Reasons for Hard Fracture of Electrodes in Submerged Arc Furnaces and Corresponding Treatment Methods

Reasons for Hard Fracture of Electrodes in Submerged Arc Furnaces and Corresponding Treatment Methods

The working end of the electrode of a submerged arc furnace, which has been sintered, breaks off due to certain reasons during the smelting process, which is called hard breakage of the electrode.

Reasons for hard fracture of electrodes in submerged arc furnaces:

1. The submerged arc furnace experiences frequent hot shutdowns, and the intermittent operation results in unstable electrode temperature. Consequently, internal stress is generated within the electrode, leading to its fracture.

2. When power is supplied after the submerged arc furnace has been shut down due to heat, the temperature of the electrodes is relatively low. If the load is increased too rapidly, the electrodes are prone to breaking.  Especially before the heat shutdown, when the furnace condition is relatively sticky, the electrodes are more likely to break during power supply.

Before the power outage for furnace maintenance, the working end of the electrode was too long, making it prone to breaking after power was restored.

If the power outage lasts for a long time, the electrodes may become stuck in the furnace material, potentially causing them to break when power is restored.

3. The reason for hard breakage of electrodes during normal smelting is often due to poor quality of electrode paste, such as excessive ash content in the electrode paste;  improper particle size ratio of electrode raw materials or improper storage of electrode paste with soil on the surface, which causes deterioration of electrode sintering quality and electrode breakage.

Treatment of hard fracture of electrodes in submerged arc furnace:

1. After a power outage, measures should be taken as soon as possible to minimize the duration of hot shutdown.

2. Try to extract the small electrode tips from the submerged arc furnace. If they are difficult to remove, apply pressure with the electrode and add an appropriate amount of silica and lime to accelerate oxidation.  Regardless of their size, any electrode tips that have broken into the small submerged arc furnace must be extracted, otherwise the electrode cannot be inserted deeply into the furnace material after power is turned on.

3. The electrode tip broken into the furnace must be removed if its length is greater than 100mm.  Otherwise, the load will be unstable after power is turned on, affecting the deep insertion of the electrode.

The length of the broken electrode is too long, and the electrode should be baked again.

4. If the working end of the electrode in the submerged arc furnace is relatively short after breaking, some electrodes should be lowered according to the sintering condition of the electrode.

However, if the electrode has not been sintered properly, it should never be lowered to prevent the accident from escalating.  After power is supplied, reduce the load on the electrode of that phase, and only lower the electrode after it has been properly sintered.

5. After handling the electrode breakage accident of the submerged arc furnace, the load should be slowly increased when power is restored, and the condition of the electrodes should be observed to prevent new electrode accidents.

The frequent hard breakage of electrodes in submerged arc furnaces is often caused by prolonged power outages or an overly rapid increase in load after power restoration. Therefore, the fundamental measures to prevent hard breakage of electrodes are:

1. Shorten the duration of hot shutdown maintenance and reduce the frequency of hot shutdowns.

2. The working period before stopping the boiler should not be too long, and the electrodes should be well maintained after stopping the boiler.