Neutralization of bioleach liquors

Mintek has been involved in the development of bioleach technology for many years, initially for refractory gold extraction, and more recently also fo r base metals extraction. Mintek, in collaboration with its Australian tech nology partner (BatTech), is the technology provider for the Beaconsfield r efractory gold bioleach plant. At present Mintek, BacTech and Penoles are c onstructing a demonstration bioleach plant for copper-tint concentrate trea tment. Bioleach liquors produced in an applications have to be neutralized, In the copper-zinc case, neutralization is required for bleeding iron from the circuit and for adjusting the pH value ahead of solvent extraction. In the refractory gold bioleach circuit, neutralization is required for produ cing a stable iron-arsenic residue. Some of the challenges encountered in each of these neutralization applicat ions are discussed, and examples of results obtained are presented.