溶融Pb浴を用いたMetal-Immersion法による鉄スクラップからの銅除去 ― 銅クラッド鋼への適用

抄録

Copper removal from ferrous scrap by a Metal-Immersion (MI) process using a molten Pb bath was investigated using a simulated scrap sample and Cu-clad steel. The specimens were immersed in molten Pb at 973-1273 K for 1 or 10 min under Ar atmosphere. In the simulated scrap sample, complete removal of Cu was achieved at 1173 and 1273 K for 10 min, whereas residual Cu remained after immersion at 1173 K for 1 min and at 1073 and 973 K. This behavior is attributed to a decrease in the dissolution rate of Cu with increasing Cu concentration in the Pb bath. In the Cu-clad steel sample, the Cu layer was completely removed by immersion at 1273 K for 10 min. Cross-sectional SEM-EDS observation showed negligible dissolution of Fe into the Pb bath, no intermetallic compound formation, and little diffusion of Pb into the steel phase. These results indicate that the Pb-bath MI process enables selective removal of Cu with minimal influence on the steel substrate, even for Cu-clad steel, which is difficult to separate by conventional physical methods.