Zafir Ekmekçi

Effects of galvanic interaction on collectorless flotation behaviour of chalcopyrite and pyrite

Abstract The effect of galvanic interactions between chalcopyrite and pyrite on their collectorless flotation behaviour have been studied. Cyclic voltammetry and microflotation tests were carried out to identify the reaction products and flotation behaviour of sulphide minerals after different types of galvanic interactions. It was found that galvanic interactions between a noble mineral (pyrite) and an active mineral (chalcopyrite) significantly affected the floatability of both minerals. The results of flotation tests carried out with different mineral-mineral combinations showed that depression of chalcopyrite and activation of pyrite depends to a great extent on their magnitude in the mixture. The dissolution behaviour of both minerals in an aqueous solution was also studied and probable electrochemical reaction mechanisms relating to activation of pyrite by copper ions were discussed.

The use of electrochemical measurements in the flotation of a platinum group minerals (PGM) bearing ore

Abstract Electrochemical potential is considered an important parameter for controlling the recovery and selectivity of sulphide minerals during flotation. The aim of this work was to use mineral potential measurements to gain an understanding of respective mineral flotation performance in the processing of a platinum group mineral (PGM) bearing ore, whilst manipulating the chemical conditions in the pulp. Sulphide mineral potentials were logged during the conditioning stage of the flotation tests. Varying the milling environment and conditioning pH affected the chemical conditions in the pulp. At any condition the mixed potential of the mineral electrodes varied, spanning a range of approximately 100 mV, and increased as follows: pyrrhotite, pentlandite, chalcopyrite, pyrite and platinum. The addition of CuSO 4 caused the potential to increase, whilst the addition of xanthate caused to the potential to decrease. The magnitude of the changes in potential for the various mineral electrodes on reagent addition was not the same and followed the recovery trend of the minerals viz. chalcopyrite>pentlandite>pyrrhotite. Chalcopyrite recovery was unaffected by differences in milling media and conditioning. Pyrrhotite flotation was inhibited when the ore was milled in the plant circuit even though the mixed potentials were similar to those measured in laboratory milled pulps. This was presumably due to excessive oxidation in the grinding and classification circuits of the plant. Acid conditioning improved the recovery of pyrrhotite through cleaning the mineral surface from hydrophilic iron oxy/sulphoxy species and also showed an enhanced reaction with xanthate. Pyrrhotite flotation was only slightly inhibited when its mixed potential was below the equilibrium potential for dixanthogen formation.