1. RED MUD AS AN ALTERNATIVE MATERIAL FOR THE PRODUCTION OF A GEOTECHNICAL COMPOSITE
Vesna ZALAR SERJUN,
Ana MLADENOVIĆ,
Radmila MILAČIČ, Janez ŠČANČAR,
Ana AŠLER, Nina ZUPANČIČ,
Irena NIKOLIĆ, Primož OPRČKAL
Athens, 7-10 May 2018,
2nd Bauxite Residue Valorisation
and Best Practices Conference

2. INTRODUCTION INTRODUCTION RED MUD (RM)
170 million tonnes produced worldwide in 2015
environmental issues: high alkalinity, the possible presence of PTE, and their leachability
efficient utilization
recovery of immobilization potential due to
critical raw materials high sorption capacity
BR2018

3. INTRODUCTION INTRODUCTION CONTAMINATED SOIL (CS)
342,000 contaminated sites in the EU
a legacy of the inappropriate disposal and treatment of waste, caused by industrial / mining activities
After: OPRČKAL, P., Innovative approaches for sustainable remediation of contaminated waters and soils : doctoral dissertation, Ljubljana, pp.
PTE
34,8 %
After: EEA, Progress in management of contaminated sites (CSI 015).
Copenhagen: European Environment Agency, 2017
• potential routes
for the migration
of contaminants
BR2018

4. INTRODUCTION INTRODUCTION IMMOBILIZATION
chemical / physical mechanisms to prevent bioavailability, and to reduce the toxicity and mobility of potential toxic elements (PTE)
The Best Available Technology
mixing the soil
with additives
After OʹDay, P., Vlassopoulos, D., Mineral-Based Amendments for Remediation. Elements, 6, pp.:
BR2018

5. AIM OF RESEARCH AIM OF THE RESEARCH To verify:
• the potential of RM to be used as an additive
for the immobilization of PTE in CS
• the environmental and geotechnical
properties of an CS/RM composite
BR2018

6. MATERIALS & METHODS MATERIALS & METHODS
RM: Podgorica, an open disposal site (Uniprom-KAP, Montenegro)
CS: one of the largest and most
degraded areas in Slovenia (the
17 ha brownfield site of the Old
Zinc-Works, Celje)
geotechnical composite: blending the
CS with 25 wt.% of RM and the optimal
amount of water; compaction up to
maximum dry density (according to the
Modified Proctor Compaction Test)
RM, CS: physical properties, chemical composition, phase composition
CS/RM geotechnical composite: physical and mechanical properties, the tank leaching procedure (after 7, 28, 56 days)
BR2018

7. BET Specific surface area (m2/g)
RESULTS
RESULTS
RM, CS – physical properties
Parameter RM CS
BET Specific surface area (m2/g)
20.1
10.0
Density (Mg/m3)
3.07
2.71 RM CS
BR2018

8. RESULTS RESULTS RM, CS – total chemical composition Parameter RM CS
(%)
Al2O3
17.84
9.57
CaO
20.85
7.46
Fe2O3
19.50
11.95
K2O
0.33
0.27
MgO
0.85
3.76
P2O5
0.32
5.03
SiO2
8.11
24.43
SO3
0.82
6.59
Parameter CS
Critical limit values*
(mg/kg) As
1790.0
55.0 Cd
166.0
12.0 Cr
78.6
380.0 Cu
1132.0
300.0 Hg
215.0
10.0 Mo
51.5
200.0 Ni
213.0
210.0 Pb
530.0 Zn
720.0
* According to the Decree on limit values, alert thresholds and critical levels of dangerous substances into the soil (Official Gazette of RS, Nos. 68/96, 41/04 – ZVO-1,1996.
BR2018

9. Inertness limit values *
RESULTS
RESULTS
RM, CS – chemical analysis of leachates
Parameter RM CS
Inertness limit values *
(mg/kg d.m.) As
0.49
0.05
0.5 Ba
<0.01
0.80 20 Cd
0.34
0.04 Cr
0.03 Cu
2.2
0.08 2 Hg
0.01 Mo
0.31
0.11 Ni
0.06
0.4 Pb
0.48 Sb Se
0.02
0.1 Zn
0.10
22.6 4
SO42-
100
10010
6000
Cl-
280
37.6
800 pH
9.0
7.4
Cond. (mS/cm)
0.3
1.45
* According to Decree
on Waste Landfill
(Official Gazette of
RS, Nos. 36/16, 2016)
BR2018

10. RESULTS
RESULTS
RM, CS - mineral composition RM CS
BR2018

11. RESULTS RESULTS CS/RM COMPOSITE The Modified Proctor Procedure
(SIST EN , 2005)
Dry density: 1.67 Mg/m3
Optimum water content: 16.1 wt.%
Water permeability
(after 28 days): 7.88×10-8 m/s
Unconfined compressive strength
(after 3, 7, 28, 56 days): MPa
BR2018

12. RESULTS RESULTS CS/RM COMPOSITE Mineral composition – no new phases!
BR2018

13. RESULTS RESULTS CS/RM COMPOSITE Leaching test (after 7, 28, 56 days)
(SIST EN , 2002)
BR2018

14. RESULTS RESULTS CS/RM COMPOSITE Leaching test (after 56 days) SO42- ZnCd Pb
(mg/kg d.m.)
Contaminated soil
10010
22.60
0.34
0.48
CS/RM Composite
3250
0.61
0.007
0.01
Quotient 3 37 48
Limit values*
6000 4
0.04
0.5
* According to Decree
on Waste Landfill
(Official Gazette of
RS, Nos. 36/16, 2016
BR2018

15. CONCLUSIONS CONCLUSIONS
RM is an effective additive for the immobilization of PTE in a CS/RM geotechnical composite.
Surface sorption was the main immobilization
mechanism in the CS/RM composite.
The CS/RM composite complies with the prescribed limit values for inert materials according to the Slovenian landfilling legislation.
BR2018

16. CONCLUSIONS CONCLUSIONS
The investigated CS/RM composite can be used for the rehabilitation of contaminated sites, as fill or for the construction of embankments.
BR2018

17. THANK YOU FOR YOUR ATTENTION
BR2018