Western Australia may ask Rio Tinto Group and BHP Billiton Ltd. to pay potentially billions of dollars to end a mining rent tax to help patch a budget decimated by lower commodity prices. The state government is seeking advice on a proposal that would see the nation’s two biggest minerspay out an iron-ore levy early in a one-off lump sum, State PremierMark McGowan said Sunday. The opposition National Party last week said in parliament that such a plan could raise as much as A$4 billion ($3 billion) for the state, whichhosts the giant Pilbara iron ore mines. “We have a very major budget issue in Western Australia and ... (full story)