Effect of Sintering Time on Crystal and Structure of Chlorine-containing Low-titanium Slag Glass-ceramics

Abstract

Glass-ceramics with akermanite, diopside, spinel and perovskite crystalline phases were prepared by using the direct sintering method and using chlorine-containing low-titanium slag as a raw material. The changes in crystalline phase composition, relative content and microstructure of glass-ceramics sintered at different times were studied. The results suggested crystalline phases remained steady while the relative content of each phase changed significantly. The relative content of akermanite decreased firstly and then increased while those of diopside changed oppositely. The relative content of spinel rose from 6.6% to 9.3% and perovskite stabilized at 10.0-11.1%. In addition, the pore size of glass-ceramics declined firstly and then increased. The optimal microstrure of glass-ceramics were obtained when crystallized at 890 °C for 60 min and sintered at 1185 °C for 60 min. In general, glass-ceramics with compact microstructures could be obtained at appropriate sintering times.

Ceramics From Ti-Extraction Blast Furnace Slag and Their Crystalline Phase, Microstructure, and Photocatalytic Performance

“…Besides, EBFS contains certain amounts of TiO 2 , MgO, Fe 2 O 3 , and Cl (7.57,6.65,3.83,and 2.58%,respectively). Moreover, the presence of chloride in EBFS leads to a strong moisture absorption, resulting in the water concentration of 5.28% (You et al, 2020). The main chemical composition of EBFS is similar to that of calcium-siliconbased ceramics, where TiO 2 and Fe 2 O 3 favor their crystallization (Rezvani et al, 2005;Zhao et al, 2014).…”

“…For this, the titanium component is first carbonized to TiC at a high temperature and then reacted with Cl 2 to form gaseous TiCl 4 at a low temperature, allowing one to effectively extract more than 70% of titanium (He et al, 2019a). Meanwhile, this method also results in a secondary industrial waste slag, the so-called Ti-extraction blast furnace slag (EBFS) (He et al, 2019b) or chlorine-containing low-titanium slag (CTS) (You et al, 2020). At present, the annual output of EBFS is continuously increasing, approaching 100,000 tons (Zhang et al, 2018).…”

Phase equilibria of MgO–Al2O3–TiO2 system at 1600°C in air: Emphasis on pseudobrookite and spinel solid solution phases

“…For perovskite, the similar dendrite structure and density with other mineral lead to the low TiO 2 enrichment rate (≤40 wt.%), 29 and the associate with spinel phase also lead to the poor dissociation. 30 The choice of rutile as the titania-rich phase requires a quite complex compositional adjustment to ensure the modified composition of titania-bearing slag located in the primary phase field of rutile. 27 In comparison, pseudobrookite solid solution has been regarded as a suitable titania enrichment phase due to the following advantages: theoretical TiO 2 concentration more than 70 wt.% and large density difference with the glass phase (4.19 and 2.8 g/cm 3 for pseudobrookite and glass, respectively).…”

“…The key of SCPS process is to select a suitable titania enrichment phase, and the titania‐containing phases of perovskite (CaO·TiO 2 ), 23–26 rutile (TiO 2 ), 27 pseudobrookite (solid solution formed by end‐members of MgO·2TiO 2 , Al 2 O 3 ·TiO 2 , FeO·2TiO 2 , and Ti 2 O 3 ) 28 are therefore received most of the attention as the titania enrichment phase. For perovskite, the similar dendrite structure and density with other mineral lead to the low TiO 2 enrichment rate (≤40 wt.%), 29 and the associate with spinel phase also lead to the poor dissociation 30 . The choice of rutile as the titania‐rich phase requires a quite complex compositional adjustment to ensure the modified composition of titania‐bearing slag located in the primary phase field of rutile 27 .…”

Recovery of Residual Carbon from Ti-Extraction Blast Furnace Slag by Flotation with Simultaneous Dechlorination

“…However, the residual slag has over 80% remaining, forming Ti-extraction blast furnace slag (EBFS) [9,10]. Affected by the features of this process, 2-5% Cl and 5-10% C remain in the EBFS, making it both hazardous and resourceful, which is not suitable for a building feedstock or storage in the open [11,12]. Therefore, solving the harm of chlorine and recover of carbon resources become the priority of treatment and utilization of EBFS.…”