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: david.arinomontoya@kuleuven.be

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