Surely they could have looked at Whyalla in South Australia for a start. Onesteel commissioned a magnetite plant in 2007 based around a concentrator/pellet plant design capability of 1.8Mtpa at ~ 69% Fe. Onesteel had issues with their concentrator as well.
It seems from what I have read that these concentrators evolve slowly. If you take the example of Cleveland-Cliffs Inc in the US and I quote from the paper on the mesto link below
"The original autogenous milling circuit, consisting of an AG mill followed by cobber magnetic separation of pebbles, pebble milling of the magnetic concentrate, a finisher magnetic separation stage and silica flotation, was installed at Empire Mines in 1963 and had six individual concentrating lines with a capacity of 1.6 Mt/a of pellets (Weiss, 1985). There have been three expansions since and, in the 1990s, Empire Mines had a total of 24 individual concentrating lines and a total plant capacity of 8 Mt/a of pellets."
In this case the 8Mt/a was 27 years in the making!!!!
Maybe the mistake with Karara was to much confidence, they wanted to get big overnight. Maybe a more staged approach would have reduced the risk for shareholders?
Below are some interesting links that help put magnetite concentration into a bit of perspective for anyone who is still interested.
