OTTAWA, ONTARIO--(Marketwire - April 11, 2011) - Orezone Gold Corporation (News - Market indicators) is pleased to report positive metallurgical test results on its 100% owned Sega gold deposit located in Burkina Faso, West Africa. All test results for the near surface oxide and transition (semi-oxidized) resources are better than expected and will improve the economics of the project. Highlights of the study results are as follows:
Bottle-roll cyanidation weighted average gold recoveries:
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84% (68 to 93%) for the oxide material, 100% passing 12.5 mm (1/2 inch)
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73% (64 to 80%) for the transition material, 100% passing 12.5 mm
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63% (61 to 66%) for the sulphide material, 100% passing 1.7 mm
Column leach tests (heap leach) average gold recoveries:
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85% (79 to 92%) for the oxide and transition material, 100% passing 12.5 mm
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Gold recovery rates were moderate to fairly rapid, and gold recoveries of 55 to 81% were obtained in the first 10 days of leaching.
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A single column leach test of sulphide material with 92% passing 1.7 mm crush size is in progress. Gold recovery rate has been fairly rapid and an estimated gold recovery of >65% was obtained in the first 30 days of leaching. The actual recovery will not be known until after the test is completed, and the leached residue has been assayed.
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Estimated binder (cement and/or lime) required for agglomeration and pH control during leaching was 9 kg/mt, or lower. Estimated sodium cyanide consumption was 0.2 kg/mt.
Carbon-in-leach (CIL) recoveries are better than 90% for all types of material tested using a grind size of 80% passing 106 microns (150 mesh).
Bond (ball mill) work indices were 7 kWh/mt for the oxide material, 11 kWh/mt for transition material and 16 kWh/mt for sulphide material. Abrasion index testing indicated low to moderate abrasion characteristics for the three types of material.
"These metallurgical results are very positive. We have the option of heap leach or CIL processing for Sega. As we proceed with the preliminary economic assessment of the project, we plan to continue to expand and upgrade the resources with further drilling," said Pascal Marquis, V.P. Exploration for Orezone.
The Sega gold deposit hosts 450,000 oz of Indicated and 150,000 oz of Inferred resources at an average gold grade of approximately 1.7 g/t. Approximately 48% of the resources are sulphide, 35% oxide and 17% transition. With many untested high priority drill targets, there is good potential to increase the current NI 43-101 resource. The Company will carry out a $2 million program designed to increase and upgrade the resources as well as complete a preliminary economic assessment by year end.
The Sega project has the potential to host an open pit gold operation with very good infrastructure compared to many projects in West Africa. Sega is located approximately 125 km northwest of the capital city of Burkina Faso, near a large water reservoir and international power grid that are both under construction and expected to be operational within two years.
Dr. Pascal Marquis, Vice President of Exploration for Orezone, supervised the metallurgical sampling program. H. C. Osborne and Associates from Commerce City, Colorado, USA designed and supervised the test work program. The test work was performed by McClelland Laboratories Inc. from Sparks, Nevada, USA. The samples sent to McClelland were selected to be representative, in terms of grades and rock types, of about 94% of the Sega gold resources inventory. Tests included head analyses, ICP and XRF analyses, comminution, coarse bottle roll leach, preliminary heap leach (including percolation, agglomeration and ABA on the leach residues), column leach, extraction on milled samples (including grind establishment, gravity separation, flotation, and cyanidation of whole ore and gravity tailings). Samples included four whole core PQ composite samples (two 290 kg of transition material and two 70 kg of oxide material), plus six 200 kg HQ-NQ half-core composite samples (three oxide, one transition and two sulphide material). Dr. Marquis and Jack S. McPartland, metallurgist and V.P. Operations of McClelland are both Qualified Persons under National Instrument 43-101 and approved the technical information in this release.
Orezone is a gold exploration and development company with significant gold resources in Burkina Faso and more than 15 years of operating experience in West Africa, one of the world's fastest growing gold producing regions. Orezone is focused on developing Bomboré, the second largest gold deposit in the country, and its pipeline of advanced gold projects. Orezone's mission is to create wealth by discovering and developing gold resources in an efficient and responsible manner for the benefit of its shareholders and other stakeholders.
FORWARD LOOKING STATEMENTS AND FORWARD LOOKING INFORMATION: This news release contains certain "forward looking statements" within the meaning of applicable Canadian securities laws. Forward looking statements and forward looking information are frequently characterized by words such as "plan," "expect," "project," "intend," "believe," "anticipate", "estimate" and other similar words, or statements that certain events or conditions "may" or "will" occur.
FORWARD LOOKING STATEMENTS are based on the opinions and estimates of management at the date the statements are made, and are subject to a variety of risks and uncertainties and other factors that could cause actual events or results to differ materially from those projected in the forward looking statements. These factors include the inherent risks involved in the exploration and development of mineral properties, the uncertainties involved in interpreting drilling results and other geological data, fluctuating metal prices, the possibility of project cost overruns or unanticipated costs and expenses, uncertainties relating to the availability and costs of financing needed in the future and other factors. The Company undertakes no obligation to update forward-looking statements if circumstances or management's estimates or opinions should change. The reader is cautioned not to place undue reliance on forward looking statements.
Readers are advised that National Instrument 43-101 of the Canadian Securities Administrators requires that each category of mineral reserves and mineral resources be reported separately. Readers should refer to the annual information form of Orezone for the year ended December 31, 2010 and other continuous disclosure documents filed by Orezone since January 1, 2011 available at www.sedar.com, for this detailed information, which is subject to the qualifications and notes set forth therein.