LINKING Cu MINERALIZATION TO HOST PORPHYRY EMPLACEMENT: Re-Os AGES OF MOLYBDENITES VERSUS U-Pb AGES OF ZIRCONS AND SULFUR ISOTOPE COMPOSITIONS OF PYRITE AND CHALCOPYRITE FROM THE IJU AND SARKUH PORPHYRY DEPOSITS IN SOUTHEAST IRAN
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The Kerman copper belt in Iran contains a number of important porphyry copper deposits, including Sarkuh and Iju. Molybdenite Re-Os isotope dating of the Sarkuh and Iju porphyry copper deposits shows that mineralization occurred at 15.14 ± 0.08 and 9.8 ± 0.06 Ma, respectively. Compared with the previous Re-Os dating of molybdenite in the region, it is revealed that Cu mineralization was an ongoing process in an arc setting during the Miocene. The available zircon dates of the granitic rocks from the Sarkuh (15.18 ± 0.43 Ma) and Iju (9.27 ± 0.50 Ma) porphyry copper deposits indicate that the mineralization occurred contemporaneously with the emplacement of collision-related ore-hosting porphyries. The Re content (1,715.40 ppm) of molybdenite and the δ^(34)S_(CDT) values (0.05‰) of pyrite-chalcopyrite from Iju are consistent with its origin of sulfur and metals from a dominantly mantle source. However, the lower Re content (302.21 ppm) of molybdenite and higher δ^(34)S_(CDT) values (3.20‰) of pyrite-chalcopyrite from Sarkuh suggest additional contributions from crustal materials. It is likely that the younger porphyry copper deposits in the Kerman copper belt, such as Iju, are related to the greater contribution of postcollisional mantle-derived magmas, while the older deposits (e.g., Sarkuh) were formed during the collisional event at the Oligocene-Miocene interval where the magma had some additions from the lower crustal melts generated during crustal thickening.Galvanic cell
Xanthate
Copper extraction techniques
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Carrier flotation is a technique that can recover fine particles by using coarse carrier particles during the flotation process. In heterogeneous carrier flotation, coarse mineral particles of different minerals are used as carriers to recover fine mineral particles. By using Cu2+-treated pyrite particles as carriers, fine chalcopyrite particles recovery could be improved. However, a disadvantage of this heterogeneous carrier flotation is that it requires a post-flotation separation process to improve the grade of the final Cu concentrate. This study tested mechanical and chemical treatments to detach finely ground chalcopyrite (D50~3.5 µm) particles from Cu2+-treated coarse pyrite particles (−125 + 106 µm) after flotation. The results showed that the ultrasonic treatment was not effective to detach chalcopyrite fines from Cu2+-treated pyrite particles. However, acid treatment was effective to detach chalcopyrite fines from coarse pyrite particles. At pH 2, approximately 96% of chalcopyrite fines were detached from coarse Cu2+-treated pyrite particles. The acid treatment of flotation froth (mixture of chalcopyrite fines and Cu2+-treated pyrite particles) decomposed the collector KAX (potassium amyl xanthate) and dissolved the Cu precipitates adsorbed on the pyrite surface. This weakened the hydrophobic attraction force between the chalcopyrite fines and coarse pyrite particles, thus promoting the detachment of chalcopyrite fines from Cu2+-treated coarse pyrite particles.
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Froth flotation
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Sulfide Minerals
Galvanic cell
Copper sulfide
Gangue
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The replacement of depressants used in sulfide mineral beneficiation, with bacteria and their metabolites, promises to reduce the environmental impact left by the mining industry. In this study, the attachment of Leptospirillum ferrooxidans, L.f, to chalcopyrite and pyrite was investigated through Scanning Electron Microscopy (SEM). The impact of selective attachment, bacterial growth conditions, and extracellular polymeric substances (EPS) was investigated through bio-flotation. L.f exhibits selective attachment to pyrite between 0 h and 168 h exposure via an indirect contact mechanism. Separation of chalcopyrite from pyrite was achieved through exposing the minerals for 72 h with an L.f culture grown on either HH media, chalcopyrite, or pyrite. The results produced 80.4, 43.4, and 47.4% recovery of chalcopyrite, respectively. However, EPS supernatant extracted from L.f grown on chalcopyrite, conditioned for 48 h, provided the best separation efficiency by the selective depression of pyrite resulting in 95.8% Cu recovery. Polysaccharide-rich EPS selectively attaches to pyrite within 48 h, depressing its floatability and ensuring successful separation with a PIPX collector.
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