Phase Relations, Activities and Minor Elements Distribution in Fe–Pb–As and Fe–Pb–Sb Systems Saturated with Carbon at 1473 K

Abstract

As a fundamental study to develop a new process for treating iron-lead base alloys, speiss, with a considerably high content of arsenic or antimony, which are produced in smelting lead ores or secondary materials of lead under a strongly reductive condition, the phase relations and the minor elements distribution of copper, silver, gold and platinum in the Fe-Pb-As and Fe-Pb-Sb systems saturated with carbon were determined at 1473 K by a quenching method. It was found that a miscibility gap composed of an iron-rich alloy phase with a very small content of lead and a lead-rich alloy phase with very few contents of iron and carbon extended over the wide concentration range. Arsenic was mostly distributed in the iron-rich alloy phase, while antimony almost evenly in both phases. For the distribution of precious metals, it was found that silver was mostly enriched in the lead-rich alloy phase, platinum in the iron-rich alloy phase, while gold and copper almost evenly in both phases. Based on the obtained data of the phase separation and using thermodynamic data for the Pb-As and Pb-Sb binary systems, the activity coefficients of arsenic and antimony in the Fe-As and Fe-Sb systems saturated with carbon at 1473 K were derived and expressed by a formula with the interaction parameters.