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Production of Graphite Electrode Raw Materials

Release time:2019-11-04 From: Zhengnai Industry in China

The difference between raw coke and calcined coke

The raw coke is obtained by delayed coking, contains a large amount of volatile matter, and has low mechanical strength. The calcined coke is obtained by calcination of raw coke.

Sponge coke is not used as a raw material for the production of graphite products

Sponge coke is a petroleum coke obtained by coking with a large amount of colloid and asphaltenes. It has a similar appearance to a sponge, contains a lot of impurities, contains many small pores inside, and has a thin focal wall between pores. The obtained artificial graphite has a relatively high coefficient of linear expansion and electrical resistivity, and thus is not suitable as a raw material for producing graphite products.


Honeycomb coke can produce RP graphite electrode

Honeycomb coke is a petroleum coke produced from medium-grade residue of colloid and asphaltene. The coke has a relatively uniform pore distribution inside, and has obvious honeycomb structure. The physical and mechanical properties are much better than sponge coke, which can be used to produce Regular power. Raw material for graphite electrodes.

Needle coke can produce HP and UHP graphite electrodes

The needle coke is obtained by coking of low-sulfur and low-ash high-quality residual oil with a small amount of asphaltenes. The outer surface has obvious streaks. The voids inside the coke block are arranged in a slender elliptical shape, which is broken into thin particles and is produced. Raw materials for high power and ultra high power graphite electrodes.

Needle coke can be divided into 2 kinds

There are two kinds of needle coke: 1. petroleum needle needle coke produced from petroleum residue as raw material, 2. asphalt needle coke (or coal needle needle coke) produced from refined coal pitch as raw material.

Parameter of HP/RP 300-800mm graphite electrode

Item Unit HP RP
300-800mm 300-800mm
Electric resistivity Electrode μΩm 5.8-6.6 7.8-8.8
Nipple 4.2-5.0 5.0-6.5
Flexural strength Electrode Mpa 10.0-13.0 7.0-12.0
Nipple 18.0-22.0 15.0-20.0
Elastic modulus Electrode Gpa 8.0-12.0 7.1-9.3
Nipple 14.0-16.0 12.0-14.0
Bulk density Electrode ≥g/cm3 1.62-1.66 1.53-1.56
Nipple 1.74-1.80 1.70-1.74
CTE(100-600℃) Electrode x10-6/℃ 1.6-1.9 2.2-2.6
Nipple 1.1-1.4 2.0-2.5
Ash   0.3 0.5


The anisotropy of needle coke is obvious

The anisotropy of physico-mechanical properties of needle coke is very obvious. It has good electrical and thermal conductivity parallel to the long axis direction of the particle, and the coefficient of linear expansion is low. During extrusion, the long axis of most of the obtained particles follows the extrusion direction. arrangement.

Raw materials affect the quality of the finished electrode

The production of different types of graphite electrodes requires the use of petroleum coke of different quality standards. This is followed by bitumen coke (including bitumen needle coke), and in addition to the use of a certain amount of metallurgical coke, silica and silica sand as auxiliary materials.

Definition of petroleum coke

Petroleum coke is a flammable solid product obtained by coking of residual oil produced by petroleum processing and petroleum coke petroleum pitch.


Petroleum coke form and use

Petroleum coke is a kind of easy-graphitized carbon, color black and porous, the main element is carbon, the impurity content is very low, it has wide application in metallurgy, chemical industry, etc. It is also the main raw material for producing various graphite products.

4 classification methods of petroleum coke

According to the different coking methods, it is divided into four types: open hearth coke, kettle type coke, delayed coke, and fluidized coke.
According to the heat treatment temperature, it can be divided into two types: raw coke and calcined coke.
According to the level of sulfur, it can be divided into high sulfur coke, medium sulfur coke and low sulfur coke.
According to the appearance and performance of petroleum coke, it can be divided into sponge coke, honeycomb coke and needle coke.


Method for improving the quality of petroleum coke

The thermal cracking residue has a higher aromatic content than the vacuum residue. Therefore, adding a part of the thermal cracking residue as a coking raw material in the vacuum residue can improve the quality of the petroleum coke.