酸素ガスによる生石灰吹き込み時の溶銑脱りん反応機構

抄録

To improve the dephosphorization of hot metal by lime injection process, it is necessary to clarify the dissolution mechanism of blown-in CaO in hot metal and the mechanism of dephosphorization reaction. For the purpose, a single-crystal lime immersion test and a lime powder injection testare conducted. Limes after immersion test and the reaction products adhered to Al₂O₃ tubes submerged into hot metal are analyzed by EPMA.
In hot metal, CaO starts to dissolve due to penetration of Fe_tO and Mn_tO. Then, dephosphorization reaction initiates between {CaO-Fe (Mn)_tO}₁ and phosphorus, and it is fixed as (CaO-SiO₂-P₂O₅)_s in the reaction layers. Dephosphorization reaction takes place mainly in the vicinity of the oxygen blowing nozzle.
The slagging rate of solid CaO decreases by increasing distance between the nozzle and the suspension position of CaO since carbon in the hot metal consumes oxygen. The dephosphorization rate decreases also by increasing the distance since Fe_tO in CaO-Fe_tO-MnO is reduced by the carbon.
In order to improve the dephosphorization rate, it is concluded that both of the slagging rate of solid lime and oxygen potential in the bath have to be increased with the injection of oxygen.