Magellan Reports Excellent Gold Recoveries of 93% to 97% From Preliminary Metallurgical Studies for Cuiu Cuiu Project, Brazil
VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 02/14/12 -- Magellan Minerals Ltd. (TSX VENTURE: MNM)(OTCQX: MAGNF) ('Magellan') is pleased to report the results of a preliminary metallurgical study of ore from the Cuiu Cuiu project which was recently conducted by RDI (Resource Development Inc) of North Wheat Ridge, Colorado.
Highlights from this work include:-
-- 94 - 97% gold recoveries in carbon-in-leach direct cyanidation tests at
P80 = 200 mesh (75 microns) for composite oxide and sulphide samples
from both the Central and Moreira Gomes deposits
-- 93 - 95% gold recoveries in carbon-in-leach direct cyanidation tests at
the relatively coarse grind of P80 = 100 mesh (150 microns) for
composite oxide and sulphide samples from the Central deposit and 88 -
90% gold recoveries at P80 = 100 mesh for composite oxide and sulphide
samples from the Moreira Gomes deposit
-- Extractions were performed over 48 hours with cyanide consumptions
generally in the range of 0.23 to 0.65kg/t
-- Gravity testing also suggests that a portion of the gold (12.7 - 59.4%)
is free and can be recovered via gravity
In total, 41 samples of drill core from the Central zone weighing a total of approximately 69.5kg, and drill core samples weighing 40.3kg from the Moreira Gomes zone were used for the testing. Samples from 18 holes were selected so as to be as representative as possible of the overall resource grade at Cuiu Cuiu.
Four composite samples representing oxide material and primary sulphide material from both the Central and Moreira Gomes deposits were compiled, with head grades ranging from 1.36 to 1.93 g/t gold. The four composite samples (1kg charges) were ground to P80of 65, 100 and 150 mesh and subjected to gravity concentration using a laboratory Knelson concentrator. The gravity concentrate was subject to cleaner gravity concentration using a Gemeni table. The gold recovery in the Gemeni concentrate ranged from 12.7% to 59.4% while the concentrate assayed 4.9g/t to 175.8g/t gold.
Whole ore carbon-in-leach tests were performed on the four composites to determine the metal extraction and reagent consumptions for future potential ore processing. Each composite sample (1kg charge) was ground to P80 of 100 (150 microns) and 200 mesh (75 microns) and slurried with water to a density of 40% solids. The slurried sample was adjusted to a pH of 11 with lime, carbon added to 20 g/l and a cyanide concentration of 1 g/l. The samples were bottle rolled for 48 hours. The pH and NaCN concentration was adjusted to 11 and 1 g/l, respectively, at 6, and 24 hours for all the tests. After 48 hours, the samples were filtered after carbon removal and the residues were thoroughly washed and dried. The dry residues were then pulverized and assayed.
The results indicate that the gold extraction from the Central oxide material was over 95%, and the cyanide consumption was reasonable at 0.234 kg/t. The gold extraction for the Central primary material was +/- 93% and the cyanide consumption was 0.239 kg/t.
At Moreira Gomes the gold extraction was dependent on grind size. Gold extraction of 94% to 96% was obtained at P80of 200 mesh. The cyanide consumption was 0.653 kg/t to 1.249 kg/t.
Tables 1 and 2 summarize the results of the whole ore carbon-in-leach cyanidation test results.
Table 1 - Central deposit
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Parameters Central Oxide Central Primary
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P80=100 P80=200 P80=100 P80=200
mesh mesh mesh mesh
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Extraction % (48 hrs) 95.1 97 92.8 94.9
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Carbon, g/t 58.6 53.12 72.92 65.93
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Residue, g/t 0.09 0.05 0.18 0.1
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Cal. Head.g/t 1.81 1.61 2.46 2.03
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Reagent consumption, kg/t
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NaCN 0.234 0.238 0.239 0.837
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Lime 6.48 2.161 2.158 2.329
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Table 2 - Moreira Gomes deposit
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Parameters Moreira Gomes Oxide Moreira Gomes Primary
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P80=100 P80=200 P80=100 P80=200
mesh mesh mesh mesh
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Extraction % (48 hrs) 87.9 96.8 90.4 94.3
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Carbon, g/t 28.20 33.40 44.73 48.86
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Residue, g/t 0.12 0.03 0.14 0.09
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Cal. Head.g/t 1.02 1.06 1.50 1.56
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Reagent consumption, kg/t
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NaCN 0.671 0.653 0.536 1.249
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Lime 10.379 10.671 3.113 2.964
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Alan Carter, President & CEO commented, 'We are extremely pleased with the results of the preliminary metallurgical test work from Cuiu Cuiu which indicate excellent gold recoveries via direct cyanidation. These results are comparable with results from the nearby Tocantinzinho deposit of Eldorado Gold which is currently undergoing a feasibility study.'
The Moreira Gomes and Central deposits at Cuiu Cuiu comprise current published resources of 1.2Moz (31Mt @ 1.2 g/t) of gold in the inferred category and 0.1Moz (3.4Mt @ 1.0g/t) of gold in the indicated category. The published block model inventory for the Central and Moreira Gomes deposits at a 0.30 g/t gold cut-off comprises 3.5Mt @ 1.0 g/t gold for 110,000 oz of contained gold and 45Mt @ 1.0 g/t gold for 1.4Moz of contained gold.
This press release was reviewed by Dennis Moore, B.Sc., M.Eng., a member of AIG, AUSIMM, and the SEG, a Qualified Person in compliance with National Instrument 43-101. Test work at RDI was performed under the supervision of Deepak Malhotra, President and a Qualified Person.
Magellan Minerals Ltd. (TSX VENTURE: MNM) is a TSX Venture Exchange listed exploration and development company with a number of gold exploration properties in the Tapajos region of northern Brazil, and is focused on the Cuiu Cuiu and Coringa projects.
This news release may contain forward-looking statements including but not limited to comments regarding the timing and content of upcoming work programs, geological interpretations, receipt of property titles, potential mineral recovery processes, etc. Forward-looking statements address future events and conditions and therefore, involve inherent risks and uncertainties. Actual results may differ materially from those currently anticipated in such statements.
News release #2012-5
The TSX Venture Exchange has not reviewed and does not accept responsibility for the adequacy or accuracy of this release.
Contacts:
Magellan Minerals Ltd.
Alan Carter
President and CEO
604.676.5663
info@magellanminerals.com
Magellan Minerals Ltd.
Jennifer Duthie
Corporate Communications Manager
778.370.0519
Jennifer@magellanminerals.com
www.magellanminerals.com