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    Thin Films of CuFeS2 Prepared by Flash Evaporation Technique and Their Structural Properties
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    The authors have arrived at the following results upon studying the idaite-bearing ores from ten different localities in Japan. 1) Idaite have been found in several deposits in Japan. The specimens from Yakuwa Mine, Yamagata Prefecture, have been unequivocally identified by X-ray powder method. The number of sites yielding idaite in Japan is expected to increase with further study. 2) Idaite occurs in the secondary enrichment zone of copper deposit in the form of secondary decomposition product of chalcopyrite and bornite, except in two sites, where it is present as final crystallization product in copper deposits formed under low temperature and pressure. 3) Hypogene idaite is contained in small quantity in bornite, together with digenite and chalcopyrite. Supergene idaite forms lattices, lamellae and veinlets buried in chalcopyrite and bornite. In some cases, it forms films between chalcopyrite and supergene chalcocite, or replaces pyrite in company with supergene chalcocite, digenite and covellite. 4) The process of secondary enrichment and oxidation of chalcopyrite and bornite may be summarized as follows; chalcopyrite→supergene bornite hypogene bornite idaite chalcocite digenite→covellite cuprite tenorite native copper
    Bornite
    Chalcocite
    Covellite
    Supergene (geology)
    Hypogene
    Marcasite
    Copper sulfide
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    Electrochemical behaviors of chalcopyrite, covellite, chalcocite and bornite in 9K medium at 65 °C were compared in this paper to verify they whether or not the intermediate products of chalcopyrite. The results confirmed that bornite, chalcocite and covellite are the intermediate products of chalcopyrite. Chalcocite and bornite can both oxidize to covellite.
    Chalcocite
    Bornite
    Covellite
    Chalcopyrite (CuFeS2) passivation during hydrometallurgical copper extraction is attributed to multiple competing mechanisms that are still not completely understood. Here we have studied the interfacial solution chemistry in situ at polarised chalcopyrite and chalcocite, using scanning electrochemical microscopy (SECM). It was observed that the copper species detected at an ultramicroelectrode (UME) positioned at the mineral:solution interface vary between the two minerals, and are dependent upon both the potential of the mineral and the polarisation time. Cu species formed in the presence of sulfide, derived from incomplete oxidation of chalcopyrite, are observed on the UME tip positioned above chalcopyrite under conditions where passivation may occur, in contrast to Cu(II) in the presence of sulfate under conditions where leaching is facile. Only Cu(II) in the presence of sulfate is observed at the interface of chalcocite. These observations via interfacial voltammetry provide experimental support to mechanistic studies on chalcopyrite leaching, and provide new information to complement previous in situ studies which have mostly focused on interfacial solids.
    Chalcocite
    Ultramicroelectrode
    Passivation
    Copper sulfide
    Pourbaix diagram
    Sulfide Minerals
    Covellite
    Scanning Electrochemical Microscopy
    Hydrometallurgy
    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 ∼0.55 V; this peak corresponds to reduced chalcocite, because it occurs at the same potential as the chalcocite oxidation peak.
    Chalcocite
    Bornite
    Copper sulfide
    Sulfide Minerals
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