Fluidization Detail

Innovative solutions for fine grained materials

Calcination Roasting Reduction Gasifi cation Combustion Decarbonization

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OxidationGas cleaningHeat recoveryCoolingDryingSpray granulation

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Fluidization technology

002 More out of ore!

50 years of technology evolutionAlumina CFB calciner, Worsley Alumina, Australia.

Lurgi constructed the fi rst reactor for roasting of sulfur bearing materials in 1950, based on the principles of fl uidized bed technology. The new system was quickly adopted by industry; multiple hearth furnaces androtary kilns were increasingly replaced by fluidized bed roasters, thereby ensuring enhanced product quality and signifi cantly reduced plant emissions. Fluidized bed combined with effi cient heat recovery and offgas treatment, including the process of converting the offgas to sulfuric acid, became state-of-the-art technology for processing sulfur bearing ores. We have delivered more than 260 plants to date. Signifi cant process improvements have been achieved by using fl uidization technology, for example in the production of alumina. The circulating fl uidized bed (CFB) was developed over 40 years ago for the high temperature treatment of fi ne and light particles. A whole variety of other CFB applications followed, with more than 170 industrial plants worldwide. The CFB has been successfully applied for coal combustion, roasting of gold containing ores, direct reduction of iron ore fi nes and other uses. In the early 1990s we introduced a new variation of fl uidization technology, the annular fl uidized bed (AFB). With the aquisition of Lurgi Metallurgie in 2001, Lurgi's fl uidization know-how was transferred to Outotec. The development of fl uidized bed technology continues and we are working on new processes utilizing solid mixtures, such as ore and coal, with different properties for industrial application.

Early FB pyrite roasting plant, BASF, Germany.

For over 50 years Outotec has developed and commercialized fluidized bed

technology for a variety of industrial applications.

More out of ore! 003

Fluidized bed typesBubbling fl uidized bed (FB)

The classical bubbling fl uidized bed is operated at relatively low gas velocities with the particles kept in balance against their own gravity. Most of the particles do not leave the surface of the fl uidized bed, typically characterized by a defi ned surface between gas and solids. The surface may show a behavior similar to a boiling liquid, depending on size and density of the particles. From the mixing point of view, the FB is a continuously stirred tank reactor with a defi ned solids residence time distribution. The mean solid velocity is close to zero with the slip velocity almost identical to the gas velocity.

Circulating fluidized bed (CFB)

At higher gas velocities the slip velocity increases and the fl uid-ized bed changes its behavior. The defi ned boiling surface disappears with the expansion of the fl uidized solids. The fl uidization gas hasenough energy to entrain solids particles. The entrained particles are separated from the gas by a cyclone and recirculated via an ex-ternal loop back into the fl uidized bed reactor. In addition an internal recirculation of the solids in the fl u-idized bed reactor takes place. Both internal and external circulation re-sults in a homogenous temperature distribution in the CFB system.

Transport or flash reactor (FR)

With further increase of the gas velocity, the solids are approaching the velocity of the gas. In the fl ash (transport) reactor the slip velocity between gas and solids is consi-derably decreased compared to the circulating fl uidized bed. At the same time the advantages of homogeneous temperature distribution and ideal heat and mass transfer are decreased. This type of reactor is used in selected applications where low gas and solid retention times are suffi cient.

Annular fluidized bed (AFB®)

This new type of fl uidized bed improves the introduction and mixing of hot dust laden process gases. These gases enter the reactor through a large central nozzle, with additional fl uidization gas introduced through an annular nozzle ring. As a result, a very intense mixing zone is achieved within the reactor above the central nozzle, comparable to the conditions achieved by an external loop of a CFB. Further advantages are excellent process control and improved mass transfer conditions.The AFB can be combined with any other fl uidized bed type.

Increasing

solids density

Increasing expansion

Gas

"Slip

velocity"

Solids

Velo

city


Bubbling fluidized bed 01 1950 First pyrite roaster, BASF, Germany, 40 tpd02 1956 First zinc roaster, Nikon Kogyo, Japan, 40 tpd03 1958 Sulfate decomposition roaster, Imperial Smelting, UK, 140 tpd04 1962 First sulfating roaster for copper ores, Chambishi, Zambia, 118 tpd05 1965 Hydrogen based reduction plant for NiO, Inco, Canada, 150 tpd06 1965 First single-stage dearsenifying pyrite roaster, Boliden, Sweden, 350 tpd07 1968 First double-stage dearsenifying pyrite roaster, Bayer, Germany, 450 tpd08 1969 First slurry feed to pyrite roaster, Gold Fields, South Africa, 2 x 125 tpd09 1971 First partial roaster for copper ore, Noranda, Canada, 900 tpd10 1973 First 123 m2 zinc roaster, Pasminco, Australia, 800 tpd11 1994 Largest coarse pyrite roaster, Wengfu, China, 2 x 1,200 tpd12 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd13 1999 Largest zinc roaster, Asturiana de Zinc SA, Spain, 1,000 tpd14 2004 Largest pyrite concentrate roaster, Tongling, China, 1,130 tpd15 2005 Ni chloride pyrohydrolysis roaster, Goro Nickel, New Caledonia, 3 x 380 tpd

Circulating fluidized bed16 1959 First laboratory CFB plant at Metallgesellschaft, Germany, 0.5 tpd17 1961 First pilot plant for alumina calcination, VAW Lünen, Germany, 24 tpd18 1968 First industrial alumina calciner, VAW Lünen, Germany, 500 tpd19 1973 First laboratory tests for iron ore reduction using CFB technology, R&D Center, Germany20 1979 Signifi cant capacity increase of alumina calciners, Interalumina, Venezuela, 3 x 1,400 tpd21 1982 First coal combustion plant, VAW Lünen, Germany, 84 MW22 1987 First gold ore roasting plant, KCGM, Australia, 575 tpd23 1990 First alumina calciner with hydrate bypass, Worsley Alumina, Australia, 1,850 tpd24 1991 Circodust demonstration plant, Thyssen, Germany, 120 tpd25 1992 Largest roaster for gold ore, Newmont, USA, 2 x 3,800 tpd26 1993 Largest CFB (11.5 x 14.7 m) based power plant, Soprolif, France, 650 MW27 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd28 2001 Oxidizing ilmenite roaster, Iscor, South Africa, 1,000 tpd29 2002 Ore preheater, HIsmelt Corporation, Australia, 4,000 tpd30 2003 Signifi cant capacity increase of alumina calciners, Alunorte, Brazil, 2 x 3,300 tpd 31 2005 Reducing ilmenite roaster, Kenmare Resources plc, Mozambique, 1,200 tpd32 2005 First preassembled module supply of alumina calciners, Alcan Gove, Australia, 2 x 3,500 tpd

Flash reactor33 1985 Flash reactor for high temperature alumina production, VAW Schwandorf, Germany, 250 tpd34 1993 Flash reactor for ilmenite preheating, Namakwa Sands, South Africa, 625 tpd35 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd

Annular fluidized bed36 1992 Waste heat boiler pilot plant, 1 tpd37 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd38 2002 Ore preheater, HIsmelt Corporation, Australia, 4,000 tpd39 2005 Reducing ilmenite roaster, Kenmare Resources plc, Mozambique, 1,200 tpd

Development in the Lurgi and Outotec companies, indicating the year of order.

Milestones in fluidized bed development


References

Bubbling fluidized bedZinc roasters 74Pyrite, copper, gold, nickel

concentrate roasters 190

Total 264

Circulating fluidized bedAlumina calcining plants 51Power plants* 82Gold ore roasting plants 5Sulphur adsorption 16Calcining of clay/lime 3 Fluorine adsorption 10Coal based reduction (Elred) 1Gas based reduction (Circored) 1Ore preheating (Circoheat) 1Circodust (demonstration plant) 1AlF3 synthesis (demonstration) 1

Total 172

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Flash reactorsIlmenite preheating 2Circored, Trinidad 1

Total 3

Annular fluidized bedBoiler pilot plant 1Circored, Trinidad 1Circoheat, Kwinana 1Ilmenite roaster, Mozambique 1

Total 4

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Numbers refer to the development stages of the list of milestones.

* No longer part of Outotec's offering

006 More out of ore!006 More out of ore!

FundamentalsFluidization systems are ideal for the treatment of fine grained materials. For processing ultra

fine materials, Outotec has developed and patented a microgranulation process. The treatment

of oversized material has to be evaluated depending on its behavior during processing.

Important design criteria

Particle size and densityDecrepitation behaviourRetention timeProcess temperatureProcess energy

requirementProduction rateDemand on product quality

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Fluidized bed phase diagram

The so-called Reh* diagram illustrates the different phase behavior of gas-solids interactions. The yellow region represents the fi xed bed operating domain. The blue region indicates the domain of the bubbling fl uidized bed where gravity and drag forces on the particles are in balance. The grey section represents the pneumatic transport domain. The orange triangular region represents the area of the circulating fl uidized bed. As the diagram is calculated for ideal spherical homogeneous particles it provides an indication only. However, coupled with experience from industrial plants the CFB operating range can be extended to area a of the diagram. This knowledge gained from operational experience is applied to the design of new plants and processes.

Flexibility in feed particle size

* Diagram developed by Prof. Dr.-Ing. Lothar Reh

Particle Reynolds Number

Pa

rti

cle

Fro

ud

e N

um

be

rf [

v², d

P]

ReP

G


AFB of ilmenite roaster, Kenmare Resources plc, Mozambique.

Application in exothermic and endothermic processes

Chemical reactions occurring between the solid particles and the fl uidi-zation gas can either be endothermic or exothermic. Endothermic pro-cesses require energy input, provided either directly by the combustion of fuels or indirectly by the introduction of hot gases and/or preheated solids. All types of fl uidized bed systems can be used for both endother-mic and exothermic processes. A typical example of an exothermic pro-cess is the roasting of sulfi de ores. An example of an endothermic pro-cess is the calcination of alumina. Whether the process is endothermic or exothermic, tight control of temperature in a fl uidized bed reactor is more easily achievable. Fluidized bed based plants may include heat re-covery systems, which allow for the effective utilization of heat from off-gas and solids streams to decrease operating costs and emissions.

Use of 3D design tools

Outotec uses modern 3D design systems as planning and design tools also for fl uidized bed based plants.

The main advantages of such systems are:High planning reliabilityImproved drawing qualityReduced modifi cation work on siteShorter job execution timeReduction in overall cost

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Outotec's pursuit of new fluidized bed applications for customer needs is supported by experimental work in the

company's in-house R&D Center. For example development of neural networks, in-situ monitoring systems and

modern mathematical methods, including computational fl uid dynamics modeling, are key elements of research.

Scale up experienceWith Outotec's experience in many state-of-the-art fl uidized bed technologies the customers do not need a large scale demonstration plant as an expensive interim step. Examples of the scale up fi gures:

Process, year From pilot plant size To industrial plant size Scale up factorAlumina calcination, 1970 D=1,000 mm/24 tpd D=3,600 mm/500 tpd 1:20Coal combustion, 1982 D=360 mm/20 kg/h D=5,000 mm/500 tpd 1:1,000Gold ore roasting, 1990 D=200 mm/22 kg/h D=3,800 mm/2,000 tpd 1:4,000Circored, 1999 D=200 mm/8 kg/h D=5,000 mm/1,500 tpd 1:3,500

R&D and scale up competence

Outotec has developed theoreticalmodels of fl uidized bed systems and specialist scale up know-how over many decades. A unique set of pilot plants, suitable for processing of feeds in the range of 100 g batches up to 1,000 kg/h continuously, is available to develop and improve existing technologies for customer applications. These pilot plants are designed to be fl exible with respect to temperature, pressure, gas and fl uidization conditions and can beconfi gured either as single or multistage units. However, the data gained in laboratory scale fl uidized bed systems are not suffi cient to provide design and performance criteria of industrial plants without the experience of operating facilities.

700 mm Circofer demonstration plant, R&D Center, Germany.

Outotec's largest CFB based test facility is the Circofer demonstration plant at the R&D Center in Frankfurt. This plant is equipped with a 700 mm diameter CFB, recycle cyclone, integrated heat generator, char separator, magnetic separator, gas cleaning system, and all necessary ancillary equipment.


Applications Outotec's portfolio related to fl uidized bed technology can be classifi ed as follows.

Reducing conditions

Dearsenifying pyrite roastingCircored (gas based fi ne ore

reduction)Circofer (coal based fi ne ore

reduction)Circodust (processing of

steel plant residues)Circosmelt (prereduction

and smelting of ilmenite)Reducing ilmenite roastingHeat recovery by fl uidized

bed cooling and CircothermCircoheat (preheating of ore fi nes)Circochar (coal charring)Circonickel (prereduction

of lateritic nickel ore)Partial roasting of copper concentrate

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Oxidizing conditions

Alumina calciningRoasting of pyrite, copper and zinc

concentratesRoasting of gold oreOxidizing ilmenite roastingHeat recovery by fl uidized bed cooling and

CircothermCircoheat (preheating of ore fi nes)Circoroast (improved pyrite roasting system)

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Diagram for fl uidized bed applications.


Alumina calcinationThe fi rst industrial plant for the calcination of alumina was de-signed in 1968. Calcination is the fi nal stage of the Bayer process, in which bauxite is digested with caustic soda to fi rst extract and then precipitate a pure aluminum hydroxide (hydrate). The hydrate from the Bayer process is then calcined to alumina in a CFB. This step was earlier carried out in rotary kilns, but today all new capa-city is installed as fl uidized bed calciners.

CFB calcination process

The CFB calciner uses a two-stage venturi preheating system to recover the waste gas heat by preheating and de-watering the hydrate. Final calcination to alumina (Al2O3) is accomplished in the CFB reactor in which the energy is provided by direct combustion of fuel (oil or gas).The energy of the hot alumina is recovered to the incoming air in a multistage cooling system including cyclones and a fl uidized bed alumina cooler.

Some energy of the hot alumina is also used for direct calcination of incoming hydrate in a so-called ”hydrate by-pass”. This effi cient heat recovery system leads to an overall fuel energy consumption of less than 3 GJ/t of alumina for the calcination process. CFB calciners operate in a range from 900 to 1,000 °C depending on product quality demands.

Due to the homogeneous temperature in the CFB reactor, product qualitiesregarding specifi c surface area, losson ignition and alpha content in the alumina can fulfi ll the demands of today’s aluminium smelters. We have installed more than 50 CFB calciner units worldwide, which represents approximately one third of the world's production of smelter grade alumina.

Alumina calcination in the CFB.

Outotec's preassembled module (PAM) technology reduces capital cost and meets the challenges of plant construction in remote areas. The fi rst PAM delivery of two large calciners took place in 2006 to the Northern Territory in Australia. The calcining units were preassembled in South East Asia and transported by ship to Alcan's Gove operation.

3,500 tpd preassembled calciner module being delivered to Alcan Gove, Australia.

Hydrate

Fuel

Secondary airPrimary air

Cooling water

Preheating stage I

Preheating stage II

CFBreactor

Calcining stage

Cooling stage I Cooling stage II

Cooling water

Alumina

Fluidized bed cooler

Hydratebypass

Electrostatic precipitator

Waste gas



Roasting of sulfide ores

Gold ore roasting in the CFB.

Pyrite roasting in the FB

The optimum reactor for roasting of extremely fi ne fl otation concentrates of copper, pyrite and zinc is a highly stable FB. These reactors, charac-terized by relatively low fl uidization velocities, are well suited to treat such fi ne materials with grain sizes down to approximately 20 microns. The established concept of a roast-ing plant consists of a FB roaster, waste heat boiler, gas cleaning and calcine handling systems. Dry feed throughput rates of over 350,000 tpa per unit are achievable. The generated SO2 gas is recovered in a dedicated sulfuric acid plant. Pyrite roasting plant, ETI Holding, Turkey.

Gold ore roasting in the CFB

The CFB roaster is the appropriate reactor for special roasting pro-cesses or higher throughput rates of over one million tpa. An example is the gold refractory ore roasting process, where sulfur and carbon removal are essential to obtain ac-ceptable gold recoveries in the sub-sequent calcine leaching steps.

The roasting of sulfi de ores and concentrates is an important process step in the production of metals and chemicals. Sulfi des of iron, zinc, copper and other metals are oxidized with air at temperatures between 600 and 1,000 °C into metal oxides and gaseous sulfur dioxide. After cleaning and cooling, the sulfur dioxide contained in the roasting gas is further processed to sulfuric acid. Both FB and CFB types of fl uidized bed reactors are commonly used depending on the material properties and specifi c process requirements.

Gold ore

Pyrite

CFB orepreheater

Fuel

02 make up

Fuel

Fuel

Sulfur

CFBreactor

Waste heat boiler

Hot electrostaticprecipitator

Gas cleaning + sulfuric acid plant

Fluidized bed cooler

Quenchtank

Calcine slurry

Tailgas acid plant


Iron ore preheating and direct reduction Circored®

The drivers for the development of the Circored process in the early 1990s were the growing demand for direct reduced iron (DRI) coupled with the advantages of using iron ore fi nes directly in the steelmaking value chain, avoiding the agglomer-ation step. The Circored process, us-ing hydrogen as the only reductant, applies a two-stage CFB/FB reactor confi guration for reduction. In addi-tion, a single CFB is utilized for ore preheating and an AFB based fl ash heater is used to achieve the DRI briquetting temperature. The fi rst commercial Circored plant, with an annual capacity of 500,000 t of hot briquetted iron (HBI), commenced operations in 1999 in Trinidad.

Circored direct reduction in the CFB/FB.

Circoheat™

The fi rst commercial Circoheat plant, operating at HIsmelt's Kwinana facility in WesternAustralia is capable of preheating approxi-mately 1,300,000 tpa of iron ore fi nes to 850 °Cusing offgas from the HIsmelt smelt reduc-tion vessel (SRV). In the Circoheat process, wet iron ore fi nes are fed to a suspension preheater system where they are preheated to approximately 500 °C prior to introduction into a CFB reactor. Hot combustible SRV offgas at a temperature of 1,000 °C is introduced into the CFB reactor via an AFB system. The offgas is partially combusted with air to gen-erate the necessary energy for preheating the iron ore. Since the SRV gas is not completely combusted, a reduction of the iron ore to the magnetite/wuestite stage is achieved. The preheated material is subsequently pressurized in a lock hopper system and injected at high temperature into the SRV via a new pneumatic hot ore conveying system.

Ore preheater, HIsmelt Corporation, Australia.

Offgasscrubber

To thickener

SuspensionpreheaterIron

ore

CFBpreheater

Air

Preheating system

Feedsystem

Bucket elevator

Recyclecyclone

ReductionsystemCFB

stageI

FB stage II

Naturalgas

Fuel Air

Process gas heater

Fuel Air

Hydrogenmake up

Flashheater

DRI discharge

CycloneProduct handlingsystem

Hotbriquettingoption

HBI

Hotchargingoption

EAFSteel

Bleedas fuel

To thickener

Process gasscrubber

Multi-clone

Process gascompressor

Process gasheat exchanger

Fuel


Steam reforming


Latest developments

Circofer®

The Circofer process has been developed to reduce iron ore fi nes utilizing coal as reductant. Similar to the Circored process, Circofer uses a two-stage CFB/FB reactor confi guration to obtain a highly metallized product. A heat generator is integrated into the CFB prereduction circuit to provide the energy necessary for the endothermic reduction reaction by partially combusting the introduced coal with oxygen. The process operates at reduction temperatures of approximately 950 °C in a closed gas circuit without the production of export gas.

Circored plant, CAL, Trinidad.

Circofer CFB prereduction step for HIsmelt.

Based on the wealth of experience gained in the field of fluidization technology, Outotec is continuously working

on improving existing processes and developing new processes and applications to meet the demands of an

industry pursuing sustainable solutions.

Co

al

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Ch

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Stand pipe

Oredryer

Hot air

Coal crushing

Pneumaticcoal feeding

Multiclone Process gas scrubber

Stage I

Preheating

Stage II Reduction

CFBreactor

Heatgene-rator

Process gasheater

Air

Bleed gas


Charseparator

Hotinjection

Recyclechar

Prereducediron and char

HlsmeltSRV

Hotmetal

with 4% C

Slag

CoalOffgas

SteamHot air

Smelting

ThickenerCO2

CO2absorber


One possible application of Circofer is as a single stage prereduction step for the HIsmelt® process, replacingthe Circoheat ore preheater. This leads to a signifi cant increase in the throughput of the HIsmelt SRV.

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Circosmelt®

The combination of ilmenite prere-duction in a single stage Circofer CFB unit with an electric smelting furnace allows for the production of a high quality TiO2 slag and pig iron, resulting in signifi cant energy savings.

Circochar®

The CFB based Circochar process, a spin-off from the circofer development, produces metallurgical char and a valuable fuel gas from fi ne grained high volatile coals. The gas quality canbe adjusted to meet the requirements for power generation by adding steam or oxygen to the process.

Circoroast®

The next generation of sulfi de ore roasting processes will have an environmental and maintenance friendly reactor design. The compact combination of roaster reactor, recycle cyclone, waste heat boiler and fl uidized bed cooler provides maximum effi ciency in heat recovery and reduced investment and operating costs.

Clay calcination

Calcined clay can be mixed in a ratio of up to 40% with Portland cement to supplement production whilst maintaining quality. The calcination temperature for the clay is signifi cantly lower than the production of equivalent Portland cement leading to considerable energy savings. Using the CFB calcination process, organic and inorganic compounds are removed to achieve a homogenous high quality intermediate product for further downstream processing.


Go

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Ilm

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Pneumatictransport

Heatgene-rator

CFB

Stage I

Preheating

Stage II

Multiclone Venturi scrubber

Hotmagneticseparation


Processgas heater

O2

Dust

Gaslift

Recylechar

PrereducedIlmenite

CO2absorber

Steam

Offgas

Titania slag

AirPig iron

Smeltingfurnace

CO2Thickener

Circosmelt: Ilmenite preheating, prereduction and smelting.

More out of ore! 015 More out of ore! 015

Circotherm®

Where applications require inten-sive mixing between solids and hot dust laden gases, a special reactordesign is needed. Circotherm is ideally suited for the quenching of hot offgases with solids, as well as condensing vapors contained in offgas streams that are diffi cult to handle. The core system comprises an AFB with integrated heat reco-very systems and a solids recovery cyclone.

Circonickel

Outotec has developed a process

where the calcination and reduction

of lateritic nickel ores to the wues-

tite/metallic state is performed in

a combination of a CFB and a FB

system. Coal and natural gas can

be used as reductants. Through im-

proved process control of the prere-

duction, considerable energy savings

in smelting of lateric nickel ores to

ferro-nickel can be achieved. The

new process avoids the production

of excessive fi ne dust as currently

generated in existing production

plants. Furthermore, dust deposits

of existing plants can be processed

recovering its nickel content.

Circotherm pilot plant, R&D Center, Germany.

Copyright © 2007 Outotec Oyj. All rights reserved.Outotec and More out of ore! are registered trademarks of Outotec Oyj.

[email protected]

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Outotec, formerly Outokumpu Technology, is a worldwide technology

leader in minerals and metals processing, providing innovative and

environmentally sound solutions for a wide variety of customers in

minerals processing, iron and steel, aluminum and non-ferrous metals

industries. Outotec Oyj is listed on the Helsinki Stock Exchange.

Fluidization Detail

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