BHP Billiton has shrugged off the global economic blues to press ahead with plans to turn its Olympic Dam mine in South Australia into the largest open cut on earth and help kick the economy back into prosperity.

But the company will stick to its controversial plan to send uranium-infused copper concentrate to China for processing, if it moves ahead with the multi-billion-dollar expansion.

A 4600-page environmental impact statement, released by the company yesterday, set out an ambitious timetable for the conversion of the copper, gold, silver and uranium mine from underground to pit operations. Preparatory work would start as early as April next year, with excavation scheduled for July.

Under the plan, the mine’s workforce would double from 4000 to 8000 when it reached full capacity next decade.

The open cut envisaged by BHP Billiton at Olympic Dam would become the biggest man-made hole on the planet and yield $1 trillion worth of ore over its century-long life, more than $100 million of which would be paid in royalties to the South Australian Government. Production would lift sixfold from 12million tonnes of ore a year to 72 million tonnes after 2020.

The news was welcomed by residents of the nearby mining town of Roxby Downs, where the boom had turned to gloom amid recent job cuts at Olympic Dam and falling local property values.

BHP’s Uranium Australia division chief operating officer Dean Dalla Valle defended the decision to send the copper concentrate to China, saying it was “exactly” what other mines did and safe transportation would not be a problem.

“The go-forward case we’ve been running for quite a while now has processing offsite for a proportion of our material,” he said. “It lets us concentrate on the things we do best.”