Quiz

1. A Fe-S-H 2 O Eh-pH diagram is provided below. The iron-sulfur species is pyrite (FeS 2 ). Pyrite itself is not valuable in hydrometallurgy, but it may contain finely disseminated gold. Then pyrite can be leached to free the gold, which can then be leached with cyanide. Pyrite leaching can be accomplished using near-ambient conditions (bioleaching using sulfur-oxidizing bacteria) through to autoclave leaching at >200°C.