Phase Equilibria Studies in the CaO–SiO₂–Al₂O₃–MgO System with CaO/SiO₂ Ratio of 1.10

Abstract

Phase equilibria and liquidus temperatures in the CaO-SiO 2 -Al 2 O 3 -MgO system with CaO/SiO 2 weight ratio of 1.10 have been experimentally determined by means of high temperature equilibration and quenching technique followed by electron probe X-ray microanalysis. Isotherms in the interval of 20 K between 1 613 and 1 733 K were determined in the primary phase fields of dicalcium silicate, wollastonite, merwinite, periclase, spinel and melilite that are relevant to ironmaking slags. Effects of Al 2 O 3 , MgO and CaO/SiO 2 ratio on the liquidus temperatures have been discussed to assist optimum operation of iron blast furnace. Compositions of the solid solutions corresponding to the liquidus have been accurately measured that will be used for development of the thermodynamic database.

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

“…At different CaO/SiO 2 ratios, the primary phase fields change greatly. In the present study, the new diagram constructed from the current results is compared with the experimentally determined phase diagram at CaO/SiO 2 ratio of 1.1, 7 and the differences in the primary phase fields can be seen clearly in Figure 10. The belite primary phase disappears as the CaO/SiO 2 ratio decreases from 1.1 to 0.9, with the wollastonite primary phase fields occupying the whole (CaO + SiO 2 ) corner.…”

“…Comparison of newly constructed diagram with phase diagram at CaO/SiO 2 ratio of 1.1 in weight (the phase boundaries and names of primary phase fields: red ‐‐ present study; black ‐‐ CaO/SiO 2 ratio of 1.1 7 ) [Color figure can be viewed at wileyonlinelibrary.com]…”

“…In recent years, EPMA analysis was carried out to accurately determine the phase equilibrium in the CaO-SiO 2 -Al 2 O 3 -MgO system with fixed CaO/SiO 2 ratio of 1.1 7 and 1.3 8 and both phase diagrams have been constructed. The studies show that discrepancies have been identified between the new measurements and the existing data, [3][4][5][6][7][8][9] and large deviations were found between the new diagrams and the calculated diagrams computed by FactSage thermodynamic software. 10 In the present study, the EPMA technique was applied to investigate the phase equilibrium in the CaO-SiO 2 -Al 2 O 3 -MgO system with fixed CaO/SiO 2 ratio of 0.9.…”

Effects of Minor Elements to the Liquidus Temperatures of Blast Furnace Slags

“…11,12) In brief, the experiments were carried out using a vertical electric resistance furnace. High-purity reagent powders of CaCO 3 , SiO 2 , MgO, Al 2 O 3 , TiO 2 , MnO, Na 2 CO 3 , K 2 CO 3 , CaS and B 2 O 3 were carefully weighted according to the experimental plans, and then thoroughly mixed and pelletized.…”

“…The temperature differences between the industrial slags and the synthetic slags generally agree with the estimations using Table 7. The studies of effects of minor element additions to the liquidus temperatures of BF slags, accompanying with the acuate determinations of liquidus temperatures in the SiO 2 -CaO-MgO-Al 2 O 3 system, 12) will help the operator to estimate the liquidus temperatures of the complex BF slags instantly and give more accurate controls for operation temperatures. The understandings of the complex BF slag liquidus temperatures will also give indications for the optimization of BF feeds.…”