Important role of needle coke | Petroleum coke

Petroleum coke is a product obtained by distilling crude oil to separate light and heavy oil, and then thermally cracking the heavy oil. From the appearance, the coke is black lumps of irregular shape and size (or Particles), with metallic luster, coke particles have a porous structure, the main element is carbon, accounting for more than 80wt%, and the rest are hydrogen, oxygen, nitrogen, sulfur and metal elements. Petroleum coke has its unique physical, chemical and mechanical properties. It is the non-volatile carbon of the heating part. The Franli factory took advantage of its high calorific value.

Classification of petroleum coke

The form of petroleum coke varies with the process, operating conditions and feed properties. Petroleum coke produced from petroleum coke factories is called green coke, which contains some volatile components of uncarbonized hydrocarbons. Green coke can be used as fuel-grade petroleum coke. If it is used as an anode for aluminum smelting or electrodes for steelmaking need to be calcined at high temperature to complete carbonization and reduce volatile matter to a minimum.

The appearance of the coke produced by most petroleum coke factories is dark brown porous solid irregular block, and this kind of coke is also called sponge coke. The second type of petroleum coke with better quality is called needle coke and sponge coke. It is more suitable for electrodes because of its lower electrical resistance and thermal expansion coefficient. Sometimes another kind of hard petroleum coke is also produced, which is called shot coke. This kind of coke is shaped like a bullet, has a small surface area and is not easy to coke, so it has few uses.

Introduction of needle coke

Needle coke is a kind of high-quality coke with obvious fiber texture in appearance, low thermal expansion coefficient and easy graphitization. When the coke block breaks, it can be split into long and thin strip particles according to the texture. An anisotropic fibrous structure can be observed under a polarizing microscope, so it is called needle focus.

The physical and mechanical anisotropy of needle coke is very obvious, and it has good electrical and thermal conductivity parallel to the long axis of the particles, small thermal expansion coefficient, and good thermal shock resistance.

Needle coke is divided into oil-based needle coke produced from petroleum oil residues and coal-based needle coke produced from refined coal tar pitch.

Needle coke’s applications

Needle coke is a kind of high-end carbon material. It is mainly used as the raw material for the production of ultra-high power graphite electrodes and artificial graphite anode materials. The most important end application fields are electric arc furnace steelmaking and power batteries for new energy vehicles.
Needle coke has broad market prospects. The development of needle coke will help meet the urgent demand for high-quality raw materials in the graphite electrode and anode material industries, and promote the realization of the goals of “carbon peak” and “carbon neutrality” in the downstream industries of the industrial chain. Driven by electric arc furnace steelmaking and new energy vehicles, the demand for needle coke, which is the upstream of the industrial chain, will show a rapid growth trend.

There are differences in the performance requirements of needle coke in the anode material and graphite electrode industries, and needle coke suitable for graphite electrodes may not necessarily obtain excellent electrochemical performance. At present, more attention needs to be paid to the application research of needle coke in the anode material industry, and the establishment and improvement of the relationship between the conventional indicators of needle coke and the electrochemical performance of anode materials and other key indicators should be accelerated.