Wheaton River Minerals (WRM-T) has received encouraging results from column-leach tests on two composite samples taken from its Bellavista gold deposit in Costa Rica.
The Toronto-based company, which owns a 100% interest in the project, is carrying out the metallurgical tests as part of a prefeasibility study scheduled for completion in April. If the results are positive, a bankable feasibility study will completed over the duration of the year.
Column-leach tests of two 60-kg composite samples with widely differing grades were compared. After 120 days of leaching, the lower-grade sample yielded 62.4% of its gold, whereas the higher-grade sample yielded 81.7% over the same leaching period. These results indicate that an average recovery rate of 72% can be achieved using conventional heap-leaching methods.
According to Wheaton River, the recent metallurgical results are substantially better than those obtained by previous owners of the project.
The company attributes this to its use of a grind-agglomeration technique, which involves the addition of cement to a mixture of finely ground, high-grade material and coarsely crushed, low-grade material. This allows the gold-stripping solutions to uniformly contact all portions of the heap.
The ongoing prefeasibility study is focused on two separate resources of 8 million tonnes grading 1.8 grams gold per tonne and 3.6 million tonnes grading 3.28 grams gold. The former resource is classified as proven and probable and is considered amenable to open-pit mining methods at a stripping ratio of 2.26 to 1. The latter resource, which is open in two directions, is potentially minable by underground methods, but requires additional drilling to be bumped up to the proven and probable category.
Wheaton River is continuing with metallurgical testing and will incorporate all of its results into the prefeasibility study.
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