Copper enrichment of iron-base alloy scraps by phase separation in liquid Fe-Cu-P and Fe-Cu-P-C systems

A clear phase separation into liquid iron-rich and copper-rich alloys was observed when a mixture of Fe, Cu and P was melted in an alumina or carbon crucible at 1373 K. Since this phase separation is considered to be useful for recovering valuable copper from iron-base alloy scraps, the phase equilibrium in the Fe-Cu-P and Fe-Cu-P-C systems was investigated in this study. The effect of carbon to the phase separation was determined in the concentration range of phosphorous between 7 and 11 mass% at 1373 K. It was found that the addition of carbon enlarged the miscibility gap of the Fe-Cu-P system. Distribution ratios of some minor elements of Au, Ag, Pd, Pt, Rh, Cr, Mn and Ni between the liquid iron-rich and copper rich phases were also measured at 1373 K. It was found that Au, Ag and Pd were enriched in the copper-rich phase, while Pt and Mn were distributed in both phases, and Rh, Cr and Ni preferentially in the iron-rich phase.