To activate this excavation node, first you need to go to the node manager at "Roud Sulfur works" and activate the node, then go up the road and talk to "Ustouvan" and he will activate the excavation node for you for 50 energy.

Black Desert, Серный рудник (Раскопки)
https://www.youtube.com/watch?v=tHlaHg-_EHU