The steel recycling and melting process uses a specialized piece of equipment called an electric arc furnace to melt and extract the metal. During the heating process, large graphite electrodes carry a lot of electricity and become incandescent. But what are graphite electrodes and how are they made?

Graphite Electrodes

Graphite electrodes are made from petroleum coke and needle coke, which are both types of carbon materials. If you are familiar with arc welding, you know that current is passed from the electrodes (rods) to the metal parts to be welded. The welding rod (made of materials such as steel or aluminum) may or may not contain a flux core. The friction of the current then heats the rod, melting it into the metal joint to form a strong weld.
In an electric arc furnace, however, the welding rod is much larger, but has the same basic principle. Large electrodes (made of carbon compounds) are available in many different sizes, depending on the needs of the steel shop facility.

Steps

Mixing and Crushing: The petroleum coke and needle coke are mixed together in a proportionate ratio and crushed to a fine powder.

Shaping: The powder is then shaped into the desired diameter and length of the electrode. This is usually done by extrusion or molding.

Baking: The shaped electrodes are baked in a furnace at a high temperature of around 2,000 degrees Celsius. This process is called calcination, which removes any volatile compounds and increases the density of the electrode.

Graphitization: After calcination, the electrodes are graphitized at a temperature of around 3,000 degrees Celsius. This process converts the amorphous carbon structure into a crystalline structure, increasing the strength and conductivity of the electrode.

Machining: Once the graphitization process is complete, the electrodes are machined to the required tolerances and surface finishes.

Quality Control: Finally, the electrodes are subjected to rigorous quality control tests to ensure that they meet the required specifications for use in various industrial applications.

Finished product

By baking the electrodes at 3000 degrees Celsius, they are transformed into graphite. In order to create a complete product, some mechanical processing is usually required (depending on the customer's specifications and needs).

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