Mechanism of Sulfate Segregation during Glass Melting

2002 ◽  
Vol 757 ◽  
Author(s):  
Pavel Hrma ◽  
John D. Vienna ◽  
Joel S. Ricklefs
Keyword(s):  
Borosilicate Glass ◽  
Sodium Sulfate ◽  
Glass Batch ◽  
Glass Melting ◽  
Gas Bubbles ◽  
Solubility Limit ◽  
Sulfate Incorporation

ABSTRACTSulfate retention in glass during the vitrification process can be as low as 1/3 of the solubility limit, or can exceed the solubility limit if suspended in the glass in the form of droplets. This study is focused on the mechanism of incorporating and segregating sodium sulfate during the melting of an alkali-alumino-borosilicate glass batch. Batches were ramp heated at 4°C/min to temperatures ranging from 600°C to 1050°C and fractured for examination. Observation of the melts showed that as the batch temperature increases and the primary oxo-anionic, predominantly nitrate melt decomposes, the sulfate residue accumulates inside gas bubbles and is transported in them to the melt surface, where it remains segregated. The degree of sulfate incorporation into the final glass depends on the relative rates of sulfate dissolution in the borosilicate melt and sulfate lifting inside bubbles.

Gadolinium Solubility Limits in Sodium-Aluminoborosilicate Glasses

1999 ◽  
Vol 556 ◽  
Author(s):  
L. Li ◽  
D. M. Strachan ◽  
L. L. Davis ◽  
H. Li ◽  
M. Qian
Keyword(s):  
Melting Temperature ◽  
Borosilicate Glass ◽  
Solubility Limit ◽  
Enthalpy Change ◽  
Glass System ◽  
Mole Percent ◽  
Molar Composition

AbstractGadolinium and lanthanum solubility limits in a sodium-alumino-borosilicate glass system were studied. As melting temperature increased from 1400°C to 1450°C, 1500°C and 1550°C, the solubility of gadolinium in the baseline glass 15B2O3-5A12O3-20Na2O-60SiO2 (in molar composition) increased from 10.1 to 11.3, 12.2 and 13.1 (in mole percent of Gd2O3). The enthalpy change of Gd2O3 dissolution in this baseline glass is about 43.6 kJ/mol. Boron effect on lanthanum solubility was studied using the following baseline glasses: xB2O3-20Na2O- 5Al2O3-60SiO2, where x equals to 5, 10, 15, and 20, respectively. It was found that lanthanum solubility limit increased from 8.4 to 10.3, 12.5 and 14.9 (in mole percent of La2O3) as B2O3 increased from 5.1 to 9.5, 13.1 and 16.2 mol%. Gd2O. and La2O3 have similar solubility limits. Solubility limits of mixtures containing different ratios of Gd2O3 to La2O3 in the baseline glass 15B2O3-20Na2O-5A12O3-60SiO2 were found insensitive to the ratio of La/Gd. As far as gadolinium is concerned, its solubility limit will decrease when other lanthanides are introduced.

Industrial trials to replace sodium sulfate with astrakanite in glass melting

1958 ◽  
Vol 15 (8) ◽  
pp. 403-406
Author(s):  
N. V. Kerbitskaya ◽  
M. P. Orlova ◽  
V. N. Sesorova ◽  
E. I. Smirnov ◽  
I. B. Shlain
Keyword(s):  
Sodium Sulfate ◽  
Glass Melting

Vitrification of high molybdenum feeds in the presence of reprocessing waste liquor

2013 ◽  
Vol 1518 ◽  
pp. 21-39
Author(s):  
Rick Short ◽  
Barbara Dunnett ◽  
Nick Gribble ◽  
Hannah Steel ◽  
Carl James Steele
Keyword(s):  
Borosilicate Glass ◽  
Solubility Limit ◽  
Test Rig ◽  
Waste Liquor ◽  
Highly Active ◽  
Waste Storage ◽  
Waste Vitrification ◽  
Processing Line ◽  
Active Waste ◽  
Glass Formulation

ABSTRACTAt Sellafield, the Post Operational Clean Out (POCO) of solids from the base of the highly active waste storage tanks, in preparation for decommissioning, will result in a high molybdenum stream which will be vitrified using the current Waste Vitrification Plant (WVP). In order to minimise the number of containers required for POCO, the high molybdenum feed could be co-vitrified by addition to reprocessing waste, using the borosilicate glass formulation currently utilised on WVP. Co-vitrification of high molybdenum feeds has been carried out using non-active simulants, both in the laboratory and on the Vitrification Test Rig (VTR) which is a full scale working replica of a WVP processing line.In addition, a new borosilicate glass formulation containing calcium has been developed by NNL which allows a higher incorporation of molybdenum through the formation of a durable CaMoO4 phase, after the solubility limit of molybdenum in the glass has been reached. Vitrification of the high molybdenum feed in the presence of varying quantities of reprocessing waste liquor using the new glass formulation has been carried out in the laboratory. Up to ∼10 wt% MoO3 could be incorporated without any detrimental phase separation in the product glass, but increasing the fraction of reprocessing waste was found to decrease the MoO3 incorporation. Soxhlet and static powder leach tests have been performed to assess the durability of the glass products. This paper discusses the results of the vitrification of high molybdenum feeds in the presence of reprocessing liquor in both the borosilicate glass formulation currently utilised on WVP and the modified formulation which contain calcium.

Study of Melting Ability of Granulated Glass Batch

2016 ◽  
Vol 690 ◽  
pp. 272-275
Author(s):  
Kanit Tapasa ◽  
Ekarat Meechoowas ◽  
Suwannee Thepbutdee ◽  
Amorntep Montreeuppathumb
Keyword(s):  
Glass Furnace ◽  
Waste Heat ◽  
Raw Materials ◽  
Glass Batch ◽  
Glass Melting ◽  
Glass Production ◽  
Melting Process ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Preheating Temperature

In the conventional soda-lime glass production, loose raw materials are normally mixed into a glass batch for melting. Dusting and segregation of the loose glass batch are always occurred during the melting process inside the glass furnace. Also, the loose glass batch has low thermal conductivity which limits the glass melting ability and pulling rate of the glass furnace. Granulation and preheating of glass raw materials have been proposed to solve the problems. In this study, the granulated soda-lime glass batch (SiO2 50% Na2CO3 22.5% CaCO3 12% NaAlSi3O8 9.5% BaCO3 2.5% ZnO 1.75% Sb2O3 1% and K2CO3 0.75% by weight) was prepared to study the melting ability in an electric furnace. The granulated batch was also preheated at 500-600°C before melting. The preheating temperature was matched to the temperature of flue gas at the bottom of the stack in the glass furnace. The purpose behind this was aiming to recover the waste heat from the furnace. The experiment exhibited the increased melting ability for the granulated-preheated glass batch

Investigation of Melting Behavior of Low-Enthalpy Glass Batches

2014 ◽  
Vol 608 ◽  
pp. 311-315 ◽  
Author(s):  
Kanit Tapasa ◽  
Ekarat Meechoowas ◽  
Usuma Naknikham ◽  
Tepiwan Jitwatcharakomol
Keyword(s):  
Raw Materials ◽  
Glass Batch ◽  
Glass Melting ◽  
Kinetic Property ◽  
Melting Process ◽  
Soda Lime ◽  
Melting Behavior ◽  
Soda Lime Glass ◽  
Chemical Heat ◽  
Heat Demand

Batch modification with low-enthalpy raw materials is the effective approach for reducing the glass melting energy. In the previous study, it was found that introducing wollastonite (CaSiO3) as a source of CaO instead of calcium carbonate (CaCO3) in the soda-lime glass batch can fasten the melting process. It is because the modified batch with CaSiO3 has lower chemical heat demand, ΔHochem, which is equivalent to the standard heat of batch-to-melt conversion. In order to investigate the kinetic property of the modified batch, the melting behaviour of 2 kg modified batch was studied. The results showed that the temperature of the modified batch increased at a faster rate than the original batch. The properties of the glass from the modified are also similar to the original batch.

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

1990 ◽  
Vol 48 (4) ◽  
pp. 728-729
Author(s):  
M.J. Kim ◽  
L.C. Liu ◽  
S.H. Risbud ◽  
R.W. Carpenter
Keyword(s):  
Quantum Dots ◽  
Borosilicate Glass ◽  
Glass Matrix ◽  
Optical Switching ◽  
Response Times ◽  
Fast Response ◽  
Processing Technique ◽  
Internal Stresses ◽  
Electron Hole ◽  
Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

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