Development of the Browns Oxide Project is proceeding towards production of copper, cobalt and nickel in early 2008.

Site work on the Browns Oxide Project will begin on completion of the environmental assessment, expected at the beginning of the 2006 dry season. A mineable reserve has been established and the mine schedule completed.

The plant is designed to produce 10,000 tonnes per annum (tpa) copper, 1,000 tpa cobalt and 750 tpa nickel from the oxide ore which overlies the major Browns sulphide deposit.

The plant will be fed at a rate of 1 million tpa of ore. After comminution, the ore will be leached with sulphuric acid in agitated tanks. Tank leaching has been selected in preference to heap leaching to achieve good control of reaction variables, including temperature, free acid concentration and residence time, to maximise metal recoveries. The comminution circuit will include primary crushing followed by closed circuit grinding. Grind size is not critical to leaching but will be fine enough (less than 250 microns) to facilitate the use of resin-in-pulp metal scavenging in the downstream circuit.

The bulk of the valuable dissolved metals is separated from the leached solids in thickeners.

Above: Solvent extraction plant purchased from Cawse

A small fraction of the valuable metals remains in solution with the solids slurry. This remaining metal fraction will be scavenged in a resin–in–pulp circuit where dissolved metals are adsorbed onto an ion exchange resin. This step ensures high metal recovery. The strong liquor from the thickeners and resin stripping is sent to solvent extraction where the copper is separated from the other metals and recovered by electrowinning as equivalent London Metal Exchange “Grade A” cathode copper.

Cobalt and nickel will then be recovered from the solution by precipitation as a mixed cobalt/ nickel sulphide.

Leached solids from the process will be stored in an engineered tailings storage facility. Water is returned from the tailings storage area to be reused in the process plant.

Above: Browns Oxide Process Flow Sheet