The process flow of artificial graphite mainly includes the following steps: raw material preparation, kneading, molding, roasting, graphitization and post-processing.
Raw material preparation: The main raw materials of artificial graphite include petroleum coke, needle coke and coal tar. These raw materials need to be screened to remove unqualified small particles or impurities to ensure that the particle size meets the requirements.
Kneading: Mix the screened raw materials with a binder (such as coal tar) and mix them evenly by stirring. This process is similar to manually stirring clay, and the stirring speed and time need to be controlled to ensure that the raw materials and binders are fully integrated.
Molding: The kneaded material is extruded or molded to form the desired shape. The pressure and time during the molding process will affect the quality of the final product.
Calcination : The formed product needs to be calcined at high temperature, usually at 2500-3000℃, to carbonize the coal tar and form asphalt coke, which consolidates the carbonaceous aggregate and powder particles together to improve the mechanical strength and stability of the product.
Graphitization : The calcined product needs to be graphitized, usually at 2300-3000℃, to convert the amorphous chaotic layer structure of carbon into an ordered graphite crystalline structure. This process requires controlling the temperature curve to ensure that the graphite interlayer spacing reaches the ideal range (0.343-0.346nm).
Post-processing : The graphitized product may also need further processing, such as spheroidization, surface coating, surface treatment, doping modification and micro-expansion treatment, to improve its performance in specific applications