Characterization of landfilled stainless steel slags in view of metal recovery
Xuan Wang1,2, Daneel Geysen3, Tom Van Gerven2, Peter T. Jones1, Bart Blanpain1, Muxing Guo1()
1. Department of Metallurgy and Materials Engineering, KU Leuven, 3001 Heverlee, Belgium 2. Department of Chemical Engineering, KU Leuven, 3001 Heverlee, Belgium 3. Department of Research and Development, Group Machiels, 3001 Heverlee, Belgium
The slag samples taken from landfill, which originated from different metallurgical processes, have been characterized in this study. The slags were categorized as electric arc furnace (EAF) slag, argon oxygen decarburization/metal refining process slag and vacuum oxygen decarburization slag based on chromium content and basicity. EAF slags have higher potential in metal recovery than the other two slags due to its higher iron and chromium contents. The size of the iron-chromium-nickel alloy particles varies from a few µm up to several cm. The recoveries of large metal particles and metal-spinel aggregates have potential to make the metal recovery from landfilled slags economically viable.
. [J]. Frontiers of Chemical Science and Engineering, 2017, 11(3): 353-362.
Xuan Wang, Daneel Geysen, Tom Van Gerven, Peter T. Jones, Bart Blanpain, Muxing Guo. Characterization of landfilled stainless steel slags in view of metal recovery. Front. Chem. Sci. Eng., 2017, 11(3): 353-362.
“A aggregate” is composed of a yellowish slag and a black slag. Large pieces (up to several cm) of metal can be observed.
A black
“A black” is a dense hard solid slag. White dots can be observed in the black slag matrix. Small pores can be found in the slag, but not in vast amounts.
“STAAL2” bucket
S aggregate
“S aggregate” appears to be a yellowish porous solid material with loose bonding structure.
S black
“S black” is a porous black solid slag. Small metal particles can be observed visually on the surface when it was crushed.
Green
“Green” is a dense hard slag, which gives a greenish color.
Yellow
Slag “Yellow” is a solid that contains large pores. The surface of the slag is in a yellowish color.
Hybrid
Slag “Hybrid” is an aggregate of two types of slags, which appear in black and yellow respectively.
Tab.1
Location
CaO
SiO2
MgO
Al2O3
Cr2O3
Fe2O3
MnO
Basicity
1
48.3
29.4
5.5
5.3
6.5
1.7
1.9
1.6
2
37.8
41.1
4.5
4.9
5.8
2.6
1.6
0.9
3
47.2
30.9
5.5
6.9
4.4
1.9
1.2
1.5
4
47.7
31.2
7.2
6.9
3.3
0.7
1.7
1.5
5
46.7
32.9
6.7
3.6
6.4
1.0
1.6
1.5
Tab.2
Slag
CaO
SiO2
MgO
Al2O3
Cr2O3
Fe2O3
MnO
Basicity
Presumed slag type
A aggregate
46.5
28.0
7.4
4.3
8.0
2.7
1.7
1.7
EAF
S aggregate
44.8
30.1
5.7
6.1
7.5
2.6
1.7
1.5
EAF
S black
35.1
21.0
4.5
3.9
19.4
8.9
2.5
1.7
EAF
Green
48.8
26.2
9.1
6.9
5.8
0.7
1.1
1.9
EAF
Yellow
44.5
29.0
5.9
7.1
6.8
2.1
1.7
1.5
EAF
Hybrid
51.3
26.7
8.2
9.1
2.3
0.6
0.5
1.9
AOD/MRP
A black
40.6
37.3
7.9
6.8
2.3
0.3
3.2
1.1
VOD
Tab.3
Mineral
Chemical formula
A aggregate
S aggregate
S black
Green
Yellow
Hybrid
A black
C2S beta
Ca2SiO4
21.6
23.2
44.5
65.5
43.7
43.2
<1.0
C2S gamma
Ca2SiO4
9.6
3.8
5.0
3.9
8.3
<1.0
<1.0
Magnesiochromite
MgCr2O4
12.7
7.2
16.9
4.9
6.7
1.6
1.6
Quartz
SiO2
1.3
1.4
1.2
<1.0
5.1
<1.0
1.5
Gehlenite
Ca2Al2SiO7
6.2
20.7
2.0
<1.0
1.6
1.4
48.9
Bredigite
Ca7MgSi4O16
8.6
4.8
3.9
5.7
4.4
27.7
<1.0
Magnesite
MgCO3
3.7
2.5
2.9
<1.0
2.5
5.0
<1.0
Merwinite
Ca3MgSi2O8
10.3
3.7
2.7
<1.0
4.4
2.1
<1.0
Calcite
CaCO3
1.3
5.1
1.5
2.3
3.3
<1.0
<1.0
Cuspidine
Ca4F2Si2O7
12.5
8.8
4.4
3.4
4.5
6.1
19.2
Akermanite
Ca2MgSi2O7
3.2
3.7
<1.0
2.0
<1.0
<1.0
15.3
Iron carbide
Fe5C2
2.1
2.9
3.4
4.2
4.2
2.0
4.3
Magnetite
Fe3O4
<1.0
<1.0
2.0
1.7
1.5
2.1
1.7
Calcium chromate
CaCr2O4
<1.0
2.8
2.1
<1.0
2.9
1.7
4.2
Wollastonite
CaSiO3
4.2
7.7
4.8
1.9
3.7
3.4
<1.0
Tab.4
Fig.9
Fig.10
Fig.11
Fig.12
Fig.13
Fig.14
Fig.15
1
Boom R, Riaz S, Mills K C. A boost in research on slags, a doubling in publications from literature since 2003. Ironmaking & Steelmaking, 2010, 37(7): 476–481 https://doi.org/10.1179/030192310X12731438632001
Adamczyk B, Brenneis R, Adam C, Mudersbach D. Recovery of chromium from AOD-converter slag. Steel Research International, 2010, 81(12): 1078–1083 https://doi.org/10.1002/srin.201000193
4
Durinck D, Jones P T, Blanpain B, Wollants P. Air-cooling of metallurgical slags containing multivalent oxides. Journal of the American Ceramic Society, 2008, 91(10): 3342–3348 https://doi.org/10.1111/j.1551-2916.2008.02597.x
5
BAM. Recycling of residues from metallurgical industry with the arc furnace technology- RECARC. EU LIFE Environment Demonstration Project, 2006
6
Ye G, Burström E, Kuhn M, Piret J. Reduction of steel-making slags for recovery of valuable metals and oxide materials. Scandinavian Journal of Metallurgy, 2003, 32(1): 7–14 https://doi.org/10.1034/j.1600-0692.2003.00526.x
7
Pillay K, Von Blottnitz H, Petersen J. Aging of chromium (III)-bearing slag and its relation to the atmospheric oxidation of solid chromium (III)-oxide in the presence of calcium oxide. Chemosphere, 2003, 52(10): 1771–1779 https://doi.org/10.1016/S0045-6535(03)00453-3
8
Santos R M, Van Bouwel J, Vandevelde E, Mertens G, Elsen J, Van Gerven T. Accelerated mineral carbonation of stainless steel slags for CO2 storage and waste valorization: Effect of process parameters on geochemical properties. International Journal of Greenhouse Gas Control, 2013, 17: 32–45 https://doi.org/10.1016/j.ijggc.2013.04.004
9
Zhang H, Hong X. An overview for the utilization of wastes from stainless steel industries. Resources, Conservation and Recycling, 2011, 55(8): 745–754 https://doi.org/10.1016/j.resconrec.2011.03.005
10
Rowbotham A L, Levy L S, Shuker L K. Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects. Journal of Toxicology and Environmental Health. Part B, 2000, 3(3): 145–178
11
Mostbauer P. Criteria selection for landfills: Do we need a limitation on inorganic total content. Waste Management (New York, N.Y.), 2003, 23(6): 547–554 https://doi.org/10.1016/S0956-053X(03)00028-X
12
Durinck D, Engström F, Arnout S, Heulens J, Jones P T, Björkman B, Blanpain B, Wollants P. Hot stage processing of metallurgical slags. Resources, Conservation and Recycling, 2008, 52(10): 1121–1131 https://doi.org/10.1016/j.resconrec.2008.07.001
13
Sripriya R, Murty C V G K. Recovery of metal from slag/mixed metal generated in ferroalloy plants — a case study. International Journal of Mineral Processing, 2005, 75(1-2): 123–134 https://doi.org/10.1016/j.minpro.2004.08.013
14
Jones P T. Degradation mechanisms of basic refractory materials during the secondary refining of stainless steel in VOD ladles. Leuven: KU Leuven, 2001, 69–71
ParkerJ A L, LovedayG K. Recovery of metal from slag in the ferro-alloy industry. In: Glen H Wed. Hidden Wealth. Johannesburg: Southern African Institute of Mining and Metallurgy, 2006, 7–15
17
SanoN. Reduction of chromium oxide in stainless steel slags.In: Proceedings of 10th International Ferroalloys Congress. Cape Town: South African Institute of Mining and Metallurgy, 2004, 670–677
16
Lee S B, Song H, Hwang H Y, Rhee C H, Klevan O S. Effects of ferrosilicon particle size on reduction rate of chromium oxide in slag. Scandinavian Journal of Metallurgy, 2003, 32(5): 247–255 https://doi.org/10.1034/j.1600-0692.2003.00649.x
17
Park J H, Song H S, Min D J. Reduction behavior of EAF slags containing Cr2O3 using aluminum at 1793 K. ISIJ International, 2004, 44(5): 790–794 https://doi.org/10.2355/isijinternational.44.790
18
Gao J, Li S, Zhang Y, Zhang Y, Chen P, Shen P. Process of re-resourcing of converter slag. Journal of Iron and Steel Research International, 2011, 18(12): 32–39 https://doi.org/10.1016/S1006-706X(12)60006-5
