Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during Conversion to Glass

Marcial, José; Chun, Jaehun; Hrma, Pavel R.; Schweiger, Michael J.

doi:10.1021/es5018625

Cited by 20 publications

(40 citation statements)

References 37 publications

(60 reference statements)

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“…Three stages can be discerned from the volume expansion results. Minor volume expansion occurs at temperatures below ~600°C, within which a large volume of gas is released from batch reactions . The gas freely escapes through open porosity, but its flow is probably hindered in feeds with small densely packed particles, as seen in Figure , when small quartz particle size fractions were used.…”

Section: Discussionmentioning

confidence: 99%

Effects of heating rate, quartz particle size, viscosity, and form of glass additives on high‐level waste melter feed volume expansion

et al. 2016

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Nuclear waste can be vitrified by mixing it with glass‐forming and ‐modifying additives. The resulting feed is charged into an electric glass melter. To comprehend melting behavior of a high‐alumina melter feed, we monitored the volume expansion of pellets in response to heating at different heating rates. The feeds were prepared with different particle sizes of quartz (the major additive component) and with varied silica‐to‐fluxes ratio to investigate the glass melt viscosity effects. Also, we used additional melter feeds with additives premelted into glass frit. The volume of pellets was nearly constant at temperatures <600°C. After a short period of volume shrinkage at ~600°C‐700°C, foam generation produced massive volume expansion. The low heat conductivity of foam hinders the transfer of heat from molten glass to the reacting feed. The extent of foaming increased with faster heating and higher melt viscosity, and decreased with increasing size of quartz particles and fritting of the additives. Volume expansion data are needed for the mathematical modeling of the cold cap.

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Section: Discussionmentioning

confidence: 99%

Effects of heating rate, quartz particle size, viscosity, and form of glass additives on high‐level waste melter feed volume expansion

et al. 2016

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“…As is well‐known, small silica particles dissolve in the glass‐forming melt early, creating copious high‐viscosity melt at lower temperatures at which gas evolution has not sufficiently declined. This results in excessive foaming, affecting both T FO and T FM and causing problems in fining commercial melts. Some important effects of the melter‐feed makeup, including quartz particle size, on T FO and T FM were examined in Ref.…”

Section: Resultsmentioning

confidence: 99%

“…The aim of the present study is to gain information about the viscosity of the glass‐forming melt within the foam layer and the TBL. The viscosity of foam was dealt with elsewhere . The viscosity of the TBL as a suspension of bubbles, liquid inclusions, and solid inclusions has not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

Viscosity of glass‐forming melt at the bottom of high‐level waste melter‐feed cold caps: Effects of temperature and incorporation of solid components

et al. 2019

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During the final stages of conversion of melter feed (glass batch) to molten glass, the glass‐forming melt becomes a continuous liquid phase that encapsulates dissolving solid particles and gas bubbles that produce primary foam at the bottom of the cold cap (the reacting melter feed in an electric glass‐melting furnace). The glass‐forming melt viscosity plays a dominant role in primary foam formation, stability, and eventual collapse, thus affecting the rate of melting (the glass production rate per cold‐cap area). We have traced the glass‐forming melt viscosity during the final stages of feed‐to‐glass conversion as it changes in response to changing temperature and composition (resulting from dissolving solid particles). For this study, we used high‐level waste melter feeds—taking advantage of the large amount of data available to us—and a variety of experimental techniques (feed expansion test, evolved gas analysis, thermogravimetric analyzer‐differential scanning calorimetry, X‐ray diffraction, and viscometer). Starting with a relatively low value at the moment when the melt connects, melt viscosity reached maximum within the primary foam layer and then decreased to its final melter operating temperature value. At the cold‐cap bottom—the boundary between the primary foam layer and the thermal boundary layer—where physicochemical reactions of a melter feed influence the driving force of the heat transfer from the melt to the cold cap, the melt viscosity affects the rate of melting predominantly through its effect on the temperature at which primary foam is collapsing.

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“…After the porosity closure, the reacting feed consists of continuous, yet inhomogeneous melt in which dissolving silica particles are suspended together with gas bubbles containing trapped residues of salt melt [41]. If the glass melt connects before all nitrates, nitrites and carbonates are fully decomposed, gas bubbles grow rapidly and turn the melt to foam.…”

Section: Discussionmentioning

confidence: 99%

“…While in bubbles and also on the melt surface, salt components continue to dissolve into the glass-forming melt, which is still inhomogeneous and contains dissolving silicate minerals (quartz particles in the case of the HLW feed [41]) and minor crystalline phases that continue to grow or dissolve. On the top surface of the melt, the salt begins to evaporate while still dissolving, releasing components according to their volatility governed by Henry's law.…”

Section: Discussionmentioning

confidence: 99%

Rhenium volatilization in waste glasses

Pierce

Hrma

et al. 2015

Journal of Nuclear Materials

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h i g h l i g h t sRe did not volatilize from a HLW feed until 1000°C. Re began to volatilize from LAW feeds at $600°C. The vigorous foaming and generation of gases from salts enhanced Re evaporation in LAW feeds. The HLW glass with less foaming and salts is a promising medium for Tc immobilization. a b s t r a c tWe investigated volatilization of rhenium (Re), sulfur, cesium, and iodine during the course of conversion of high-level waste melter feed to glass and compared the results for Re volatilization with those in low-activity waste borosilicate glasses. Whereas Re did not volatilize from high-level waste feed heated at 5 K min À1 until 1000°C, it began to volatilize from low-activity waste borosilicate glass feeds at $600°C, a temperature $200°C below the onset temperature of evaporation from pure KReO 4 . Below 800°C, perrhenate evaporation in low-activity waste melter feeds was enhanced by vigorous foaming and generation of gases from molten salts as they reacted with the glass-forming constituents. At high temperatures, when the glass-forming phase was consolidated, perrhenates were transported to the top surface of glass melt in bubbles, typically together with sulfates and halides. Based on the results of this study (to be considered preliminary at this stage), the high-level waste glass with less foaming and salts appears a promising medium for technetium immobilization.Published by Elsevier B.V.

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Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during Conversion to Glass

Cited by 20 publications

References 37 publications

Effects of heating rate, quartz particle size, viscosity, and form of glass additives on high‐level waste melter feed volume expansion

Effects of heating rate, quartz particle size, viscosity, and form of glass additives on high‐level waste melter feed volume expansion

Viscosity of glass‐forming melt at the bottom of high‐level waste melter‐feed cold caps: Effects of temperature and incorporation of solid components

Rhenium volatilization in waste glasses

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