HEAP OPERATING SCHEDULE

In the GEOCOAT® process for refractory gold ores, the concentrate-coated support rock is stacked on an “on-off” pad for biooxidation and then unloaded for separation of the oxidized concentrate for cyanidation.

The preferred method of operation is to stack and reclaim simultaneously from the opposite sides of a “slot” which advances continuously from one end of the rectangular heap to the other - the so-called “moving slot method”. Depending on pad size and site topography, alternative configurations may be considered.

For a small operation, stacking and unloading would typically take place on day shift only. This requires that adequate surge capacity be provided ahead of the stacking and coating system (for flotation or gravity concentrate) and downstream of the stripping operation (for oxidized concentrate) since it is likely that both the flotation (or gravity concentration) plant and the cyanidation plant will operate continuously. In larger operations, stacking and unloading will be continuous to maximize utilization of the equipment and obviate the need for very large surge volumes.

For GEOCOAT® processing of base metal concentrates, the concentrate-coated support may be stacked on a single-use pad. The pad is expanded as required to accommodate the new concentrate production. Alternatively, additional lifts may be stacked on top of the first. Even when the oxidized residue contains no values, it may be advantageous to use an on-off pad. This might be the case where insufficient space is available for a continuously expanding pad.