Thermodynamic behavior of metal chlorides and sulfates under the conditions of incineration furnaces

Thermodynamic equilibrium calculations performed with the program ChemSage reproduce the observed behavior of metals in refuse incineration furnaces and reveal general trends. Presentation of the results as a series of small graphs allows a quick overall View of the significant species. The calculations predict that all of the Hg present and most of the Cd and Pb volatilize, as is observed in practice. The amounts of Zn and Cu volatilized depend on the reduction conditions and on the amount of Cl present. As and Sb also volatilize, but Mg, Ca, Fe, and Mi do not volatilize under the prevailing oxidizing conditions. The presence of sulfur stabilizes many of the metals in sulfate phases at low temperature but has little influence above 800 degrees C. Under locally reducing conditions, it may favor the volatilization of Sn as SnS. More detailed studies, in which comparison is made with data from industrial furnaces with measurements carried out under well-defined conditions, are required to answer specific questions.