Electrochemical interaction of bornite with grinding media and its effect on flotation

The electrochemical interaction and pulp chemistry during grinding of bornite were investigated by measuring the Eh, dissolved oxygen, rest potential and polarisation curves during grinding with the Magotteaux Mill combined with a potentiostat. The effect of mild steel and high chromium media (15, 21 and 30% chromium media) on the galvanic current through bornite and its flotation was investigated. The magnitude of galvanic interaction of bornite with grinding media increased with an increase in the electrochemical activity of the grinding media, as well as the concentration of dissolved oxygen in the pulp. Galvanic interaction during grinding enhanced the oxidation of the grinding media and the production of oxidised iron species, leading to lower bornite floatability. Less electrochemically active grinding media are beneficial to the flotation of fine (< 10 mu m) bornite.