You need to understand why BHP are now blustering about walking away.
They, along with Rio, were going to save BILLIONS of $ on the RIO/BHP pilbarra merger. It was going to ofsett much of the MRRT cost. This has now backfired.
This is BHP /RIO starting the ball rolling to try and get out of the MRRT. It tells you that the Govt take was going to be quite juicy. I hope the govt takes them on and changes MRRT to include all metals... copper, zinc etc.