The raw materials for carbon refractories fall into two categories: carbon raw materials such as petroleum coke, pitch coke, metallurgical coke, anthracite, and natural graphite, and binders such as coal tar and coal tar pitch. The properties of carbon refractories depend largely on the properties of the carbon raw materials, making the characteristics and selection of these raw materials extremely important.
Petroleum coke is a high-purity coke produced by dry distillation of natural pitch, petroleum pitch, or heavy petroleum-based oils. It is an essential raw material for artificial graphite. Petroleum coke is currently produced using the delayed coking process. The properties of petroleum coke vary significantly, not only depending on the origin of the oil but also on the manufacturing method. Petroleum coke with a low sulfur content, a low linear expansion coefficient, and high mechanical strength is are excellent prerequisite for the production of carbon refractories.
Pitch coke is produced by dry distilling pitch in coking ovens such as copper coke ovens, honeycomb coke ovens, distillation drums, and delay towers. Pitch coke is primarily used as a raw material for artificial graphite and carbon refractories. Its performance is inferior to that of petroleum coke, so it is rarely used. Pitch coke is characterized by its low sulfur and vanadium content.
Metallurgical coke is produced by coking coal in ovens such as Koppers, Otto, and honeycomb coke ovens. Using dense, hard, and low-ash foundry coke as a raw material for carbon refractories produces products with strong wear resistance and excellent performance. However, its dimensional stability when heated is poor, making it a poor choice for products requiring specific thermal stability requirements.