Coal-based activated carbon is made from high-quality anthracite or bituminous coal, undergoing a series of physical and chemical treatments to produce a highly adsorbent carbon material. It is widely used in water treatment, air purification, chemical catalysis, and other fields. The production process primarily includes key steps such as raw material pretreatment, forming, carbonization, activation, and post-processing.
Raw material pretreatment is the first step in production. It involves crushing, screening, and drying the raw coal to ensure uniform particle size (typically below 200 mesh) and remove moisture and impurities to improve the efficiency of subsequent processes.
In the forming stage, coal powder is pressed into a compacted form by adding a binder (such as coal tar or lignin sulfonate). Common shapes include columns, granules, or powders. Controlling the forming pressure and temperature directly affects the mechanical strength and pore structure of the activated carbon.
Carbonization involves heating the coal compact to 400-600℃ in an airless environment to decompose organic matter and form a preliminary carbonaceous skeleton. This process requires a slow temperature increase to avoid cracking, while volatiles are removed, leaving behind the foundation of a porous structure.
Activation is the core step in imparting activated carbon with its high adsorption properties. Water vapor or carbon dioxide is typically used to react with the carbon at temperatures of 800-1000℃, etching a well-developed micropore and mesopore structure. Activation time and temperature directly influence key indicators such as specific surface area (which can reach 800-1500 m²/g) and iodine value.
Finally, post-processing includes acid and water washing to remove ash and impurities, followed by drying and screening to obtain the finished product. Some high-end products also require impregnation modification to enhance performance for specific applications.
The production process for coal-based activated carbon requires strict control of parameters at each stage to ensure that its adsorption properties, strength, and purity meet the requirements of different applications. With increasing environmental protection requirements, clean production and resource recovery technologies are also being continuously optimized.