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Carbon paste electrodes in mineral processing: an electrochemical study of galena

Publication Date
DOI: 10.1016/0304-386x(93)90033-a
  • Chemistry


Abstract Electrochemical theories are often used to explain leaching of sulphide minerals and it is therefore desirable to study the individual processes with electrochemical methods. For good conducting minerals this comprises no difficulties since the mineral itself can be used as an electrode. However, for poorly conducting minerals this is not possible and direct electrochemical measurements cannot be performed. The aim of the present study was to examine the applicability of the carbon paste electrode technique to mineral processing. The mineral is embedded in graphite and the reaction at the heterogeneous electrode/electrolyte interface is investigated. In order to quantify the use of carbon paste electrodes a conducting mineral was chosen: galena. This makes a critical comparison of the electrochemical properties of the carbon paste-galena electrode and pure galena electrode possible. Potentiodynamic sweeps in acidic perchlorate solutions and with both stationary and rotating disk electrodes were used for the qualitative examination. In order to investigate the nature of the overall anodic dissolution reaction of galena, chronocoulometry in conjunction with atomic absorbance spectrometry was used. It was exclusively shown that the electrochemical behaviour of the carbon paste-galena system was the same as for pure galena. The overall anodic dissolution reaction involves two electrons and the stoichiometry of the galena sample was determined to be Pb 1.1S.

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