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Pelletizing

Pelletizing is the process of compressed or molding of product into the shape of a pellet. A large range of different products are pelletized including chemicals, iron ore, animal compound feed, and more.

Pelletizing of iron ore
Pelletizing of iron ore produces spheres of typically 8–18 mm (0.31–0.71 in) diameter. The process combines agglomeration and thermal treatment to convert the raw ore into pellets with characteristics appropriate for use in a blast furnace.

In case of iron ore which is transported over a large distance,the ore becomes powder due to friction. Therefore it is first sintered and then compressed into pellets.[citation needed]

Preparation of raw materials
Additional materials are added to the iron ore (pellet feed) to meet the requirements of the final pellets. This is done by placing the mixture in the pelletizer, which can hold different types of ores and additives, and mixing to adjust the chemical composition and the metallurgic properties of the pellets. In general, the following stages are included in this period of processing: concentration / separation, homogenization of the substance ratios, milling, classification, increasing thickness, homogenization of the pulp and filtering.

Formation of the raw pellets
The formation of raw iron ore pellets, also known as pelletizing, has the objective of producing pellets in an appropriate band of sizes and with mechanical properties high enough to maintain its usefulness during the stresses of transference, transport, and use. Both mechanical force and thermal processes are used to produce the correct pellet properties. From equipment point of view there two alternatives for industrial production of iron ore pellets: drum and pelletizing disk.

Thermal processing
In order to confer to the pellets high resistance metallurgic mechanics and appropriate characteristics, the pellets are subjected to thermal processing, which involves stages of drying, daily pay burn, burn, after-burn and cooling (in a cooling tower). The duration of each stage and the temperature that the pellets are subjected to have a strong influence on the final product quality.