Red mud presentation tms2014 balomenos et al
-
Upload
victor-james -
Category
Environment
-
view
196 -
download
1
Transcript of Red mud presentation tms2014 balomenos et al
THE ENEXAL BAUXITE RESIDUE TREATMENT PROCESS: INDUSTRIAL
SCALE PILOT PLANT RESULTS
Efthymios Balomenos, Dimitrios Kastritis, Dimitrios Panias, Ioannis Paspaliaris, Dimitrios Boufounos
Aluminion of Greece Laboratory of Metallurgy, NTUA
Bauxite Residues (BR)
Bayer Process: 5 kg of Bauxite ore is split into 3 kg of hydrated alumina and 2 kg of BR (dry basis)
Bauxite Residues (BR)• Produced as a
slurry• 100 -120 Mt / year• Usual handling
practice: Disposed in sealed or unsealed artificial impoundments
Hungary 2010
Bauxite Residues (BR) Dewatering BR in
Filter Presses The filter cake has a
moisture content to 25%, which makes it easier to handle
AoG was one of the first Western European plants to apply this technology
AoG Produces 650,000 t BR per year
Can this BR cake be a potential resource?
Bauxite Residues in AoGChemical Species
%wt (dry basis)
Fe2O3 47.74%
Al2O3 16.22%
CaO 10.73%
SiO2 6.09%
TiO2 5.93%
Na2O 2.51%
V2O5 0.21%
-SO3 0.60%
-CO2 1.63%
H2O(cry) 8.35%
Resource for Pig-
Iron Production
• Dried BR are dusty and therefore require agglomeration prior to feeding to conventional reactors (blast furnace/EAF)
• Sodium causes problems with blast furnace refractories
• Un-economic process
Resource for
Mineral Wool
production• High Added
Value product
• Complementary production with Pig Iron reduces energy consumption
• Economic, Zero Waste process
ENEXAL BR Treatment Use of AMRT-
EAF technology allows feeding without agglomeration
No Solid/liquid wastes in the process
Mineral wool produced at 70% less energy cost (no melting req.)
ENEXAL BR TreatmentProcess Design
Define conditions for optimum iron recovery (temperature, carbon addition)
Define physico-chemical properties of the slag through appropriate fluxes (CaO, SiO2) in order to produce a melt suitable for mineral wool production
Thermodynamically Model the Process
Test in Lab, Semi-Industrial and Industrial Pilot Scale
Pig iron standards%C ~ 4%%S <0.02%%P <0.05%%Si 0.4-0.8%
Empirical indexes for mineral wool production(SiO2 +Al2O3 + TiO2)/(CaO+MgO; < 1.8 4.9/[(MgO+CaO+Fe2O3 +Na2O + TiO2)/(SiO2 +Al2O3)] -0.45 < 15
[100 – (SiO2 + Al2O3)]/( SiO2 +Al2O3) 0.8 -1(SiO2 +Al2O3)/(1.4 MgO+ 0.4 Fe2O3 + CaO + TiO2) 1.3 - 1.4 Na2O + MgO + CaO 30 – 40
ENEXAL BR TreatmentAoG Pilot Plant
1 MVA AMRT-EAF (AC, 3-electrode, dust treating, batch capacity 1t)
Melt Fiberizing Line
Static Bed Electric Dryer
One year of operation treating 25 tons of BR
ENEXAL BR TreatmentAMRT-EAF Carbothemic SmeltingOpen bath operationContinuous feeding 6.65 kg/minMelt Temperature app 1600oC Energy Consumption: 1508 kWh/t of BRDust in filters 4% wt of feed
Feed Batch Dry BR (kg) 700Silica (kg) 126 Lime (kg) 105Coke (kg) 140Total Feed (kg) 1071
10
The AMRT Dust Treating EAF technology
• The EAF treats directly dusty material feed• Open bath operation (material reacts upon contact with the bath)• Pattended PLC system regulates power supply depending on real time measurement of melt impendence
ENEXAL BR TreatmentPig Iron ProductionProduced metal within specification for use in secondary steel industry, as an up to 20% steel scrap substitute High Cr presence due to initial refractory dissolution (Reft1)More than 5t pig iron produced in total
Pig Iron Refr1 Refr2Fe (%wt) 95.47 93.44C (%wt) 3.36 4.59S (%wt) 0.26 0.07P (%wt) 0.08 0.22Si (%wt) 0.01 1.12Cr (%wt) 0.82 0.50Total 99.99 99.94
White Iron grinding balls produced from BR iron
(21%wt subs)
ENEXAL BR TreatmentMineral Wool ProductionSlag melt within empirical indexesFibre with good quality :
λ = 0,034 W /(mk) [UNI EN 12667] Average fiber diameter 7 micron Bright color (low Mn content)
High Mechanical resistance due to high TiO2
Slag Refr1 Refr2Fe2O3 5.0 1.1SiO2 27.6 26.5CaO 25.3 23.4Al2O3 20.9 31.1Cr2O3 3.0 0.1MgO 8.89 8.3TiO2 5.6 6.1Na2O 2.4 1.8
Mineral wool used inside the plant
ENEXAL BR Treatment
BR Mineral Wool
Commercial Mineral Wool
ENEXAL BR Treatment
Smelting energy 14.5% in excess of thermodynamic requirement
Overall plant consumption 2 MWh/t BR
Exergy Utilization efficiency 32%
Increase of alumina refinery exergy utilization by 8 percentile points
ENEXAL BR Treatment Up-scaling will bring higher
energy efficiency, especially in BR drying
Initial studies show the process to be profitable
Break-even point is achieved with a fairly low mineral wool price
but
Pig iron revenues account for only 25% of the operating costs
Treating the AoG annual BR production would produce 0.5 Mt of Mineral Wool products
The ENEXAL BR treatment is successful but it should be a starting point for further BR
and BR-slag product development
Future Research
• The AoG BR also contain app 0.1%wt in REE (mainly as Sc, Ce and Nd)
• In the ENEXAL process these REE concentrate in the slag – can they be recovered?
“EURARE: Development of a sustainable
exploitation scheme for Europe’s REE ore
deposits”
eres2014.conferences.gr
Thank you for attention
The research leading to these results has received funding
from the European Union Seventh Framework Programme
([FP7/2007-2013]) under grant agreement n°
ENER/FP7EN/249710/ENEXAL