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What kind of raw materials are used for graphite electrodes?

May 21,2019January 10, 2019
Graphite electrode is made of petroleum coke and needle coke as aggregate, coal pitch is used as binder, and it is kneaded and formed.
A high temperature resistant graphite conductive material produced by a series of processes such as type, roasting, dipping, graphitization, and machining. The graphite electrode is an important high-temperature conductive material for electric steelmaking. The graphite electrode is used to input electric energy to the electric furnace, and the high temperature generated by the arc between the electrode end and the charge is used as a heat source to melt the charge for steel making. Other ore furnaces that smelt materials such as yellow phosphorus, industrial silicon, and abrasives also use graphite electrodes as conductive materials. The excellent and special physical and chemical properties of graphite electrodes are also widely used in other industrial sectors. The raw materials for the production of graphite electrodes are petroleum coke, needle coke and coal tar pitch.
 Petroleum coke is a flammable solid product obtained by coking coal residue and petroleum asphalt. Black and porous, the main
The element is carbon and the ash content is very low, generally below 0.5%. Petroleum coke belongs to the class of easily graphitized carbon. Petroleum coke has a wide range of uses in chemical and metallurgical industries. It is the main raw material for producing artificial graphite products and carbon products for electrolytic aluminum.
 Petroleum coke can be divided into two types: raw coke and calcined coke according to heat treatment temperature. The former is delayed coking.
The obtained petroleum coke contains a large amount of volatile matter and has low mechanical strength, and the calcined coke is obtained by calcination of raw coke. Most refineries in China produce only coke, and calcination operations are mostly carried out in carbon plants.
 Petroleum coke can be divided into high sulfur coke (containing more than 1.5% sulfur) and medium sulfur coke (including
Sulfur 0.5%-1.5%), and low sulfur coke (0.5% or less sulfur), graphite electrodes and other artificial graphite products are generally produced using low sulfur coke.
Coal tar is one of the main products of coal tar deep processing. As a mixture of many hydrocarbons, often
The temperature is black high viscosity semi-solid or solid, no fixed melting point, softens after heating, and then melts, the density is 1.25-1.35g/cm3. According to its softening point, it is divided into low temperature, medium temperature and high temperature asphalt. The medium temperature asphalt yield is 54-56% of coal tar. The composition of coal tar is extremely complicated, which is related to the properties of coal tar and the content of heteroatoms, and is also affected by the coking process system and coal tar processing conditions. There are many indicators for characterizing coal tar pitch, such as bitumen softening point, toluene insolubles (TI), quinoline insolubles (QI), coking values, and coal pitch rheology.  Coal tar is used as a binder and impregnant in the carbon industry, and its properties are suitable for carbon products.
Production process and product quality have a great impact. The binder asphalt generally uses a medium-temperature or medium-temperature modified asphalt having a moderate softening point, a high coking value, and a high β resin. The impregnating agent is a medium temperature asphalt having a low softening point, a low QI, and good rheological properties.