London Mining has completed a prefeasibility study (PFS) for phase 2 of the Marampa project in Sierra Leone.

Phase 2 will consist of three stages: low capex expansion will take place in phase 2a, hard rock expansion in phase 2b and reconfiguration of phase 2a for hard rock processing in phase 2c.

According to the study, the estimated capital cost of phase 2a is $659m and can be initially expanded to 8Mtpa. The estimated capital cost of phase 2b is $1.18bn and estimates for phase 2c stand at $523m.

Construction is expected to begin in the first quarter of 2012 and production is set to commence in the third quarter of 2014.

The new production plan will extend the life of the Marampa mine to 2036 and will generate a post-tax NPV10 of $2.2bn with an internal rate of return of 28.8%.