What are giant piles of mining waste called?

The mining wastes are known as tailings.

Explanation:

Tailings are the set of residues, a mixture of ground ore with water and other compounds, that remains from having extracted the minerals in the flotation process. These wastes are transported using gutters or pipes to generally authorized places, where the water is recovered or evaporated to be disposed as a layered deposit of fine materials.

pop pop pop on a opp