THERMODYNAMIC ANALYSIS ON THE CHLORIDIZATION REACTION IN DUST RECYCLING PROCESSES

摘要

The behavior of halide impurities in pyrometallurgical processes such as Wealtz kiln and MF process has been discussed based on the thermochemical data and the reported data of PbO activity in PbCl_2-PbO melts. The role of PbCl(g) has been estimated to be significant in the chloridization evaporation reaction. From reported data on the PbO activity in PbCl_2-PbO melts, activity of PbCl_2 has been calculated by the numerical integration of Gibbs-Duhem equation, and the stability domains and the composition of the liquid phase as well as the vapor pressure of PbCl_2 have been estimated as functions of log P_(HCl)~2/P_(H_2O) and temperature. From the discussion of the path during cooling process on the log P_(HCl)~2/P_(H_2O) vs. temperature diagram, the authors proposed a possible dechloridization process that utilize water vapor as a dechloridizer for the direct precipitation of PbO from gas phase.