The value and limitations of electrochemical measurements in flotation of precious metal ores

Electrochemical measurements have successfully been used to interpret flotation behaviour of sulphide ores as their flotation performance is considerably affected by the oxidation state and amount of different minerals in the ore, the galvanic interactions between grinding media/sulphide minerals and sulphide minerals with different rest potentials, chemicals and dissolved ions in the pulp. However, although the Merensky ore obtained from Bushveld Igneous can be considered as a complex sulphide ore in terms of variety of the sulphide minerals, the total sulphide mineral content is less than 1%. Therefore, the usefulness of the electrochemical measurements in flotation of Merensky ore was discussed based on the mineral potential measurements taken from the experiments performed with different types of milling media in the presence and absence of copper sulphate. The results revealed that it could be misleading to relate flotation behaviour of the sulphide minerals in Merensky ore directly with the electrode potentials, presumably due to presence of very low content of sulphide minerals and the influence of other factors such as froth stability which changed depending on the type of milling media and copper sulphate addition.