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- Rapid leaching rates
with very high nickel and cobalt extraction in metallurgical tests.
- Beneficiation tests
indicate 20% upgrade to limonite.
- Results indicate
potential for very low processing cost operation.
EDMONTON, Alberta; December
13, 2010 - Mindoro Resources Ltd. (TSXV: MIO; ASX: MDO; Frankfurt: WKN
906167) today announced that hydrometallurgical test results have
demonstrated exceptionally fast leaching rates with high nickel and cobalt
recoveries from its Agata nickel laterite project in northern Mindanao, the
Philippines.
High pressure acid leach (HPAL) testing extracted approximately 98 percent of
the nickel and 95-96 percent of the cobalt from limonitic material within 20
minutes. This leaching rate is 50 percent faster for HPAL processing than
previously assumed in the scoping study announced on October 2, 2010 and
filed on SEDAR in a NI 43-101 Technical Report dated November 19, 2010. With
half the leaching time, the HPAL circuit throughput could be doubled, with
higher nickel extraction than previously reported and resulting in
significantly lower processing cost projections. Testing also demonstrated
faster processing times and higher nickel recoveries for Atmospheric Leach
(AL) processing than assumed in the scoping study.
SGS Lakefield Oretest in Perth, Western Australia, a NATA certified
laboratory, conducted the bench scale hydrometallurgical test work,
evaluating the metallurgical response of nickel laterite from the Agata
Project. Testing was conducted on a total of nine samples representing the
grade ranges in the deposit from limonite, saprolite and transition material.
"We are extremely pleased with these metallurgical results which advance
our investigations into establishing a low-cost integrated processing
operation at Agata," said Mindoro's President and Chief Executive
Officer Jon Dugdale. "These results justify commencing a larger scale
and more systematic metallurgical testing program in early 2011 as a
precursor to commencing a pre-feasibility study."
The program investigated HPAL processing a limonite and transition composite,
as well as atmospheric leaching (AL) of saprolite. Beneficiation potential --
the process of upgrading ore through crushing/scrubbing and screening, and
slurry settling properties were also investigated.
HPAL tests of limonite were performed at 255°C and acid addition rates
from 276 to 351 kg per tonne of material. Results demonstrated exceptionally
fast leaching rates, with nickel extractions of 98 percent within 20 minutes,
at residual free acid concentrations as low as 32 g/L. Cobalt extractions
were 95-96 percent.
The limonite HPAL test results are summarized as follows:
Residence
Time:
|
20
Minutes
|
30
Minutes
|
Acid
Addition
(kg/t ore)
|
Residual
Free
Acid (g/L)
|
Ni
Ext'n %
|
Co Ext'n
%
|
Residual
Free
Acid (g/L)
|
Ni Ext'n
%
|
Co Ext'n
%
|
276
|
32.2
|
97.9
|
96.1
|
35.7
|
98.2
|
94.8
|
325
|
42.4
|
98.4
|
96.1
|
42.4
|
98.4
|
95.5
|
351
|
42.7
|
98.2
|
94.1
|
46.4
|
98.5
|
95.9
|
Atmospheric Leach (AL) testing was conducted on saprolite at 95°C at acid
addition rates from 850 to 1000 kg per tonne of material. Results
demonstrated favourable leaching rates, with nickel extractions of 95 to 98
percent in four hours at residual free acid concentrations of 24-39 g/L. The
scoping study assumed six hours AL residence time and only 90 percent nickel
extraction. The SGS results demonstrate that the AL circuit can be downsized
by 33 percent (to four hours residence time) with higher nickel extraction
than reported in the scoping study findings.
The saprolite AL test results are summarized as follows:
Residence
Time:
|
4 Hours
|
6 Hours
|
Acid
Addition
(kg/t ore)
|
Residual
Free
Acid (g/L)
|
Ni Ext'n
%
|
Co Ext'n
%
|
Residual
Free
Acid (g/L)
|
Ni Ext'n
%
|
Co Ext'n
%
|
900
|
24.1
|
94.9
|
89.1
|
21.7
|
95.4
|
90.8
|
950
|
28.2
|
96.6
|
91.9
|
24.6
|
96.9
|
92.9
|
1000
|
39.2
|
97.6
|
93.6
|
32.1
|
97.8
|
93.5
|
Beneficiation upgrading tests (prior to leaching) established that scrubbing
to reduce the size of (de-agglomerate) the ore particles, followed by
screening out material larger than 0.25 mm, could potentially provide a 20
percent upgrade of the limonite and transition HPAL feed material, with 90
percent nickel recovery and 19 percent mass rejection. Forty one percent of
the magnesium and 38 percent of the silica would be screened out with the
larger material which would reduce acid consumption and improve solid-liquid
separation (CCD performance). Saprolite ore did not exhibit potential for
upgrading using these methods.
Ore slurry settling tests in two meter raked columns demonstrated that
limonite and transition HPAL feed material can be settled to approximately 40
weight percent solids at a flocculent dosage of 150 g/t solids, and saprolite
ore can be settled to approximately 36 weight percent solids at a flocculent
dosage of 200 grams per tonne solids. As the scoping study assumed 35 weight
percent solids in HPAL feed, the test results mean that 14% more ore can be
processed through the HPAL autoclave than previously assumed.
Tests are also underway to evaluate using saprolite to neutralize the acid
and CCD (leach discharge) settling properties.
The markedly improved results, relative to the assumptions applied in the
scoping study, indicate potential to significantly decrease the estimated
average cash-costs of production from the US$2.47 per pound of nickel
(without cobalt credits) currently assumed for the base case integrated HPAL
/ Atmospheric Leaching project.
The bench scale hydrometallurgical testing program was coordinated by Boyd
Willis, MAusIMM, of Boyd Willis Hydromet Consulting (BWHC), an independent
qualified person as defined by NI 43-101 and a competent person as defined by
the JORC Code, in conjunction with SGS Lakefield Oretest in Perth, Western
Australia, a NATA certified laboratory. Boyd Willis has verified and
authorized the technical information detailed in this release.
Jon Dugdale,
President and CEO
For further information or to discuss any aspect of this release, please
contact:
Australia: Jon Dugdale, President and CEO, Tel: +61 3 9614 5055 or email jon@mindoro.com
Canada: Penny Gould, VP Investor Relations, Tel: +780.413.8189, toll free
1.877.413.8187 or email penny@mindoro.com
Germany: Robert Sarcher, Director, Tel: +49.821.6089051 or email robert@mindoro.com
ABOUT MINDORO
Mindoro is a Tier 1 Issuer trading on the TSX Venture Exchange (MIO),
Australian Securities Exchange (MDO) and Frankfurt Stock Exchange (WKN 906167).
Mindoro is focused on nickel, copper and gold exploration in the Philippines
with a strategy of advancing early-stage opportunities to production or joint
venture.
Mindoro is assessing the potential to develop a value-added direct shipping
ore (DSO) nickel operation to generate early cash flow as well as large scale
potential for an onsite processing plant in the Surigao District, Mindanao,
where the company controls major nickel laterite resources.
Mindoro has NI 43-101 Mineral Resource estimates on its Agata nickel-cobalt
project totaling Measured and Indicated 32.6 million dry metric tonnes (DMT)
at 1.04% Nickel and 0.05% Cobalt and Inferred 1.68 million DMT at 1.04%
Nickel, 0.04% Cobalt. The Surigao regional Exploration Target is 50 million to
70 million DMT at 0.9% to 1.2% Nickel (see press releases dated January 11
and September 8, 2010). Drilling of the Surigao nickel laterite exploration
target is in progress.
Mindoro also has NI 43-101 Mineral Resource estimates on its Lobo and
Archangel (Kay Tanda) gold-silver projects and has identified 22 porphyry
copper-gold prospects; three projects in the Batangas area of southern Luzon
are the subject of a farm-in arrangement whereby Gold Fields Ltd may earn 75
percent interest through direct project expenditure. Gold Fields is currently
drilling high-grade gold targets at Lobo.
Drilling on the American Tunnels project at Agata has confirmed potential for
a near-surface gold target and deeper porphyry copper-gold potential; at Pan
de Azucar, the company has commenced drilling copper-gold and massive pyritic
sulphide targets. Other gold and copper-gold targets in the Surigao region
will be reviewed prior to developing proposals for further drilling or joint
venture.
Neither 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.
The Company's DSO and large scale production objectives are
intended to provide an indication of management's current expectations and
are still conceptual in nature. It is uncertain that sufficient resources
will be established and if established that these resources will be converted
into economically viable mining reserves. Until a feasibility study has been
completed, there is no certainty that these objectives will be met. Potential
quantity and grade of the Exploration Target is also conceptual in nature; it
is uncertain if further exploration will result in the Exploration Target being
delineated as a mineral resource and there is no guarantee that resources, if
delineated, will be economic or sufficient to support a commercial mining
operation.
Information in this report relating to Exploration Results has been
reviewed and is based on information compiled by Tony Climie, P.Geol. Mr.
Climie is Mindoro's COO and has sufficient experience which is relevant to
the style of mineralization and type of deposits under consideration and to
the activity which he is undertaking to qualify as a Qualified Person as
defined by National Instrument 43-101 and a Competent Person as defined by
the JORC code. Mr. Climie consents to the inclusion in the release of the
matters based on his information in the form and context in which it appears.
This release may contain forward-looking statements including
management's assessments of future plans and operations, and expectations of
future production. These statements are based on current expectations that
involve a number of risks and uncertainties which could cause actual results
to differ materially. These risks include, but are not limited to, risks
associated with the mining and exploration industry (e.g. operational risks
in development, exploration and production; delays or changes in plans with respect
to exploration or development projects or capital expenditures; uncertainty
with respect to reserve estimates; results of exploration, estimates and
projections relating to production and availability of capital). Although
considered reasonable at the time of preparation, assumptions used may prove
to be imprecise and, as such, undue reliance should not be placed on
forward-looking statements. The Company does not undertake to update forward
looking statements except where required by law.
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