Fluidization Detail

Fluidization technology

Innovative solutions for fine grained materials n n n n n n

Calcination Roasting Reduction Gasification Combustion Decarbonization

n n n n n n

Oxidation Gas cleaning Heat recovery Cooling Drying Spray granulation

00 More out of ore!

Alumina CFB calciner, Worsley Alumina, Australia.

50 years of technology evolution For over 50 years Outotec has developed and commercial ized fluidized bed technology for a variety of industrial applications.

Early FB pyrite roasting plant, BASF, Germany.

Lurgi constructed the first reactor for roasting of sulfur bearing materials in 1950, based on the principles of fluidized bed technology. The new system was quickly adopted by industry; multiple hearth fur naces and rotary kilns were increasingly replaced by fluidized bed roasters, thereby ensuring enhanced product quality and significantly reduced plant emissions. Fluidized bed combined with efficient heat recovery and of fgas 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 t han 60 plants to date. Significant process improvements have been achieved b y using fluidization technology, for example in the production of alumina. The circulating fluidized bed (CFB) was developed over 40 years ago for the high temperature treatment of fine and light particles. A whole variet y of other CFB applications followed, with more than 170 industrial plants worldwide. The CF B has been successfully applied for coal combustion, roasting of gold containing ores, direct r eduction of iron ore fines and other uses. In the early 1990s we introduced a new variation of fluidization technology, the annular fluidized bed (AFB). With the aquisition of Lurgi Metallurgie in 001, Lurgi's fluidization know-how was transferred to Outotec. The development of fluidized bed technology continues and we are working on new processes utilizing solid mixtures, such as ore and coal, with different properties for industrial application.

More out of ore! 003

Fluidized bed types Bubbling fluidized bed (FB)

Circulating fluidized bed (CFB)

Transport or flash reactor (FR)

The classical bubbling fluidized 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 fluidized bed, typically characterized by a defined 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 defined solids residence time distribution. The mean solid velocity is close to zero with the slip velocity almost identical to the gas velocit y.

At higher gas velocities the slip velocity increases and the fluidized bed changes it s behavior. The defined boiling surface disappears with the expansion of the fluidized solids. The fluidization gas has enough energy to entrain solids particles. The entrained particles are separated from the gas by a cyclone and recirculated via an external loop back into the fluidized bed reactor. In addition an internal recirculation of the solids in the fluidized bed reactor takes place. Both internal and external circulation results in a homogenous temperature distribution in the CFB system.

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 considerably decreased compared to the circulating fluidized 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 sufficient.

y t i c o l e V

"Slip velocity"

Gas Solids

Annular fluidized bed (AFB ®)

This new type of fluidized bed improves the introduction and mixing of hot dust laden process gases. These gases enter the reactor through a large central noz zle, wi th additional fluidization gas introduced through an annula r 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. Furt her advantages are excellent process control and improved mass tr ansfer conditions. The AFB can be combined with any other fluidized bed type.

Increasing solids density

Increasing expansion

004 More out of ore!

Milestones in fluidized bed development Bubbling fluidized bed 01 1950 First pyrite roaster, BASF, Germany, 40 tpd 0 1956 First zinc roaster, Nikon Kogyo, Japan, 40 tpd 03 1958 Sulfate decomposition roaster, Imperial Smelting, UK, 140 tpd 04 196 First sulfating roaster for copper ores, Chambishi, Zambia, 118 tpd 05 1965 Hydrogen based reduction plant for NiO, Inco, Canada, 150 tpd 06 1965 First single-stage dearsenifying pyrite roaster, Boliden, Sweden, 50 tpd 07 1968 First double-stage dearsenifying pyrite roaster, Bayer, Germany, 450 tpd 08 1969 First slurry feed to pyrite roaster, Gold Fields, South Africa,  x 15 tpd 09 1971 First partial roaster for copper ore, Noranda, Canada, 900 tpd 10 197 First 1 m zinc roaster, Pasminco, Australia, 800 tpd 11 1994 Largest coarse pyrite roaster, Wengfu, China,  x 1,00 tpd 1 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd 13 1999 Largest zinc roaster, Asturiana de Zinc SA, Spain, 1,000 tpd 14 00 4 Largest pyrite concentrate roaster, Tongling, China, 1,10 tpd 15 005 Ni chloride pyrohydrolysis roaster, Goro Nickel, New Caledonia,  x 80 tpd Circulating fluidized bed 16 1959 First laboratory CFB plant at Metallgesellschaft, Germany, 0.5 tpd 17 1961 First pilot plant for alumina calcinati on, VAW Lünen, German y, 4 tpd 18 1968 First industrial alumina calciner, VAW Lünen, Germany, 500 tpd 19 197 First laborator y tests for iron ore reduction using CFB technology, R&D Center, Germany 0 1979 Significant capacity increase of alumina calciners, Interalumina, Venezuela,  x 1,400 tpd 1 198 First coal combustion plant, VAW Lünen, Germany, 84 MW  1987 First gold ore roasting plant, KCGM, Australia, 575 tpd 3 1990 First alumina calciner with hydrate bypass, Worsley Alumina, Australia, 1,850 tpd 4 1991 Circodust demonstration plant, Thyssen, Germany, 10 tpd 5 199 Largest roaster for gold ore, Newmont, USA,  x ,800 tpd 6 199 Largest CFB (11.5 x 14.7 m) based power plant, Soprolif, France, 650 MW 7 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd 8 001 Oxidizing ilmenite roaster, Iscor, South Africa, 1,000 tpd 9 00 Ore preheater, HIsmelt Corporation, Australia, 4,000 tpd 30 00  Significant capacity increase of alumina calciners, Alunorte, Brazil,  x ,00 tpd 31 005 Reducing ilmenite roaster, Kenmare Resources plc, Mozambique, 1,00 tpd 3 005 First preassembled module supply of alumina calciners, Alcan Gove, Australia,  x ,500 tpd Flash reactor 33 1985 Flash reactor for high temperature alumina production, VAW Schwandorf, Germany, 50 tpd 34 199 Flash reactor for ilmenite preheating, Namakwa Sands, South Africa, 65 tpd 35 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd Annular fluidized bed 36 199 Waste heat boiler pilot plant, 1 tpd 37 1996 Circored direct reduction plant, CAL, Trinidad, 1,500 tpd 38 00 Ore preheater, HIsmelt Corporation, Australia, 4,000 tpd 39 005 Reducing ilmenite roaster, Kenmare Resources plc, Mozambique, 1,00 tpd

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


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

References Flash reactors

Bubbling fluidized bed n n

Zinc roasters Pyrite, copper, gold, nickel concentrate roasters

74

n

190 Total

n n n n n n n n n n

Alumina calcining plants Power plants* Gold ore roasting plants Sulphur adsorption Calcining of clay/lime Fluorine adsorption Coal based reduction (Elred) Gas based reduction (Circored) Ore preheating (Circoheat) Circodust (demonstration plant) AlF  synthesis (demonstration) Total

Ilmenite preheating Circored, Trinidad

 1 Total

3

64

Circulating fluidized bed n

n

51 8 5 16  10 1 1 1 1 1 17

Annular fluidized bed n Boiler pilot plant n Circored, Trinidad n Circoheat, Kwinana n Ilmenite roaster, Mozambique Total

* No longer part of Outotec's offering

1 1 1 1 4


Fundamentals Fluidization 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.

Flexibility in feed particle size

Fluidized bed phase diagram

The so-called Reh* diagram illustrates the different phase behavior of gas-solids interactions. The yellow region represents the fixed bed operating domain. The blue region indicates the domain of the bubbling fluidized 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 fluidized 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.

] P

d , ² G v [ f

Important design criteria n n n n n

n n

Particle size and density Decrepitation behaviour Retention time Process temperature Process energy requirement Production rate Demand on product quality

r e b m u N e d u o r F e l c i t r a P

Particle Reynolds Number

* Diagram developed b y Prof. Dr.-Ing. Lothar Reh

Re P


Application in exothermic and endothermic processes

Chemical reactions occurring between the solid p articles and the fluidization gas can either be endothermic or exothermic. Endothermic processes require energy input, prov ided either directly by the combustion of fuels or indirectly by the introduction of hot gases and /or preheated solids. All ty pes of fluidized bed systems can be used for both endothermic and exothermic processes. A typical example of an exothermic process is the roasting of sulfide ore s. An example of an endothermic process is the c alcination of alumina. Whether the process is endothermic or exothermic, tight control of temperature in a fluidized bed reactor is more easily achievable. Fluidized bed based plants may include heat recovery sys tems, which allow for the effective utilization of heat from of fgas and solids streams to decrease operating costs and emissions.

Use of 3D design tools

Outotec uses modern D design systems as planning and design tools also for fluidized bed based plants. The main advantages of such systems are: High planning reliability Improved drawing quality Reduced modification work on site Shorter job execution time Reduction in overall cost n n n n n

AFB of ilmenite roaster, Kenmare Resources plc, Mozambique.


R&D and scale up competence 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 fluid dynamic s modeling, are key elements of research.

Outotec has developed theoretical models of fluidized 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 flexible with respect to temperature, pressure, gas and fluidization conditions and can be configured either as single or multistage units. However, the data gained in laboratory sc ale fluidized bed systems are not sufficient to provide design and performance criteria of industrial plants without the experience of operating facilities.

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, rec ycle cyclone, integrated heat generator, char separator, magnetic separator, gas cleaning system, and all necessary ancillar y equipment.

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

Scale up experience With Outotec's experience in many state-of-the-art fluidized b ed technologies the customers do not need a large scale demonstration plant as an expensive interim step. Examples of the scale up figures: Process, year

From pilot plant size

To industrial plant size

Scale up factor

Alumina calcination, 1970 Coal combustion, 198 Gold ore roasting, 1990 Circored, 1999

D=1,000 mm/4 tpd D=60 mm/0 kg/h D=00 mm/ kg/h D=00 mm/8 kg/h

D=,600 mm/500 tpd D=5,000 mm/500 tpd D=,800 mm/,000 tpd D=5,000 mm/1,500 tpd

1:0 1:1,000 1:4,000 1:,500


Applications Outotec's portfolio related to fluidized bed technology can be clas sified as follows.

Diagram for fluidized bed applications.

Reducing conditions n n

n

n

n

n n

n n n

n

Dearsenifying pyrite roasting Circored (gas based fine ore reduction) Circofer (coal based fine ore reduction) Circodust (processing of steel plant residues) Circosmelt (prereduction and smelting of ilmenite) Reducing ilmenite roasting Heat recovery by fluidized bed cooling and Circotherm Circoheat (preheating of ore fines) Circochar (coal charring) Circonickel (prereduction of lateritic nickel ore) Partial roasting of copper concentrate

Oxidizing conditions n n

n n n

n n

Alumina calcining Roasting of pyrite, copper and zinc concentrates Roasting of gold ore Oxidizing ilmenite roasting Heat recovery b y fluidized bed cooling and Circotherm Circoheat (preheating of ore fines) Circoroast (improved pyrite roasting system)


Alumina calcination The first industrial plant for the calcination of alumina was designed in 1968. Calcination is the final stage of the Bayer process, in which bauxite is digested with caustic soda to first 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 capacity is installed as fluidized bed calciners.

Preheating stage I

Electrostatic precipitator Waste gas

Hydrate

Preheating stage II

Cooling stage I

Cooling stage II

CFB reactor Hydrate bypass

Cooling water Alumina

Calcining stage Fuel

Fluidized bed cooler

Secondary air Primary air Cooling water

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 (Al 2 O 3 ) is accomplished in the CFB reactor in which the energy is provided by direct combustion of f uel (oil or gas). The energy of the hot alumina is recovered to the incoming air in a multistage cooling system including cyclones and a fluidized bed alumina cooler.

Alumina calcination in the CFB.

Some energy of the hot alumina is also used for direct calcination of incoming hydrate in a so-called ”hydrate by-pass”. This ef ficient heat recovery system leads to an overall fuel energy consumption of less than  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 qualities regarding specific surface area, loss on ignition and alpha content in the alumina can fulfill 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.

Outotec's preassembled module (PAM) technology reduces capital cost and meets the challenges of plant construction in remote areas. The first PAM delivery of two lar ge calciners took place in 006 to the Northern Territory in Australia. The calcining units were preassembled in South East Asia and transported b y ship to Alcan's Gove operation.

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



Roasting of sulfide ores The roasting of sulfide ores and concentrates is an impor tant process step in the product ion of metals and chemicals. Sulfides 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 pro cessed to sulfuric acid. Both FB and CFB t ypes of fluidized bed reactors are commonly used depending on the material properties and specific process requirements. Pyrite roasting in the FB

The optimum reactor for roasting of extremely fine flotation concentrates of copper, pyrite and zinc is a highly stable FB. These reactors, characterized by relatively low fluidization velocities, are well suited to treat such fine materials with grain sizes down to approximately 0 microns. The established concept of a roasting plant consists of a FB roaster, waste heat boiler, gas cleaning and calcine handling systems. Dry feed throughput rates of over 50,000 tpa per unit are achievable. The generated SO 2 gas is recovered in a dedicated sulfuric acid plant.

Pyrite roasting plant, ETI Holding, Turkey.

Gold ore roasting in the CFB.

Gold ore roasting in the CFB Waste heat boiler Gold ore

CFB ore preheater

CFB reactor

Hot electrostatic precipitator

Gas cleaning + sulfuric acid plant

Pyrite

Sulfur

Fluidized bed cooler

Fuel Quench tank

Fuel

02 make up Fuel

Calcine slurry

Tailgas acid plant

The CFB roaster is the appropriate reactor for special roasting processes 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 acceptable gold recoveries in the subsequent calcine leaching steps.

01 More out of ore!

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 fines directly in the steelmaking value chain, avoiding the agglomeration step. The Circored process, using hydrogen as the only reductant, applies a two-stage CFB/FB reactor configuration for reduction. In addition, a single CFB is utilized for ore preheating and an AFB based flash heater is used to achieve the DRI briquetting temperature. The first commercial Circored plant, with an annual capacity of 500,00 0 t of hot briquetted iron (HBI), commenced operations in 1999 in Trinidad.

Recycle cyclone

Offgas scrubber

Process gas compressor

Reduction CFB system stage I

To thickener Iron ore

Process gas heat exchanger

Suspension preheater

Multiclone

Feed system

To thickener Bleed as fuel FB stage II

CFB preheater

Cyclone Product handling DRI system discharge

Fuel Air

Process gas scrubber

Bucket elevator

Flash heater

Natural gas

Preheating system

Steam reforming

Hydrogen make up

Hot briquetting option

Fuel Air Process gas heater

HBI

Hot charging option

EAF Steel

Fuel Air

Circored direct reduction in the CFB/FB.

Ore preheater, HIsmelt Corporation, Australia.

Circoheat™

The first commercial Circoheat plant, operating at HIsmelt's Kwinana facilit y in Western Australia is capable of preheating approximately 1,00,000 tpa of iron ore fines to 850 °C using offgas from the HIsmelt smelt reduction vessel (SRV). In the Circoheat process, wet iron ore fines 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 s ystem. The offgas is par tially combusted with air to generate the necessary energy for preheating the iron ore. Since the SR V 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.



Latest developments Based on the wealth of exper ience gained in the field of fluidization technol ogy, Outotec is continuously working on improving existing processes and developing new processes and applications to meet the demands of an industry pursuing sustainable solutions.

Circofer®

The Circofer process has been developed to reduce iron ore fines utilizing coal as reductant. Similar to the Circored process, Circofer uses a two-stage CFB/FB reactor configuration 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. l a o C

e t e i r m o o n r l a o o h D r I C

Multiclone

Process gas scrubber

Stand pipe

Stage I

CO Preheating

Ore dryer

Stage II

Hot air Coal crushing

Thickener Smelting

Reduction

Prereduced CFB iron and Recycle reactor char char

Pneumatic coal feeding

CO2 absorber Steam

Hot air

Offgas Coal

Hot injection

Heat generator

Slag Char separator

O

Hlsmelt SRV

Hot metal with 4% C

Process gas compressor

Process gas heater

Bleed gas Air

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


Circosmelt®

The combination of ilmenite prereduction in a single stage Circofer CFB unit with an electric smelting furnace allows for the production of a high quality TiO  slag and pig iron, resulting in significant energy savings.

e t i n l r e a a o h l m G C I

Multiclone

Venturi scrubber

Stage I Hot Thickener magnetic CO2 separation

Preheating Dust Stage II Gas lift

CO

absorber

Prereduced Steam Ilmenite Recyle char

CFB

Process gas

Offgas compressor

Circochar®

Pneumatic transport O

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

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

Heat generator Smelting furnace

Process gas heater Pig iron

Circosmelt: Ilmenite preheating, prereduction and smelting.

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 significantly 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.

Titania slag

Air


Circotherm®

Where applications require intensive mixing between solids and hot dust laden gases, a special reactor design 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 difficult to handle. The core system comprises an AFB with integrated heat recovery systems and a solids recovery cyclone. Circonickel

Outotec has developed a process where the calcination and reduction of lateritic nickel ores to the wuestite/metallic state is performed in a combination of a CFB and a FB system. Coal and natural gas can be used as reductants. Through improved process control of the prereduction, considerable energy savings in smelting of lateric nickel ores to ferro-nickel can be achieved. The new process avoids the production of excessive fine 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.

7 0 0 2 y a M . d n a l n i F , i k n i s l e H , s i r b i L / a t n i P . N E 5 5 0 3

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.

[email protected] www.outotec.com

Copyright © 007 Outotec Oyj. All rights reserved. Outotec and More out of ore! are registered trademarks of Outotec Oyj.

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