Abstract
An electrode system to study the mechanism of fine microgram powder sulfide mineral dissolution was developed by using a relatively simple method that enables the attachment of micrograms of fine powder to a platinum plate surface. This system yields highly reproducible results and is sensitive compared with conventional electrode systems for various sulfide minerals such as pyrite, chalcopyrite, chalcocite, enargite, and tennantite. The leaching behavior of chalcopyrite was re-examined in a test of the application of this electrode system. Chalcopyrite dissolution is enhanced in specific potential regions because it is believed to be reduced to leachable chalcocite, but this result is inconclusive because it is difficult to detect the intermediate chalcocite. Powder chalcopyrite in the new powder electrode system was held at 0.45 V in the presence of copper ion and sulfuric acid media followed by an application of potential in the anodic direction. Besides the chalcopyrite oxidation peak, a small peak resulted at âź0.55 V; this peak corresponds to reduced chalcocite, because it occurs at the same potential as the chalcocite oxidation peak.
Highlights
In the mining industry, the electrochemical behavior of sulfide minerals has been studied to elucidate their surface chemistry for hydrometallurgical, mineral processing, and environmental purposes
Massive sulfide electrodes are used widely for electrochemistry, and normally these are fabricated from a flat sulfide mineral sample with one side that is connected to copper wire and cemented with epoxy resin
If sensitivity of this result was compared with the result obtained by a solid electrode [5] or a sample mixed in a carbon paste electrode [6], the new electrode system seems superior
Summary
The electrochemical behavior of sulfide minerals has been studied to elucidate their surface chemistry for hydrometallurgical, mineral processing, and environmental purposes. The carbon paste electrode is used most frequently as a powder electrode, and is fabricated as follows [2,3]: Conductive carbon powder and a small amount of sulfide powder mineral is mixed to form a paste with paraffin oil as an inactive binder to form a homogeneous paste This paste is inserted into a cylindrical tube; one side is used as the electrode and the other is used as an electrode connector with a connection to a copper wire. The authors developed a new attachment method in which a sulfide powder suspension is attached to the surface of carbon paste with alcohol and the material is allowed to dry [4]. An improvement in, and the development of, a new fine microgram powder electrode system was achieved Various estimates, such as the reproducibility and sensitivity were achieved with this method, and a quantitative analysis was attempted. An estimation of chalcopyrite dissolution, for which the dissolution mechanism has been controversial, was carried out using this new method
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