Pb-Cu-As, Pb-Fe-Cu-As系の1200℃における2液相分離範囲と銀の分配

Abstract

Following the preceding report, the miscibility gap and the distribution of silver between molten lead and speiss in the Pb-Cu-As ternary system and the Pb-Fe-Cu-As quarternary system have been determined at 1200°C.The accuracy of the quenching method was confirmed by the fact that the miscibility gaps determined by direct sampling from the equilibrated phases under an inert atmosphere agreed well with those determined by the quenching method.In the Pb-Cu-As system, a rather wide miscibility gap was observed at 1200°C, in spite of the fact that no miscibility gap was found in the Pb-Cu binary system. The shape was almost the same as those determined at 1000°C in a prior studyFor the Pb-Fe-Cu-As system, the compositions of speiss were established in the range between the two ternary systems, Pb-Fe-As and Pb-Cu-As, and presented on a pseudo-ternary phase diagram. The compositions of speiss were strongly affected by the ratio of copper and iron in speiss while the compositions of metallic lead were found on the same line as that for the Pb-Cu-As system.The distribution coefficient of silver between speiss and metallic lead, KAg, for the Pb-Cu-As system at 1200°C was approximately 1.2 over a wide range of arsenic content in speiss and was independent of temperature.Distribution coefficients for the quarternary system were determined and were distributed between the values for the two ternary systems.The values of KAg increased with increasing copper-iron ratio-and arsenic content in speiss.The distribution coefficients of silver calculated from practical data agreed well with the present results.From this study, it was concluded that the copper-iron ratio in speiss should be kept as low as possible in operations to concentrate arsenic in speiss.