The mineral resource of La Arena Project comprises an oxide portion containing gold mineralization and a sulphide fraction containing both primary and secondary copper mineralization. The gold bearing oxide material is processed via a dump leach and, in the future, the copper sulphide ore will be treated via a conventional grinding and flotation circuit.

Sulphide Metallurgy

In November 2006, IAMGold completed a pre-feasibility study for the development of La Arena. Extensive metallurgical testwork was undertaken to assess the mineralogical, comminution and flotation characteristics of the three sulphide mineralisation types. This testwork focused on copper recovery and enabled key process design parameters to be established. In the pre-feasibility study, the copper concentrate was regarded as clean without any major penalty elements.

The pre-feasibility study was based on a crushing and grinding circuit generating an 80% passing 95 microns pulp that was processed via a conventional flotation circuit with rougher, pre-cleaner, regrind and three cleaning stages to produce a copper-gold concentrate grading approximately 28% Cu at 88% recovery. Total gold recovery to the copper concentrate was approximately 40%. The preliminary testwork indicates that it is possible to recover approximately 50% of the gold rejected to the flotation tail with relatively little reagent and residence time requirements.

There is additional testwork to be completed, most importantly further composite and variability testwork to confirm concentrate metal grades and recoveries of copper and gold. Molybdenum recovery to the final concentrate ranged between 35% and 65% even though the final flowsheet development did not focus on molybdenum recovery.