Final Results from Dutwa Metallurgical Testwork
NICKEL PROJECT IN TANZANIA
* Leach tests using 1m columns performed exceptionally well
* Rapid leach kinetics; good nickel and cobalt recovery; low acid consumption
* Nickel extraction of 73-82% within 30 days and 86-92% after 100 days
* Cobalt extraction up to 60% within 30 days and 80-85% after 100 days
* Tank leach tests gave 80-85% nickel extraction within 8 hours
African Eagle's Managing Director Mark Parker comments, "We are delighted with
the results of our phase 2 column and tank leach tests, which show that Dutwa
ore could be processed by either heap leaching or tank leaching at normal
atmospheric pressure, without recourse to the high cost and hi-tech
complications of high pressure acid leach (HPAL).
"The leaching reaction proceeds very quickly, especially for the first
two-thirds of the contained nickel, and the acid consumption is much lower that
for comparable deposits elsewhere. This opens a wider range of leach options
and, if heap leaching is used, implies that working capital should not be tied
up for a long period while the heap reaches full productivity."
African Eagle has now received the final results for the second phase of
metallurgical testwork carried out as part of African Eagle's pre-feasibility
study on Dutwa. The tests were performed by Mintek Laboratories in South Africa
on 250 kg of sample taken from seven drill cores from the main Dutwa nickel
deposit (Wamangola Hill). They included column and tank leach tests, preliminary
agglomeration tests and preliminary ore characterisation tests. Details of the
tests and results may be found on the Company's web site,
www.africaneagle.co.uk/p/dutwa_met.asp
Column tests
Column leach tests were performed to obtain information on the likely behaviour
of the ore in the heap leaching process. Three tests were performed in columns
1 metre high, filled with ore crushed to 25mm or less in size and agglomerated
using sulphuric acid of different strengths. Each column was continuously
leached for 150 days with 100 g/L sulphuric acid, about 1/4 the strength of
battery acid.
Initial leaching was extremely fast, with 60 to 65% of the nickel being
extracted within two weeks. The rate of leaching then slowed somewhat, reaching
73 to 82% after one month and 90 to 94% over the full five month test. The acid
consumed to achieve these extractions was low, averaging 199, 273 and 360
kg/tonne respectively. Clearly, more than half of the nickel in Dutwa ore is
contained in a readily leachable mineral phase.
The fast initial leaching is especially encouraging. Extraction of 65% of the
contained nickel in two weeks using approximately 200kg/t of acid means that
working capital will not be tied up for a long period while the heap reaches
full productivity. Whilst the remainder of the nickel leaches more slowly,
extractions of up to 92% were demonstrated in the comparatively short leach time
of 100 days. Such a short leach cycle extends the heap engineering options and
offers the potential to use dynamic heaps (on/off leach pads).
The ore samples also showed good mechanical behaviour in all three column tests,
with no indications of percolation or permeability problems and compaction
averaging 13%.
Tank leach tests
Five tank leach tests were performed at 90°C and atmospheric pressure. For these
tests, the ore was pulverised and leached as slurry for 24 hours in agitated
tanks, using sulphuric acid of various initial concentrations.
In all five tests, the reaction was very fast, most of the nickel leaching
within the first hour. Nickel extraction of up to 70% occurred in the first
hour, with up to 85% after 8hrs and final nickel extractions averaging 94% over
the full 24hr test.
Planned work
A geochemical domain model of the deposit has been completed and will be used to
design a programme of bulk sampling to provide a large representative ore sample
across the Dutwa nickel deposit for the next phase of metallurgical testwork.
This will include: large scale column tests, with columns 6-8m high to replicate
typical heap leach stack heights, mineralogical analyses, beneficiation tests to
assess the potential to upgrade the ore prior to tank leaching, and further tank
leach and agglomeration tests to optimise these processes. Results of this work
will be used to develop further the optimum processing route for Dutwa ore.
Qualified Person
Information in this report relating to metallurgical test results is based on
data reviewed by Chad Czerny PhD, Project Manager, Metallurgy for African Eagle
Resources, who is a Member of the Australasian Institute of Mining and
Metallurgy, has more than 20 years' relevant experience in the mining and
metallurgical industry, and is a Qualified Person under AIM guidelines. Dr
Czerny consents to the inclusion of the information in the form and context in
which it appears.
Technical terms
A glossary of technical terms used by African Eagle in this announcement and
other published material may be found atwww.africaneagle.co.uk/p/glossary.asp
For further information:
Mark Parker
Managing Director
African Eagle
44 20 7248 6059
44 77 5640 6899
Nicola Marrin
Seymour Pierce Limited, London
Nominated Adviser
44 20 7107 8000
Charmane Russell
Russell & Associates, Johannesburg
27 11 8803924
27 82 8928052
Ed Portman / Leesa Peters
Conduit PR, London
44 20 7429 6607
44 77 3336 3501
About African Eagle
Since discovering major nickel laterite deposits at Dutwa in northern Tanzania,
African Eagle is in transition from a diversified explorer into a nickel mining
company. The Company completed a positive scoping study on the Dutwa deposit in
July 2009, and is now working towards a full feasibility study.
African Eagle is evaluating a second promising nickel laterite deposit at Zanzui
in Tanzania, 60km south of Dutwa.
The Company also holds a 49% interest in the Mkushi Copper Mines joint venture
in Zambia, for which a draft feasibility study was completed in Q4 2008. In
addition, it holds a half million ounce gold resource at the Miyabi project in
Tanzania, and a portfolio of gold and base metal exploration assets, including
two projects in the Zambian Copperbelt.
The Company is seeking partners or buyers for its "non-core" copper, gold and
uranium projects.
More information may be found on the Company's website, www.africaneagle.co.uk
African Eagle's oxide nickel projects
The Dutwa oxide nickel project, discovered in mid-2008, consists of two deposits
within blankets of laterite or weathered rock on the tops of low ridges. African
Eagle believes that the deposits together contain around 500,000 tonnes of
nickel with by-product cobalt. Because the deposits lie at surface, mining costs
will be very low.
The deposits lie 100km east of the railhead at Mwanza and close to the main
Mwanza-Nairobi trunk road, a major power line and the shore of Lake Victoria.
The Company holds a 90% interest in the main Dutwa deposit, with option to
acquire 100%, and is earning up to 75% of a second nickel deposit at Ngasamo,
6km to the west.
Since discovering the deposits in June 2008, African Eagle has explored the
project very quickly and cost-effectively, completing within 9 months an interim
JORC-compliant resource estimate based on the drilling to September 2008 and
laboratory metallurgical and mineralogical tests which showed that the deposit
can be processed efficiently by sulphuric acid leaching.
In July 2009, the Company announced the results of a "proof of concept" scoping
study by GRD Minproc, which indicated that the project would be profitable if it
were in production today. At current nickel prices (~$10 to $11/lb), earnings
over the life of mine would be of the order of $3 to 4 billion on an EBIT basis,
giving an internal rate of return around 30%, after tax. African Eagle has now
begun work towards a definitive feasibility study.
The economic viability of any nickel laterite deposit depends on its metallurgy,
its resource geology and its location. Metallurgical tests have shown that the
Dutwa ore is unusually, perhaps uniquely, amenable to acid leaching, with very
low acid consumption and a very fast leach reaction compared to other nickel
laterites around the world. These characteristics should allow the ore to be
processed at atmospheric pressure using straightforward heap or tank leaching.
In addition to the Dutwa deposits, African Eagle holds the Zanzui nickel
project, which is only 60km from Dutwa and offers potential economies of scale.
Zanzui is possibly as large as Dutwa and preliminary metallurgical tests suggest
that it shares the same fast, low-acid leaching characteristics. The Company is
aware of at least two other, similar deposits in Tanzania.
[HUG#1418027]
Unternehmen: African Eagle Resources PLC - ISIN: GB0003394813