Causes of graphite electrode breakage in electric arc furnace smelting

Causes of graphite electrode breakage in electric arc furnace smelting

In view of the breakage of graphite electrodes in steelmaking, the analysis of the ultra-high power graphite electrodes from the perspective of the internal quality and smelting process operation were analyzed. They can be summarized into the following three categories:

1.Operation reasons;

2.Control reasons;

3.Electrode quality reasons.

First: Reason for Operation

(1) Collapse the material and break the electrode.

If the scrap steel in the furnace has formed a bridging structure during the smelting process, especially when it is close to melting, the long-term short-arc operation at this time will generate a large side impact force of the collapsed material. Due to the thinning of the oxidation-accelerating electrode, the probability of breakage here is also high.

(2) The electrode is broken by resonance.

Electrodes are subject to electromagnetic force during the smelting process, which will definitely cause vibration. If the mechanical vibration frequency of the electrode column is close to or synchronized with the electromagnetic force vibration frequency, it will cause the electrode to resonate and easily cause the electrode to break.

(3) The electrode is broken due to irregular clamping operation.

If the electrode and the holder cannot be kept perpendicular, the electrode will have an additional horizontal force component; if there is a foreign object on the clamping surface, the clamping point is liable to cause stress concentration; these bad operations can easily cause the electrode to break during the smelting work process.

Second: control reasons

(1) There are non-conductive objects under the electrodes in the furnace.

In the process of electrode drive lowering, after the lower end of the electrode contacts a non-conductive object, the electrode adjuster cannot accurately determine that the electrode has been lowered into place, but the electrode adjuster controls the electrode to continue to descend, causing the electrode and the scrap steel to be longitudinally squeezed and broken.

(2) The electrode regulator cannot detect the decrease of the relative ground voltage

If the connection between the neutral point of the voltage transformer and the bottom shell of the electric furnace is disconnected, the electrode regulator cannot detect the decrease of the relative ground voltage, and it cannot be judged that the electrode has fallen into place, causing the electrode regulator to control the electrode to continue to fall, resulting in the electrode Extruded and broken with scrap steel.

Pictures from the Internet
(3) Arc current cannot be detected by the electrode regulator

If the electrode arc cannot be detected by the electrode regulator after the arcing of the electrode, or the arc current is very small, the electrode regulator will control the second phase electrode to continue to fall, which will cause the second phase electrode and the scrap steel to be crushed and broken.

(4) The condition of the hydraulic actuator of the electrode regulator is abnormal.

Third: the internal quality of the electrode

(1) Reasons for broken joints;

(2) Reasons for electrode breakage;