Product Introduction
Calcination of needle coke is an important step in the production process of needle coke.
Needle Coke is a high-quality variety vigorously developed in carbon materials, with a silver-gray and metallic luster appearance. Its structure has obvious flowing textures, with large but few pores and slightly elliptical shapes. The particles have a large aspect ratio, similar to fibrous or needle-like texture, and have a lubricating feel to the touch. It can be used as a raw material for producing high-end carbon products such as high-power and ultra-high-power graphite electrodes, as well as negative electrode materials for power lithium batteries.
Calcination of needle-shaped coke is usually carried out in a rotary kiln. Needle coke produced by delayed coking contains high moisture and volatile components, known as raw coke, and requires high-temperature calcination treatment under isolated air conditions. During the calcination process, the structure and elemental composition of needle coke undergo a series of changes, thereby improving its physicochemical properties. The purpose of calcination is to remove moisture and volatile components from the raw coke and to improve the carbon content, density, strength, conductivity, and chemical stability of the coke.
The raw coke enters from one end of the kiln and comes into contact with the high-temperature calcination exhaust gas. At the outlet end, there is a gas or oil burner, and the calcination zone temperature can reach up to 1500 ℃. The rotational speed of the kiln body has a decisive impact on the residence time and heating speed of coke inside the kiln. An important evaluation indicator of calcination efficiency is the true density of needle coke after calcination, and needle coke with a true density greater than 2.13g/cm ³ is of better quality.
According to different production materials, needle coke can be divided into oil-based needle coke and coal-based needle coke. The raw material for oil-based needle coke is heavy oil from petroleum processing plants. It is necessary to select heavy oil with high aromatic hydrocarbon content and low sulfur content, and remove impurities from it; The raw material of coal-based needle coke is coal tar pitch, which needs to be pre-treated to remove components such as quinoline insoluble substances that hinder the growth of small spheres, and to carry out component modulation.
Whether it is oil-based needle coke or coal-based needle coke, the production process includes three parts: raw material pretreatment, delayed coking, and calcination. In the delayed coking process, the process flow of the two is similar, but there are certain differences in the fractionation system, process parameters, operating cycle, and coke yield.
The following is an example of some specification parameters for Korean imported calcined needle coke provided by a company for your reference:
Fixed carbon: 99.3%
- Moisture: 0.2%
- Expansion degree: 4.2
