I have always had a hard time with the undergroun mill idea. For 4 reasons.

1) I have only ever seen one underground mill in my life and that was located in a mountain in Chile. It was built to utilize gravity . i.e the mill was below the mine and the load out for conc. was below the mill. Thats not to say building a mill undergroud is impossible but it is a logistical nighmare.

2) According to the pre feasibilty study the mill will be "tuned" differently to run massive ore and net textured ore (page 110). This means there will need to be some sort of area to stockpile ore underground near the mill in order to batch the different types of ore. Even if this could be done seamlessly mines that are supposed to run at 3000 t/d do not run at 3000 t/d everyday while mills that are designed for 3000 t/d tend to operate at pretty much 3000t/d. Again not impossible but difficult, looking at the mine plan on page 121 it doesnt look like there is any storage facilities.

3) Ventilation could be an issue but looking at the plan it looks like Micon took this into consideration. Blasting in the mine while attempting to mill could cause some problems though.

4) The cost of opening up enough ground to house the mill complex. If you figuire it costs 7500-10000 $ to open 4mx 4m x 4m underground that is alot of money to open enough ground to house a mill.

I am not saying these are impossible issues to deal with but they are fairly complex and in my opinion it is something that Noront will have to take a very close look at. On the flip side the actual mine plan looks state of the art to me so maybe the logistics of milling underground will be a piece of cake.