BHP Billiton Ltd has pressed the button on a $2.5 billion expansion of its Worsley Alumina refinery, after rising costs threatened to derail both the Worsley project and a similar expansion planned by Alcoa at its Wagerup alumina refinery.

BHP Billiton Ltd has pressed the button on a $2.5 billion expansion of its Worsley Alumina refinery, after rising costs threatened to derail both the Worsley project and a similar expansion planned by Alcoa at its Wagerup alumina refinery.