Maureen,
Thanks for checking. I am trying to trim down the cost of air lifting the bulk sample out. Hence, let's assume 100 tonnes and the Hercules can take a load of 20 tonnes/one way trip and go to the RoF empty to pick up another load. So, it would take 5 round trips to take out 100 tonnes.
There was some cost estimate to ship 5 black rhinos (say 10 tonnes for 5 big ones) from South Africa to Ethiopia (distance 4000 km, fly time 7 hours) which could be used as a (very) rough estimate/indication for the air lifting cost.
The cost or the above round trip for 5 rhinos was estimated to be about 50k or so, noting that here are so many differences, such as distances (shorter for RoF), current cost of fuel, insurance, more severe weather conditions (sub-zero tempeature), etc. Take $50k per round trip (for 20-tonne load) x 5 trips = $250,000.
Even if a factor of 2 were thrown in for conservatism, the cost of $0.5 M for air lifting 100 tonnes of bulk sample out of the RoF is not exorbitant. It could be a lot less given a much shorter distance.
Moe L. should have some idea on the cost based on the previous experience in 2009, but it should be easy enough for KWG to get an accurate quote from First Air.
Just speculating folks.
goldhunter