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Pelletizing

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

Pelletizing of animal feeds can result in pellets from 1.2mm (Shrimp feeds), through to 3-4mm (Poultry feeds) up to 8-10mm (Stock feeds). The Pelletizing of stockfeed is done with the pellet mill machinery, which is done in a feed mill.

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Pelletizing of Iron Ore

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 usefulnes during the stresses of transference, transport, and use. Both mechanical force and thermal processes are used to produce the correct pellet properties.

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.

Pelletizing of Animal Feeds

Preparation of raw ingredients

Feed ingredients are normally first hammered by a hammer mill to reduce the particle size of the ingredients. Ingredients are then batched, and then combined and mixed thoroughly by a feed mixer. Once the feed has been prepared to this stage the feed is ready to be pelletized.

Formation of the feed pellets

Pelletizing is done in a pellet mill, where feed is normally conditioned and thermal treated in the fitted conditioners of a pellet mill. The feed is then pushed through the holes and a pellet die and exit the pellet mill as pelleted feed.

After pelleting processes

After pelleting the pellets are cooled with a cooler to bring the temperature of the feed down. Other post pelleting applications include post-pelleting conditioning, sorting via a screen and maybe coating if required.