Research on the Activity of Components in Fundamental System of Iron Blast Furnace Slag. II : Measurement of the Activity of Alumina in the System CaO-SiO_2-Al_2O_3

The e. m. f. of the following cell Fe-Al-C_ | CaO-SiO_2-Al_2O_3 (I) | C or MgO | CaO-SiO_2-Al_2O_3 (II) | Fe-Al-C_. was measured at 1630℃ with the reference slags CaO 45.2, SiO_2 2.2 and Al_2O_3 53.7 wt % respectively. It was found that the e. m. f. sharply increased with increasing concentration of lime, and then decreased gradually. On the other hand, with constant alumina series, a marked increase of the e. m. f. was observed in the range near the liquidus of 2CaO-SiO_2. Now choosing the standard state as the solid alumina at 1630℃, the activity of alumina. in a given slag was calculated from the e. m. f. by the following equation : E=RT/6Flna_ From the authors\u27 data, the isoactivity lines were drawn on the ternary coordinates of CaO-SiO_2-Al_2O_3. And symmetrical isoactivity lines were obtained about the straight line connecting between 2CaO-SiO_2 at CaO-SiO_2 system and Al_2O_3 coordinate, which may be explained by the change of existing anion species of aluminum in the slag. Finally the most probable anion species and their stabilities were discussed