Using the solubility method, the solubility of CuCl2 in liquid-undersaturated HCl-bearing water vapor was investigated experimentally at temperatures of 330-370 ℃ and pressures of 4.2-10 MPa. The re-sults have shown that hydration could significantly enhance copper solubility and the concentrations of copper were positively correlated with PH2O. The solubility of copper in vapor phase increased with increasing PH2O at the constant temperature. CuCl2 was transported as hydrated species CuCl2(H2O)ngas in water vapor. The formation of complexes is proposed to be the result of the following reaction: CuCl2solid + nH2Ogas = CuCl2 (H2O)ngas The hydration number n decreased slightly with increasing temperature. Statistical hydration numbers are 4.0, 3.6 and 3.3 at 330, 350 and 370 ℃ , respectively.
In order to understand the capacity of water vapor to transport copper and its mechanism, using the solubility method, the solubility of copper in undersaturated water vapor was investigated experimentally at temperatures from 310 °C to 350 °C and pressures from 42×10^5 to 100×10^5 Pa. Results of these experiments show that the presence of water vapor increases the concentration of Cu in the gas. At a constant temperature, the solubility of copper increases with increasing water vapor pressure. Copper may exist as hydrated gaseous particles in the vapor phase, and the dissolution process can be described by the following reaction： CuCl^solidm＋nH2O^gas=CuCIm·（H2O）^gasn （m=1,2 ）. The hydration number decreases with increasing temperature, varying from -6 at 310 °C , to -5 at 330 °C , and -4 at 350 °C. The results show that interactions between gas-solvent H2O and copper will significantly enhance the dissolution and transport capacity of copper in the gas phase.
