Material definition on March 30, 2018: graphite electrode is an amorphous carbon product calcined by graphitization furnace, graphite electrode is graphitized carbon product. According to the "carbon Industry Special report: carbon (I) for Iron and Steel" released on June 26, 2017, "carbon products are divided according to whether they are graphitized or not, according to the demand for graphite electrodes for new electric furnaces, technological progress, and the enhancement of concentration to help long-term development." It can be divided into two categories, one is carbon products which are not graphitized and composed of non-graphite carbon, the other is graphite products which are made up of graphite carbon after graphitization. Graphitization is a high temperature heat treatment process in which carbon products are heated above 2300 ℃ in a high temperature electric furnace to transform amorphous carbon into planar hexagonal layered graphite with three dimensional order. The graphitization of carbon materials was carried out at 2300 ℃ at 3000 ℃. Because it is difficult to obtain such a high temperature for the combustion of fossil fuels, it can only be achieved by electric heating and roasting in industry. Usually graphitization furnace, the furnace type has Acheson (Acheson) graphitization furnace and internal heat tandem (LWG) furnace. (2) production process: Petroleum coke, needle coke, coal tar pitch and other raw material costs account for 66.88% of the cost. The production cycle exceeds 50 days and the super-high power reaches 65 days 1. Raw material and cost: Petroleum coke, Raw materials such as needle coke and coal bitumen account for 66.88% of the cost of graphite electrode (1) raw materials: low sulfur petroleum coke, coal series needle coke as bone material, coal pitch as binder graphite electrode, petroleum coke, needle coke and so on as raw materials, coal pitch as binder.
Needle coke: needle coke is a kind of high quality coke with obvious fibrous texture, low thermal expansion coefficient and easy graphitization. The anisotropy of the physical properties of needle coke is very obvious. Parallel to the long axis of particle, the needle coke has good conductivity and low coefficient of thermal expansion, so needle coke is the key material for manufacturing high power or ultra high power graphite electrode. The graphite electrode has low resistivity, low coefficient of thermal expansion and good thermal shock resistance. Needle coke can be divided into two kinds according to the source of raw material: oil system needle coke produced from petroleum residue and coal series needle coke produced from refined coal pitch raw material. According to Zhang Yifeng's 2013 article "Needle Coke and Graphite electrode" published in the Journal of carbon Technology, the high quality oil system needle coke is often preferred as the main raw material coke in the production of large specification, high power and ultra-high power graphite electrodes by foreign carbon enterprises. At present, the needle coke in our country is mainly coal-based needle coke, oil-based needle coke is imported from Japan Water Island Company and British HSP Company.