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How are iron ore pellets made from concentrated iron ore?
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iron processing
Iron ore is one of the most abundant elements on Earth, and one of its primary uses is in the production of steel. When combined with carbon, iron changes character completely and becomes the alloy steel.
To produce iron ore pellets from concentrated iron ore, the material undergoes a process called pelletizing. First, moistened concentrates are fed into a rotating drum or an inclined disc. The tumbling action within this equipment forms soft, spherical agglomerates known as green balls.1
These green balls are subsequently dried and hardened by firing in air at temperatures ranging from 1,250° to 1,340° C (2,300° to 2,440° F), followed by a slow cooling process. This hardening can be achieved through several methods:1
- Traveling-grate process: Pellets are carried through successive sections of equipment where they are dried, preheated, fired, and cooled.1
- Grate-kiln system: This combines a horizontal traveling grate with a rotating kiln and a cooler, allowing the drying, firing, and cooling stages to be performed separately.1
- Shaft furnace: An older method where the charge moves downward by gravity and is heated by a counterflow of hot combustion gases.1
The resulting finished pellets are typically 10 to 15 millimetres in diameter, providing an ideal, evenly sized charge for the blast furnace.12