Analysis of the Scrap Melting Rate in High Carbon Molten Iron

A mathematical model has been developed for analyzing scrap melting process, considering operation conditions and thermal interaction between molten iron and scrap. This model is composed of a model for single-scrap melting and heat & mass balance model. Furthermore, experiments on melting of rotating steel rod in 300 kg heating furnace and on scrap melting in 5t converter, were carried out to obtain data required for model calculations. The results obtained by model analyses and the experiments, are as follows.(1) Nondimensional correlation for mass transfer obtained in melting of rotating steel rod is Sh= 0.163 Re0.78 Sc0.356.(2) Correlation between heat and mass transfer coefficients has been obtained. This correlation approximately coincides with Chilton-Colburn's analogies.(3) In 5t converter tests, the following value was obtained about heat (h) and mass transfer coefficient (u). h: 20 00040 000 (kcal/m2h°C ), u: 0.30.7 (m/h), [3 500 ≤ε ≤ 12 000 (W/t)]Further, the results obtained from model analyses concerning the effect of some operation conditions are summarized as follows:(4) Increase of mixing power is effective for reducing melting time and bath temperature, but isn't so effective beyond a certain range.(5) For stable operation, melting in the iron with high C is preferable than in the one with low C, in respect to bath solidification.(6) Increase of charging rate of scrap improves the productivity of scrap melting process, within the range where excess solidification doesn't occur.