Crystallization of Coal Ash Melts

Kalmanovitch, D. P.; Williamson, J.

doi:10.1021/bk-1986-0301.ch018

Cited by 33 publications

(32 citation statements)

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“…Riboud et al,63) using the Urbain model with corrected compositions dependences of A and B, successfully applied it to describe the viscosities of some industrial mould fluxes (in the Al 2 O 3 -CaO-Na 2 OSiO 2 -CaF 2 system). In the Kalmanovich-Frank (KF) model 64) the parameters A and B of the Urbain model have been modified to describe viscosities of the particular coal ash slags. Browning et al 65) developed the "T-shift" model for describing the viscosity of particular coal ash slags.…”

Section: Comparison Of Viscosity Modelsmentioning

confidence: 99%

“…10(a)-10(b). Apart from the QCV model each of these models [62][63][64][65][66] was developed to describe experimental data over a limited range of compositions, and Figs. 10(a)-10(b) clearly demonstrate that they do not provide accurate predictions of viscosities over the whole range of slag compositions in the quaternary system.…”

Section: Comparison Of Viscosity Modelsmentioning

confidence: 99%

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Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System. Part 3. Summary of the Model Predictions for the Al2O3–CaO–MgO–SiO2 System and Its Sub-systems

Hayes

Jak

2006

ISIJ Int.

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A structurally-based quasi-chemical viscosity model for fully liquid slags in the Al 2 O 3 -CaO-'FeO'-MgOSiO 2 system has been developed. The focus of the work described in the present paper is the analysis of the experimental data and viscosity models in the quaternary system Al 2 O 3 -CaO-MgO-SiO 2 and its subsystems.A review of the experimental data, viscometry methods used and viscosity models available in the Al 2 O 3 -CaO-MgO-SiO 2 and its sub-systems is reported. The quasi-chemical viscosity model is shown to provide good agreement between experimental data and predictions over the whole compositional range.KEY WORDS: slag viscosity; viscosity model; Al 2 O 3 -CaO-MgO-SiO 2 .The rotational cylinder method appears to be the technique most commonly used to measure the slag viscosities in the Al 2 O 3 -CaO-MgO-SiO 2 system and its sub-systems. There are two modifications of this method: rotation of the inner cylinder (or bob) and rotation of the outer cylinder (or crucible). The rotational cylinder method is suitable for use over a wide range of slag viscosities. Other viscometry techniques commonly used to measure the viscosity of slags are the oscillating cylinder (normally bob) and falling (or counter-balanced) sphere methods. "Vibrational" or "Torsional" techniques indicate some modification of the oscillating cylinder method, while "Rotational" means the rotational cylinder method; details of the experimental setups and descriptions used in these cases were not published.Most of the researchers used either Mo 29,37,42,44) or Pt (or Pt-Rh alloys) 10,12,24,[31][32][33][34][35]39,41) for containers and sensors. These materials are more suitable for high temperature viscosity measurements in the Al 2 O 3 -CaO-MgO-SiO 2 system and its sub-systems compared to graphite used by Gul'tyai 21) and Kawai. 22) Not all the investigators reported the atmosphere in which viscosity experiments were carried out. Nonetheless, at higher temperatures in the case of using molybdenum it is important to carry out experiments in neutral atmosphere (Ar, N 2 ) instead of air, which can oxidise molybdenum. There is also some evidence of solubility of gases such as argon or nitrogen in the molten silicate slags. 45) One of the major sources of experimental errors in slag viscosity measurements is due to the contamination of the slag sample by container or/and sensor materials. The dissolution of the sensor and container can lead to changes not only in slag composition but also in container/sensor geometry. Measurements of the slag compositions after experiments reduce these potential errors. Temperature control using a thermocouple adjacent to the sample has better precision compared to an optical pyrometer. These and other considerations were used in the critical review of the data.The viscosity and temperature ranges investigated for different slags in the Al 2 O 3 -CaO-MgO-SiO 2 system and its MgO-containing sub-systems are summarised in Table ISIJ International, Vol. 46 (2006) Optimisation ProcedureThe optimisation proced...

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Section: Comparison Of Viscosity Modelsmentioning

confidence: 99%

Section: Comparison Of Viscosity Modelsmentioning

confidence: 99%

Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System. Part 3. Summary of the Model Predictions for the Al2O3–CaO–MgO–SiO2 System and Its Sub-systems

Hayes

Jak

2006

ISIJ Int.

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“…Several viscosity models have been developed on the basis of the Urbain formalism. 5,6) The Kalmanovich-Frank model 5) adopted the Urbain model for viscosity of the particular coal ash slags. Riboud et al 6) corrected the Urbain formalism to describe the viscosities of some industrial mould fluxes (in the Al 2 O 3 -CaO-Na 2 O-SiO 2 -CaF 2 system).…”

Section: )mentioning

confidence: 99%

Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System. Part 1. Description of the Model and Its Application to the MgO, MgO–SiO2, Al2O3–MgO and CaO–MgO Sub-systems

2006

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A new mathematical formalism has been developed to describe the viscosities of molten oxides as a function of composition and temperature.1,2) The formalism, hereafter referred to as the quasi-chemical viscosity (QCV) model, enables the internal structural information of complex slags to be related to this physicochemical property. The internal structural information changes systematically with changing bulk composition and temperature and is derived from consideration of the thermodynamic equilibrium in the system. The QCV model provides a link between fundamental thermodynamic and physicochemical properties of the slags, and enables the slag viscosities for all compositions and temperatures in the chemical system to be predicted using the same set of model parameters. Application of this approach and the evaluation of QCV model parameters for the system Al 2 O 3 -CaO-'FeO'-SiO 2 have previously been reported by the authors.2)The present paper is the first in a series describing the effect of MgO on slag viscosities and extending the QCV model to the quaternary system Al 2 O 3 -CaO-MgO-SiO 2 . The present paper provides descriptions of the quasi-chemical viscosity model and optimisation procedure, outlines the principles applied in the evaluation of experimental data and the resultant viscosity models for the MgO, Al 2 O 3 -MgO, CaO-MgO and MgO-SiO 2 systems.Many of the materials that are used as feedstocks for pyrometallurgical processes include MgO-containing minerals. In some cases MgO is deliberately added to these hightemperature processes to adjust and to optimise the chemical and/or physicochemical characteristics of the systems. The influence of MgO on melt viscosity is therefore significant not only from a fundamental scientific point of view, but also because of its relevance to a wide range of industrial applications.A number of viscosity models found in the literature on the Al 2 O 3 -CaO-'FeO'-MgO-SiO 2 system have recently been reviewed by the authors.3) It would appear that at present no viscosity model accurately describes this property over the whole range of chemical compositions. The Urbain formalism is one of the most widely used slag viscosity models and is based on the application of polynomial functions of slag composition to describe the pre-exponential and exponential terms in the Weymann-Frenkel equation. 4)Urbain reported 4) different model parameters for each ternary system Al 2 O 3 -MgO-SiO 2 and Al 2 O 3 -CaO-SiO 2 , and suggested a method of extrapolating model predictions to multi-component systems. However, this method does not provide close agreement between the model predictions and experimental data in the Al 2 O 3 -CaO-MgO-SiO 2 systems over the whole compositional range. Several viscosity models have been developed on the basis of the Urbain formalism. 5,6) The Kalmanovich-Frank model 5) adopted the Urbain model for viscosity of the particular coal ash slags. Riboud et al. 6) corrected the Urbain formalism to describe the viscosities of some industrial mould fluxes (in th...

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“…8) Effects of MgO and Al 2 O 3 on the system "FeO"-SiO 2 were reported by Bowen and Schairer 9) in the system "FeO"-MgO-SiO 2 and Schairer and Yagi 10) in the system "FeO"-Al 2 O 3 -SiO 2 . In multi-component systems, Muan and Osborn 11) and Kalmanovitch and Williamson 12,13) reported pseudo-ternary sections of dicalcium silicate -gehlenite -"FeO" and CaO-SiO 2 -Al 2 O 3 with fixed "FeO" from 5 to 30 wt%. Very few experimental data are available in the system "FeO"-CaO-SiO 2 -Al 2 O 3 -MgO in equilibrium with metallic iron which is important for BF slags.…”

Section: Introductionmentioning

confidence: 99%

Phase Equilibria in the System “FeO”–CaO–SiO2–Al2O3–MgO with CaO/SiO2 1.3

Jang

Zhu

et al. 2016

ISIJ International

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A series of "FeO"-containing slags are present in iron blast furnace. Phase equilibria play an important role in optimum operation of blast furnace which involves complex chemical reactions. Phase equilibria studies have been carried out in the system "FeO"-CaO-SiO 2 -Al 2 O 3 -MgO in equilibrium with metallic iron. The technique used includes high temperature equilibration followed by quenching and electron probe X-ray microanalysis. Pseudo-ternary sections of the phase diagrams are presented in the form of (CaO + SiO 2 )-Al 2 O 3 -MgO at fixed CaO/SiO 2 ratio of 1.3 and "FeO" concentrations of 5 and 10 wt%. This is the first systematic study in the system "FeO"-CaO-SiO 2 -Al 2 O 3 -MgO important to the blast furnace operations. It was found that melilite, Ca 2 SiO 4 , merwinite, spinel and (Mg,Fe 2 + )O are the primary phase fields in the composition range investigated. Liquidus temperatures increase in the melilite and spinel primary phase fields and decrease in the merwinite and Ca 2 SiO 4 primary phase fields with increasing Al 2 O 3 concentration. The liquidus temperature is not sensitive with Al 2 O 3 in the spinel primary phase field. Effects of MgO and "FeO" on liquidus temperature are also discussed. Extensive solid solutions can be formed in this system that have significant influence on the liquidus temperatures and the data will be used for optimisation of the thermodynamic models.KEY WORDS: phase equilibrium; liquidus temperature; "FeO"-CaO-SiO 2 -Al 2 O 3 -MgO system; blast furnace slag.

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Crystallization of Coal Ash Melts

Cited by 33 publications

References 0 publications

Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System. Part 3. Summary of the Model Predictions for the Al2O3–CaO–MgO–SiO2 System and Its Sub-systems

Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System. Part 3. Summary of the Model Predictions for the Al2O3–CaO–MgO–SiO2 System and Its Sub-systems

Development of a Quasi-chemical Viscosity Model for Fully Liquid Slags in the Al2O3–CaO–‘FeO’–MgO–SiO2 System. Part 1. Description of the Model and Its Application to the MgO, MgO–SiO2, Al2O3–MgO and CaO–MgO Sub-systems

Phase Equilibria in the System “FeO”–CaO–SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub>–MgO with CaO/SiO<sub>2</sub> 1.3

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