Recent metallurgical test work by SGS Lakefield Research indicates that oxide ores form QGX‘ (QGX-V) Golden Hills project in western Mongolia are amenable to heap leaching.
SGS tested four composite samples prepared from 22 samples totalling 382.9 kg. The composite represented a range of lithologies with average head grades ranging from 2.3-3.5 grams gold and 12-28 grams silver per tonne. The material was collected in the fall from the gossan material overlying the massive sulphide bodies at Golden Hills.
Cyanide leaching tests on coarse or (up to 1/2 inch in size) indicates gold recovery of about 75% and silver recovery of 40-50%. Gold recovery improved to around 84-88% when the composite was ground so that about 80% of the material passed through a 64-micro sieve. Silver recoveries will little improved at 45-55%.
In both cases more than half the gold was extracted with in the first 24 hours. The test work also indicated low cyanide consumption.
Says David Anderson QGX’s CEO, “These results support the concept of establishing a low-cost, run-of-mine heap-leach operation to process the gold and silver in oxide, thus substantially lowering the total capital required to build the project”.
Optimization of the heap leach process for oxide ores continues. Testing of high-grade sulphide ores is planned for the second quarter.
The Golden Hills project comprises three massive sulphide zones and associated gold- and silver-bearing gossans. The Central zone was discovered in mid-2002, when crews came across quartz-chalcedony boulders rich in gold and associated with a larger alteration zone. Subsequent drilling and geophysical surveying led to the discovery of the South and North zones in mid-2003.
QGX can earn an 80% interest in the Golden Hill lease by spending US$450,000 on the property by 2005. The company can acquire the project outright by paying US$1 million thereafter.
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