ORALS

The San Gabriel (SG) orebody is an intermediate sulphidation epithermal deposit with mainly Au, Ag and Cu mineralization. The geometallurgical modelling of San Gabriel project was based on the geological model which describe the mineralization as a genetic relationship with breccia lithology. Breccia was subclassified in phreatomagmatic, monomictic and polymictic. From a geometallurgical point of view, only monomictic and polymictic breccias are important as these host the economic mineralization. To flowsheet development and parameters definition it was performed several metallurgical tests during the last decade using CIL cyanidation, gravity concentration and froth flotation of the head ore and tailings also. Finally, it was decided to apply gravity concentration and CIL cyanidation due to the effectiveness in gold recovery. The geometallurgical modelling to support the Feasibility Study was made over a total of 162 tests results that assess their representativeness, considering main features as geochemistry, lithology, alteration, mineral composition, and structure type. As per the metallurgical test results, polymictic breccia has an amenable metallurgical behavior with higher metal recovery, on the other hand, part of monomictic breccia is associated with a lower metallurgical recovery. There is not any relation of low recovery ore with any metal element or geochemical characteristic other than the presence and high concentration of organic matter. Geometallurgical domains are defined in function of gold extraction and there is a strong relationship between metallurgical recovery and the silver grade in the ore as a predictor of gold extraction. Furthermore, gold recovery together with silver head grade allows to define the geometallurgical units (UGM as per its Spanish acronym) into the orebody to apply the recovery criteria in the block model. Overall gold extraction algorithms regarding to each defined UGM were defined for this modelling. Gold metallurgical extraction were loaded to the resources block model using algorithms defined during this work and the production program and gold extraction predicted for the Feasibility Study are based on the inventory of economically exploitable mineral resources and the aforementioned considerations.

References:
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