マット中のPbSの熱力学的研究 (第1報)

抄録

Thermodynamics of copper mattes in Cu₂S-PbS system and copper saturated-mattes in Cu₂S-PbS-Cu system were studied in the temperature range from 1, 150°C to 1, 250°C.
The vapor pressures of PbS or Pb in these mattes of various compositions were measured by the dew point method and the thermodynamic functions were calculated from this experimental data.
In Cu₂S-PbS system, the activity curve of PbS deviates positively from Raoult's law in the mole fraction range of PbS from 0 to 0.3, negatively from Raoult's law in the mole fraction range of PbS from 0.3 to 1 and the activity curve of Cu₂S deviates positively from Raoult's law. The values of activity coefficient, γ are 0.3-3.0 for PbS and 1.0-1.4 for Cu₂S.
By using these activity data, free energy change, enthalpy and entropy change of mixing, and chemical potentials of PbS, Cu₂S in Cu₂S-PbS system were obtained. In Cu₂S-PbS-Cu system, the activity curve of Pb deviates from Raoult's law and activity coefficient was found to be 1.4-3.7 at 1, 200°C
The distribution of Pb into two liquid phases, matte phase and metal phase, in Cu₂S-PbS-Cu system was measured by chemical analysis of these phases and were shown by distribution coefficient L_Pb (L_Pb=Pb wt% in matte/Pb wt% in metal) or L'_Pb (L'_Pb=Pb mol% in matte/Pb mol% in metal). The value of Lpb or L'pb was 3.8 and 9.6 at 1, 200°C.