Dark IronFollow

I am level 57 and just now getting around to going into Blackrock Depths. While in there I want to learn to Smelt Dark Iron as it seems most of my armorsmithing recipes require the stuff. Where in BRD do I go to learn this and is there a quest or NPC trainer that lets me learn? Anything special I need to take into the instance with me when I go? Do I need my mining to be over 300 (with +mining glove enchants or somesuch?)

http://wow.allakhazam.com/forum.html?forum=69&mid=1112402933588005204&num=3