Phase equilibria studies in the CaO–SiO₂–Al₂O₃–MgO system with CaO/SiO₂ ratio of 0.9

Abstract

Phase equilibria and liquidus temperatures in the CaO-SiO 2-Al 2 O 3-MgO system at a CaO/SiO 2 weight ratio of 0.9 in the liquid phase have been experimentally determined employing high-temperature equilibration and quenching technique followed by electron probe X-ray microanalysis. Isotherms at 1573, 1623, 1673, and 1773 K were determined and the primary phase fields of wollastonite, melilite, olivine, periclase, spinel, and corundum have been located. Compositions of the olivine and melilite solid solutions were analyzed and discussed. Comparisons between the newly constructed diagram, existing data, and FactSage predicted phase diagrams were performed and differences were discussed. The present study will be useful for guidance of industrial practices and further development of thermodynamic modeling.

Phase Equilibrium Studies of the CaO-MgO-Al2O3-SiO2 System for Iron Blast Furnace Slag: A Review

“…Figure 10. Experimentally determined pseudo-ternary phase diagram (CaO + SiO 2 )-Al 2 O 3 -MgO at a constant CaO/SiO2ratio of 0.9[13]. (a) Compare with the data reported by Osborn et al[7], Gutt and Russell[11], and Slag Atlas[25], (b) compare with the FactSage prediction.…”

“…A schematic of the vertical tube furnace is shown in Figure 1. The sample is placed in the hot zone of the furnace next to a thermocouple so that the equilibration temperature can be accurately monitored [13]. The equilibrated sample was dropped into water directly to attain rapid cooling.…”

“…The pseudo-ternary phase diagrams (CaO + MgO)-Al 2 O 3 -SiO 2 with constant MgO/CaO ratio of 0. iron BF operation, CaO/SiO2 ratio is usually fixed for a specific blast furnace. The third set of pseudo-ternary phase diagrams (CaO + SiO2)-Al2O3-MgO with constant CaO/SiO2 ratios of 0.9, 1.1, 1.3 and 1.5 were experimentally determined [13][14][15][16]. However, to face the increasing challenge of complex ironmaking raw feeds, the published phase diagrams could not provide enough information.…”

“…For a given BF, CaO/SiO 2 is usually kept constant to maintain a stable operation and hot metal quality. Following the requirements from BF operators, a series of pseudo-ternary phase diagrams (CaO + SiO 2 )-Al 2 O 3 -MgO at constant CaO/SiO 2 ratio were constructed by using the quenching-EPMA technique [13][14][15][16]. Figure 9 shows the representation of the pseudo-ternary phase diagrams CaO + SiO 2 )-Al 2 O 3 -MgO at constant CaO/SiO 2 ratios.…”

“…The phase equilibrium in the system CaO-MgO-Al 2 O 3 -SiO 2 has been studied extensively by many researchers [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and the phase diagrams were presented in different forms. Muan et al [24] and the Slag Atlas [25] collected and summarised most of the existing data.…”