Resource-Reserve History of the Estero Hondo Alluvial Gold Mine, Ecuador

From December 1994 to November 1997 Odin MiningÆs Estero Hondo alluvial gold mine in western Ecuador washed almost 3.2 million bank cubic metres of gravel to produce just over 2600 kilograms of pure gold at a recovered grade of about 0.8 grams per bank cubic metre. The operation was a simple open pit. Draglines stripped the overburden, backhoes mined the gravel, and trucks transported the ore to a stationary, gravity-based wash plant for processing. At start-up the planned throughput was 55 000 bank cubic metres/month, but a year later this had been increased to 100 000 bank cubic metres/month. From April 1993 to July 1997 a total of 440 churn drill holes and 15 pits were sunk to test the property. The methods used to prepare the resource and reserve estimates from the raw field data are described, and seven sets of completed estimates are used to track the evolution of the projectÆs resource/reserve base through the exploration, feasibility and production stages.