I'm posting here because @ceh2009 seemed to be chucking around numbers without basis. Perhaps I have been doing so too. I prefer to lay out all of my numbers in the posts and I'm happy to be corrected.
I haven't looked into spot concentrate terms. Where do your data come from? If they are correct my total is short by A$314 per tonne of con or US$224 per tonne of con. So a margin of US$55 per tonne of con, cash flow positive still but not gloriously so. Is this closer to your understanding?
The DFS info is below - page 22 of the release on 28/11/17. I note that the SRK review largely supports your numbers. DMOR.
NCZ Price at posting:
58.5¢ Sentiment: Hold Disclosure: Held