Guidelines for Selecting Pellet Plant Technology I. Cameron, M. Huerta, J. Bolen M. Okrutny, K. O’Leary
AusIMM, Iron Ore Conference , Perth WA | 13‐15 July 2015
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Introduction •
The availability of lump ore and sinter fines is declining; lower grade iron ore resources must be finely ground to upgrade Fe content to acceptable levels.
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Eventually, new investments in pelletizing capacity are required to bring Fe concentrates into the steelmaking value chain.
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The straight grate (SG) and grate kiln (GK) are the only two commercially proven processes.
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Hatch compared both technologies to help investors better understand how best to pelletize concentrates.
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Contents •
Iron Ore Pelletizing Technologies
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Plant Capacity
•
Fuel Options and Energy Consumption
•
Pellet Product Quality
•
Capex and Opex
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Environmental Performance
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Summary
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The Growth of Iron Ore Pelletizing Regional growth since 1950
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Iron ore pelletizing has grown since its origins in 1950’s and accelerated in recent times.
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With depletion of high quality DSOs and sinter fines, global pellet feed production will substantially increase.
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Pelletizing capacity will continue to grow to supply direct reduced iron plants and blast furnaces.
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Usage of pellet feed at sinter plants will increase.
World Pelletizing Capacity (Mtpa)
500 400 300
China Middle East Rest of Asia / Australia Europe CIS South America North America
200 100 0 1949 1968 1975 1982 1990 1998 2004 2010
Year
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Straight Grate (SG) and Grate Kiln (GK) The Straight Grate (SG) pelletizing process
The Grate Kiln (GK) pelletizing process
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New Emerging Technology: Circular Pelletizing Technology (CPT) Primetals Technologies’ Circular Pelletizing Technology (CPT)
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Alternative to SG and GK.
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Essentially a SG induration furnace arranged in a circle to reduce the plant footprint.
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Current plant sizes on offer 0.6 to 3.0 Mtpa.
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First plant under construction in India.
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Iron Ore Mineral Pelletized Pelletizing capacity by iron ore mineral World Pelletizing Capacity (Mtpa)
300
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The SG technology is proven for magnetite, hematite and mixed ores.
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The GK is proven for magnetite ores and mixtures of magnetite and hematite; less experience with hematite ores than the SG.
Other Ores Hematite Magnetite + Hematite Magnetite
250 200 150 100 50 0
SG
GK 00/2014
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Pellet Plant Capacity Increase Since 1960 Annual Capacity of Individual Pellet Lines (Mtpa)
9.0 8.0 7.0
SG Improvements GK Improvements SG/GK Improvements
Expert Systems
Deep Bed
Carbon Addition
4.0
Automation Systems
3.0
Cooler Recoup
2.0 1.0 1960
Advanced Process Control
Double Deck Roller Screen
6.0 5.0
1970
Mathematical Models
Hearth Layer Bin Separation
High Pressure Grinding Rolls Hyper‐ Activation
Reduced Air Leakage
Roller Screen
Fans with Variable Frequency Drives
Coal Fired Kiln
1980
1990
2000
2010
2020
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Fuel Options Ability of SG and GK to use various fuels Fuel
SG
GK
Gaseous Fuels
Liquid Fuels
Solid Fuels, such as coal Solid Carbon Addition to Hematite Concentrate
Limited
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Energy Consumption Thermal energy consumption for selected pellet plants Magnetite
Electricity consumption for process fans
GK SG
Magnetite
Technology
Typical (kWh/t)
Lowest Reported (kWh/t)
SG
20 - 25
13
GK
15 - 20
12
Mag ‐ Hem Mag ‐ Hem Magnetite Mag ‐ Hem Magnetite 0
200
400
600
800
1000
1200
Thermal Energy Consumption (MJ/t pellet)
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Pellet Product Quality •
Both SG and GK produce quality fired pellets for BF and DR applications.
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Fired pellet quality depends on ore type, end user demands, type and quality of fluxes and binders, balling technology, screening equipment, etc.
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The GK produces fired pellets with more uniform physical strength due to the nature of material flow in the rotary kiln that exposes all green pellets to the peak firing temperature.
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The SG generates less fines due to the absence of transfer points and little relative movement/abrasion between pellets and furnace parts.
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Both SG and GK report experience with organic binders; more data is needed to fully understand how best to use organic binder and produce top quality pellets. 00/2014
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Capex and Opex Comparison Capex Comparison – SG and GK
Opex Comparison – SG and GK Cost Items
SG
GK
Iron Ore Concentrate
similar
similar
Additives/Binder
similar
similar
Fuel
▼
▲
Electricity
▲
▼
similar
similar
▼
▲
Other Consumables
similar
similar
Labour
similar
similar
▼
▲
similar
similar
Relative Capital Cost
100 80 60
Water
40
Refractory
20
Maintenance
0 Straight Grate
Grate Kiln
Overall
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Environmental Performance •
Air pollutants of concern are dust, SOx, NOx and greenhouse gases (GHG).
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Both technologies use ESPs or bag houses for dust control.
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Newer plants are considering de-S equipment to reduce emissions.
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The SG can utilize ultra low NOx burners in a separate combustion chamber with controlled atmosphere; this approach is not possible in the GK.
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Low NOx burners can be used in the GK, but the ultra low levels projected for the SG are probably not possible for the GK.
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GHG production, particularly CO2 is directly related to the type and amount of fossil fuel combusted and the calcination of fluxes.
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Overall Comparison – SG and GK Variable 1)
2)
3)
SG
GK
yes yes yes
limited use yes yes
yes yes
yes no
yes yes no high amount
yes yes yes limited use
Iron Ore Mineral a) Hematite b) Magnetite c) Hematite/Magnetite Mixture Unit Capacity a) 3-7 Mtpa b) 7-9 Mtpa Fuel Type a) Natural Gas b) Fuel Oil c) Pulverized Coal d) Carbon Addition to Hematite Ore Mix Legend:
Remarks GK is best suited for magnetite and magnetite/hematite mixtures while SG is suitable for all minerals.
GK has not demonstrated unit capacities beyond 7.0 Mtpy.
SG has not demonstrated operation with pulverized coal while GK can operate will all fuels. SG can operate with high amounts of carbon additions to hematite ore mixes whereas the use of GK for this application is limited.
Competitive advantage No advantage/disadvantage Disadvantage Technical constraint
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Overall Comparison – SG and GK Variable 4)
Thermal Energy Consumption
5) 6)
Electrical Energy Consumption Product Quality
7)
Fines Generation
SG
GK
slightly lower higher slightly lower
slightly higher lower slightly higher more fines limited use slightly lower similar slightly lower
less fines 8)
Organic Binder Use
9)
Capex
10) 11)
Opex Environmental Performance
yes slightly higher similar slightly higher Legend:
Remarks Slight advantage for SG. Advantage for GK due to smaller process fans. GK provides better fired pellet temperature uniformity. Advantage to SG due to lack of transfer points. In general, advantage to SG, although some have reported advantage to GK. Slight advantage for GK in process fan cost, no hearth layer return system and less building costs. Site specific. More potential to reduce NOx for the SG in a separate combustion chamber, otherwise no obvious advantage.
Competitive advantage No advantage/disadvantage Disadvantage Technical constraint
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Acknowledgements •
The authors are pleased to acknowledge the following contributors for their valuable input: – David Tucker – Jose Murilo Mourão – Miguel Sabanero – Urano Medeiros – Kelly Scott – Mike Walsh
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Thank You Ian Cameron Senior Director – Iron & Steel Phone +1-905-403-4052
[email protected]
For more information, please visit www.hatch.ca
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