Mechanism of Fume Formation during the Decarburization of High Carbon Iron Melt

Abstract

Charactristics of fume formation during the decarburization of high carbon iron melt by O₂, O₂-Ar or O₂-CO₂ were studied using a 15 kg induction furnace. The results obtained are summarized as follows ;
(1) Remarkable increase in the rate of fume evolution accompanied by fine iron droplets emission was observed when the oxygen flow rate and oxygen content of top blowing gas exceeded some critical values. This critical condition seemed to correspond to the onset of CO bubble formation beneath the bath surface.
(2) It was found that the temperature of the jet impinging zone measured by a two-color pyrometer through the oxygen lance rose up to 2 200°C only when bubble bursting took place. Bubble bursting was supposed to be the main cause of fume formation both by bursting itself and by accelerating the vaporization of iron.
(3) The effects of bath temperature and C, S, Si, Mn and Al contents of hot metal on the critical oxygen flow rate of bubble bursting were examined and it was made clear that they had significant effects on this critical condition.