Experimental Determination of the Phase Diagram of the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 System

Abstract

slags are important for the smelting of vanadiumtitanium bearing magnetite. In the current study, the pseudo-melting temperatures were determined by the single-hot thermocouple technique for the specified content of 5 to 25 pct TiO 2 in the CaO-SiO 2 -5 pctMgO-10 pctAl 2 O 3 -TiO 2 phase diagram system. The 1573 K to 1773 K (1300°C to 1500°C) liquidus lines were first calculated based on the pseudo-melting temperatures according to thermodynamic equations in the specific primary crystal field. The phase equilibria at 1573 K (1300°C) were determined experimentally using the high-temperature equilibrium and quench method followed by X-ray fluorescence, X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscope analysis; the liquid phase, melilite solid solution phase (C 2 MS 2 ,C 2 AS) ss , and perovskite phase of CaOAETiO 2 were found. Therefore, the phase diagram was constructed for the specified region of the CaO-SiO 2 -5 pctMgO-10 pctAl 2 O 3 -TiO 2 system.

Experimental Study on the Phase Relations of the SiO2-MgO-TiO2 System in Air at 1500°C

“…Based on their composition, industrial titaniabearing slags 1,21,28 conform to the Al 2 O 3 -CaO-SiO 2 -MgO-TiO 2 -Ti 2 O 3 system. 29 The phase relations of the Al 2 O 3 -CaO-SiO 2 -MgO-TiO 2 system have been intensively investigated under varying conditions 27,[29][30][31][32][33][34][35][36][37][38][39][40][41][42] by using different thermodynamic modeling tools and experimental methods. These studies provide guidance for the selective crystallization of rutile (TiO 2 ), perovskite (CaOAETiO 2 ), and pseudobrookite (MgTi 2 O 5 -Al 2 TiO 5 ) phases.…”

Effect of Al₂O₃ Addition on the Phase Equilibria Relations of CaO-SiO₂-5 wt%MgO-Al₂O₃-TiO₂ System Relevant to Ti-bearing Blast Furnace Slag

“…In order to clarify the transformation of equilibria phase relations related to practical composition of Ti-bearing slag system, the compositions of the experimental samples were designed mainly basing on the typical composition 29,30) of Ti-bearing slag ( Table 1) generated from the high blast furnace smelting process. During last few years, the equilibria phase relations at constant Al 2 O 3 content of 10 wt%, 28,35) 20 wt% 26) and 30 wt% 27) with varying w(CaO)/w(SiO 2 ) were continuous investigated by present authors, 25) which lays the foundation of studying equilibria phase relations for Ti-bearing slag system and makes it possible to carry out the analysis of the influence of Al 2 O 3 addition on the equilibria phase relations for CaO-SiO 2 -MgO-Al 2 O 3 -TiO 2 system. Therefore, samples from previous studies [25][26][27][28]35) with fixed w(CaO)/w(SiO 2 ) of 1.00 and different Al 2 O 3 content up to 30 wt% were selected to analysis the influence of Al 2 O 3 addition on the equilibria phase relations, and the projections of the sample compositions in tetrahedron and pseudo-ternary phase diagrams were shown in Figs.…”

“…Equilibria Experiment The experimental processes have been explained in detail in previous works [25][26][27][28]35) and will be simply described in this section. Generally, the experimental process could be divided into two parts, i.e.…”

“…Inspired by the SCPS technique with anosovite phase as the Ti-rich phase, Zhen Wang et al 18,22) conducted the phase equilibria study for the TiO 2 rich part of CaO-SiO 2 -TiO 2 -10wt%Al 2 O 3 system 18) and CaO-SiO 2 -TiO 2 -10wt%Al 2 O 3 -5wt%MgO system 22) to explore the primary crystal field of anosovite phase, however, the primary phase region of anosovite phase was not found within the composition and temperature ranges studied by Zhen Wang et al 18,22) Zhao et al 23 As point out and studied by Zhongmin Li et al 24) that the precipitation of Ti-rich phases could be obviously influenced by the addition of Al 2 O 3 , therefore, the phase equilibria relations for CaO-SiO 2 -MgO-Al 2 O 3 -TiO 2 system with the addition of Al 2 O 3 up to 30 wt% will be studied in present work, which is also a part of continuous researches aim at systematic studying the thermodynamic properties for Ti-bearing slag conducted during the past few years. [25][26][27][28]35) The results from present work will not only provide direct thermodynamic data for the comprehensive recovery of Ti-bearing slag and the high blast furnace smelting process of magnetite ore, but also can be served as important references for the optimization and development of Ti-containing thermodynamic database, i.e. Factsage, and HSC software, etc.…”

Phase equilibria of the CaO–SiO2–TiO2–Al2O3–MgO system in air at 1250–1400 °C

“…The primary phase field of anosovite (i.e., the pseudobrookite solid solution in the present study) in the TiO 2 -rich corner was obtained. The phase relations of the CaO-SiO 2 -TiO 2 -Al 2 O 3 -MgO system with fixed 5-10 wt% MgO and 10-30 wt% Al 2 O 3 at 1250-1500 °C were systematically studied by Shi et al [27][28][29][30][31][32] and Sun et al [33][34][35]. They paid a lot of attention to the perovskite primary phase field.…”