RE: KeMag NPV Hi James,
30% may not provide enough of a margin of safety as Anglo Americans Minas-Rio iron ore project in Brazil will likely come in at 8 billion for expenditures compared to the 5.75 billion estimate or a 40 % cost overrun. Some are calling for an increase to 10 billion while the value of the Mina Rios has fallen from 13.5 billion to 7 billion. High cost inflation on the project which includes open-pit mines, a benefication plant ( high grade pellet feed) and a 525km slurry pipeline ( comparable to NML: proposal). The only reason I mention this James is that NML had a high cost overrun on a much smaller dso project, I believe 40 % is a safer number to use on the taconites.
good Luck