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MATERIALS AND METHODS
Mineralogy Composition Control FR2 FR4
Alite Ca3SiO5 55 59 61
β Belite β Ca2SiO4 13 10 5
γ Belite γ Ca2SiO4 1 2 2
Aluminate Ca3Al2O6 6 2 0
Ferrite Ca2AlxFe2-xO5 10 14 3
Srebrodolskite Ca2Fe2O5 0 1 13
Portlandite Ca(OH)2 0 0 1
Quartz SiO2 0 0 1
Amorphous 12 9 10
INCREASING THE Fe2O3/Al2O3 RATIO IN ORDINARY PORTLAND
CEMENT CLINKER, AIMING TO INCORPORATE HIGHER
CONTENTS OF BAUXITE RESIDUEDavid ARIÑO MONTOYA1,2,*, Marios KATSIOTIS1, Nikolaos PISTOFIDIS1, Giannis GIANNAKOPOULOS1, Dimitris
PAPAGEORGIOU1, Remus Ion IACOBESCU2, Yiannis PONTIKES2
1 TITAN Cement Co, Athens, Greece 2 KU Leuven, Department of Materials Engineering, 3001 Heverlee, Belgium
* Contact e-mail: [email protected]
ACKNOWLEDGEMENTS
RESULTS
The research leading to these results has received
funding from the European Community’s Horizon 2020
Programme ([H2020/2014-2019]) under Grant
Agreement no. 636876 (MSCA-ETN REDMUD). This
publication reflects only the author’s view, exempting
the Community from any liability. Project website:
http://www.etn.redmud.org.
REFERENCES
CONCLUSIONSThe substitution of Al2O3 by Fe2O3 affected the
resulting phases increasing the formation of Ca3SiO5
and Ca2Fe2O5. A decrease in Ca2SiO4 and Ca3Al2O6
phases formation was also observed.
The elemental composition results shows a higher
intake of foreign elements in Ca2AlxFe2-xO5 than in
Ca3SiO5.
INTRODUCTION
Ca3SiO5 Chemical Formulae Ca2AlxFe2-xO5 Chemical Formulae
Ca Si Al Fe O Ca Si Al Fe O
Control 32.8 10.7 0.6 0.4 55.6 Ca3.0Si1.0O5.0 22.5 1.6 10.8 9.2 55.8 Ca2.0Al1.0Fe0.8Si0.1O5.0
FR2 32.7 10.7 0.5 0.4 55.6 Ca2.9Si1.0O5.0 23.1 1.5 8.1 11.7 55.7 Ca2.1Al0.7Fe1.0Si0.1O5.0
FR4 32.1 10.7 0.0 0.6 55.5 Ca3.0Fe0.1Si1.0O5.0 23.1 1.1 0.4 19.8 55.6 Ca2.1Fe1.8Si0.1O5.0
Table 3: EPMA results of the Ca3SiO5 and Ca2AlxFe2-xO5 phases (mol%)
1 T. Hertel, L. Arnout, A. Peys, L. Pandelaers, B.
Blanpain, Y. Pontikes. "A proposal for a 100% use of
bauxite residue: the process, results on the novel Fe-
rich binder and how this can take place within the
alumina refinery” In Bauxite Residue Valorisation and
Best Practices Conference, pp. 231-239 (2015)2 Y. Pontikes, G. N. Angelopoulos. "Bauxite residue in
cement and cementitious applications: Current status
and a possible way forward." Resources, conservation
and recycling 73: 53-63 (2013)
Table 1: XRF results and quality indexes
Table 2: QXRD results of the produced clinkers (wt%)
Bauxite residue (BR) is obtained during the alumina extraction process. It is known that between 1 and 1.5 tonnes of BR are produced for each tonne of alumina adding up to
150 million tonnes annually worldwide. The necessity to identify suitable high volume applications for bauxite residue and minimize landfilling is directing significant research
efforts towards the production of building materials1.
Ordinary Portland cement (OPC) annual production in 2015 was estimated to be over 4 billion tonnes. Among other valorisation methods, incorporation of BR into OPC
production appears as a very promising alternative to landfilling and could lead to substantial reduction of currently stored amounts. The typical composition of BR (high iron
oxide and aluminium oxide content) means that only limited use is feasible for standard cement production2. Aiming to achieve higher implementation, it is meaningful to study
the production of cement clinker with higher contents of Fe2O3 in the raw meal. In this work, the impact of increased Fe2O3 content on clinker phase formation is studied for
synthetic cement clinkers by means of X-Ray Diffraction (XRD) and Electron Probe Micro-Analysis (EPMA).
Synthetic Portland cement clinkers were prepared using reagent chemicals (CaCO3, SiO2, Al2O3 and Fe2O3).
Control mix was designed following specifications from TITAN Cement S.A. while FR2 and FR4 were variations on
the original mix, replacing Al2O3 by Fe2O3 on a molar basis.
Pellets were prepared by mixing the reagent chemicals with water and dried for 24 hours at 105ºC followed by a
clinkerization process, with a heating rate of 10ºC/min and two 30 minutes stops at 800 and 1450ºC. After
calcination, clinker was rapidly cooled to room temperature.
XRD characterisation with D8 Advance, settings: 40 kV and 40 mA, monochromatic CuKα radiation,
measurement range 5 -70º 2θ, step size 0.02º and step time 0.5s. Specimens were wet-milled with a McCrone
micronizing for 10 minutes using n-Hexane as grinding agent. Amorphous phase was quantified using external
standard method (corundum). Phase identification was performed with “Diffrac.Eva V4.1.1” and the subsequent
quantification with “Topas-Academic V5”.
EPMA of the clinker phases was performed with FEG-EPMA Jeol JXA 8530F.
CaO SiO2 Al2O3 Fe2O3 LSF SM AM
Control 67.7 22.2 5.6 4.3 92.9 2.2 1.3
FR2 66.8 21.7 4.2 6.3 95.6 2.1 0.7
FR4 65.5 21.3 0.3 12.5 95.3 1.7 0.0
Figure 2: EPMA mapping of the produced clinkers
10 15 20 25 30 35 40 45 50 55 60
Inte
nsi
ty (
a.u
.)
2θ
FR4
FR2
OPC
Figure 1: XRD patterns of the produced clinkers (A: Alite,
B: Belite, a: aluminate, F: Ferrite, S: Srebrodolskite)
A
S A SS S
A
A
A
A AA
B
AA
F A A AA
B
aF A A
A
AA A
A
B
Control FR2 FR4
