Ore processing in fluidized bed technologies

Ore processing in fluidizedbed technologies

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Overview• Fundamentals in fluidized bed technology.• Outotec‘s experience in fluidized bed technologies.• CFB/FB applications for iron containing ores.• CFB aplications for alumina calcination.• Technology and project development.


Bubbling fluidized bed

(FB)

Circulating fluidized bed

(CFB)

Transport or flash reactor (FR)

• In a fluidized bedparticles are heldsuspended by theupward.

• Increasing gas velocitieswill create different flowregimes.

• The highest slip velocityis reached in CFB,leading to high mass &heat transfer rates.

• Outotec has appliedCFB, FB, AFB and FRfor treatment of differentfine ores.

Fluidized bed systems - fundamentals

Annular fluidized bed (AFB)


Circulating fluidized bed advantages• High mass & heat transfer

Uniform temperature, low energyconsumption.

• Direct processing of finesMinimum fines losses and accretions.

• High productivityMinimum plant downtime & lowspecific investment costs.

• No heavy rotating equipmentEasy and flexible control, low operation& maintenance costs.

• Easy and exact control of temperatureand retention time.

• Direct combustion of natural gas in theCFB furnace.

Gas

CFB

Gas

Fuel NG

Air

Air

Circulating fluidized bed

Outotec‘s experience in fluidized bed technologies


CFB applications

6

Rio Tinto Alcan Gove 3 CFB calciners.

HBI Circored plant Trinidad. Capacity 0.5 million t/a


7

CFB applications

Outotec‘s fluidized bed applications


8

CFB applications – iron ore processing

• Outotec has built CFB plantsfor preheating, roasting andhydrogen based reduction ofiron ores.

• In the case of iron orepreheating & calcination, thetarget is to remove LOI andto preheat the ore for downstream processes (e.g. directreduction or smeltingreduction).

• For ilmenite roasting thetarget is to change magneticproperties of the ore to allowthe removal of chromite bymagnetic separation.

Hot ore

CFB preheater with 1 stagesuspension venturi.

CFB preheater with 2 stages suspension venturi.


9

CFB applications – iron ore processing

9

• One Circored plant for directreduction of iron ore was built,using hydrogen as reductant:Circored plant Trinidad 1996.

• Two ilmenite roasters were builtby Outotec: Exxaro 2001,Empangeni South Africa; andMoma Sands 2005Mozambique.

• Two iron ore preheaters werebuilt by Outotec: preheater forCircored plant Trinidad 1996 andpreheater for HIsmelt Australia2002.

Circored plant Trinidad

HBI stockpile at the Circored plant Trinidad


1010

CFB/FB applications – DRI/HBI production

Circored is the only hydrogenbased direct reduction processfor iron ores available in themarket.

Hydrogen is used as reductant,which is normally supplied fromsteam-methane reforming plant.

Up to 95% metallization degreecan be achieve using tworeduction stages (CFB/FB).

Final product could be HBI orDRI as feed to other processes(e.g. EAF steelmaking, BFironmaking).

Process water

Process Gas

Off Gas

Raw Iron Ore

Off Gas

Process water

Nat. Gas

Air

PreheatedIron ore Recycle Gas

H2

Slurry

SlurryOff Gas

Treatment

Preheating Section

Depressurising & discharge system

Process Gas Treatment

Solids Gas

Liquids

N2

CFB /FB Reduction

Section

Reduced Iron ore

Circored process - Block diagram


1111

Iron orestockyard

Ore preheater Hydrogenplant

HBI stockyard

Reduction plant

Jetty

Circored plant Trinidad. 0.5 Million t/a HBI plant.

CFB/FB applications – DRI/HBI production


1212

Circoheat® iron ore preheater for HIsmelt

Iron ore preheater

CFB applications – iron ore preheating


1313

Circoheat® iron ore preheater

CFB applications – iron ore preheating


1414

Moma Sands 2005 – Mozambique, South Africa

• Capacity of roaster: 1200 tpdroasted ilmenite

• Roasting under reducing conditionsat 800oC temperature.

• Ilmenite: 57 % TiO2, 27 % Fe

• Circulating fluidized bed for optimalprocess control (temperature andretention time).

• External hot gas generator forsubstoichiometric combustion ofdiesel fuel oil.

• Reactor dimensions: 3 m, 21 mhigh.

CFB applications – ilmenite roasting


1515

Exxaro 2001 – Empangeni, South Africa

• Capacity of roaster: 1000tpd roasted ilmenite.

• Start-up: 1999.

• Roasting under oxidizingconditions to be able todecrease the chromitecontent by magneticseparation before smelting.

• Ilmenite: 49 % TiO2, 37 %Fe.

• Circulating fluidized bedwith internal combustion ofSasol gas.

• Reactor dimensions: 1.9m, 12 m high.



1616

Exxaro ilmenite roaster process flowsheet



1717

CFB applications: alumina calcination

• Calciners built: 52

• Calcinersupgraded: 11

• Total CFBCapacity: >36 MTPY(40 % of world production)

• Under construction: 2 CFBs


1818

CFB Applications: alumina calcination

Technology and projectdevelopment


20

Technology development

• Process design • Process flowsheets, mass and energy

balances of processes, operating points, sensitivity analyses.

• Plant design: equipment dimensioning and functionality.

• Test work (lab scale, batch, continuous, pilot scale):

• For plant design, scale-up and process guarantees.

• For production of material to be tested further.

R&D Way of workIterative interplay between process design & test work

Com

plem

enta

ry

Outotec R&D Center, Frankfurt, Germany.


21

Scale up experience

Process Pilot plant size Commercial plant size

Factor(approximate)

Alumina calcining 1966 125 mm Ø5 kg/h

1.0 m Ø1 t/h 1:200

Alumina calcining 1970 1,000 mm Ø1,000 kg/h

3.6 m Ø20 t/h 1:20

Coal combustion1982

360 mm Ø20 kg/h

5 m Ø21 t/h 1:1,000

Gold ore roasting1990

200 mm Ø22 kg/h

3.8 m Ø83 t/h 1:4,000

Circored1999

200 mm Ø18 kg/h

5.0 m Ø63 t/h 1:3,500


Project development time frame and costs

0.1

Rel

ativ

e pr

oces

s de

velo

pmen

t cos

ts (%

)

Execution (months)

100

10

1

6 12

Experimental200 mm CFB pilot plant for process validation

Basic engineeringFlowsheetProcess controlProprietary equipment designPhase I

Bench scale tests 50mm FB; 80mm FB

CAPEX & OPEX +/- 30 - 40%

3 9

EngineeringProcurementConstructionOperation

Increasing accuracy of CAPEX & OPEX estimates Phase II

CAPEX & OPEX +/- 15%

Mineralogy


Conclusions

• Outotec‘s CFB technology presents several advantagesfor thermal treatment of different fine ores.

• The direct combustion of natural gas in the CFB furnaceresults in an efficient method for fine ore heating,minimizing fuel consumption.

• The use of hydrogen for DRI & HBI production has beendemonstrated, and combined with EAF could representsan alternative route for steel production.

• Outotec has a vast experience accumulated for morethan 50 years in different fluidized bed applications.

Thank you

Ore processing in fluidized bed technologies

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