Re-Leaching of Heap Spent Residues at Quebrada Blanca

摘要

In 20 years of operation, Quebrada Blanca has stockpiled some 80 million tons of leached residues from spent heaps. These residues average a sequential copper content of 0.23 %. A number of investigations were made into the potential of recovering this copper value: through re-leaching the residues in various forms; or leaching blends of residues and fresh ore, be it crushed or run-of-mine. Residues by themselves were leached in 6 m columns. Residues blended with crushed ore were also leached in 6 m columns. Residues blended with run-of-mine ore were leached in 1 m~3 cribs. Copper recoveries were higher if the residues were re-agglomerated prior to leaching, and aerated during leaching. Simply rinsing the residues resulted in lower recovery but higher value because of the reduced cost. Blending residues with run-of-mine supergene ore increased copper recovery in synergistic fashion. However, blending with crushed ore did not increase recovery but decreased production due to the ore grade being diluted upon adding residues.