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Calcination of ggraphite electrode

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

An important means of testing the degree of calcination

Determination of the electrical resistivity of the calcined coke is an important means to test the degree of calcination. The change of resistivity of petroleum coke during calcination can be roughly divided into three stages.

Calcination temperature determines calcination quality

Carbonaceous raw materials must meet certain quality standards for calcination in raw material production plants or carbon plants. The quality of calcination depends mainly on the calcination temperature and is related to the duration at high temperatures.

Calcination time affects calcination quality

The original coke has insufficient residence time in the high temperature zone, the volatile matter cannot be exhausted, and the structural shrinkage is insufficient. The calcined coke is necessarily low in true density and high in electrical resistivity.

Rotary kiln calcined needle coke quality is relatively bad

Calcination of needle coke using a rotary kiln or a horizontal rotating bed calciner, because the needle coke is affected by a sharp rise in temperature in a short time, the coke after calcination has low mechanical strength and is easily broken, so the number of large particles is relatively reduced. This is not good for the production of large-size graphite electrodes.

There are 4 kinds of carbonaceous raw material calcining equipment.

The main equipment for carbonaceous raw material calcination includes rotary kiln, tank calcining furnace, horizontal rotating bed calcining furnace and electric calcining furnace.

Different calcining equipment used in different factories

There are many rotary kiln and tank calciner, which have their own advantages and disadvantages. The horizontal rotary bed calciner is only used in a few factories. The electric calciner is mainly used for calcining anthracite or small-scale calcined petroleum coke.

Size of graphite electrode

Item Unit UHP
300-600mm 650-800mm
Electric resistivity Electrode μΩm 4.8-5.8 4.6-5.8
Nipple 3.8-4.5 3.8-4.5
Flexural strength Electrode Mpa 10.0-14.0 10.0-14.0
Nipple 20.0-26.0 22.0-26.0
Elastic modulus Electrode Gpa 9.0-13.0 10.0-14.0
Nipple 15.0-18.0 15.0-18.0
Bulk density Electrode ≥g/cm3 1.68-1.74 1.70-1.74
Nipple 1.77-1.82 1.78-1.84
CTE(100-600℃) Electrode x10-6/℃ 1.1-1.4 1.1-1.4
Nipple 0.9-1.2 0.9-1.2
Ash   0.3 0.3