Optimization and control of selenium chemistry and color in flint glass melts [Elektronische Ressource] / vorgelegt von Tepiwan Jitwatcharakomol

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2005
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Optimization and Control of Selenium Chemistry and Color
in
Flint Glass Melts




Von der Fakultät für Georessourcen und Materialtechnik
der Rheinisch-Westfälischen Technischen Hochschule Aachen



zur Erlangung des akademischen Grades eines
Doktors der Ingenieurwissenschaften


genehmigte Dissertation


vorgelegt von M.Sc.


Tepiwan Jitwatcharakomol

aus Petchaburi, Thailand




Berichter: Univ.-Prof. Dr.rer.nat. Reinhard Conradt
PD Dr.rer.nat. Andreas Kasper


Tag der mündlichen Prüfung: 29. April 2005

Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar
Acknowledgement

My first deepest gratefulness is for my teacher, Professor Dr. rer. nat. Reinhard
Conradt who has been my supervisor both for master degree in Chulalongkorn
university, Thailand and for doctoral degree in RWTH, Aachen, Deutschland. I
had a very hard time in the first year staying here, nearly to give up. The kind
understanding for a foreigner’s problem of him and his wife Frau Marianne
Conradt helped me getting through. Working under his coaching is my honor; I
appreciate for what he taught how to handle any problems in a systematic
research way with his patience and encouragement in spite of many other
commitments. His scientific advice not only made this work accomplished but
also enlarged my vision in glass research field which is accordingly beneficial to
my future carrier.

I also would like to thank Dr. rer. nat. Andreas Kasper who kindly accepted the
responsibility for being a co-supervisor. I deeply appreciate his readiness and
enthusiastic response in the limited time.

My next gratitude is expressed to Dr. Eberhard Stötzle, my group leader who
always spared time for me. Whenever I was stuck, his experience-guided
suggestion would come on time then the problems were solved.

I am indebted to Saint-Gobain Glass Deutschland GmbH, Herzogenrath
especially Herr Jürgen Klinkers for his kindly help and skills in XRF analysis
through out the work. Special thanks to Herr Henning Katte, ilis GmbH for his
generosity lending us the sophisticated optical properties determination
software. The most appreciation is to Ocean Glass Public Company Limited,
Thailand who provided all glass samples, technical data and raw materials.

For friends and colleagues in the Institut für Gesteinshüttenkunde, it was my
pleasure being a part of team. A particular thanks to the Geasee family for their
assistance. Thanks all of you for each personnel skillful suggestion and for your
friendship.

Finally, I convey my deepest and touching feeling to my beloved husband, Mr.
Prayuth Jitwatcharakomol who let me fulfill my dream though his personal
sacrifices, taking care of our sons by his own. Pee Yuth, I thank you for your
love and always being aside me. Joke and Up, my dearest sons, mom thanks for
always well behave and make me relief even we were far away.

For my mom and my dad in heaven, I hope you are watching and happy for me.

Abstract

The selenium chemistry in the decoloration process in flint glass melts was
investigated both in commercial practice and in laboratory. Samples were taken
from two furnaces of a flint glass production site, analysed with respect to Se,
Fe, redox state, and color. Color defects during production could be attributed to
an unduly high Se loss which, in turn, could be traced back to production
periods with too high temperatures in the combustion space. Pull rate changes
did, however, not have an unanimous effect. In lab experiments, the relation
between redox state, total Se, Co, Fe, S on the one side, and the resulting color
on the other side, were thoroughly investigated in an empirical way. Due to the
very loss Se level, a speciation of Se could, however, not be performed. With
2+respect to 0.05 % iron containing glass, the ratio Fe to total Fe should not
exceed 0.12 and the amount of sulfate should be ∼ 0.4 wt. %. Otherwise the Se
loss might reach 100 %. Oxidizing conditions with a redox number about 15 was
also found the optimum condition for the decoloration. The same absorption
range of spectra between 220 ppm Se–iron free glass and 2 ppm Se–iron
containing industrial glass, suggests FeSe may act as the dominating coloring
agent in the decoloration process. This got along well with the constructed phase
stability diagrams of Na-O-Se system. Finally, a strategy of vectors addition in
the L*a*b* color space diagram was developed by which optimal decoloration
conditions can be swiftly determined. The strategy was verified with a glass
containing total Fe as high as 0.1 wt. %.



















Kurzfassung

Die Chemie des Selens im Entfärbungsprozess bei der Weißglasherstellung
wurde sowohl in der Industrie als auch durch Laborexperimente untersucht. Es
wurde Proben von zwei Weißglaswannen genommen und auf den Gehalt von
Se, Fe, den Redoxzustand und die Farbe hin analysiert. Farbdefekte während der
Produktion konnte auf unzulässig hohe Se-Verluste zurückgeführt werden, die
wiederum auf Produktionsperioden mit zu hoher Oberofentemperatur
zurückgeführt werden könnten. Wechsel des Durchsatzes hatten dagegen keine
eindeutiger Effekt. In Laborexperimenten wurde der Zusammenhang zwischen
Redoxzustand und Se-, Co-, Fe-, S- Gehalt einerseits und der resultierenden
Farbe andererseits empirisch gründlich aufgeklärt. Wegen der geringen Se-
Gehalt konnte allerdings eine Spezies-Analyse für Se nicht durchgeführt
2+werden. Bei Proben mit 0.05 % Fe sollte das Fe zu Gesamteisen Verhältnis
einen Wert von 0.12 nicht überstreiten, der Sulfatgehalt unter 0.4 Massen-%
bleiben. Andernfalls erfolgt ein vollständiger Verlust von Se. Oxidierende
Bedingungen entsprechend einer Redoxzahl von ca. 15 wurden als optimal für
die Entfärbung identifiziert. Der gleiche Absorptionsbereich, der in Fe-freier
Gläsern mit 220 ppm Se und in eisen haltigen Gläsern mit nur 2 ppm Se
gefunden wurde, legt nahe, dass FeSe die Rolle des dominierenden
Chromophors bei der Entfärbung übernehmen kann. Die Annahme der Existenz
des FeSe unter den gewählten Bedingungen wird durch thermodynamische
Rechnungen unterstützt. Schließlich wurde eine Strategie der Vektoraddition im
L*a*b*- Farbraum entwickelt, mit deren Hilfe optimale Bedingungen für die
Entfärbung rasch bestimmt werden können. Die Strategie wurde erfolgreich an
einem mit 0.1 Massen- % sehr eisenreichen Glas erfolgreich getestet.
















Contents

Chapter 1
Introduction 10
1.1 Motivation 10
1.2 Objective and scope 12
1.3 Review of literatures 13
1.3.1 Oxidation states of selenium 13
1.3.2 Literature reviews on Se chemistry 14
1.3.3 The effect of sodium nitrate and antimony oxide 16

Chapter 2
Theortical part 18
2.1 Optical measurements 18
2.1.1 General aspect
2.1.2 Method of internal transmission measurement 20
2.1.3 The determination of concentration of FeO and Fe O 24 2 3
2.1.4 The procedure for color measurement (DIN 5033) 26
2.1.5 The L*a*b* color system 29
2.2 X-ray fluorescence analysis method 30
2.3 Phase stability diagrams 31
2.3.1 Fundamentals 33
2.3.2 Data estimation by linear interpolation 34
2.3.3 Example of calculation 36
2.3.4 Results 37

Chapter 3
Investigation an industrial glass 47
3.1 Data of the factory 47
3.2 Sample preparation and experimental procedure 49
3.3 Results of the production data and by XRF 49
3.3.1 Calculation 49 2Rests 50
3.3.3 Evaluation 52
3.3.4 Selenium balance 55
3.4 Results by spectrophotometry 57
3.4.1 Color space diagram 58
3.4.2 Chromaticity 59
3.5 Conclusions 61

Chapter 4
Experimental part 62
4.1 Glass compositions 62
4.1.1 The iron-free parent glass 62
4.1.2 Glasses with additions of Fe, S, Se and Co 63
4.2 Procedure 65

Chapter 5
Results and discussion 67
5.1 Results of the iron-free parent glass 67
5.2 of the 0.05% iron glasses 71
5.2.1 Results by XRF 71
5.2.2 Color data 74
5.3 Results of 0.1 % iron glasses 80

Chapter 6
Optimization of X26 glass 87
6.1 Experimental 87
6.2 Results by XRF 88
6.3 Spectrophotometrical results 88
6.3.1 Spectrum
6.3.2 Color space diagram 89
6.3.3 compensation strategy 91
6.4 Experimental vertification 91
6.41 results 93