1. FROM BAUXITE RESIDUE TO A NOVEL BINDER: Options for the Alumina Refinery
Tobias Hertel, Lukas Arnout, Silviana Onisei, David Ariño Montoya, Bart Blanpain, Yiannis Pontikes
2nd Bauxite Residue Valorisation and Best Practices Conference, Athens, 2018
May 7, 2018

2. OXIDES Motivation The secondary resource: Bauxite Residue (BR)
Only 1 – 3 % (by mass) is industrially valorised

3. Why? Motivation Effective valorisation with large-volume applications
LEGISLATIVE BARRIER
strict waste legislations, complicated licensing to use BR
 barrier for some industrial sectors to reuse BR;
landfilling often more economical and easy solution
 policy actions needed
TECHNICAL BARRIER
availability of well-established raw materials at low price
- robust and simple valorisation processes needed
- economic benefit
Effective valorisation with large-volume applications
Construction materials as promising route

4. Geopolymer/Inorganic Polymer
Performance of BR as a binder material
Motivation
Geopolymer/Inorganic Polymer
Cement
water
Ca-Si-Hydrates
Ca(OH)2
Alkali (silicate) solution
Inorganic Polymer
cement
(hydraulic phases)
(ferro)aluminosilicate source
(mainly amorphous, glassy phase)
water
Alkali (silicate) solution BR
No hydraulic phases
(exception BR from sinter process)
No reactive glass phase

5. Performance of BR as a binder material Motivation
Mechanical
properties

6. Technology readiness level
Aim of the present work
Presentation of selected processes to transform BR into novel binders
(where BR actively participates to the properties of the final building material)
INDUSTRIAL SCALE
PILOT PLANT SCALE
Proposals, flowsheet
LABORATORY SCALE
demonstrated
TRL
Technology readiness level

7. [Ordinary Portland Cement]
Use of BR in raw meal of clinker production
[Ordinary Portland Cement]
Addition of BR
limited to about 5 wt%
Firing at 1450 °C
Ariño Montoya et al. 5th International Slag Valorisation Symposium; 2017.​
Low additions of BR

8. [Calciumferrosulfoaluminate cements]
Use of BR in raw meal of clinker production
[Calciumferrosulfoaluminate cements]
Addition of BR
of about 40 wt%
Compressive Strength of 40 MPa
Firing at 1200 – 1300 °C
-> formation of hydraulic phases
CSFA clinker
+ Gypsum
MPa
CSFA cement
+ Water, Sand
CSFA mortars
Onisei et al. Slag Valorisation Symposium Leuven 2017, Leuven 3-5 April 2017

9. [Aluminoferrite and ferrobelitic clinkers cements]
Use of BR in raw meal of clinker production
[Aluminoferrite and ferrobelitic clinkers cements]
Tuesday, 8th – 14:40
David Ariño Montoya et al.
Bauxite Residue as a main raw material in the production of calcium sulfo ferroaluminate clinker
Firing at 1250 °C
CSFA cement
+ Water, Sand
CSFA mortars

10. > 40 MPa Transformation of BR into precursor for inorganic polymers
BR slag as reactive component in binder
Trivial additions
Firing at °C
-> formation of reactive glass phase
Water quenching
BR slag
+ alkaline activator
Compressive Strength
> 40 MPa
Inorganic Polymer

11. Compressive strength up to 55 MPa
Transformation of BR into precursor for inorganic polymers
integrated, near-zero-waste processes
→ metal recovery
→ building materials
Firing at 1250 °C
Compressive strength up to 55 MPa
Water quenching
BR slag Fe
MPa
+ alkaline activator
+ sand
Inorganic Polymer Mortar

12. Transformation of BR into supplementary cement. material
Firing at 1200 °C
Water quenching
Tuesday, 8th – 16:20 – Poster
SIVAKUMAR et al.
Modified bauxite residue as an alternative supplementary cementitous material
BR slag
supplementary cement. material

13. Alternative heat treatment technologies
microwave assisted furnace
C as microwave
energy absorber
Firing at °C
Water quenching
BR slag
Options to reduce overall environmental footprint
Use of established, robust processes
Reduction of risks, cost, complexity
Tuesday, 8th – 16:20 – Poster
HERTEL & Cardenia et al.
Microwave treatment of bauxite residue for the production of inorganic polymers
+ alkaline activator
pressing
Inorganic Polymer Binder

14. Alternative heat treatment technologies
sinter-pot furnace (pilot plant scale)
(conventionally used for iron ore sintering)
Firing at °C
Water quenching
BR slag
Tuesday, 8th – 15:40
ARNOUT et al.
Increasing the reactivity of bauxite residue for the use as building material: an alternative activation treatment
+ alkaline activator
pressing
Inorganic Polymer Binder

15. > 50 MPa Reducing the overall environmental footprint
Firing at °C
Water quenching
BR slag
Compressive Strength
> 50 MPa
+ alkaline activator
84 % of BR in binder
Less BR needs to be fired
pressing
Inorganic Polymer Binder

16. Use of BR slurry in hybrid binders (cement / reactive slag)
less BR is treated towards slag
valorisation of BR slurry in as-it-is state
No additional alkaline activator needed
L/S = 0.75
liquid content: 43 %
Compressive Strength of 45 MPa
with > 80 wt% BR (BR in BR slag + BR slurry)
curing
MPa
Hybrid Binder Mortar

17. Alkali silicate solution
Binder from BR – flowsheet – options for the alumina industry
BR slurry
filter press
alkaline solution
water
B2O3
SO3
SiO2
CaO C
cake
alkalis
soluble SiO2
autoclave
SiO2
Alkali silicate solution

18. Binder from BR – flowsheet – options for the alumina industry
Thermal treatment furnace
rotary kiln
top rotary
blown converter
microwave
sintering furnace

19. Ordinary Portland cement
Binder from BR – flowsheet – options for the alumina industry
1100 – 1200 °C ° °C
> 1300 °C
granulation
equipment
Calciumsulfo-
aluminate
-ferrite clinker
Portland cement
clinker
BR slag
BR slag
SO3
milling equipment
milling equipment
magnetic
separator
milling equipment
CSFA cement
magnetic
non-
magnetic Fe
Ordinary Portland cement
BR slag precursor

20. BR slag precursor casting pressing CSFA cement
Ordinary Portland cement
BR slag precursor
Alkali silicate solution
H2O
H2O
BR slurry
mixer BR
Soluble
silicates
shaping
casting
pressing
BR in
disposal area
curing
chamber
Farming
amphiroll
Inorganic polymers
Hybrid binder
Calciumsulfoferroaluminate cement
Ordinary Portland cement
Pozzolanic cement
densified,
storable aggregate
Building products
Aggregates, cements, bricks, blocks, tiles, porous materials, fire resistant materials

21. Conclusions
crucial for a sustainable management of the residue towards novel binders
indispensable factors to convince industrial partners
Industrial implementation
Focus on technical feasibility on real-life conditions and economic and environmental aspects
currently investigated in a pilot plant scale in the framework of the EIT KIC RECOVER and in the upcoming H2020 RemovAl project
Possibilities of various binder formation from mainly BR derived materials are proven in a laboratory scale

22. Thank you for your kind attention
Acknowledgements
Thank you for your kind attention
FROM BAUXITE RESIDUE TO A NOVEL BINDER: Options for the Alumina Refinery
Tobias Hertel, Lukas Arnout, Silviana Onisei, David Ariño Montoya, Bart Blanpain, Yiannis Pontikes
The research leading to these results has received funding from the European Community’s Horizon Programme ([H2020/2014–2019]) under Grant Agreement no (MSCA-ETN REDMUD).
This publication reflects only the authors’ view, exempting the Community from any liability. Project website:
This work has received funding from EIT RawMaterials, a European Institute of Innovation and Technology (EIT) Knowledge and Innovation Community (KIC) under the Project Agreement No (RECOVER). Project website:
Further thank goes to (alphabetic order):
Chiara Cardenia, CRM Group/Liège, Theodoros Karachalios, Pithchai Pandian Sivakumar,
who contributed to this work