How to choose high quality petroleum coke?

The quality of petroleum coke depends largely on the nature of the raw material and its processing conditions. The main quality indicators are:

1. Purity refers to the content of sulfur and ash, etc. in petroleum coke. High sulfur coke will lead to gas expansion of products during graphitization, causing cracks in carbon products. High ash content will hinder the crystallization of the structure and affect the performance of the carbon products.

2. Crystallinity refers to the structure of the coke and the size of the intermediate phase blobs. The coke formed by small spheres has a porous structure like sponge, and the coke formed by large spheres has a dense structure like fiber or needle, and its quality is superior to that of sponge coke. In the quality index, true density roughly represents this performance, and high true density indicates good crystallinity.

3. Thermal shock resistance refers to the rupture resistance of the coke products when they are subjected to the thermal shock of sudden rise to high temperature or sharp cooling from high temperature. Needle coke products have good resistance to thermal shock, and thus have high value for use. The coefficient of thermal expansion represents this property. The lower the coefficient of thermal expansion, the better the resistance to thermal shock.

4. Granularity reacts to the relative content of powdered coke and lumpy granular coke (available coke) contained in the coke. Most of the powder coke is crushed by extrusion and friction and other mechanical effects in the process of removing coke and storage and transportation, so the amount of size is also an expression of mechanical strength. Raw coke can be prevented from breaking after calcination to mature coke. Coke with more granular coke and less powder coke has a higher use value.