Effect of converter dust on phosphorus migration behavior in molten iron

Abstract

In order to make better use of converter dust to achieve effective pre-dephosphorization of molten iron, the influence of the addition ratio of dedusting ash and oxide scale on dephosphorization of molten iron was compared, so as to reveal the reasons for the decrease of dephosphorization rate caused by dust. Through theoretical analysis, XRD, SEM-EDS, Raman and infrared spectroscopy, the influence of mineral phase structure, polymerization degree and phosphorus structure of pre-dephosphorization final slag on pre-dephosphorization was studied. The results show that when the proportion of dedusting ash in the oxidant increases from 0 to 25%, the dephosphorization rate decreases from 50.8% to 38.71%, and the dephosphorization rate increases to 50% after adding fluorite. The increase in the proportion of dedusting ash will lead to the decrease of phosphorus-rich phase and the increase of RO phase and iron-rich phase, which will affect the dephosphorization effect. When the dedusting ash ratio increased from 0% to 25%, the proportion of Q⁰(Si), Q⁰(P), Q¹(P) and [FeO₆]^9- structures in the pre-dephosphorization final slag increased, which was beneficial to the diffusion in the slag, but unfavorable to the migration of phosphorus. In addition, by adding fluorite in the experiment with 25% dedusting ash, it was found that the molar fractions of Q¹(Si), Q³(Si), Q⁰(P) and Q²(P) in the pre-dephosphorization final slag increased, and the phosphorus migrating into the silicon-oxygen network structure gradually increased. This study can provide reference for iron and steel enterprises to realize the secondary utilization of dedusting ash.