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African Eagle Resources PLC : Dutwa Beneficiation Results and Metallurgical Update

Released 07:15 22-Jan-2013

African Eagle Resources PLC : Dutwa Beneficiation Results and Metallurgical Update

22 January 2013: African Eagle Resources plc ("African Eagle" or the "Company") (AIM: AFE; AltX: AEA) is pleased to announce test work results that confirm the positive beneficiation results for the Wamangola and Ngasamo Ferruginous Siliceous ("FeSi") and Transition ores, following completion of a targeted metallurgical variability test work campaign. The results compare favourably to those already obtained for the Wamangola FeSi ores (see press release dated 12 September 2012) and extends the knowledge of beneficiation performance to the full resource base.

The variability test work programme involved tests on both Dutwa deposits (Wamangola and Ngasamo) and both principal ore types (FeSi and Transition).  Further test work on the leach response of the beneficiated ores is still underway and will be finalised and reported later in Q1 2013.

Principal Conclusions from recent tests:

Additional Metallurgical Leach Testing Undertaken:

Prior test work performed in 2012 indicated that the leach behaviour of beneficiated FeSi ore from Wamangola is generally superior to that of RoM ore.  As a means of confirmation, a further metallurgical programme has been undertaken to confirm the leach response of the beneficiated ores.  This test programme is nearing completion and the results are expected to be announced during Q1 2013. The leach test programme is designed to confirm the leach response (metal recoveries and acid demand) of both beneficiated "FeSi" and beneficiated Transition products with testing of further samples from Wamangola and Ngasamo and extend the understanding of the overall leach performance and acid demand.

Ore beneficiation is anticipated to positively impact the Dutwa project, as it minimises both the acid requirements per unit of nickel leached and optimises the capacity of the processing plant.

Summary Details of Beneficiation Test Results
Extensive and comprehensive metallurgical variability test work has been conducted to verify the beneficiation responses observed on bulk samples by taking measurements across a range of ROM ore grades on samples from both the Wamangola and Ngasamo deposits.

In conformance with expectations, the results indicated that:

Statistical analysis of the overall results from the variability testing has, importantly, determined empirical mathematical relationships between the upgrade factors of the key metals (Ni, Fe, Mg, Al) and the silica (SiO2) concentrations in the RoM ores.  These relationships in turn enable the reasonable prediction of beneficiation recoveries and product grades by mining block, and will be applied to optimise the mining schedule for the Dutwa project. The key findings of the variability test program are summarised in Table 2 below.

Furthermore the reliability of reagent consumption and operating costs estimations has been significantly improved through greater geometallurgical understanding of the beneficiation response of the ores from Wamangola and Ngasamo.

The beneficiation batch test work was performed by ALS Metallurgy (Perth, Western Australia) to determine the energy requirements for effective scrubbing.  The work with bulk samples was performed using a large ~0.8 tonne composite sample prepared from multiple drill holes whilst variability programmes undertaken by SGS Lakefield Oretest (Perth, Western Australia) as well as by ALS Metallurgy utilised smaller sample sizes corresponding to either 3m or 9m lengths of core from single drill holes. In both cases samples were created from diamond drill cores from each deposit, selected in accordance with the expected mining schedule.  

The diamond drill hole locations were selected to be spatially representative of the planned pit shells. Beneficiation tests comprising scrubbing in a simple rotating drum mill followed by size separation by screening. The test work was performed with nip-crushed (100% passing 50mm) ore samples prepared with potable water.

Mass and metal recoveries from individual beneficiation tests (at 4kWh/t energy input) on representative sub-samples (~50kg dry weight) of the bulk composites and variability composites are summarised in Table 1 and Table 2, respectively:

Table 1:  Beneficiation Results for Dutwa Bulk Composite Ore Samples

Deposit/Ore Type % Mass Recovery % Nickel Recovery 1 Feed Grade
% Nickel
Beneficiated Grade % Nickel Upgrade Factor
Wamangola - FeSi 40.0 78.5 1.01 1.99 1.97
Wamangola -Transition 58.4 79.3 1.15 1.56 1.36
Ngasamo - FeSi 40.3 59.9 0.93 1.39 1.49
Ngasamo - Transition 40.2 57.3 0.73 1.05 1.43
  1. Percentage recovery to beneficiation product only. 

Table 2: Beneficiation Characteristics of Dutwa Ores  (Mean values) from Variability Testing

Deposit - Ore Type % Mass Recovery % Nickel Recovery 1 Feed Grade (ROM ore) % Ni Beneficiated Grade
% Nickel
Upgrade Factor
Wamangola "FeSi" 47.0 75.9 1.01 1.68 1.67
Wamangola "FeSi"
(PW core)
48.6 77.2 1.17 1.85 1.62
Wamangola "Transition"
(PQ and PW)
55.5 63.5 1.72 1.89 1.17
Ngasamo "FeSi" 40.0 69.9 1.01 1.77 1.79
Ngasamo Transition" 48.0 78.0 1.10 1.91 1.78
  1. Percentage recovery to beneficiation product only. 

The Wamangola FeSi variability samples achieved an upgrade factor of between 1.62 and 1.67 on average for a 3.35 mm cut size, with nickel recoveries of 76 to 77%.  

For the variability samples, increase in the upgrade factor for Wamangola FeSi to 1.86 was noted with a hypothetical 0.5 mm cut size although nickel recovery was lowered to 73.15%.  The difference in the beneficiated FeSi grade at the 0.5 mm cut size was slight (0.2% Ni increase).

Whilst the results from both the bulk and variability beneficiation test work indicate the potential to beneficiate the transition ores, it is evident that transition ores are less amenable to beneficiation by wet scrubbing and screening than FeSi ores, particularly for Wamangola, as shown in Tables 1, 2 and 4. However, the ability to recover nickel from RoM transition ores using atmospheric tank leaching has been previously demonstrated, as announced on 12 September 2012.

Further work to quantify the cost-benefit relationships of leaching beneficiated versus un-beneficiated transition ores has been undertaken by the Company, with results expected later in Q1 2013.

Table 3:  Beneficiation Results for Wamangola Bulk FeSi Ore versus Screen (Cut) Size used to obtain Product

Screen Size (mm) % Mass Recovery % Nickel Recovery 1 Feed Grade (ROM ore) % Ni Beneficiated Grade
% Nickel
Upgrade Factor
- 3.35 43.3 81.2 1.09 2.04 1.88
- 1.18 40.3 80.2 1.09 2.16 1.99
- 0.5 38.0 79.2 1.09 2.27 2.08
  1.  Percentage recovery to beneficiation product only. 

Table 4:  Beneficiation Results for Wamangola Bulk Transition Ore versus Screen (Cut) Size used to obtain Product

Screen Size (mm) % Mass Recovery % Nickel Recovery 1 Feed Grade (ROM ore) % Ni Beneficiated Grade
% Nickel
Upgrade Factor
- 3.35 58.4 79.3 1.15 1.56 1.36
- 1.18 55.7 77.3 1.15 1.60 1.39
- 0.5 52.6 74.6 1.15 1.63 1.42
  1. Percentage recovery to beneficiation product only. 

Reasonable upgrade factors were obtained from Ngasamo FeSi ores as shown in Tables 2 and 5, but also resulted in more nickel reporting to the reject stream, with lower nickel recoveries versus Wamangola. Overall, slightly better results were determined for the Ngasamo variability samples with around 69.9% of the nickel being recovered on average from FeSi ores using a 3.35 mm cut point.  The beneficiated grade averaged 1.77% Nickel (at 3.35mm).

Table 5:  Beneficiation Results for Ngasamo Bulk FeSi Ore versus Screen (Cut) Size used to obtain Product

Screen Size (mm) % Mass Recovery % Nickel Recovery 1 Feed Grade (ROM ore) % Ni Beneficiated Grade
% Nickel
Upgrade Factor
- 3.35 40.3 59.9 0.93 1.39 1.49
- 1.18 36.7 58.4 0.93 1.48 1.59
- 0.5 34.4 57.4 0.93 1.58 1.67
  1.  Percentage recovery to beneficiation product only. 

Technical terms
A glossary of technical terms used by African Eagle in this announcement and other published material may be found at www.africaneagle.co.uk/p/glossary.asp.

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.

For further information, please visit www.africaneagle.co.uk or contact:

African Eagle Resources plc
Trevor Moss, CEO
Alex Buck
+44 20 7248 6059

Canaccord Genuity Limited (NOMAD and Joint Broker)
Rob Collins or Andrew Chubb
+ 44 20 7523 8000

Ocean Equities Limited (Joint Broker)
Guy Wilkes
+44 20 7786 4370

Russell & Associates, Johannesburg
Charmane Russell or Marion Brower
+27 11 880 3924

About African Eagle
African Eagle Resources plc is a nickel development and exploration company listed on the London AIM (AFE) and Johannesburg AltX (AEA) stock exchanges. The Company's flagship project is the Dutwa Nickel project in Tanzania located about 25km south of Lake Victoria and 110km east of Mwanza within greenstone gold belts which host many of Tanzania's operating and developing gold mines. The Company is currently conducting a Bankable Feasibility Study, which is due for publication during 2013.




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(i) the releases contained herein are protected by copyright and other applicable laws; and
(ii) they are solely responsible for the content, accuracy and originality of the
information contained therein.

Source: African Eagle Resources PLC via Thomson Reuters ONE

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African Eagle Resources PLC : Dutwa Beneficiation Results and Metallurgical Update - RNS