Enhanced Metal Recovery

Enhanced metal recovery is a subsurface leaching program to help draw down the remaining metal inventory in heap leach piles where mineral resource is leached with a reagent.  Large heap leach operations cover many hectares and contain millions of metric tons of low-grade ore.  The size fraction and types of ore, plus the method of ore placement on the leach pad can lead to discrete areas of compaction and densification.  Leaching around these compacted zones will cause channeling of solution, with the potential of many dry or chemically unaltered zones remaining within the heap.  These zones may contain significant quantities of underleached passive inventory that present recovery and forecasting challenges.

HGI’s Enhanced metal recovery technology helps draw down remaining metal inventory in heap leach piles.

Unfortunately, few operational techniques exist to truly improve recovery of the passive inventory.   Secondary recovery methods, i.e., processes used to rework the heap after cessation of the initial leaching cycle, have typically involved recontouring of side slopes, reripping, and managing solution and reagent delivery strictly at the surface.  These methods indirectly promote an enhancement of recovery, as the solution is diverted from existing surficial channels in hopes of reaching the more distant underleached ore.  The key to significantly reducing metal inventory in a heap leach pad, however, is to promote direct contact of the lixiviant to the location of the underleached zones, which cannot be conducted from surface work alone.