Source: BHP Billiton, 2011.

BHP Billiton announced in late March 2011 its Olympic Dam expansion project in South Australia has advanced to the feasibility study stage. The decision came ahead of pending release of the project's Supplementary Environmental Impact Statement (SEIS) and the start of the formal assessment of the project by the national, state, and territory governments.

The proposed Olympic Dam expansion centers on the creation of a new open-pit mine that would operate simultaneously with the existing underground mine and lift ore production from 12 million mt/y currently to 72 million mt/y for the combined operations. A new concentrator would be built, and copper concentrate production would increase from 600,000 mt/y to 2.4 million mt/y.

Refined copper production would increase from 235,000 mt/y to 750,000 mt/y; uranium oxide production would increase from 4,500 lb/y to 19,000 lb/y; gold bullion production would increase from 100,000 oz/y to 800,000 oz/y; and silver bullion production would increase from 800,000 oz/y to 2.9 million oz/y.

The expansion project's progression to feasibility followed the release of its Draft Environmental Statement in May 2009 and subsequent assessment of the more than 4,000 public submissions on a range of issues. A final decision on the project by the pertinent governments is expected in the second half of 2011.

BHP Billiton describes the Olympic Dam orebody as being shaped like a frying pan. The proposed open-pit would mine the 'pan,' while the underground operation would continue to take ore from the 'handle.' Over 40 years, the pit would grow to be 4.1 km long, 3.5 km wide, and 1 km deep.

Major infrastructure construction to support the expansion would include a coastal desalination plant and a 320-km pipeline to provide water for the project, a new power line and possibly a gas-fired power station, a rail line, an airport, port facilities, a village to accommodate workers, and more housing, retail, commercial and community facilities in the mining community of Roxby Downs. The proposed expansion would be a progressive development, requiring construction activity over a period of 11 years. The project schedule ultimately will depend on the timing and nature of government approvals and a final investment decision by the BHP Billiton board.