Enhancement of Evaporation Removal Rate of Copper in Molten Iron by the Silicon and/or Carbon Addition

It is important to establish the efficient removal method of the tramp elements such as copper and tin in recycling ferrous scraps, because the elements cause adverse effects on the mechanical properties of steel products. In the present study, the activity coefficient of copper in molten iron is increased by adding silicon and/or carbon, which have a strong affinity with iron, and the effects of silicon and carbon on the evaporation rate of copper in molten iron have been investigated at 1923 K under the chamber pressure of 133 Pa. In the case of the Fe-Si-Cu alloy, the apparent evaporation rate constant of copper has a maximum value at about 3mass%Si. The appearance of the optimum silicon content at which the copper evaporation rate is maximized can be thermodynamically explained. The enhancement effect of copper evaporation by the carbon addition is larger than that by the silicon addition. Moreover, the addition of both silicon and carbon introduced twice higher removal rate of copper. The optimum composition of Fe-Si-C alloy at which the copper evaporation rate is enhanced is around the composition of Fe-1.5mass%Si-3mass%C.