You've put the 'Fire In The Hole' achievement in the wrong order/place. It needs to be put BEFORE 'Smells Like Team Spirit'. Otherwise you'll complete the Mine section and not be able to get it until another playthrough.
Glad I scanned ahead before I completed that area. I'd also mention that it needs to be done and achieved before you deliver the 3rd cart. After that, the miner doesn't through anymore dynamite.