it will cost $90 million to build, but the irr and npv numbers appear to using the historic 3-year trailing averages, so i wouldnt attach much importance to them. at near current market prices the irr of 58% and npv of $109 million look a lot more attractive:

Esperanza Silver Corp. (TSX-V:EPZ - News)(PINK SHEETS:ESPZF - News) (EPZ) reports that it has completed its preliminary review of the San Luis Feasibility Study provided to it by Silver Standard Resources Inc., its joint-venture partner on the Peruvian gold and silver project. Esperanza now anticipates a forthcoming joint-venture meeting to discuss the study and determine the best path toward production.

The Feasibility Study estimates an internal rate of return of 26.5% and a net present value, discounted at 5%, of US$39.2 million using base case prices of US$800/ounce gold and US$12.50/ounce silver. At near current prices (US$1170/ounce gold and US$18.50/ounce silver) the rate of return is 58.0% and the net present value is US$109 million.

Capital expenditures are estimated to be US$90.4 million (+/- 15%) for a 400 tonne/day underground mine with annual production of 78,000 ounces of gold and 1.86 million ounces of silver annually over its 3.5 year mine life.

Resources and Reserves

Resource and reserve grades were derived from a geologic block model provided by Resource Evaluation Inc. and Resource Modeling Inc. in 2009. The block model resource estimate used a cut-off grade of 6 g/t gold-equivalent based on a 65:1 gold-silver ratio and metals prices of US$600/troy ounce gold and US$9.25/troy ounce silver. Metallurgical recoveries and net smelter returns were assumed to be 100%.

In this resource estimate, measured and indicated resources totalled 484,000 tonnes grading 22.4 grams of gold and 578.1 grams of silver per tonne containing 348,100 ounces of gold and 9,003,300 ounces of silver.

http://finance.yahoo.com/news/Esperanza-Provides-San-Luis-iw-1400443422.html?x=0&.v=1