Not bad, though I'd give them only a 5+ save (Dwarf Miners don't have shields, and a sacrifice should be made for their special rules- right now they have the same stats as Dwarf Warriors, plus special rules, for 30 points less). Alternatively, give them 4 attacks and a 6+ save (as they have little armour but two-handed weapons).
I would clarify exactly when the Miners can appear. Presumably it would be during the regular orders phase, so they can't appear and then charge by initiative?