Here is my estimate based on a scaled drawing of the Pit.
I have found 2 areas to drill and turned them into blocks.
60x60x110 deep
82x82x162 deep
This will drill out the 7 year pit.
Estimate RC Drilling in Brazil $65/m
Drilling 10x10m blocks the required meters will be,
6^2 x 110 = 3960m
8.2^2 x 162 = 10892m
Total Cost = $65 x (3960+10892) = $965,380