Gammon encouraged by column tests

Halifax-based Gammon Lake Resources (GAM-T) has received initial results from column leach test work on composite bulk core samples from the Plaza de Gallos and Refugio ore bodies on the Ocampo gold-silver property in Mexico’s Chihuahua state.

After 143 days under leach, one sample comprising material with 80% passing through a 6.3 mm screen averaged gold recovery of 88% and 63% for silver. Leaching of material with 80% passing a 1.7-mm sieve for 117 day resulted in recoveries of 91% and 76% for gold and silver, respectively.

The test work was completed by Reno-based Kappes, Cassiday & Associates (KCA). It also indicates low reagent consumption. The coarser material required 0.28 kg of sodium cyanide and 1 kg of calcium hydroxide per tonne treated. The finer grind consumed 0.69 kg sodium cyanide and 1.02 kg calcium hydroxide per tonne.

The company says it is encouraged by the silver recoveries as the metal represents about 40% of the in situ resource value.

Additional column tests are planned to determine spatial variability in and between the various deposits and to find the optimum crush size for a feasibility study.

Based on the results, KCA recommends the use of discounted recovery rates of: 85% for gold and 60% for silver at a crush size of 6.3 mm; and 88% for gold and 73% for silver at 1.7 mm.

Plaza de Gallos and Refugio are two of several deposits that have been mined intermittently by various interests since 1804.

A scoping study on the property (by KCA and Reno-based Mines Group) identified an area capable of holding 21 million tonnes. Several nearby areas, capable of holding more material, were also identified.

The estimated price tag is US$1.9 million for construction of an initial leach pad and pond complex capable of holding 7 million tonnes of ore. Expansion of the pad to a capacity of 21 million tonnes would cost another US$2.4 million.

Based on extensive drilling and sampling in 2000, Gammon Lake was able to triple the resource base at Ocampo to 21.7 million tonnes grading 1.44 grams gold and 57 grams silver per tonne in the measured and indicated category (1.8 million contained ounces gold-equivalent), plus 5.8 million inferred tonnes of 1.7 grams gold and 86 grams silver (637,000 contained ounces gold-equivalent).