It should be remembered that all of the ore mined at Olympic Dam is processed on site, and a rail link was never seen as viable.
The Plans for the proposed expansion do however call for a rail link, but then the expansion will mean a massive increase in production.
Does this costing approach also account for the environmental impacts of using many trucks per day to the port of adelaide? Even if trucks were to be used, then why not have a siding on the Alice line as an interchange point?
My understanding is they require enormous tonnages of cement to fill in parts of the mine so they can remove ore alongside where they've been before. I guess a laymans way of describing it is that if you look at the ore body like a brick wall, and you want to remove every brick without it collapsing, then you have to replace the bricks with something else like cement as you remove them.
If anybody has a better understanding how Olympic Dam is mined please add. I might be incorrect but that's my basic grasp if how it operates.
You'll see Linfox's cement tanker road trains on Port Wakefield Road every day. They are specially made cement tankers to carry copper plates for the trip back to Adelaide.
With the expansion to go open cut, the cement isn't needed so the copper as a one way freight could make rail more competative.
I doubt any drums of Uranium yellowcake ever going on rail. We don't any smelly, hairy hippies ( and that's just the women) protesting on a main rail line.