ROLE OF NaCl IN ORE-FORMING OF SAND-SHALE TYPE COPPER DEPOSITS
(College of Resource, Environment and Civil Engineering,Central South University of Technology, Changsha 410083, P. R. China)
Abstract: Ore-forming fluids of sand-shale copper deposits in Meso-Cenozoic Diwa basins in South China are hot brine solutions composed mainly of NaCl, an important mineralizer. Studies on chemical kinetics and thermodynamics showed that NaCl plays an important part in the ore-forming process of sand-shale copper deposits: (1) NaCl can obviously increase the dissolution rate of copper minerals in source bed, and catalyse the dissolution and migration of copper; (2) Cu and Cl- can form stable cuprous chloride complexes to migrate, which are mainly CuCl0, CuCl2- and CuCl2-3; (3) the increase of NaCl concentration in solutions can enlarge the solubility of copper by orders of magnitude.
Key words: dissolution kinetics thermodynamics cuprous chloride complex NaCl sand-shale type copper deposits