Abstract
Chalcopyrite and bornite are two important copper minerals, and they often coexist. In this study, the co-bioleaching of chalcopyrite and silver-bearing bornite by mixed moderately thermophilic culture at 50 °C was investigated. The bioleaching results show that the extraction percentage of Cu for co-bioleaching of chalcopyrite (Ccp) and silver-bearing bornite (Bn) (Ccp/Bn = 3:1) was 94.6%. Compared to bioleaching of chalcopyrite or silver-bearing bornite alone, the Cu extraction percentage was greatly enhanced when they were bioleached together. The leaching residues were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Silver-bearing bornite dissolved preferentially compared to chalcopyrite, due to galvanic interactions. Simultaneously, Ag+ was released from the silver-bearing bornite into solution. Ag2S formed on the surface because Cu and Fe in the chalcopyrite were replaced by Ag+, accelerating chalcopyrite dissolution and enrichment of Ag on the surface of the chalcopyrite.
Highlights
Chalcopyrite (CuFeS2 ) is a primary copper resource worldwide [1,2], and hydrometallurgy of chalcopyrite has been attracting more and more research attention [3,4,5,6]
The leaching efficiency of chalcopyrite can be improved by the addition of pyrite, because of its galvanic interaction [26,27], and the addition of silver ions or silver-bearing materials greatly enhances the dissolution of chalcopyrite [28,29,30,31,32,33]; several different mechanisms have been proposed for silver-catalyzed chalcopyrite leaching [34,35,36,37,38]
The objective of this research was to investigate the co-bioleaching of chalcopyrite and silver-bearing bornite using a mixed moderately thermophilic culture at 50 ◦ C
Summary
Chalcopyrite (CuFeS2 ) is a primary copper resource worldwide [1,2], and hydrometallurgy of chalcopyrite has been attracting more and more research attention [3,4,5,6]. Chalcopyrite is difficult to be leached, though, owing to the passivation of the mineral surface [7,8,9,10], which contains. Crundwell et al [17] argued that the rate of chalcopyrite dissolution is intrinsically slow due to its semiconducting properties, and is not limited by passivation film. Several studies have been undertaken to improve chalcopyrite leaching [18,19,20,21]. The ratio of Fe3+ /Fe2+ , is considered to play a key role in chalcopyrite leaching [8,9,22,23,24]. The leaching efficiency of chalcopyrite can be improved by the addition of pyrite, because of its galvanic interaction [26,27], and the addition of silver ions or silver-bearing materials greatly enhances the dissolution of chalcopyrite [28,29,30,31,32,33]; several different mechanisms have been proposed for silver-catalyzed chalcopyrite leaching [34,35,36,37,38]
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