Prospects and physical limits of processes and technologies in glass melting

Conradt, Reinhard

doi:10.1080/21870764.2019.1656360

Cited by 27 publications

(31 citation statements)

References 21 publications

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“…The parametric study examines the cases of natural versus forced convection by bubbling and the effects of increased primary foaming (the gas evolution rate, G e ) beneath the cold cap, set at 1G e , 5G e , and 10G e . Corresponding to the typical gas evolution rate from a collapsing primary foam during the melting of high-level waste (HLW) nuclear melter feed, 25 the base set of simulations was performed with a constant G e of 1.71 × 10 −7 kg s −1 for a solid disk. For the cases with forced convection bubbling, the base mass flow rate of 1150°C air from the bubbler is set to 2.26 × 10 −5 kg s −1 (101 slpm m −2 as used in experiments, [21][22][23] where the gas evolution rate is scaled by the cold cap surface area).…”

Section: Methodsmentioning

confidence: 99%

Heat transfer from glass melt to cold cap: Computational fluid dynamics study of cavities beneath cold cap

Abboud

Guillen

Hrma

et al. 2021

Int J of Appl Glass Sci

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Efficient glass production depends on the continuous supply of heat from the glass melt to the floating layer of batch, or cold cap. Computational fluid dynamics (CFD) are employed to investigate the formation and behavior of gas cavities that form beneath the batch by gases released from the collapsing primary foam bubbles, ascending secondary bubbles, and in the case of forced bubbling, from the rising bubbling gas. The gas phase fraction, temperature, and velocity distributions below the cold cap are used to calculate local and average heat transfer rates as a function of the bubbling rate. It is shown that the thickness of the cavities is nearly independent of the cold cap shape and the amount of foam evolved during batch conversion. It is ~7 mm and up to ~15 mm for the cases without and with forced bubbling used to promote circulation within the melt, respectively. Using computed velocity and temperature profiles, the melting rate of the simulated high‐level nuclear waste glass batch was estimated to increase with the bubbling rate to the power of ~0.3 to 0.9, depending on the flow pattern. The simulation results are in good agreement with experimental data from laboratory‐ and pilot‐scale melter tests.

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Section: Methodsmentioning

confidence: 99%

Heat transfer from glass melt to cold cap: Computational fluid dynamics study of cavities beneath cold cap

Abboud

Guillen

Hrma

et al. 2021

Int J of Appl Glass Sci

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“…As previously stated, landfilling and stockpiling unrecycled soda-lime-silica container glass represents a considerable failure in sustainability considering the extensive energy-consumption and environmental impact associated with its manufacture and distribution (Mishra, 2015;Grbeš, 2016;Conradt, 2019). In response to this problem, recent research has been carried out to synthesize zeolites from flint, amber and green container glasses under various alkaline hydrothermal conditions (Espejel-Ayala et al, 2014;Terzano et al, 2015;Elmes et al, 2018;Lin et al, 2019;Majdinasab and Yuan, 2019a;Majdinasab and Yuan, 2019b;Collins et al, 2020;Taylor et al 2020).…”

Section: Waste Container Glass For the Synthesis Of Zeolitesmentioning

confidence: 99%

“…Soda-lime-silica container glass accounts for 45% of the worldwide manufacture of all glasses and typically between 30 and 70% waste cullet is included in the feedstock (Conradt, 2019). It is theoretically possible to recycle up to 90% cullet in the production of new container glass; however, many technical and economic factors give rise to considerable variation in the extent to which it is actually recycled across the globe.…”

Section: Introductionmentioning

confidence: 99%

“…The production of container glass is an energy-intensive process with a substantial environmental impact (Mishra, 2015;Grbeš, 2016). Currently, the minimum energy consumption for container glass produced from 50% recycled cullet using the most efficient furnaces is estimated to be 3.85 MJ kg -1 (Conradt, 2019). Furthermore, despite the considerable abundance of silica in the lithosphere, the mining of sand for the production of glass is associated with catastrophic environmental problems such as erosion, flooding, land degradation, loss of biodiversity and myriad forms of pollution (Mishra, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal synthesis of zeolites from green container glass

Maisuria¹,

Elmes²,

Hurt³

et al. 2020

Physicochem. Probl. Miner. Process.

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Landfilling and stockpiling unrecycled colored container glass represents a considerable failure in sustainability with respect to the conservation of energy and mineral resources. In this study, the single-step hydrothermal synthesis of low-silica zeolites from a mixture of waste green container glass and aluminum foil (Al:Si = 1) in 4 M NaOH(aq) at 125 °C was followed at 1, 3, 7 and 14 days. The principal phases, sodalite and cancrinite, appeared within 1 day accompanied by minor quantities of hydrogarnet and tobermorite arising from a stoichiometric excess of calcium ions in the parent glass. Products of 63, 67, 71 and 72% crystallinity were obtained at 1, 3, 7 and 14 days, respectively, with partial successive conversion of sodalite to cancrinite over time. Ion-exchange and catalytic applications of sodalite and cancrinite arise from the high anionic charge of the 1:1 ratio of alternating SiO4 4-and AlO4 5units within their aluminosilicate frameworks. In this respect, the uptake capacity of the 14-day zeolitic product for Cu 2+ and Cd 2+ ions (1.58 meq g-1 and 1.66 meq g-1 , respectively) was within the expected range for zeolites and compared favorably with those reported for other inorganic sorbents derived from industrial and municipal wastes. The 14-day product was also found to be an effective basic heterogeneous catalyst for the Knoevenagel condensation reaction.

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“…It is estimated that approximately 200 Mt of waste soda-lime-silica container glass are landfilled per annum [1]. In order to conserve energy and natural resources, it is theoretically possible to recycle up to 90% of waste container glass, although this potential is undermined by a range of geographical, economic and technical challenges [2][3][4]. In particular, poor collection infrastructure and colour mismatch restrict regional demand for coloured waste container glass that can be recycled as new bottles and jars.…”

Section: Introductionmentioning

confidence: 99%

Mixed-Phase Ion-Exchangers from Waste Amber Container Glass

2021

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This study investigated the one-pot hydrothermal synthesis of mixed-phase ion-exchangers from waste amber container glass and three different aluminium sources (Si/Al = 2) in 4.5 M NaOH(aq) at 100 °C. Reaction products were characterised by X-ray diffraction analysis, Fourier transform infrared spectroscopy, 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy and scanning electron microscopy at 24, 48 and 150 h. Nitrated forms of cancrinite and sodalite were the predominant products obtained with reagent grade aluminium nitrate (Al(NO3)3∙9H2O). Waste aluminium foil gave rise to sodalite, tobermorite and zeolite Na-P1 as major phases; and the principal products arising from amorphous aluminium hydroxide waste were sodalite, tobermorite and zeolite A. Minor proportions of the hydrogarnet, katoite, and calcite were also present in each sample. In each case, crystallisation was incomplete and products of 52, 65 and 49% crystallinity were obtained at 150 h for the samples prepared with aluminium nitrate (AN-150), aluminium foil (AF-150) and amorphous aluminium hydroxide waste (AH-150), respectively. Batch Pb2+-uptake (~100 mg g−1) was similar for all 150-h samples irrespective of the nature of the aluminium reagent and composition of the product. Batch Cd2+-uptakes of AF-150 (54 mg g−1) and AH-150 (48 mg g−1) were greater than that of AN-150 (36 mg g−1) indicating that the sodalite- and tobermorite-rich products exhibited a superior affinity for Cd2+ ions. The observed Pb2+- and Cd2+-uptake capacities of the mixed-product ion-exchangers compared favourably with those of other inorganic waste-derived sorbents reported in the literature.

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Prospects and physical limits of processes and technologies in glass melting

Cited by 27 publications

References 21 publications

Heat transfer from glass melt to cold cap: Computational fluid dynamics study of cavities beneath cold cap

Heat transfer from glass melt to cold cap: Computational fluid dynamics study of cavities beneath cold cap

Hydrothermal synthesis of zeolites from green container glass

Mixed-Phase Ion-Exchangers from Waste Amber Container Glass

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