Effect of water vapour content in H2–H2O–CO–CO2 mixtures on MgO solubility in slag under conditions of novel flash ironmaking technology

Abstract

The effects of different gas atmospheres on the solubility of MgO in CaO–FeO–Al2O3–SiO2–P2O5–MnO slags were studied in the temperature range of 1550–1650°C with wt-%CaO/wt-%SiO2 of 0·8–1·4 and under pO2 = 10−10 to 10−9 atm. The investigated gas atmospheres were H2/H2O (H2 reductant), CO/CO2H2/H2O (natural/coal gas) and CO/CO2. MgO solubility was found to decrease with basicity and FeO content, and increased with temperature. The following correlation was developed for MgO solubility as a function of slag composition and temperature This correlation adequately predicts MgO solubility in slags with FeO contents of 1–50 wt-%, CaO/SiO2 ratios of 0·4–1·6 and temperatures of 1550–1650°C. In addition, MgO solubility was correlated with temperature and basicity defined as: B = (wt-%CaO+0·7 wt-%FetO+0·59 wt-%MnO)–(0·5 wt-%SiO2+0·6 wt-%Al2O3), as follows The MgO solubility at 1550°C and pO2 of 1·6×10−5 atm, which represent typical ironmaking conditions, was 17, 20 and 26 wt-% respectively for slags under CO/CO2H2/H2O, H2/H2O and CO/CO2. Therefore, water vapour would decrease lining wear, as MgO solubility in slag under H2O containing atmospheres is substantially smaller than that under CO/CO2 in typical ironmaking conditions. It was found also that MgO solubility in slag shows a small increase with increasing pH2O beyond ironmaking conditions.For the first time, the effects of water vapour on MgO solubility in slag have been determined.