10/10/2011 01:02 EDT | Updated 12/09/2011 05:12 EST

Australian and state governments approve $29 billion expansion of BHP-Billiton Olympic mine

ADELAIDE, Australia - The Australian government and South Australia state on Monday approved a massive expansion of BHP Billiton's Olympic Dam uranium and copper mine that might see it become the world's biggest mining operation.

State Mineral Resources Development Minister Tom Koutsantonis said BHP's board is expected to give final approval to the Australian dollars 30 billion ($29 billion) expansion by March after agreement is reached on royalties for South Australia.

Federal Resources Minister Martin Ferguson said the open pit mine in South Australia state "has the potential to become one of the world's largest mines, if not the largest."

The size and scale is unprecedented for a single mining project in Australia, he said.

Shares of BHP, the world's biggest miner, closed Monday down 0.3 per cent at AU$37.10 while the broader Australian market finished higher.

The Olympic Dam mine's expansion over 11 years will lift copper production by more than fourfold to about 825,000 tons (750,000 metric tons) a year. Uranium oxide production will increase by about 21,000 tons (19,000 metric tons) a year.