Caspiche Project Study Positive on Oxide-Sulphide Development
Capital expenditures to develop the project are estimated at $4.8 billion.
The oxides-sulphides PFS evaluated three mining and processing options for the Caspiche deposit. All options in-cluded an open-pit to mine the near-sur-face, heap-leachable ore. The preferred development option is an open-pit opera-tion processing 150,000 mt/d of sul-phide ore and a heap-leach operation at an initial design production rate of 72,000 mt/d. The PFS envisages the heap leach operation will start before the main concentrator, with the leachable ore being removed as part of the pre-strip-ping operation.
A key component of the PFS is the inclusion of high-tonnage, in-pit crushing and conveying (IPCC) systems for the movement of waste rock. The cost savings per ton of total material moved using the IPCC system instead of a large truck fleet is estimated at about $0.25/mt, or $0.80/mt of ore mined. In addition to the operational savings, Exeter estimates an initial and sus-tainable capital saving of approximately $1 billion by building the tailings dam wall largely from a conveyor-stacker system rather than using conventional truck haulage for material movement. The waste dump would form the backbone of an engi-neered tailings dam face and provide a sig-nificant margin of safety in the event of an earthquake or other event.
The oxide ore and some low-copper sulphide ore would be treated in a con-ventional valley-fill heap leach operation. The sulphide orebody would be pro-cessed through a conventional concen-trator. The copper concentrate produced would be treated in an offsite roaster to ensure that its arsenic content is below 0.2%. Additional gold recovery would be achieved by leaching the flotation scav-enger tailings.