Commissioning continues at Alumbrera

Commissioning of the Bajo de la Alumbrera copper-gold mine in northwestern Argentina is on schedule and on budget, reports Rio Algom (ROM-T).

The company and its partners expect commercial production to be achieved in the first quarter of this year, with average daily throughput reaching design capacity of 80,000 tonnes on a sustained basis by the end of March.

Situated in Catamarca province, Alumbrera is on track to produce an average of 180,000 tonnes copper and 640,000 oz. gold over 20 years. Rio Algom has a 25% stake in the project, as does partner North Limited of Australia. MIM Holdings, also based in Australia, holds a 50% interest.

Total capital costs to build the mine have swelled to US$1.2 billion, which includes working capital and refundable value-added tax payments. The original cost estimate for Alumbrera was US$800 million.

Some of the cost overuns involve re-routing of the slurry concentrate pipeline, which was required to protect against flooding during the wet season. This work was completed late last year, and the pipeline is now reported to be operating satisfactorily.

Rio Algom reports that gold recoveries have averaged 50-60% from weathered ore and 65-70% from primary ore. These recoveries are expected to advance toward the target rate of 78% as commissioning of the gravity gold circuit progresses.

Copper recoveries are averaging 65-75% from the weathered near-surface ore and are approaching the design rate of 91% from the deeper, primary sulphide ore.

The mine and primary crusher are performing within design and budget expectations. More than 100,000 tonnes of concentrate containing 30,000 tonnes of copper were produced by the end of 1997, with 88,000 tonnes of concentrate shipped to smelters.