inarea in iron ore pelletisation

Iron Ore Pelletization (Pelletisation) Process Overview

Iron ore pelletization is a process that converts fine iron ore concentrate into spherical pellets (typically 8–16 mm in diameter) suitable for use in blast furnaces or direct reduction steelmaking. The process enhances the efficiency of iron production by improving handling, reducing dust, and optimizing metallurgical performance.

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Key Steps in Iron Ore Pelletization:

1. Ore Preparation:
– Crushing & Grinding: Low-grade iron ore is crushed and ground to liberate iron oxide particles.
– Beneficiation: Techniques like magnetic separation or flotation remove impurities (e.g., silica, alumina).
– Filtering: The concentrate is dewatered to achieve ~9% moisture content.

2. Mixing & Binder Addition:
– Bentonite clay (0.5–2%) is added as a binder to improve pellet strength.
– Other additives (limestone, dolomite) may be included for fluxing properties.

3. Ball Formation (Green Pellets):
– The mixture is fed into a disc pelletizer or drum pelletizer, where rolling action forms wet (“green”) pellets.
– Water spray controls size and uniformity.

4. Drying & Preheating:
– Green pellets are dried (~105°C) to prevent cracking during firing.
– Preheating (~900–1100°C) oxidizes magnetite (Fe₃O₄) to hematite (Fe₂O₃) and removes volatiles.

5. Induration (High-Temperature Firing):
– Pellets are fired at 1250–1350°C in a traveling grate or rotary kiln.
– This sinters the particles, creating strong, porous pellets with high iron content (>65% Fe).

6. Cooling & Screening:
– Pellets are cooled gradually to avoid thermal stress.
– Oversized/fines are recycled; product pellets are shipped.

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Advantages of Pelletization:

• Improved blast furnace efficiency (better permeability vs. lump ore/sinter).
• Reduced emissions (lower fines/dust).
• Enables use of low-grade ores through beneficiation.
• Consistent size/chemistry for uniform smelting.

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Pellet Types:

1. Blast Furnace Pellets: High hematite content (~65% Fe), acidic/neutral.
2. Direct Reduction Pellets: High purity (>67% Fe), low silica/alumina for DRI processes.

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Challenges:

• Energy-intensive induration (~4–6 GJ/ton pellets).
• Binder cost (bentonite adds silica; organic alternatives are being researched).
• Environmental concerns (CO₂ emissions from firing).

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Industry Trends:

• Shift toward hydrogen-based reduction (H₂-DRI) favors high-grade pellets.
• Carbon capture/utilization in pellet plants.
• Use of alternative binders (e.g., organic polymers).

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