It is reported that BHP Billiton has pushed back the start date for its giant Olympic Dam copper and uranium expansion until at least 2015. This was to include digging the world's biggest open pit mine.

In a long awaited presentation, BHP was tight lipped on development costs which have been tipped by analysts to be USD 15 billion, and indicated it would not reveal them until the project was approved, in 2010 at the earliest.

BHP's ambitious plans for the deposit will see it ramp up in three major stages over 10 or 11 years with the planned huge pit eventually eating into the existing underground mine and mill around 2025.

The end result would be a pit 7 kilometer long, 5 kilometer wide and 1 kilometer deep that dwarfs the current contenders for World’s biggest pit the Escondida copper mine in Chile and Bingham Canyon copper mine in the US.