How you did it? I'm trying everything and still nothing.
I tried Observing, not Observing, Small talk, a mixture of all options, all the time protecting him and still nothing happens. I'm capped at like 60 with him.
On the way to the Munbury Mountain, I chose to not service the Northcrest guard (to unlock his heart you have to be a submissive bottom to get this interaction).
Once Dulrig started to mine emerine, I walked around the dungeon until the Golems appeared (I didn't use teasing attacks to defeat them), just ate Dulrig out ONCE (I think that interacting with him too much may affect the results of the mining but i might be wrong), and at the end I put 5 emerine crystals of my own.
those are all the steps that I followed, and I used the game log and the wiki for some help. Sorry if my explanation or writing is a bit faulty (。﹏。*)
If you didn't figure it out yet. When your on the trip. You need to to click "Ignore it" when the option comes up. then when your at the mine.
You need to successfully (the option comes up if you go to him) protect Dulrig (submitting works too if the golems are at high lust) then you need to eat Dulrig out 2 times but no more than that. I had problems with it too so don't worry.