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Miguel A. G. Aranda
Departamento de Química Inorgánica, Universidad de Málaga
g_aranda@uma.es
http://webpersonal.uma.es/~mag-aranda/
Cementos
belíticos
y sulfobelíticosa way for reducing CO2
emissions
Monday, 13 September 2010
Outline Outline
1. Introduction to cement industry environmental problem
2. Searching for sustainable materials and processes
6. Conclusions
4. Laboratory active belite cements
5. Laboratory active belite sulfoaluminate cements
3. Methodology (mainly at Universidad de Málaga)
Industrial production of Ordinary Portland Cement
Dry processDry processQuarry
Kiln
1450ºC
Raw materials:Limestone (Ca)Clays (Al, Si)FeldsparsFe2 O3 (iron ore / rust)
Rawmix mill
Cement mill(s)
Gypsum and additions
Green house gases: CO2
, etc.
CaCO3 CaO
+ CO2
0.54 Tons / ton of clinker
The overall CO2
emissions of cementindustry (~
0.98 T) are
6% of all
anthropogenic carbon dioxide release
Cement industry contributes to the global warming of the planet in
4%
Other emissions: ~
0.34 T from fuel burning
~
0.10 T from electricity
T=1450ºC
OPC
Outline Outline
1. Introduction to cement industry environmental problem
2. Searching for sustainable materials and processes
6. Conclusions
4. Laboratory active belite cements
5. Laboratory active belite sulfoaluminate cements
3. Methodology (mainly at Universidad de Málaga)
2.1. Addition of mineralizers and/or fluxes, to enhance burnability and/or decrease the firing temperature.
2.2. Partial replacement of clinker by an active hydraulic compound (blended cements).
2.3. The use of (slightly) different mineralogical systems to decrease the burning temperature and/or to obtain highly reactive constituents.
2. Searching for sustainable materials and 2. Searching for sustainable materials and processes for reducing COprocesses for reducing CO
22
emissionsemissions
2.1. 2.1. MineralizersMineralizers / fluxes (as an example)/ fluxes (as an example)
Sulfates, chlorides, carbonates, phosphates, fluorides, fluorosilicates etc…
Phosphogypsum (PG) as raw material: CaSO4 ·2H2 O + Na2 SiF6
10% PG
1200ºC
0.4 % CaOfree Alite & belite
low crystal sizes
liquid phase: porosity grinding
High mechanical strength 28 days Valorization of waste materials
Kacimi
et al., J. Hazardous
Mat. 2006
2.2. Partial replacement of clinker by 2.2. Partial replacement of clinker by an active hydraulic compoundan active hydraulic compound
As an example: Pozzolanic
based cements
Pozzolanic
reactionProduct of OPC hydration
The hydration of alite
with silica fume (S) gives 1.76 times much C-S-H / C3
S consumed
Up to a reduction of 43%
of CO2
emitted from raw materials (compared to pure C3
S) could be obtained.
Gartner, Cem. Concr. Res. 2004
Alkaline activation of fly ashes
Alkaline activation of slags
They will be treated in other lectures
(among other systems)
2.3. Alternative mineralogical systems2.3. Alternative mineralogical systems
CO2
emissions relationship between
OPC(ordinary Portland cement;
based on alite, and others)&BSA(belite sulfoaluminate
cements;
based on belite, C4
A3
$, and others)
1.- ‘Active’ belite Portland cements:To decrease the LSF from 98 to 71 leads to a
11% reduction of CO2
emissions (less calcite as raw material). Furthermore, extra reduction (close to 3%) may be attained from burning at lower temperatures (1350 ºC instead of 1450 ºC)
since less fuel is needed.
2.- ‘Active’ iron-rich belite sulfoaluminate cements:Plus the above described savings ~ 10% from substituting alite
by belite (smaller LSF)
~
5 % from burning the clinker at 1300 ºC (fuel saving) ~ 15%
from partial substitution of CaCO3
by CaSO4
.Therefore, more than 30% of CO2 emissions savings can be obtained.
C2
S C4
A3
S C4
AF
2.3. Alternative mineralogical systems2.3. Alternative mineralogical systems
2.3. Alternative mineralogical systems2.3. Alternative mineralogical systems
Problem:Low early mechanical strengths
a) High-belite cements:
LSF: higher C2
S less C3
S b) Sulfoaluminate based cements: C4
A3
S
ActivationActivation
of belite clinkers of belite clinkers Higher mechanical strength at early agesHigher mechanical strength at early ages
Quenching. Chemistry stabilisation.
-forms stabilisation by oxides such as Na2 O , SO3 , BaO and K2 O.
Hydraulicallynon-active.
Hydraulically very active.
Ordinary Portland clinker component.Mechanical strength at later ages.
'
L '
H
1425ºC1160ºC
780-860ºC
690ºC< 50
0ºC
'
L '
H
1425ºC1160ºC
780-860ºC
690ºC< 50
0ºC
High-belite cements - Quenching
LSF: higher C2
S less C3
S
High-belite cements
Decrease
CO2
emissionsin the decomposition of calcite
(8%).
The optimum clinkerizationtemperature is roughly 100 ºC lower
Belite based concretes are moredurable
.
Wolter, Cement
International 2005
Quenching
mechanical strength3000 K/min vs. 100 K/min
in belite cements
(at 28 days)
Belite sulfoaluminate cements # 1
Raw materialsCalcite (Ca)bauxite (Al)Fluidized bed combustion
(FBC) (Ca, Si, Al & S)Fly ash (Al, Si)Red mud (Al, Si & Fe)
Potential mineralogical clinker compositions (main phases)
CSA cements
Flue Gas Desulfuration (FGD) gypsum
Thermal treatment: 2h @ 1150-1300ºC
Advantages Easier to grind (
liquid phase
porosity)
synthesis temperature
CO2 emissions
Used (valorization) of waste materials
porosity on hydrated samples
durability
Valenti et al., W3-11.2, 12th ICCC, Montreal 2007Canonico et al., W3-11.4, 12th ICCC, Montreal 2007
M7
M8
Belite sulfoaluminate cements # 2
Clinkering temperature = 1300ºC
Li et al., TH3-15.3, 12th ICCC, Montreal 2007
1/3
Li et al., TH3-15.3, 12th ICCC, Montreal 2007
’-forms’-forms
’-forms
2/3
Belite sulfoaluminate cements # 2
Outline Outline
1. Introduction to cement industry environmental problem
2. Searching for sustainable materials and processes
6. Conclusions
4. Laboratory active belite cements
5. Laboratory active belite sulfoaluminate cements
3. Methodology (mainly at Universidad de Málaga)
C3S
C3S
C3S C
3S
C3SC2S
C2S
C2S
C2S
C2S
C3A
C4A
F
C4A
FC
3S
NK
SN
KS
NK
SN
KS
C
8.5 9 9.5 10 2º 10.5
I (u.
a.)
C3S
C3S
C3S C
3S
C3SC2S
C2S
C2S
C2S
C2S
C3A
C4A
F
C4A
FC
3S
NK
SN
KS
NK
SN
KS
C
8.5 9 9.5 10 2º 10.5
I (u.
a.)
C3S
C3S
C3S C
3S
C3SC2S
C2S
C2S
C2S
C2S
C3A
C4A
F
C4A
FC
3S
NK
SN
KS
NK
SN
KS
C
8.5 9 9.5 10 2º 10.5
I (u.
a.)
Synchrotron powder diffraction data,=0.44 Å
Transm
ission
Convert the divergent X-ray beam from a tube in line focus position to an intense beam
that focuses onto the goniometer
circle.
Sample
X-Rays tube
Convergent beam
Goniometercircle
Mirror
FocusDivergent incident beam
Laboratory X-ray Powder data collectionIn-situ hydration
Application laboratory of PANalytical
(Almelo, The Netherlands)
=1.5418 ÅFlat sample
Synchrotron X-ray Powder data collectionIn-situ hydration
W/C= 0.5
Slits Sample
X-Rays
~2 mm
Transm
ission
Cement Water
Image plate detector: two data collection strategies
BM08 beam line @ ESRF=0.6888 Å
Debye Scherrer
configurationFlat sample
Translating mode
2D single pattern
Clinkering process for belite clinkers is not well knownPolymorphic transformations at high temperatureLiquid appearance temperature(s)Influence of minor elements in these reactions
Why an in-situ study?
Selected compositions
1.00.50.5Bel_10S05K05N
1.0-1.0Bel_10S10K
-0.50.5Bel_05K05N
-1.5-Bel_15N
--1.0Bel_10K
---B_ref
SO3/%Na2O/%K2O/%sample
1.00.50.5Bel_10S05K05Na
1.0-1.0Bel_10S10K
-0.50.5Bel_05K05Na
-1.5-Bel_15Na
--1.0Bel_10K
---B_ref
SO3/%Na2O/%K2O/%sample
1.00.50.5Bel_10S05K05N
1.0-1.0Bel_10S10K
-0.50.5Bel_05K05N
-1.5-Bel_15N
--1.0Bel_10K
---B_ref
SO3/%Na2O/%K2O/%sample
1.00.50.5Bel_10S05K05Na
1.0-1.0Bel_10S10K
-0.50.5Bel_05K05Na
-1.5-Bel_15Na
--1.0Bel_10K
---B_ref
SO3/%Na2O/%K2O/%sample
Clinkerization process for an ordinary Portland Clinker
700-900ºC Decarbonation (CO2 )
900-1300ºC free lime, Al & Fe rich phases and silicates
1300-1450ºC liquid phase + silicates
Quenching Phase stabilisation + subcooled liquid
CO 2
CaCO 3
-Cuarzo
Arcill a
-cuarzo
CaOAlitaC 3 S
BelitaC 2 S
Fe 2 O 3
C 12 A 7C 4 AF líquido C 4 AF
C 12 A 7
140012001000 1000800600 T (ºC)
Pro
porc
ión
de C
ompu
esto
s
CO 2
CaCO 3
-Cuarzo
Arcill a
-cuarzo
CaOAlitaC 3 S
BelitaC 2 S
Fe 2 O 3
C 12 A 7C 4 AF líquido C 4 AF
C 12 A 7
140012001000 1000800600
CO 2
CaCO 3
-Quartz
Clays
-cuarzo
CaOAlitaC 3 S
BelitaC 2 S
Fe 2 O 3
C 12 A 7C 4 AF liquid C 4 AF
C 3 A
140012001000 1100800600 RT
Por
tions
by
wei
ght
C3 AC4 AF
C2 S
C3 S
Temperature (ºC) cooling
Thermo-diffractometric
data collection
Pt capillaryØ=0.6 mm
Metallic sample holderMgO refractory
capillary
Refractory ceramic adhesive
Raw mix inside
Data collection
ESRF (Grenoble)ID31 diffractometer=0.3007 ÅDebye Scherrer configurationCapillaries were spunAngular range 2.5-30o (in 2) 15 minutes per run3 runs for a single pattern
Real temperature was checked by Pt peak positions
Samples were heated from 900 to 1450ºC
0
10
20
30
40
50
60
70
80
wt%
900 1000 1100 1200 1300 1400
T / ºC
0
10
20
30
40
50
60
70
80
wt%
900 1000 1100 1200 1300 1400
T / ºC
Reference
belite clinker
(B_ref) on
heating
1240ºC
Free lime (CaO
) 9.6(2)wt%
(1) Primary formation of C4
AF ( )
Free lime (CaO
) 4.2(1)wt%(3) Formation of C3
A ( )(4) Crystal size growth of C4
AF ( )
1055ºC
C
CaOCaO
3C S
AFC4AF
-C2S
’H-C2S ’L-C2S
C A3
Liquid phase
C
CaOCaO
3C S
AFC4AF
-C2S
’H-C2S ’L-C2S
C A3
Liquid phase
0
10
20
30
40
50
60
70
80
wt%
900 1000 1100 1200 1300 1400
T / ºC
0
10
20
30
40
50
60
70
80
wt%
900 1000 1100 1200 1300 1400
T / ºC
1350ºC
(7)
’H
-C2
S -C2
S( )
C3
S ( )
1300ºC
C
CaOCaO
3C S
AFC4AF
-C2S
’H-C2S ’L-C2S
C A3
Liquid phase
C
CaOCaO
3C S
AFC4AF
-C2S
’H-C2S ’L-C2S
C A3
Liquid phase
B_ref on heating (continuing) (5) Melting
of
C3
A ( ) & C4
AF ( )(6)
’H
-C2
S( ) + CaO
C3
S ( )
Free lime (CaO
) 0.0wt%
Liquid phase ( )
Liquid
phase
(B_ref) on
heating
Nominal
compositionC4AF/% C3A/%
16 81180ºC 17.7(3) 6.2(2)
Melting
Formation
Formation/sinterization
6.30 6.35 6.40 6.45 6.50
2/º
920 ºC
1055 ºC
1180 ºC
1300 ºCCC44 AFAF
CC33 AA
Active belite clinker 1.0% K2
O
(B_10K) on cooling
10.0--6.5(3)3.5(1)9.5(2)10.3(2)60.2(1)--1055 ºC
10.5--6.2(3)3.3(2)9.4(2)--70.6(1)--1175 ºC
11.1--5.6(3)3.3(2)9.3(2)--70.7(2)--1238 ºC
20.0------7.6(2)----72.4(1)1310 ºC
20.0----7.1(2)----72.9(1)1308 ºC
20.0------7.3(2)----72.7(1)1440 ºC
--4.6(1)14.0(2)6.0(2)----75.4(1)--1200 ºC
Liquid phaseCaOC4AFC3AC3S'L-C2S'H-C2S-C2SB_1.0K
10.0--6.5(3)3.5(1)9.5(2)10.3(2)60.2(1)--1055 ºC
10.5--6.2(3)3.3(2)9.4(2)--70.6(1)--1175 ºC
11.1--5.6(3)3.3(2)9.3(2)--70.7(2)--1238 ºC
20.0------7.6(2)----72.4(1)1310 ºC
20.0----7.1(2)----72.9(1)1308 ºC
20.0------7.3(2)----72.7(1)1440 ºC
--4.6(1)14.0(2)6.0(2)----75.4(1)--1200 ºC
Liquid phaseCaOC4AFC3AC3S'L-C2S'H-C2S-C2SB_1.0K
5.0 5.5 6.0 6.5 7.0
1400ºC
1350ºC
1300ºC
1250ºC1200ºC
1100ºC
RT
2/º
cool
ing
5.0 5.5 6.0 6.5 7.0
1400ºC
1350ºC
1300ºC
1250ºC1200ºC
1100ºC
RT
2/º
cool
ing
We have carried out a similar in situ type of study for belite sulfoaluminate
clinkering,
to be reported very soon.
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