Sissonhttps://sissonpartnership.com/i/seiar/4-Other-Documents/02-Sisson-43-101-Technical-Report-Final-Jan13.pdf
relevant information is on page 271 and there is a sensitivity analysis also. The study may be somewhat out of date. In such studies, NPV is discounted to account for the fact that the authors don't expect the mine to be built overnight, I think.