Denial,
The mining cost is $3.40 PER TONNE OF DIRT EXTRACTED.
They need to shift 4 tonne of dirt to get 1 tonne of ore. That means its $13.60 per tonne of ore.
Read the announcement carefully as it doesnt say that the mining is per tonne of ore.
The $3.40 per tonne of dirt fits with the going rate at other open cuts.