East Africa Metals Reports on Metallurgical Testwork VANCOUVER, BC--(Marketwired - June 22, 2016) - East Africa Metals Inc. (TSX VENTURE: EAM) ("East Africa" or the "Company") is pleased to report the initial results of ongoing independent metallurgical testwork for the Terakimti Gold Project in Ethiopia. The initial results are positive and support Management's view that industry standard heap leaching technology will be appropriate for the extraction of gold and silver at Terakimti.
Testwork Program Summary
The objectives of this program are to test the amenability of the Terakimti near surface oxide material to extraction of gold and silver utilizing industry standard heap leaching or agitated leaching technology, and to determine parameters for preliminary process design.
The key results of the testwork completed to date are as follows:
- gold extractions averaged 75.3% in simulated heap leach tests on samples crushed to 100% passing 16mm;
- gold extractions averaged 75.5% and 78.2% respectively for agitated leach tests on samples passing 80% minus 106 microns and 80% passing 75 microns;
- the oxide material achieves satisfactory solution percolation rates with moderate agglomeration; and,
- the oxide deposit has relatively soft rock.
Sample Collection
In November of 2015 East Africa Metals completed a dedicated metallurgical drilling program at Terakimti to collect samples strictly for metallurgical testwork. The six holes were completed along the strike of the deposit with each hole drilled through the entire depth of the oxide zone. The drill holes were located to collect samples representative of the overall oxide zone and of the six mineralized lithologies identified within the oxide zone.
The cores from each hole were logged, weighed and photographed at the Terakimti site. The complete, whole core from each hole was packaged, sealed and prepared for transport to the SGS Mineral Laboratory in Johannesburg, South Africa. The core drilling, logging and preparation for transport was performed under the supervision of Steve Gardoll, East Africa's geologist at Terakimti and Jeff Heidema, P.Geo., East Africa's Vice President of Exploration.
Simulated Leach Tests
A series of simulated heap leach tests were performed as a first step to assess if the Terakimti oxide deposit may be amenable to heap leach extraction. Three separate tests were performed on composite samples at material crushed to particle sizes of 80 percent minus 6 mm, 11 mm and 16 mm. The gold extractions were 66.9%, 72.0% and 72.2% respectively for these tests with an average of 70.4%. The bulk of the gold extracted within 24 hours.
A second series of six simulated heap leach tests were performed, one on each of the six different mineralized lithologies present in the Terakimti oxide deposit. Gold extractions averaged 75.3%, and the leach kinetics were rapid with most of the gold extraction achieved within 24 hours. These tests were performed at a crush size of 100% minus 16 mm.
Percolation and Agglomeration
Percolation tests were also performed on three composite samples to assess the percolation rates through the samples. The tests were performed on material crushed to 100% minus 16 mm. The test results indicate satisfactory percolation rates can be achieved with the addition of cement for agglomeration.
Agitated Leach Tests
A total of 24 agitated cyanide leach tests (bottle rolls) were performed on samples representing the six mineralized lithologies. The average gold recovery was 78.3% at a particle size of 80% minus 75 microns, and 75.5% at a particle size of 80% minus 106 microns. The leach kinetics for the minus 75 microns material were rapid with an average gold extraction of 76.9% achieved within 12 hours. Silver extractions were variable, with an average of 46%.
Bond Grinding Testwork
Three composite samples representing different oxide lithologies of the Terakimti deposit were subjected to Bond Ball Grinding testwork to determine the hardness of the Terakimti oxide material. The Bond Work Indices averaged 7.6 kwh/tonne indicating the material is very soft when compared to other oxide gold deposits.
Moving Forward
The metallurgical testwork results received to date are positive and support the potential for development of the Terakimti gold project via either heap leach or agitated leach methodology. Collectively the positive gold extractions achieved in the simulated heap leach tests on coarse crush material, combined with the satisfactory percolation results, indicate that heap leaching may be the preferred technology for Terakimti. Therefore, East Africa has initiated a second phase of testwork to further assess the heap leach potential. This phase will utilize column leach tests on samples of minus 16mm, minus 38 mm and minus 38.1 mm crush material, operating over a 60 day leach period, to extract gold and silver. These column leach tests are specifically designed to assess, at a higher level of confidence, the amenability of heap leaching and to provide initial design parameters for a heap leaching operation.
About East Africa
The Company's principal assets and interests include both the 70%-owned Harvest polymetallic VMS exploration Project, which covers approximately 86 square kilometres in the Tigray region of Ethiopia, 600 kilometres northnorthwest of the capital city of Addis Ababa, and the Adyabo Project, covering 225 square kilometres immediately west of the Harvest Project. The Company owns 80% of the Adyabo Project, and upon execution of an NSR agreement the Company will own 100% of the Adyabo Project, subject to a 2% NSR. East Africa now has mineral resources defined at both projects in Ethiopia and continues to test priority targets. Additionally, the Company owns the 93 square kilometre Handeni Property located in north-eastern Tanzania. Handeni includes the Magambazi Project, a gold deposit discovered in 2009. East Africa has entered into a definitive agreement with an arm's length private exploration and development company to advance the project.
More information on the Company can be viewed at the Company's website: www.eastafricametals.com.
Sean Waller, P.Eng., Director, a Qualified Person under the definitions of National Instrument 43-101, has reviewed and approved the contents of this news release.
On behalf of the Board of Directors:
Andrew Lee Smith, P.Geo., CEO