Structural aspects of blast furnace slag

Tiwary, J. N.; Sarkar, S.; Mishra, B.; Mohanty, U. K.

doi:10.1680/emr.12.00033

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…4 is polymerized, more O 2− is shared, and the structure of the silica-oxygen complex ion becomes more complex (from the point, line and surface of the body). In addition, the empirical formula of anions in the range of Si/O = 0.25-0.33 is shown in Table 4 [32], which indicates that the structure of the silica-oxygen complex ions tends to increase in complexity with an increase in the Si/O atomic ratio. (2) Al 2 O 3 can absorb oxygen ions to form AlO 5− 4 complex ion groups, forming complex compounds with strong crystallinity and a high melting point.…”

Section: Theoretical Analysismentioning

confidence: 99%

Effect of Unburned Pulverized Coal on the Melting Characteristics and Fluidity of Blast Furnace Slag

et al. 2021

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A substantial amount of attention has been paid to viscosity due to its substantial effect on the fluid dynamics of molten blast furnace slag and slag metal reaction kinetics during the pyrometallurgy process. To clarify the influence mechanism of unburned pulverized coal (UPC) on blast furnace (BF) slag viscosity, the effects of different contents of UPC on the BF slag viscosity, free-running temperature and viscous flow activation energy were investigated. The slag viscosity was measured by the rotating cylinder method, and the microstructure of the cooled slag was observed by SEM. As a result, the main reason for a change in the slag viscosity, free-running temperature and viscous flow activation energy was that the UPC entering the slag formed a large number of white particles that predominantly comprised deposited carbon and a high melting point solid solution. In addition, the disintegration or polymerization of the SixOz- y structure was also a contributing factor. When the content of the UPC was 0.6%, the free-running temperature and viscous flow activation energy of slag were 1623 K and 120.969 kJ/mol, respectively, which are lower than those of the slag without UPC. However, the free-running temperature and viscous flow activation energy increased to 1668 K and 286.625 kJ/mol, respectively, when the content of UPC increased to 4%, which are higher than those of slag without UPC.

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Section: Theoretical Analysismentioning

confidence: 99%

Effect of Unburned Pulverized Coal on the Melting Characteristics and Fluidity of Blast Furnace Slag

et al. 2021

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“…According to the structural study of aluminosilicate glasses using 29 Si MAS NMR spectroscopy, alkali metal as charge compensator leads to an increase in the proportions of Q 4 (4Al) and Q 4 (3Al) species (when compared to other Q 4 (mAl) species), while an alkaline earth metal as the charge compensator results in an increased proportion of Q 4 (2Al) and Q 4 (1Al) species (when compared to other Q 4 (mAl) species) [48,58]. It has been reported that cations with higher charge density, such as Mg, have a greater tendency to form wider distribution of Q n species (i.e., formation of highly polymerized species (like Q 4,I ) as well as formation of highly depolymerized species (like Q 0 , Q 1 ) [30,59].…”

Section: Plos Onementioning

confidence: 99%

Towards designing reactive glasses for alkali activation: Understanding the origins of alkaline reactivity of Na-Mg aluminosilicate glasses

Sreenivasan

Cao

et al. 2020

PLoS ONE

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Alkali-activated materials (AAMs), sometimes called geopolymers, are eco-friendly cementitious materials with reduced carbon emissions when compared to ordinary Portland cement. However, the availability of most precursors used for AAM production may decline in the future because of changes in industrial sectors. Thus, new precursors must be developed. Recently there has been increased interest in synthetic glass precursors. One major concern with using synthetic glasses is ensuring that they react sufficiently under alkaline conditions. Reactivity is a necessary, although not sufficient, requirement for a suitable precursor for AAMs. This work involves the synthesis, characterization, and estimation of alkaline reactivity of Na-Mg aluminosilicate glasses. Structural characterization showed that replacing Na with Mg led to more depolymerization. Alkaline reactivity studies indicated that, as Mg replaced Na, reactivity of glasses increased at first, reached an optimal value, and then declined. This trend in reactivity could not be explained by the conventional parameters used for estimating glass reactivity: the non-bridging oxygen fraction (which predicts similar reactivity for all glasses) and optical basicity (which predicts a decrease in reactivity with an increase in Mg replacement). The reactivity of the studied glasses was found to depend on two main factors: depolymerization (as indicated by structural characterization) and optical basicity. Depolymerization dominated initially, which led to an increase in reactivity, while the effect of optical basicity dominated later, leading to a decrease in reactivity. Hence, while designing reactive synthetic glasses for alkali activation, structural study of glasses should be given due consideration in addition to the conventional factors.

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“…In slag utilization and supplementary cementitious material (SCM) glasses, NBO/T is often used to predict alkali reactivity (NBO/T: non-bridging oxygen per tetrahedral cation) (Durdziński et al, 2015;Tiwary et al, 2013). In complex multicomponent systems such as slag and basalt glasses the calculation of NBO/T is not straightforward and several assumptions have to be made.…”

Section: A) B)mentioning

confidence: 99%

Phase separation in alumina-rich glasses to increase glass reactivity for low-CO2 alkali-activated cements

Kinnunen

Sreenivasan

Cheeseman

et al. 2019

Journal of Cleaner Production

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Ways to reduce cement-related carbon emissions are actively sought. One possible solution is partial substitution of Portland cement by alkali-reactive glass. We report on low-CO2 glass compositions that have high alkali solubility derived from industrial basaltic stone wool compositions. We found that highly alkali-soluble glasses can be formed with glass compositions that in principle can be made using silicate minerals which have no raw material-related CO2 emissions. The reason behind the reactivity of these glasses is thought to be caused by the dilution of the main network-forming species, silicon, which is further enhanced by phase separation, forming phases with high-silicon and low-silicon concentrations. Phase separation in aluminarich samples is further studied and occurs at moderate cooling rates. The effect of glass-glass phase separation is discussed in the context of reactive glasses in cementitious systems. The results indicate that controlled phase separation could decouple CO2 emissions from the reactivity of glassy supplementary cementitious materials.

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Structural aspects of blast furnace slag

Cited by 12 publications

References 27 publications

Effect of Unburned Pulverized Coal on the Melting Characteristics and Fluidity of Blast Furnace Slag

Effect of Unburned Pulverized Coal on the Melting Characteristics and Fluidity of Blast Furnace Slag

Towards designing reactive glasses for alkali activation: Understanding the origins of alkaline reactivity of Na-Mg aluminosilicate glasses

Phase separation in alumina-rich glasses to increase glass reactivity for low-CO2 alkali-activated cements

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