2021 Volume 6 Pages 71-76
Japan's steel stock has been increasing every year and the amount of steel scraps has been increasing as well.Therefore, it is necessary to utilize a lot of steel scraps as an iron source in the future. However, steel scraps generally contain tramp elements that are difficult to be removed when they are once dissolved in molten steel. Copper, which is one of the tramp elements, cannot be removed by oxidation because it is more noble than iron. Therefore, a new principle to remove copper from molten iron must be developed. Since silver is more noble than copper, it is possible to remove copper from molten iron by oxidation via silver. In this work, the mass transfer of copper through adjacent phases of Fe-C(l), γFe(s) and Ag(l) under a temperature gradient was investigated. The results show that copper in the Fe-C(l) phase is transferred through the γFe(s) phase into the Ag(l) phase, and the diffusion of copper in the γFe(s) phase was found to be the rate limiting step based on the variation of the mass transfer of copper with time. Limitation of copper removal was also discussed, and it is found that the copper content can be decreased down to 0.050 mass% by the oxidation via γFe(s) and Ag(l) phases under the temperature gradient.
