Impurity removal from carbon saturated liquid iron using lead solvent : New systems and processes in recycling and high performance waste treatments

Abstract

A new technique for removal of tramp-elements from steel scrap is required for saving energy and protecting the environment. An extraction method using phase separation in a liquid Fe-Pb-C system was investigated at 1453 K to obtain fundamental information on removal of copper, tin and zinc from molten iron. A mixture of iron, lead and carbon melted in a carbon crucible separates into two phases of lead and iron containing carbon. The compositions on the miscibility gap in the Fe-Pb-C system are 95.4mass% Fe-4.5 mass% C-0.1 mass% Pb and 99.9mass% Pb-0.1 mass% Fe. Distribution ratios of copper, tin and zinc between the lead and the iron phases, L X =[mass%X in molten Pb]/ (mass%X in molten Fe), are 2.2, 2.2 and 1.4, respectively. By adding a same amount of lead to an iron scrap, 70% of copper and tin from the iron scrap can be eliminated. Gold, silver and palladium are enriched in the lead rich phase. However, platinum and rhodium are more distributed to the iron rich phase than to the lead phase.