Au在SiO_2-HCl-H_2O体系中200℃溶解度测定──硅化对金矿化的意义初探

GOLD SOLUBILITY IN THE SiO_2-HCl-H_2O SYSTEM AT 200℃:A PRELIM1NARY ASSESSMENT OF THE IMPL1CATIONS OF SILICIFICATION WITH REGARD TO GOLD MINERALIZATION

实验标定了200℃时Au与SiO2间的络合反应：热力学计算表明，在具地质意义的物理化学条件下，AuH3SiO40的浓度远远高于AuCl2-,指出以硅络合对Au的活化迁移比氯重要得多。在含硫和硅的体系中，随着SiO2的增高，AuH3SiO40的作用将比Au（HS）2-更显重要。Au在SiO2水溶液中的溶解可表述为：SiO的沉淀是导致Au沉淀析出的有效机制，因此说明硅化与金矿化具有内在的联系。

The complexation between gold and silica was experimentally confirmed and calibrated at200℃:Thermodynamic calculations show that AuH3SiO40 would be far more abundant than AuCl2- under physicochemical conditions of geological interest, suggesting that silica is much more importantthan chloride as ligands for gold transport. In systems containing both sulfur and silica, AuH3SiO40would be increasingly more important than Au (HS)2 as the proportion of SiO2 in the system increases.The dissolution of gold in aqueous SiO2 solutions can be described by the reaction:which indicates that SiO2 precipitation is an effective mechanism governing gold deposition, andthus explains the close association of silicification with gold mineralization.