supercooling of slags: design of inorganic polymer precursors · slow cooling vs. supercooling 0 20...
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Supercooling of slags: Design of inorganic polymer precursors Lieven Machiels, Y. Pontikes, S. Onisei, L. Pandelaers, L. Cuyvers, D. Geysen, T. Jones, B. Blanpain
Centre for High Temperature Processes and Sustainable Materials Managment Geopolymer Camp, July 9-11, 2012 1
Introduction – Slag to geopolymer precursor
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Introduction – Slag to geopolymer precursor
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Introduction – Slag to geopolymer precursor
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Introduction – Slag to geopolymer precursor
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Slow cooling in slag yard -‐ Difficult to control -‐ Heterogeneous -‐ Waste or low value applica=on
E.g. aggregates
Slow cooling vs. Supercooling
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Example: cooling of Thermal Valoriza=on Slag Standard prac=ce = Slow cooling in slag pot
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Can we make Inorganic polymers of this? Yes, 90 MPa can be reached, but .. hardening takes weeks to months.. very slow reac=on rate To increase reac=vity ⇒ Very fine milling => energy ⇒ High pH => highly concentrated NaOH ⇒ Costly
Slow cooling vs. Supercooling
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Slag pot Slow cooling
Slow cooling vs. Supercooling
Quenched in water Supercooling
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Slow cooling vs. Supercooling
90% crystalline phases
90% glassy phase
Slag pot Slow cooling
Quenched in water Supercooling
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Slow cooling vs. Supercooling
0 20 40 60 80 100
0
500
1000
1500
2000
2500
Con
cent
ratio
n (p
pm)
Time, h
Al Water Quenched Si Water Quenched Al Slag Pot Si Slag Pot
10M NaOH
Dissolu=on at alkaline pH => reac=vity as inorganic polymer
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Slow cooling vs. Supercooling
10M NaOH -‐ 24h
0
10
20
30
40
50
60
70
80
90
100
diss
olve
d %
A l S i
Quenched
Slag pot
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Slow cooling vs. Supercooling
Inorganic polymer from supercooled precursor ⇒ Very high reac=on rate ⇒ hardening in minutes But: crack forma=on, lower strength, 60 MPa ⇒ less fine grain size ⇒ less NaOH needed => used friendly ⇒ less costly
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Slow cooling vs. Supercooling
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Inorganic Polymer Chemistry
Mass(%) Na2O 18,22 CaO 3,44 Al2O3 28,25 FeO 14,67 SiO2 33,10 Total 99,21
Al Si
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
160015001400 1300120011001000 900 800 700 600 500 400 300 200 100
Phase amount
Temperature (°C)
g-‐xid-‐SLAGA#1 g-‐xid-‐SPINA#1 g-‐CaAl2Si2O8(s2) g-‐xid-‐OlivA#1g-‐xid-‐PERO g-‐xid-‐cPyrA#1 g-‐SiO2(s)
Melt
Spinel
Feldspar
Fayalite
Pyroxene
Water quenching Slag pot
Thermodynamic modelling
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
160015001400 1300120011001000 900 800 700 600 500 400 300 200 100
Phase amount
Temperature (°C)
g-‐xid-‐SLAGA#1 g-‐xid-‐SPINA#1 g-‐CaAl2Si2O8(s2) g-‐xid-‐OlivA#1g-‐xid-‐PERO g-‐xid-‐cPyrA#1 g-‐SiO2(s)
Melt
Spinel
Feldspar
Fayalite
Pyroxene
Water quenching Slag pot
Thermodynamic modelling
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⇒ Determine amount of crystal/glass ⇒ Crystallisa=on = modifica=on melt
chemistry
⇒ Moderate reac=vity, hardening in
hours ⇒ Strength > 100 Mpa ⇒ No Cracks
Controlled cooling rate
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Controlled cooling rate = improved properties
22 Contact: [email protected]
Dr. Lieven Machiels
KULeuven
Centre for High Temperature Processes and Sustainable Materials Managment
Kasteelpark Arenberg 44 -‐ room 02.47
BE-‐3001 Leuven, Belgium
Tel: +32 16 32 12 18 Mobile: +32 494 91 86 49 Skype: lieven.machiels