The size of iron ore required for smelting depends on the type of furnace used and the desired efficiency. Generally, iron ore is processed into specific sizes to optimize smelting performance. Here are the typical size requirements:
1. Blast Furnace (Most Common for Iron Smelting)
– Lump Ore: 10–30 mm (preferred for direct charging).
– Sinter Feed: <10 mm (must be agglomerated into sinter pellets before use).
– Pellet Feed: <0.15 mm (finely ground and pelletized before smelting).
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2. Direct Reduction Processes (e.g., MIDREX, HYL)
– Requires high-g
e pellets (8–16 mm) or lump ore (6–30 mm).
3. Electric Arc Furnace (EAF, mostly for scrap but can use DRI)
– Uses Direct Reduced Iron (DRI) pellets or briquettes (5–20 mm).
Why Size Matters?
– Smaller particles improve reaction rates but may cause gas flow issues in blast furnaces.
– Larger lumps ensure proper permeability but must not be too big to avoid incomplete reduction.
Ore Preparation Methods:
– Crushing & Screening – For lump ore.
– Agglomeration (Sintering/Pelletizing) – For fine ores (<10 mm).
For optimal smelting, most modern blast furnaces use a mix of lump ore, sinter, and pellets to balance efficiency and cost.