Sulphide-bearing rock if left exposed to oxygen, or oxygenated water can result in metal leaching/acid rock drainage (ML/ARD). Not all exposed rock contains sulphides, but a lot where mines are do.
Onset times can be relatively fast (years) to long term (decades).
Tailings can be a huge source of this, so can waste rock piles. To stop this, we often create engineered covers to limit infiltration and reduce exposure to oxygen. In cases where we can’t manage this, the water is directed to a mined out pit or something similar and treated either actively or passively
Sulphide-bearing rock if left exposed to oxygen, or oxygenated water can result in metal leaching/acid rock drainage (ML/ARD). Not all exposed rock contains sulphides, but a lot where mines are do.
Onset times can be relatively fast (years) to long term (decades).
Tailings can be a huge source of this, so can waste rock piles. To stop this, we often create engineered covers to limit infiltration and reduce exposure to oxygen. In cases where we can’t manage this, the water is directed to a mined out pit or something similar and treated either actively or passively
Oh word, sulphides and mining waste, I knew about that.