© 2 0 04 A L C A N I N C.
By: Guy Forté, Collaborator: Régis GirardAlcan International Ltd., Bauxite & Alumina, Arvida R&D Centre, Jonquière, QC
Bayer Process Alumina Production -
Alcan Bayer Experimental Centre
© 2 0 0 4 A L C A N I N C. October 2004 Slide 2 B&A
Outline> The Making of Aluminium
> The Bayer Process– Bauxite– Alumina– Bayer Process Flowsheet and Chemistry
> The Alumina Industry Challenges– Alumina Technology Roadmap
> Alcan Bayer Experimental Centre– Historical Background– Environment, Health and Safety (EH&S)– Tested Technologies and Applications in the Alumina
Industry
> Conclusions
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The Making of Aluminium
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The Making of Aluminium
Bayer Bayer Hall-HéroultHall-Héroult Casting/Casting/RollingRolling
> Alcan production capacity in Canada:– 1.7 million tons aluminium and 1.3 million tons alumina
> Alcan world production capacity:– 3.2 million tons aluminium and 6.4 million tons alumina
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The Making of Alumina
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The Bayer Process> Inventor:
– Karl Josef Bayer, an Austrian chemist (1847-1904)
> Patented in 1888
> What it is:– A caustic pressure hydrometallurgical process which
extracts aluminium species from bauxite ore andproduces alumina, an aluminium oxide (Al2O3), via anintermediate product called hydrate, which is analuminium oxide tri-hydrate (Al2O3.3H2O)
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Bayer Refineries
Gove, Australia
Vaudreuil, Jonquière, Québec
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Bauxite Mine
>> World production:World production:– 130 million tons/year
from which 70 % in Australia, Guinea, Brazil and Jamaica
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Bauxite: Typical Composition
ComponentsWt. %
(as metallic oxideif not indicated
otherwise)Al2O3Fe2O3SiO2TiO2
Organic Carbon (as C)P2O5 CaOV2O5ZnO
Ga2O3Cr2O3
SF
Hg (ppb)
30-601-30
<0.5-10<0.5-10
0.02-0.400.02-1.0
0.1-20.01-0.10
0.002-0.100.004-0.0130.003-0.300.02-0.100.01-0.1050-1000
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Bauxite: Typical Composition-Majors
< 0.2 - 20 %Al2O3 (boehmitic)
30 - 60 %Al2O3 (gibbsitic)
0.2 - 10 %SiO2 (as quartz)
0.3 - 10 %TiO2
1.0 - 30 %Fe2O3
0.3 - 6 %SiO2 (as clay)
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Bauxite: Typical Minerals
MajorElements Mineral Formula
Caustic Soluble at °C(operating kPa)
Aluminium GibbsiteBoehmiteDiaspore
Al(OH)3 or Al2O3.3H2OAlOOH or Al2O3.H2OAlOOH or Al2O3.H2O
150 (800)250 (5500)
> 260 (>6000)
Silicon QuartzKaolinite
SiO2Al2Si2O5(OH)4 orAl2O3.2SiO2.2H2O
250 (5500)150 (800)
Iron HematiteGoethite
Fe2O3FeOOH or Fe2O3.H2O
ii
Titanium AnataseRutile
TiO2TiO2
250 (5500)i
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Bauxite: Typical Composition
GibbsiteAl2O3 3H2O
BoehmiteAl2O3 H2O
DiasporeAl2O3 H2O
HematiteFe2O3
AluminianGoethite
(Fe,Al)2O3 H2O
AnataseTiO2
RutileTiO2
Kaolinite, HalloysiteAl2O3 2SiO2 2H2O
QuartzSiO2
Phosphate (Crandallite, Apatite)CaAl2 (PO4)2(OH)5H2O
3Ca3(PO4)2 Ca(F,Cl,OH)2
* May be present in significant concentrations in Jamaican bauxite
MajorLegend :
Minor or Trace
Manganese (Lithiophorite)(Li,Al)MnO2(OH)2
Calcium (Calcite)CaCO3
Organic CarbonHumic materials Vanadium
V2O5 ChromiumCr2O3 Arsenic
As2O5
GalliumGa2O3 Fluorine
F
SulphurS
MercuryHg
ZincZnO
.
.
..
. .
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Alumina> A commodity product
> The raw material of the Hall-Heroult electrolysis processto produce aluminium
> Also a speciality chemical:– spark plugs– fire retardant– synthetic marble– catalyst– tooth paste– alun, aluminium fluoride– ceramic– refractory
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Alumina Typical Composition
Constituents Wt.%(as metallic oxide)
Al2O3 (by diff.)Na2OSiO2CaOFe2O3TiO2ZnOP2O5Ga2O3V2O5SO3
99.3-99.70.30-0.50
0.005-0.025<0.005-0.0400.005-0.0200.001-0.008
<0.001-0.010<0.0001-0.0015
<0.005-0.015<0.001-0.003< 0.05-0.20
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The Bayer Process
BAUXITE GRINDING
CALCINATION
RESIDUE TREATMENT
BAUXITE LIME
FLOCCULANTWASH
WATER
WASHEDRESIDUE
FLOCCULANTLIME
ALUMINA
LIQUOR CYCLE
CLASSIFICATION
CLARIFICATION
DIGESTION
DECANTATION
FILTRATION
PRECIPITATION
PRED
ESIL
ICAT
ION
STEAM CAUSTIC
HEATEXCHANGER
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The Bayer ProcessHydrate
Precipitation&
Classification
ResidueSettlers and
Washers
Autoclaves
HeatExchangers
LiveSteam
Digestion
Extraction S/L SeparationPrecipitation
Bauxite Handling and Grinding
Residue Disposal
Alumina Calciners
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The Bayer Chemistry> In Digestion:
– Al2O3.3H2O sol + 2NaOH aq 2 NaAlO2 aq + 4H2O– Al2O3.H2O sol + 2NaOH aq 2 NaAlO2 aq + 2H2O– a) 3(Al2O3.2SiO2.2H2O) sol + 18 NaOH aq
6Na2SiO3 aq + 6NaAlO2 aq + 15H2Ob) + Na2CO3 aq 3(Na2O.Al2O3.2SiO2.2H2O)Na2CO3 sol + 12 NaOH aq + 3 H2O
> In Precipitation:– 2 NaAlO2 aq + 4H2O Al2O3.3H2O sol + 2NaOH aq
> In Calcination:– Al2O3.3H2O sol Al2O3 sol + 3H2O vap
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Alumina Technology Roadmap> Initiators:
– The Aluminium Association– The U.S. Department of
Energy, Office of IndustrialTechnologies
– Australian Mineral IndustriesResearch Association(AMIRA)
– Australian Department ofIndustry, Science andResources
> Contributors:– Alcan Inc– Alcoa World Alumina– Aluminium Pechiney– Comalco Aluminiun Limited– CSIRO Minerals– Eurallumina S.p.A.– Hydro Aluminium Metal Products– Hindalco Industries Limited– Kaiser Aluminium– Nabalco Pty Ltd.– Queensland Alumina Ltd.– The AJ Parker Research Centre– Worsley Alumina Pty Ltd.
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Alumina Industry Goals 2001-2020> Reduce operating costs of existing refineries by 3 % per
year
> Reduce total energy consumption by 25 % from currentbest practice
> Target new plants capital costs at < US $500/annual tonwith IRR > 18 %
> Target major expansion capital costs at < US $250/annual ton
> Contribute to reduce impact on environment, health andsafety
> Contribute to global sustainable development
> Produce a commodity product that meets customer’scurrent and future needs.
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Specific Goals> Increase refineries productivity, yield by 20 %
> Reduce caustic consumption by 50 % to 30 kg/ton Al2O3
> Reduce process variability to < 5 %
> Reduce effects of scaling and blockages
> Improve calcination and cogeneration
> Develop combustion and power generation from wasteheat sources
> Reduce or recycle inputs and outputs including water,odours, VOCs, mercury, oxalates, organics, impurities,etc.
> Develop ecological, sustainable storage of residueand/or reuse
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R&D Opportunities>> Accelerate precipitation ratesAccelerate precipitation rates
> Residue: cost effective inerting and alternative uses
> Conversion of monohydrate to a more beneficial state
> Direct reduction of bauxite or other aluminium materials
> Full automation/improved control strategies
> Impurity removal from bauxite (beneficiation)
> Impurity removal from Bayer liquor
> Knowledge management and best practices
> Reduction in caustic consumption
> Scale management
> Technical solutions for refinery releases
> Waste heat recovery
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Precipitators> Tanks of 4000 to 6000 m3
> Slow kinetic with 48 hours ofresidence time
> Phenomena:– nucleation– agglomeration– growth– attrition
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R&D Opportunities> Accelerate precipitation rates
>> Residue: cost effective inerting and alternative usesResidue: cost effective inerting and alternative uses
> Conversion of monohydrate to a more beneficial state
> Direct reduction of bauxite or other aluminium materials
> Full automation/improved control strategies
> Impurity removal from bauxite (beneficiation)
> Impurity removal from Bayer liquor
> Knowledge management and best practices
> Reduction in caustic consumption
> Scale management
> Technical solutions for refinery releases
> Waste heat recovery
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Residue Stacking/Reuse
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R&D Opportunities> Accelerate precipitation rates
> Residue: cost effective inerting and alternative uses
> Conversion of monohydrate to a more beneficial state
> Direct reduction of bauxite or other aluminium materials
> Full automation/improved control strategies
> Impurity removal from bauxite (beneficiation)
> Impurity removal from Bayer liquor
> Knowledge management and best practices
>> Reduction in caustic consumptionReduction in caustic consumption
> Scale management
> Technical solutions for refinery releases
> Waste heat recovery
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Alcan Deep Thickeners
> More efficient washing, higherunderflow solid content
> More compact:– Typically 10 m in diameter
against 30 m forconventional thickeners
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R&D Opportunities> Accelerate precipitation rates
> Residue: cost effective inerting and alternative uses
> Conversion of monohydrate to a more beneficial state
> Direct reduction of bauxite or other aluminium materials
> Full automation/improved control strategies
> Impurity removal from bauxite (beneficiation)
> Impurity removal from Bayer liquor
> Knowledge management and best practices
> Reduction in caustic consumption
> Scale management
> Technical solutions for refinery releases
> Waste heat recovery
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Alcan Bayer Experimental Centre -BEC - Historical Background> Located at the Alcan Arvida R&D Centre in Jonquière,
QC, 58 years of tradition with a Bayer pilot plant
The Bayer Experimental Centre-BEC was built in 1990– today, it is worth about $ 3.5 million CAD– with working space of 370 m2 on two floors
> Justifications:– the need for a rugged experimental step between lab
or bench scale tests and industrial applications.
> It is now an R&D tool for development of newtechnologies and successful scaling up and technologytransfer
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Arvida R&D Centre
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Alcan Bayer Experimental Centre -BEC - Historical Background> Located at the Alcan Arvida R&D Centre in Jonquière,
QC, 58 years of tradition with a Bayer pilot plant
> The Bayer Experimental Centre-BEC was built in 1990– today, it is worth about $ 3.5 million CAD– with working space of 370 m2 on two floors
> Justifications:– the need for a rugged experimental step between lab
or bench scale tests and industrial applications.
> It is now an R&D tool for development of newtechnologies and successful scaling up and technologytransfer
© 2 0 0 4 A L C A N I N C. October 2004 Slide 31 B&A
Bayer Experimental Centre
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Bayer Experimental Centre - BECHistorical Background> Located at the Alcan Arvida R&D Centre in Jonquière,
QC, 58 years of tradition with a Bayer pilot plant
> The Bayer Experimental Centre-BEC was built in 1990– today, it is worth about $ 3.5 million CAD– with working space of 370 m2 on two floors
> Justifications:– the need for a rugged experimental step between lab
or bench scale tests and industrial applications.
> It is now an R&D tool for development of newtechnologies and successful scaling up and technologytransfer
© 2 0 0 4 A L C A N I N C. October 2004 Slide 33 B&A
BEC - Capacity and Equipment> 150 L/h of solution, 20 kg/h of bauxite ore (scale 1:12,000)
> Batch or continuous operation around the clock
> Grinder (wet and dry)
> Tanks with mixers
> Preheaters (steam, electric)
> Digestion– LT autoclaves– HT autoclaves– HHT tube autoclave– Flash vessels
> S/L separation– atmospheric decanters– pressure decanters– filters (vacuum, pressure)– C-FLOCTM, a dynamic settling analyser
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Process Flowsheet
Residue
Flashtank
F8-416
Pressure decanterF3-307/317
Pregnant liquor
Bauxite Spent liquor
Preheaters
G2-208 G2-209
Autoclaves
F3-301 F3-302 F3-303
Control valve
Control valveBlow-off
tankA7-500
Flowmeter
Atmosphere
TC TC
TC
TCTC
TCTC
PC
PC
Predesilicationtank
A7-202
Liquortank
A7-509
Conductivity
Flowmeter
Density
Turbidity
Flowmeter
© 2 0 0 4 A L C A N I N C. October 2004 Slide 35 B&A
BEC - Capacity and Equipment> 150 L/h of solution, 20 kg/h of bauxite ore
> Batch or continuous operation around the clock
> Grinder (wet and dry)
> Tanks with mixers
> Preheaters (steam, electric)
> Digestion– LT autoclaves– HT autoclaves– HHT tube autoclave– Flash vessels
> S/L separation– atmospheric decanters– pressure decanters– filters (vacuum, pressure)– C-FLOCTM, a dynamic settling analyser
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Low Temperature Autoclaves
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High Temperature Autoclaves
© 2 0 0 4 A L C A N I N C. October 2004 Slide 38 B&A
BEC - Capacity and Equipment> 150 L/h of solution, 20 kg/h of bauxite ore
> Batch or continuous operation around the clock
> Grinder (wet and dry)
> Tanks with mixers
> Preheaters (steam, electric)
> Digestion– LT autoclaves– HT autoclaves– HHT tube autoclave– Flash vessels
> S/L separation– atmospheric decanters– pressure decanters– filters (vacuum, pressure)– C-FLOCTM, a dynamic settling analyser
© 2 0 0 4 A L C A N I N C. October 2004 Slide 39 B&A
Pressure Decanters
© 2 0 0 4 A L C A N I N C. October 2004 Slide 40 B&A
BEC - Capacity and Equipment> 150 L/h of solution, 20 kg/h of bauxite ore
> Batch or continuous operation around the clock
> Grinder (wet and dry)
> Tanks with mixers
> Preheaters (steam, electric)
> Digestion– LT autoclaves– HT autoclaves– HHT tube autoclave– Flash vessels
> S/L separation– atmospheric decanters– pressure decanters– filters (vacuum, pressure)– C-FLOCTM, a dynamic settling analyser
© 2 0 0 4 A L C A N I N C. October 2004 Slide 41 B&A
C-FLOCTM- Settling Analyser
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BEC - Equipment> Precipitators
> Rotary calciner
> Positive displacement reciprocating metering pumps
> Flow-meters, density-meters
> Conductivity-meters, turbidity-meters
> Data acquisition system, fully integrated control systemand supervisory control
> Programmable logic controller
> Services: laboratory, compressed air, water, lowpressure steam, heating, ventilation, lifting equipmentand drainage, control room.
© 2 0 0 4 A L C A N I N C. October 2004 Slide 43 B&A
Metering Pumps
© 2 0 0 4 A L C A N I N C. October 2004 Slide 44 B&A
BEC - Equipment> Precipitators
> Rotary calciner
> Positive displacement reciprocating metering pumps
> flow-meters, density-meters
> conductivity-meters, turbidity-meters
> Data acquisition system, fully integrated control systemand supervisory control
> Programmable logic controller
> Services: laboratory, compressed air, water, lowpressure steam, heating, ventilation, lifting equipmentand drainage, control room.
© 2 0 0 4 A L C A N I N C. October 2004 Slide 45 B&A
Control System Structure
© 2 0 0 4 A L C A N I N C. October 2004 Slide 46 B&A
Typical Control Page
© 2 0 0 4 A L C A N I N C. October 2004 Slide 47 B&A
BEC - Equipment> Precipitators
> Rotary calciner
> Positive displacement reciprocating metering pumps
> flow-meters, density-meters
> conductivity-meters, turbidity-meters
> Data acquisition system, fully integrated control systemand supervisory control
> Programmable logic controller
> Services: laboratory, compressed air, water, lowpressure steam, heating, ventilation, lifting equipmentand drainage, control room.
© 2 0 0 4 A L C A N I N C. October 2004 Slide 48 B&A
Control Room
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BEC - EH&S> Designed like a real plant
> Environment:– drainage pit, waste tank, no reject to the environment
> Health and safety:– ergonomical with various lifting and handling devices– showers with eye washers and PPE against the
corrosive caustic solution– Monel alloy protecting against stress corrosion
cracking or steel caustic embrittlement– Rupture disks, relief valves, pressure sensors for
automatic shut-off, hydrostatic tests, audits againstoverpressure risks
> Documented risk assessment procedure, more than 100assessments archived
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Low Temperature Autoclaves
© 2 0 0 4 A L C A N I N C. October 2004 Slide 51 B&A
BEC - EH&S> Designed like a real plant
> Environment:– drainage pit, waste tank, no reject to the environment
> Health and safety:– ergonomical with various lifting and handling devices– showers with eye washers and PPE against the
corrosive caustic solution– Monel alloy protecting against stress corrosion
cracking or steel caustic embrittlement– Rupture disks, relief valves, pressure sensors for
automatic shut-off, hydrostatic tests, audits againstoverpressure risks
> Documented risk assessment procedure, more than 100assessments archived
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BEC - Industrial Applications
> Patented Alcan Double Digestion Process to reduceenergy consumption
– This is a process by which gibbsite is extracted first atnormal temperature, then the residue, containingboehmite, is digested again at lower than usualtemperature to recover boehmite.
– Tested on two Jamaican bauxites for potentialexpansion of one former Alcan plant
– Tested on two Australian bauxites. Results are beingused as design specifications for a brownfieldexpansion
© 2 0 0 4 A L C A N I N C. October 2004 Slide 53 B&A
BEC - Industrial Applications> Patented Alcan Pressure Decantation to reduce caustic
consumption– This is a decanter operating under pressure to
separate residue from pregnant solution at thedigestion conditions.
– Tested on two Jamaican muds. In one case, anindustrial prototype was built in one former Alcanplant; in the second case, a full-scale industrialapplication is in operation in the United States ofAmerica. The plant performances are as predicted bythe BEC tests.
– Tested also on two potential applications in Australia.In one case, again, the results are being used asdesign specifications for a brownfield expansion.
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Industrial Pressure Decanters
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Conclusions
> The alumina industry is facing significantchallenges and the Alumina TechnologyRoadmap addresses the technology issues.
> To achieve significant technical improvements,Alcan has been running its R&D Centre inQuébec for 58 years and the BEC was built 14years ago as a development tool to increase theodds of successful scaling up and technologytransfer.
© 2 0 0 4 A L C A N I N C. October 2004 Slide 56 B&A
Conclusions (cont.)> The Alcan Bayer Experimental Centre has
proven to be a reliable development tool totransfer key Alcan proprietary technologies.These technologies represent a partial answer tothe roadmap as they reduce energy and causticconsumption in the Bayer refineries. It is also atool that helps reducing investment costs as theequipment can be sized properly.
> The BEC also presents several challenges inEH&S and, at Alcan, EH&S is a journey ofcontinuous improvement.
© 2 0 04 A L C A N I N C.
By: Guy Forté, Collaborator: Régis GirardAlcan International Ltd., Bauxite & Alumina, Arvida R&D Centre, Jonquière, QC
Bayer Process Alumina Production -
Alcan Bayer Experimental Centre
