Mine life of 32 years is low in my mind. I remember comments along the lines of doing enough drilling to justify a profitable project and then stopping. The ore body is open in all directions, ie: no drill holes have been done to define the outside edges of the ore body in any compass direction or how deep the ore goes. So I expect this mine will be producing when my grandkids are collecting dividends.
No ore body has a consistent stable distribution of recoverable elements, and a +/- of 5-10% points would not be unusual from one cubic meter to another. Subsequent drilling will identify those pockets of the ore body which are richer (or poorer) of each element and there will be some flexibility to increase the Sc production if the market demand (say for fuel cells) really takes off.
I my mind this is a solid project. It appears that most of the variables (selling prices, recovery rates, CAPEX, and OPEX, production rates, etc.) are on the conservative side so changes, or "surprises", are probably not going to be significant enough to change this from a solid project to a risky project and may even make it a very solid project.