Colombian Mines Achieves 91.6% Extraction In Yarujmalito Column Leach Tests
VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 09/25/12 -- Colombian Mines Corporation ("Colombian Mines" or "the Company") (TSX VENTURE: CMJ)(FRANKFURT: X6C) is pleased to announce 91.6% recovery of contained gold in column leach tests of oxide mineralization crushed to 80% passing 12.5 mm (1/2 inch) from the Escuela zone at the Company's Yarumalito property in Colombia. Similar column leach tests of mixed and sulfide mineralization crushed to 1.7 mm achieved 80.6% and 63.0% recovery respectively. Table 1 below presents summary results for these column leach tests.
Table 1. Escuela Zone Column Leach Results
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Head Assay
(grams/ Tonnes/ Crush Leach Reagent
tonne) Meter3 Dimension Duration consumption Recovery (%)
Mineral --------------------------------------------------------------------
Type gold silver (T/m3) (mm) (days) (kg/T) gold silver
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OXIDE 0.47 2.4 2.3 12.5 118 2.56 91.6 59
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MIXED 1.98 1.7 2.6 1.7 106 2.04 80.6 44
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SULFIDE 0.54 1.48 2.7 1.7 98 1.49 63.0 56
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As shown in Figure 1 below, initial leaching proceeded rapidly with each mineral type yielding 50 to 80% gold recovery within the first 20 days. This leach profile is typical of mineralization that is well suited to heap leaching. Oxide mineralization was leached to extinction while mixed and sulfide type mineralization were continued to yield incremental amounts of gold. With the extended leaching times typical of an operating heap leach operation, recoveries for mixed and sulfide mineral types may exceed those achieved in laboratory scale tests.
To view Figure 1, click on the following link: http://media3.marketwire.com/docs/c924m.pdf
Composite samples were selected by the Company's Qualified Person (QP) from appropriate mineralized core intervals within the La Escuela Target at Yarumalito. Sample intervals were collected by the Company's personnel at its secured core facility in Medellin, Colombia. Intervals of each mineral type were selected to represent a range of grades and locations, and to approximate as nearly as possible the deposit, both as to grade and natural variation. All intervals were of the remaining half of HQ diameter diamond core that had been previously logged, diamond saw split and assayed. Sample composites were placed in containers, sealed and shipped to McClelland Laboratories in Reno, Nevada where all further sample treatment and processing were conducted under the supervision of McClelland personnel.
Discussion of Results
These results support and confirm earlier preliminary metallurgical studies by the company and strongly suggest the Escuela zone at Yarumalito is amenable to cost effective, bulk heap leaching technology. Some operations utilizing heap leach recovery technology and other similar parameters achieve direct operating costs of less than $500 per ounce of gold produced.
Gold recovery at 91.6% was better than expected from the 12.5 mm crush in the oxide zone. Finer crushing was necessary to achieve recoveries of 80.6 and 63.0 % in the mixed and and sulfide zones respectively. Fine crushing will result in incrementally higher construction and operating costs, but are expected to be well below the cost of building and operating a conventional mill for flotation and leaching.
About Yarumalito
The Yarumalito intrusive complex is comprised of multiple gold-copper bearing intrusive porphyry zones situated along the highly prospective Middle Cauca section of the Andean porphyry belt. This highly prospective belt is known to host both large porphyry and intrusive hosted gold deposits including Marmato Mountain where Gran Colombia Resources has recently announced identified resources containing 11.8 million ounces of gold, and AngloGold's 25 million ounce La Colosa Deposit. The 1,457 hectare Yarumalito property covers 6 potential porphyry targets, La Escuela, El Guico, Balastreras, Via El Scure, El Guico and the recently identified La Suiza zone together with the 3 kilometer long, high grade, Culebra shear zone with drill intercepts to 1.9 meters at 33.4 grams of gold per tonne.
Since the initiation of the metallurgical work Teck Resources Limited ("Teck"), through its Colombian subsidiary, has signed an option to earn up to a 70% indirect joint venture interest in the Yarumalito Project by sole funding the next $10 million in exploration expenditures and making certain cash payments to, and private placements in Colombian Mines. Colombian Mines, through its wholly owned Colombian subsidiary, Corporacion Minera de Colombia, will manage all exploration programs at Yarumalito until Teck has earned at least its initial 55% indirect joint venture interest.
Upcoming Events
Colombian Mines will be exhibiting at the Medellin Mining Show (Feria Minera de Medellin) in Medellin, Colombia, October 17 through 19 and the New Orleans Investment Conference, booth 127, October 24-27. The Company cordially invites all interested persons to visit us at one of the fine conferences and take advantage of the opportunity to meet the management and staff, get a "hands on" feel for the Company, our projects and joint ventures in Colombia.
Sample Collection - Quality Control - Quality Assurance
The Company's samples are collected in accordance with accepted industry best practices. As standard procedure, the Company collects duplicate samples at the rate of approximately 1:30 or higher. All metallurgical samples were selected by the Company's QP, Robert Carrington, and were delivered to McClelland Metallurgical Laboratories of Reno, Nevada in sealed containers for processing.
Mr. Robert G. Carrington, P.Geo., President and CEO of the Company, is a Qualified Person as defined by National Instrument 43-101 and has reviewed and verified the technical information contained in this news release.
About Colombian Mines Corporation
Colombian Mines Corporation is focused on developing shareholder value through the exploration and development of high quality mineral properties in its 100% owned portfolio of Colombian projects. In addition to exploration for its own account, Colombian Mines has ongoing joint ventures on its Venecia project with Colombia Crest Gold Corp. (TSX VENTURE: CLB), and on its Yarumalito project with Teck Resources (NYSE: TCK; TSX: TCK.A and TCK.B) through Tecks. More than $3 million in combined exploration expenditures are currently planned to be executed on the Company's projects over the next 12 months. Colombia is widely recognized as a highly prospective, yet under-explored country with excellent discovery potential. Further information can be found on our website at www.colombianmines.com.
Robert G. Carrington, President and CEO
Forward-Looking Statements:
Certain statements in this news release are "forward-looking" within the meaning of Canadian securities legislation. They include statements about the potential commercial value of the Teck transaction, the potential proceeds to be realized from the proposed Teck private placement and expenditures to be made and payments received pursuant to the Teck transaction. Forward-looking statements are necessarily based upon the current belief, opinions and expectations of management that, while considered reasonable by the Company, are inherently subject to significant business, economic, competitive, political and social uncertainties and other contingencies. Many factors could cause the Company's actual results to differ materially from those expressed or implied in the forward-looking statements. These factors include, among others, the actual results of exploration activities, fluctuations in the price of gold and silver, political and foreign risks, production risks, environmental regulation and liability, government regulation and other factors that may affect development of the Yarumalito Project and TLS' decision to exercise its options. Investors are cautioned not to put undue reliance on forward-looking statements due to the inherent uncertainty therein.
Neither the TSX Venture Exchange nor the Investment Industry Regulatory Organization of Canada accepts responsibility for the adequacy or accuracy of this release.
Contacts:
Colombian Mines Corporation
Robert G. Carrington
President & CEO
(604) 669-0868
(604) 688-1157 (FAX)
Colombian Mines Corporation
Sharon Hebgin
Corporate Communications
(604) 649-9195
shebgin@colombianmines.com
Colombian Mines Corporation
Kim C. Casswell
Corporate Secretary
(604) 669-0868
kcasswell@colombianmines.com
www.colombianmines.com