| Copper solubility in water vapor and liquid was measured in the HCl-NaCl-H 2O system at temperatures up to 400°C and vapor-saturated pressure by two series of experiments. The thermodynamic data from these experiments were then applied to model the genesis of volcanogenic massive sulfide deposits and the partitioning of copper between vapor and liquid.; The solubility of copper in liquid was measured in vapor-saturated aqueous HCl/NaCl solutions at temperatures ranging from 40 to 300°C, total chloride concentrations from 0.01 to 1 m, and pH from 0 to 3.5. Copper was found to dissolve primarily as CuCl(aq), CuCl2− and CuCl32−. Data collected from the experiments were regressed to determine the equilibrium constants as functions of temperature (K): Cu(s) + 1/4O2(g) + H+ + xCl− = CuClx1−x +1/2 H2O(l), where x varied from 1 to 3.; Data obtained on the solubility of copper in the liquid phase were used to model gold-copper and gold-zinc mineralization in VMS deposits. Equilibrium path calculations, employing EQ3/6, predict temperatures of precipitation, the paragenetic sequence of minerals, and the chemical composition of chimneys associated with vents on the seafloor at 21°N, East Pacific Rise. The modeling results suggest that the co-precipitation of gold with copper and zinc at different temperatures is determined by the behavior of their complexes in the solution. However, among the models simulated, only the conductive cooling model and combined mixing and cooling model predict the co-precipitation of gold and copper at high temperature (>300°C) and gold-zinc at low temperature (<250°C), which is common in VMS deposits.; The solubility of CuCl(s) in the vapor was measured in a vapor-saturated H2O(I)-H2O(v)-NaCl-HCl (NaCl/HCl; 9:1) system at temperatures ranging from 360 to 400°C, and total chloride concentration from 0.01 to 5 m. At 360°C, the copper solubility can be described by the reaction: CuCl(s) + H2O(v) = CuCl·H2O(v), and the equilibrium relationship for this reaction by KC = , where is the molality of copper in the vapor phase and is the density of water vapor; the log KC value is ∼−2.01. At 380°C and 400°C, copper solubility is controlled by the reaction: CuCl(s) + 4 H2O(v) = CuCl · 4H 2O(v). The equilibrium relationship for this reaction is KC = , and the values of log KC values are 0.22 and 1.17 at 380 and 400°C, respectively.; Partition coefficients for copper between vapor and liquid were calculated for the CuCl-NaCl-HCl-H2O(l)-H2O(v) system at the following conditions, where T = 400°C, P = water vapor saturated pressure, mNaCl = 0.5–2.3m, and mHCl = 0.001 m. The close similiarity of the partition coefficients for copper to those of sodium under the same conditions suggests that partitioning data for NaCl can be used to estima... |
