Weight (kg) Lithology
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AHAD 098A 342.05 343.80 1.75 6.0 Haquira porphyry
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AHAD 098A 381.80 383.45 1.65 5.0 Haquira porphyry
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AHAD 102 491.10 493.05 1.95 6.4 Haquira porphyry
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AHAD 102 496.50 498.0 1.50 4.4 Haquira porphyry
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Composite No.2
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Drill Hole # From (m) To (m) Interval Weight (kg) Lithology
----------------------------------------------------------------------------
AHAD 103 269.05 271.05 2.0 7.5 Haquira porphyry
----------------------------------------------------------------------------
AHAD 105 168.05 169.95 1.9 6.4 Haquira porphyry
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AHAD 106 217.70 219.70 2.0 6.5 Haquira porphyry
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AHAD 106 241.45 243.45 2.0 7.0 Haquira porphyry
----------------------------------------------------------------------------
Each composite was thoroughly blended and crushed to nominal 6 mesh size. The
composite sample was then split into 20 individual one-kilogram charges using a
twenty-way rotary splitter. A one kg sample of each composite was pulverized to
minus 150 mesh and a representative sample split out for copper, molybdenum,
gold and silver analyses as well as other elements. The pulverized samples were
sent to Florin Analytical Services, LLC, in Reno, Nevada for assaying.
Analytical results for copper, molybdenum, gold, silver, and total sulphur
are:
Composite No.1
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Copper (Total) Molybdenum Gold Silver Sulphur (Total)
----------------------------------------------------------------------------
1.592% 40 ppm 0.27 g/t 18.02 g/t 1.06%
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Composite No.2
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Copper (Total) Molybdenum Gold Silver Sulphur (Total)
----------------------------------------------------------------------------
0.754% 275 ppm 0.21 g/t 8.58 g/t 0.62%
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MINERALOGICAL EVALUATION: The two composite samples were investigated
microscopically in polished sections to identify mineral constituents that
account for contained copper, molybdenum and other metals of interest.
Mineralogical work was performed by OTX-Mineralogy of Bountiful, Utah.
Sulphide minerals in Composite No. 1 are comprised of about 50% chalcopyrite,
40% bornite, 4% chalcocite, 4% secondary copper sulphides (digenite-covellite),
1% molybdenite and 1% pyrite. Chalcopyrite and bornite grains are about 75%
liberated at a minus 28 mesh grind. Chalcopyrite and bornite grains range from
350 microns down to 5 microns, or smaller. Small plates of molybdenite were
observed locked in quartz grains. Molybdenite books exhibit inter-plate gangue
that may require fine grinding for liberation.
Sulphide minerals in Composite No. 2 are comprised of approximately 50% bornite,
45% chalcopyrite, 4% molybdenite, and 1% pyrite. The sample contains a
significantly larger amount of magnetite-hematite. Molybdenite is closely
associated with chalcopyrite and also locked with silicate gangue. Chalcopyrite
grains, as small as several microns, were observed locked in silicate gangue.
BOND'S BALL-MILL WORK INDEX: Ten kilograms of 1/2 core, HQ/NQ size, was crushed
to P100 of minus 6 mesh and the sample was used to determine the Bond's ball
mill work index at minus 100-mesh grind. The Bond's ball mill work index was
determined to be 12.76. This value is similar to those reported for other
porphyry copper ores.
FLOTATION TESTS: Eight scoping flotation tests, four on each composite, were
performed to recover copper, molybdenum, gold and silver values into a rougher
concentrate. Varying concentrations of potassium amyl xanthate (PAX), diesel
fuel and methyl isobutyl carbonyl (MIBC) were used in the tests. Two
supplementary collectors, known for recovering gold, were tested as additional
collectors in the rougher flotation (AP 3477 and AP 404). The other variable
investigated was primary grind size (P80 of 100 and 150 mesh). Timed
concentrates were collected for a total of 9 minutes of flotation time.
A summary of the test data indicates the following:
-- The rougher concentrate recovered approximately 95% of the copper for
Composite No. 1 at a primary grind of P80 of 150 mesh and with a simple
reagent suite of potassium amyl xanthate (PAX), diesel fuel and methyl
isobutyl carbonyl (MIBC). The molybdenite recovery ranged from 46% to
68%, and gold recovery was approximately 80%. The final rougher
concentrate contained 14% to 18.6% Cu.
-- The rougher concentrate recovered 90% to 92.6% of copper, 79.7% to 95%
of molybdenite and 43% to 54% of gold for Composite No. 2. The final
rougher concentrate contained 7.2% to 12% Cu.
-- Concentrations of potentially deleterious elements (As, Pb, P, etc) are
very low resulting in a clean and highly marketable concentrate.
-- Review of the kinetic data indicated that 88% of the copper floated in
two minutes of flotation time at a concentrate grade of 29.64% Cu for
Composite No. 1 (Test No. 1). For Composite No. 2, two minutes of
flotation recovered 78.2% of copper at a concentrate grade of 21.64% Cu
(Test No. 5).
-- Precious metal recoveries were reasonable for both composites and
molybdenite recovery is dependent on the feed grade. Higher molybdenum
feed grades result in higher molybdenite recovery.
PROJECTED PROCESS FLOW SHEET AND METALLURGY: Based on this scoping study, RDi
projects a conceptual process flow sheet for the sulphide ores. The flow sheet
would consist of crushing and grinding the ore to P80 of 100 to 150 mesh, and
floating copper, molybdenum and precious metals in a bulk-rougher concentrate.
The bulk-rougher concentrate would be subjected to first bulk-cleaner flotation.
The tailings from the first bulk-cleaner flotation would be reground and
subjected to scavenger flotation and scavenger-cleaner flotation. The
scavenger-cleaner flotation would be combined with first-cleaner flotation
concentrate and subjected to second-cleaner flotation. The second-cleaner
flotation concentrate would be subjected to Cu/Mo separation and molybdenite
would be upgraded in the cleaner circuit. The need for regrind or the number of
cleaner flotation stages for the molybdenite upgrading circuit is unknown at
this stage of scoping study.
Based on past experience with Cu/Mo plants, an attempt has been made to project
the recoveries of Cu, Mo and Au in the proposed process flow sheet. The
following assumptions have been made for overall recoveries:
-- Projected rougher recoveries are 93% for copper, 60% for molybdenite,
and 75% for gold. Bulk-cleaner flotation circuit will recover 97% of
copper and 95% of molybdenite and gold present in the rougher
concentrate.
-- Following the copper/molybdenite separation circuit, 96% of copper and
gold and 3% of molybdenite will report to copper concentrate and 2% of
copper and gold and 95% of molybdenite will report to molybdenite
concentrate. The scavenger flotation tailing will contain 2% of copper,
2% of molybdenite and 2% of gold. Based on the above assumptions,
process recoveries are estimated as follows:
- Copper concentrate will contain 89.3% of copper and 72% of gold.
- Molybdenite concentrate will contain 57% of molybdenite.
The above estimates are projections based on similar bulk flotation projects.
Additional test work is needed to confirm these projections.
About the Haquira Copper Project, Peru
The Haquira project is located in southern Peru and offers excellent potential
for an initial low-strip, low-cost SX-EW copper operation with a subsequent
transition to a higher grade primary porphyry copper-molybdenum
mill/concentrator operation. Antares has recently announced an updated resource
estimate for the Haquira project (see press release of February 26th, 2010). The
estimate encompasses all the known mineralization at the Haquira East and
Haquira West deposits as well as the immediately surrounding areas (Potato Patch
zone), but does not reflect the mineralization recently discovered at the nearby
Cristo de los Andes prospect. It includes both the near-surface secondary
(leachable) copper mineralization as well as the underlying primary
(mill/concentrate) mineralization. This resource estimate utilizes all drilling
completed to date at the Haquira project (through drill hole AHAD-174).
Highlights from this interim resource estimate at a cut-off of 0.3% total Cu for
primary mineralization and 0.2% total Cu for leachable secondary mineralization
are as follows:
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Table 1. Mineral Resource Summary Haquira Project - All Zones - February
2010
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Cu lbs Cu
Resource Tonnes Eq(1) Cu Mo Au Ag lbs Cu Eq(1)
Classification (millions) % % % g/t g/t (billions) (billions)
----------------------------------------------------------------------------
Primary Copper Mineral Resources (Mill/Concentrate) - 0.3% Cu cut-off
----------------------------------------------------------------------------
Measured 68.9 0.78 0.64 0.015 0.045 1.84 0.97 1.18
Indicated 285.7 0.75 0.63 0.014 0.044 1.78 3.93 4.74
Inferred 333.7 0.62 0.54 0.009 0.032 1.59 3.94 4.59
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Secondary Copper Mineral Resources (leachable - SX/EW) - 0.2% Cu cut-off
----------------------------------------------------------------------------
Measured 59.4 0.52 0.52 0.68 0.68
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Indicated 155.6 0.44 0.44 1.52 1.52
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Inferred 72.2 0.41 0.41 0.65 0.65
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Antares announced in May, 2008, the results of a preliminary economic assessment
("PEA") for the near-surface, SX-EW amenable portion of the Haquira project.
This PEA was based upon the an earlier resource estimate announced in October,
2007 which defined leachable resources at Haquira within two deposits (Haquira
East and Haquira West) with a combined indicated resource of 133.7 million
tonnes at 0.53% total Cu with an additional inferred resource of 43.6 million
tonnes at 0.44% total Cu (0.3% total Cu cut-off, leachable secondary copper
sulphide and oxide mineralization only). This resource is projected to support a
50,000 t/d SX/EW heap leach operation that will produce an average of 109
million lbs of copper cathode for 11 years of mine life. The capital cost to
construct the operation is estimated at US$301 million with a projected IRR of
26.9% and an NPV of US$224 million utilizing a copper price of US$2.00/lb and a
discount rate of 8%.
The project is located contiguous to, and immediately south of, Xstrata Copper's
Las Bambas Cu-Au project and consists of two blocks of property acquired or
optioned under separate agreements as well as additional concessions acquired by
Antares for a total of 20,635 hectares of area. Antares has fulfilled the terms
of an option agreement and acquired a 100% interest in the original Haquira
project by completing optional payments totalling US$15 million over a five-year
period (see Antares press release dated March 17, 2005).
Antares also has an option agreement with Minera del Suroeste S.A.C. (MISOSA), a
wholly owned subsidiary of Hochschild Mining PLC, whereby Antares can acquire up
to a 60% interest in the Cristo de los Andes project, located contiguous to, and
immediately south of the Haquira project (see Antares press release dated April
28, 2008).
Additional information about the Haquira project is available on our website at
www.antaresminerals.com.
About Antares
Antares is a successful mineral exploration company with highly experienced
technical and management teams. The Company is focused on precious- and
base-metal exploration properties in Latin America that can be quickly and
cost-effectively advanced to the discovery and production stage. In addition to
the Haquira Project in Peru, Antares is also currently exploring the Rio Grande
(Cu-Au porphyry) project in Salta Province of NW Argentina in a 50/50
option/joint-venture basis with Pachamama Resources Ltd., a spin-off from
Mansfield Minerals Inc.
The TSX Venture Exchange does not accept responsibility for the adequacy or
accuracy of this release.
(1) CuEQ = Copper Equivalent is calculated for intervals dominated by primary
mineralization using US$1.50/lb Cu, US$500/oz Au, US$10/oz Ag and US$10.00/lb Mo
and is not adjusted for metallurgical recoveries as these remain uncertain.
Metallurgical recoveries and net smelter returns are assumed to be 100%. The
formula used is as follows: CuEQ = Cu% + (Au g/t x 0.4862) + (Mo% x 10.00/1.50)
+ (Ag g/t x 0.0077). Copper Equivalent contributions are only applied to primary
sulphide mineralization.
All of Antares' exploration programs and pertinent disclosure of a technical or
scientific nature are prepared by, or prepared under the direct supervision of
John Black, Antares' President, who serves as the qualified person (QP) under
the definitions of National Instrument 43-101.
Antares' security, chain of custody and quality control is described on their
website under the section on best practices - sampling methodologies.
Mineral resources do not have demonstrated economic viability and future in-fill
drilling and scoping, pre-feasibility and feasibility studies will determine
what percentage of the inferred resource can be placed into the mineable
category. Antares is not aware of any environmental, permitting, legal, title,
taxation, socio-political, marketing or other issue which may materially affect
this estimate of mineral resources.
Certain disclosure in this release, including management's assessment of
Antares' plans and projects, constitutes forward-looking statements that are
subject to numerous risks, uncertainties and other factors relating to Antares'
operation as a mineral exploration company that may cause future results to
differ materially from those expressed or implied. Readers are cautioned not to
place undue reliance on forward-looking statements.
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