Thermodynamic Behavior of Carbonate in CaO Based Slags
송효석Hyo Seok Song,이창희Chang Hee Rhee
Abstract
Carbon in slag might be dissolved as carbide or carbonate ion, depending on various conditions such as oxygen potential and slag basicity, etc. Carbonate solubilities were measured for CaO bearing slag systems at 1600℃ under different thermodynamic conditions by using equilibration techniques. Carbonate solubility increased with activity of (CaO). The reaction mechanism of the carbonate dissolution in slag can be expressed reaction between CO₂ gaseous phase and oxygen ion to form carbonate (CO^(2-)_3). Carbonate capacities of various slags depended not only on oxygen ion but also activity coefficient of carbonate ion. The activity coefficient of carbonate ion in CaO-SiO₂ slag changed with CaO content, but that of CaO-Al₂O₃ slag did not change remarkably. Substitution of MgO by CaO on solubility of carbonate had a similar effect as in the case of carbide in CaO-SiO₂-MgO slag. The critical oxygen potential for carbide and carbonate stability found to be 10^(-10) atm.