The Difference And Characteristics Of Graphite Electrodes And Ultra-high Graphite Electrodes

 What is a graphite electrode? Composition of graphite electrode

Graphite electrode mainly uses petroleum coke and needle coke as raw materials, coal tar pitch is used as a binder, and is made by raw material calcination, crushing and grinding, batching, kneading, pressing, roasting, impregnation, graphitization, and machining. High temperature resistant graphite conductive material, also known as artificial graphite electrode. It is an important high temperature conductive material for electric furnace steelmaking, yellow phosphorus smelting, industrial silicon, abrasives and other materials.

Graphite electrode history

• In 1810, Humphry Davy used charcoal to make carbon electrodes

• In 1846, Stair and Edwards mixed coke powder and sucrose, pressurized them, and calcined at high temperature to produce another carbon electrode

• In 1877, C.F.Brush and W.H.Lawrence of Cleveland, USA, used calcined petroleum coke to develop low-ash carbon electrodes

• In 1897, E.G. Acheson of the American Carborundum Co. produced the first batch of artificial graphite electrodes using petroleum coke as a raw material in a resistance furnace for the production of emery.

• In the early 20th century, electric furnace steelmaking mainly used carbon electrodes with anthracite as raw materials or natural graphite electrodes with natural graphite as raw materials.

• The maximum diameter of graphite electrodes made from 1914 to 1918 is only 356mm

• In the 1960s and 1970s, high-power and ultra-high-power graphite electrodes were successfully developed

How to make petroleum coke in the production of petroleum coke?

Petroleum coke is a combustible solid product obtained by coking petroleum residue and petroleum pitch. It belongs to the category of easily graphitized carbon and is the main raw material for the production of artificial graphite products. Graphite electrode production generally uses low-sulfur coke production.

Classification of petroleum coke

Press coking method

• Open hearth coke

• Axe coke

• Delayed focus

• Sulfide coke

According to the level of sulfur

• High sulfur coke

• Medium sulfur coke

• Low sulfur coke

According to heat treatment temperature

• Coke

• Calcined coke

Needle Coke

Needle coke is a kind of high-quality coke that has obvious fibrous texture, low thermal expansion coefficient and easy graphitization. The anisotropy of the physical and mechanical properties is very obvious, parallel to the long axis of the particle, it has good electrical and thermal conductivity, and the thermal expansion coefficient is low. Needle coke is the key raw material for the manufacture of high-power or ultra-high-power graphite electrodes. The made graphite electrodes have low resistivity, low thermal expansion coefficient and good thermal shock resistance.

Classification of needle coke

Needle coke is divided into oil-based needle coke produced with petroleum residue as raw material and coal-based needle coke produced with refined coal pitch raw material. The two needle coke production processes are not exactly the same, but the uses are basically the same. The petroleum series is represented by the United States, and the coal series is represented by Japan.

Coal pitch

Coal pitch is one of the main products of coal tar processing. It is the residue after coal tar distillation extracts the fraction.

Coal pitch classification

Softening point

• Low temperature asphalt

• Medium temperature asphalt

• High temperature asphalt

Characteristics of coal pitch

Coal pitch is used as a binder and impregnant in the carbon industry, and its performance has a great impact on the production process and product quality of carbon products. Binder asphalt generally uses medium temperature or medium temperature modified asphalt with moderate softening point, high coking value, and high β resin. As impregnant, use medium temperature asphalt with low softening point, low QI and good rheological properties.

Graphite electrode classification

The main indicators reflecting the quality and performance of graphite electrodes are: electrical resistivity ρ, bulk density db, flexural strength σ, elastic modulus E, thermal expansion coefficient α, and ash content A%. According to the differences in these indicators and the differences in raw materials and manufacturing processes, the national standard (YB/T 4088/89/90-2000) divides graphite electrodes into ordinary power graphite electrodes (RP) and high power graphite electrodes (HP) , Ultra-high power graphite electrode (UHP) three kinds. In the post-graphite electrode production plant, two types of high-density graphite electrodes (HD) and quasi-super-high graphite electrodes (SHP) have been added according to user needs.