You still have costs of moving the waste piles and treating it...

You still have costs of moving the waste piles and treating it in the plant, also I think the 2 ports can handle 24mill, outter harbour capacity is 13Mt year, inner I'm not sure. But 24 rings a bell. But the issue would be railing it, most they ever railed is 9Mt, I doubt they could do more, even more trains wouldn't get that higher as the time to unload it at Port and the congestion on track wouldn't allow it, to break 9 you'd need southern iron back up.