pelletizer

A pelletizer is a machine designed to convert bulk materials into small, uniform cylindrical pellets. Pelletizers are used across multiple industries, including plastics processing, wood and biomass fuel production, animal feed, and fertilizer manufacturing. They can produce pellets from a wide range of materials, with equipment and settings tailored to the specific feedstock and final application.

Most pelletizing processes share a common sequence. The material is first sized and sometimes conditioned with moisture, heat, or additives to improve plasticity and flow. It is then fed to a die or a set of dies where the material is compressed or extruded through small orifices. The extruded strands or filaments are cut to a desired length by a knife or cutter as they exit the die. The resulting pellets are typically cooled and screened to remove fines and to achieve uniform size.

Common pelletizer configurations include strand pelletizers, ring-die and flat-die pellet mills, and underwater or water-quenched pelletizers. Strand pelletizers are often used for plastics and polymers, producing continuous strands that are then cut. Underwater pelletizers force the material through the die while submerged in water to rapidly cool and pelletize. Ring-die and flat-die mills are widely used for biomass, wood pellets, and animal feed, chosen for throughput and pellet quality.

Key components commonly found in pelletizers are a feeding system (hopper and conveyor), a conditioning or extrusion system (die and rollers), a cutting mechanism, and a cooling and screening stage. Important performance factors include pellet size and shape, moisture content, density, durability, throughput, and wear resistance of the dies and rollers.