In terms of raw material selection, coal or wood powder (fineness above 200 mesh) is usually adopted, combined with binders such as coal tar or lignosulfonate (accounting for 15%-30%). By mixing and stirring, the moisture content of the raw materials is controlled at 25%-35% to form a plastic paste. The core forming processes include two types: screw extrusion and hydraulic forming. The screw extruder continuously extrudes the material through the die holes at a pressure of 3-5 mpa, forming cylinders with diameters of 1-10mm. Hydraulic forming uses high-pressure molding at 20-50MPa and is suitable for manufacturing large-diameter (10-50mm) shaped products.
The formed wet green body needs to go through two stages of drying: first, remove the surface water at a low temperature of 80-120℃, and then deeply dry at 150-200℃ until the moisture content is less than 5%. The subsequent carbonization process is carried out in an oxygen-deficient environment at 600-800℃, reducing the volatile matter content to less than 10%. Finally, it is activated by steam at 900-1100℃ to form a well-developed pore structure (with a specific surface area of 800-1200m²/g). The pellet carbon produced by this process has a mechanical strength of over 90% and is widely used in fields such as VOCs adsorption and water treatment.
https://www.naturecarbon.com/coal-based-activated-carbon/activated-charcoal-pellets.html
