supercooling of slags: design of inorganic polymer precursors · slow cooling vs. supercooling 0 20...

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

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Sustainable inorganic materials managment

Contact:  Lieven.machiels@mtm.kuleuven.be  

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Sustainable inorganic materials managment

Jones  et  al.,  JOM,  2011.  

Contact:  Lieven.machiels@mtm.kuleuven.be  

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Sustainable inorganic materials managment

Contact:  Lieven.machiels@mtm.kuleuven.be  

22  Contact:  Lieven.machiels@mtm.kuleuven.be  

   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