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利用可变形金袋热液设备,在300℃,50 MPa和NNO氧缓冲剂存在的条件下,测定了金和石英在不同pH的0.01,0.10和1.00 mol/kg NaCl溶液中的溶解度.推断了An-SiO_2-NaCl-H_2O体系中金的存在形式,求得下列溶解反应的平衡常数:Au+H_2O=AuOH~0+1/2H_2,logK(AuOH_0)=-7.92±0.25;Au+Cl~-+H_2O=AuO-HCl~-+1/2H_2,logK(AuOHCl~-)=-7.56±0.65.研究表明,在地质上合理的pH、氯化物浓度和f(O_2)条件下,成矿溶液中金主要成AuOH~0和AuOHCl~-迁移.讨论了热液金矿床中常见的Au和SiO_2共生的原因.
The solubilities of gold and quartz in 0.01, 0.10 and 1.00 mol / kg NaCl solutions at different pHs were determined using deformable gold bag hydrothermal equipment at 300 ℃, 50 MPa and NNO buffer. An-SiO 2-NaCl-H 2 O system, the equilibrium constants of the following dissolution reactions are obtained: Au + H 2 O = AuOH 0 + 1 / 2H 2, log K AuOH 0 -0 7.92 ± 0.25, Au + Cl ~ + H_2O = AuO-HCl ~ - + 1 / 2H_2, logK (AuOHCl ~ -) = -7.56 ± 0.65.The results show that under the conditions of geologically reasonable pH, chloride concentration and f Au mainly migrated into AuOH ~ 0 and AuOHCl ~ -. The reasons for the coexistence of Au and SiO 2 in hydrothermal gold deposits are discussed.