exchemist
Valued Senior Member
Yes it is basalt overburden they are talking about, rather than tailings. Tailings would tend to have a lot more heavy metals of course - and would not be basalt, generally speaking.Not sure you are clear on how all this works here.
Mining takes stuff out of the ground. Then, if the tailings/overburden is not used, it is put back into the ground. It's not contaminated somehow and then put back. It's just put back.
So the only "toxic subtances" we are putting back are the same "toxic substances" that were there to begin with. In fact, if you are mining (for example) copper, the stuff you put back is LESS toxic because you removed the most 'contaminated' (i.e. most metal bearing) layers.
I did not make that argument. Perhaps you were referring to someone else?
The paper also mentions that by raising the pH of the soil, this procedure can actually reduce the mobility of some hazardous elements, such as arsenic.