Yale Completes Preliminary Metallurgical Studies

VANCOUVER, BC - Yale Resources Ltd. reported that preliminary metallurgical studies on mineralization from within the La Verde Grande Mine in Sonora, Mexico has shown that excellent recoveries can be obtained for copper and zinc. Bottle roll tests indicate that recoveries of 84.3 % for copper and 76.5 % for zinc are obtainable. Gold and silver recoveries were not part of this first test.
The study was completed in Hermosillo by Consulores Entalpia who have acted as metallurgical consultants to many of the copper mines in Sonora, including Piedras Verdes (Frontera Copper), Cananea (Penoles), and La Caridad (Grupo Mexico). The study was performed on approximately 150 kg of material from the lower level of the La Verde Grande Mine, which had an average grade of 2.21 % copper and 0.68 % zinc.
Historic metallurgical studies and production data have resulted in a wide variety of results with emphasis on either copper or silver depending on their relative value at the time and always involved the flotation of the oxide mineralization. The most recent, performed in 1981, studied the recovery of silver and gold by floatation with the recovery of copper from the tails. This resulted in total metal recoveries estimated at 81 % for copper, 80 % for silver and 60 % gold -- with no consideration for zinc.
In bringing the metallurgical studies to current standards, a key component is to test the viability of a heap leach scenario for the La Verde Grande mineralization. A preliminary column test performed by Yale showed recoveries of 66.61 % copper after 30 days on 30 kg of 'run of mine' (no crushing) mineralization. The results of this initial test indicate that better recoveries could be obtained with a longer leach time and that recoveries may also be improved with crushing.
The company's address is 600 - 890 West Pender St., Vancouver, BC V6C 1K4, 604-678-2531, fax: 604-678-2532.