What steps are required to make graphite from calcined petroleum coke？

To make graphite from calcined petroleum coke, a series of steps are required. These steps involve several processes, including preparation, mixing, forming, baking, and graphitization. Here is a detailed explanation of each step:

1. Preparation of Raw Materials:

   • Calcined Petroleum Coke: This is the primary raw material. Calcined petroleum coke is produced by heating green petroleum coke to remove volatile matter and moisture.
   • Binder Pitch: A binder, usually coal tar pitch, is used to bind the coke particles together.

2. Mixing:

   • The calcined petroleum coke is crushed and ground to a fine powder.
   • The powdered coke is then mixed with the binder pitch. The ratio of coke to pitch is carefully controlled to ensure the right consistency and properties of the final product.
   • The mixture is heated to a temperature where the pitch becomes soft and sticky, allowing it to coat the coke particles thoroughly.

3. Forming:

   • The hot mixture is then shaped into the desired form. This can be done using various methods such as extrusion, molding, or pressing.
   • The formed shapes are called "green bodies" or "green compacts."

4. Baking:

   • The green bodies are placed in a baking furnace and heated to temperatures between 800°C and 1200°C. This process is known as carbonization.
   • During baking, the binder pitch carbonizes, binding the coke particles together and forming a solid carbon structure.
   • The baking process also removes any remaining volatile matter.

5. Impregnation (Optional):

   • In some cases, the baked carbon bodies are impregnated with additional pitch to fill any pores and increase density.
   • The impregnated bodies are then rebaked to carbonize the additional pitch.

6. Graphitization:

   • The final step is graphitization, where the carbonized bodies are heated to extremely high temperatures, typically between 2500°C and 3000°C.
   • At these temperatures, the carbon atoms rearrange into a crystalline graphite structure.
   • The graphitization process significantly improves the electrical conductivity, thermal conductivity, and mechanical strength of the material.

7. Machining and Finishing:

   • After graphitization, the graphite bodies are machined to the desired dimensions and specifications.
   • Any surface defects are removed, and the final product is inspected for quality.

8. Quality Control:

   • Throughout the entire process, various quality control measures are implemented to ensure the final graphite product meets the required standards.
   • This includes testing for properties such as density, strength, electrical conductivity, and purity.

By following these steps, calcined petroleum coke can be transformed into high-quality graphite, which is used in a wide range of applications, including electrodes for electric arc furnaces, batteries, and various industrial processes.