Phosphate Capacities of CaO-FeO-SiO 2 -Al 2 O 3 /Na 2 O/TiO 2 Slags

Abstract

To effectively increase the dephosphorization efficiency of hot metals or the previous stage in the converter steelmaking process, phosphate capacities (CPO43-) of CaO-FeO-SiO 2 -Al 2 O 3 /Na 2 O/TiO 2 slags at 1300-1400°C were examined by laboratory experiments using equilibrating slag and pure solid iron foil. The data suggested that (CPO43-) increases with decreasing temperature and increasing slag basicity. Compared to basicity, temperature considerably affected the phosphate capacities and tended to be the most important factor. The phosphate capacities of slag considerably decreased at a high temperature of 1400°C even under high binary basicity as well as high contents of Na 2 O and FeO. Moreover, with the increase in the content of FeO and Al 2 O 3 in the slag, (CPO43-) decreased. A low content of Na 2 O led to the increase in the phosphate capacities of slag, particularly at low temperatures of 1300-1350°C. The content of TiO 2 in the slag considerably exhibited a weaker effect on (CPO43-) . Furthermore, by regression analysis, (CPO43-) was expressed as a function of the temperature and slag compositions as follows: logCPO43-=logCPO3-4 = 0.041(%CaO)-0.086log(%FeO)-0.024(%SiO 2 )-0.02(%Al 2 O 3 ) + 0.067(%Na 2 O) + 0.039(%TiO 2 ) + 56767=T-14.58, (R = 0.978).