Oil series needle coke and coal series needle coke are two types of needle coke produced from different feedstocks and have distinct properties. The primary differences between the two are as follows:

1. Feedstock Source:

   - Oil Series Needle Coke: Oil series needle coke is derived from specific heavy petroleum feedstocks, such as decant oil or slurry oil, through a thermal cracking process in a coking unit. These feedstocks are obtained from crude oil refining.

   - Coal Series Needle Coke: Coal series needle coke, as the name suggests, is produced from coal tar pitch, a byproduct of coal coking. The raw material for coal series needle coke is obtained from coal conversion processes.

2. Carbon Content:

   - Oil Series Needle Coke: Oil series needle coke typically has a higher carbon content, often exceeding 97% or even higher. This high carbon purity makes it suitable for high-temperature applications.

   - Coal Series Needle Coke: Coal series needle coke may have a slightly lower carbon content compared to oil series needle coke, but it can still be of high quality and suitable for certain industrial applications.

3. Impurities:

   - Oil Series Needle Coke: Oil series needle coke generally has low levels of impurities like ash and sulfur due to its production from specific petroleum feedstocks.

   - Coal Series Needle Coke: Coal series needle coke may contain slightly higher levels of impurities, including sulfur and metals, due to its origin from coal tar pitch.

4. Crystal Structure:

   - Oil Series Needle Coke: Oil series needle coke typically has a well-aligned and distinct needle-like crystal structure, which is ideal for applications requiring high thermal conductivity and low coefficient of thermal expansion.

   - Coal Series Needle Coke: Coal series needle coke may have a less defined crystal structure compared to oil series needle coke, but it can still exhibit some needle-like properties.

5. Applications:

   - Oil Series Needle Coke: Oil series needle coke is primarily used in the production of graphite electrodes for electric arc furnaces (EAFs), anodes for aluminum smelting, and in certain specialty applications like nuclear and aerospace industries.

   - Coal Series Needle Coke: Coal series needle coke is used in various applications, including graphite electrodes for some specific EAF processes and other carbon and graphite products.

Both types of needle coke have their unique advantages and applications, and their suitability depends on the specific requirements of the industries they serve. The choice between oil series and coal series needle coke will depend on factors such as the end-use application, desired properties, availability, and cost considerations.