The Au\|SiO\-2 and Sn\|SiO\-2 complexes have been experimentally calibrated at varying temperature, silica concentration and pH: Au\+++H\-3SiO\+-\-4AuH\-3SiO\-4lgK=-1.65436+9611.21/T Sn\+\{4+\}+4H\-3SiO\+-\-4Sn(H\-3Si...The Au\|SiO\-2 and Sn\|SiO\-2 complexes have been experimentally calibrated at varying temperature, silica concentration and pH: Au\+++H\-3SiO\+-\-4AuH\-3SiO\-4lgK=-1.65436+9611.21/T Sn\+\{4+\}+4H\-3SiO\+-\-4Sn(H\-3SiO\-4)\-4lgK\-\{200℃\}=42.73Compared with Au\|Cl, Au\|HS and Sn\|OH complexes, AuH\-3SiO\-4 and Sn(H\-3SiO\-4)\-4 complexes can be recognized as the dominant transport forms in Si\|bearing solutions under pH and Eh conditions of general interest. The decrease of SiO\-2 concentration and oxygen fugacity would reverse the direction of dissolution\|complexing reactions, resulting in the precipitation of gold and silica, as well as cassiterite and silica. This study illustrates the significance of SiO\-2\|complexation in hydrothermal solutions for gold, tin and other metallizations.展开更多
文摘The Au\|SiO\-2 and Sn\|SiO\-2 complexes have been experimentally calibrated at varying temperature, silica concentration and pH: Au\+++H\-3SiO\+-\-4AuH\-3SiO\-4lgK=-1.65436+9611.21/T Sn\+\{4+\}+4H\-3SiO\+-\-4Sn(H\-3SiO\-4)\-4lgK\-\{200℃\}=42.73Compared with Au\|Cl, Au\|HS and Sn\|OH complexes, AuH\-3SiO\-4 and Sn(H\-3SiO\-4)\-4 complexes can be recognized as the dominant transport forms in Si\|bearing solutions under pH and Eh conditions of general interest. The decrease of SiO\-2 concentration and oxygen fugacity would reverse the direction of dissolution\|complexing reactions, resulting in the precipitation of gold and silica, as well as cassiterite and silica. This study illustrates the significance of SiO\-2\|complexation in hydrothermal solutions for gold, tin and other metallizations.
