When ferrosilicon is smelted in a submerged arc furnace with a larger capacity, the furnace conditions become sticky and the furnace conditions cannot be completely reversed for a long time. At this time, lime is added for treatment to facilitate slag removal and allow the electrodes to be inserted deeply, thereby enlarging the crucible and increasing the furnace temperature.
If the current fluctuates greatly, some lime can be added to stabilize the electrode so that the electrode does not continue to rise.
How to add lime:
You should choose lime with good sintering quality and suitable block size, and add 200~300 kilograms at a time to adjust the furnace conditions. This method has quick results. You can also add 5 to 10 kilograms of lime to the batch material, which will also have better results.
After the furnace condition is normal, the addition of lime should be stopped.
Silica in silica is an acidic oxide with a melting point of 1710°C. Calcium oxide (CaO) in lime is an alkaline oxide with a melting point of 2570°C. Under high temperature conditions in the furnace, these two compounds react to generate low melting point compounds, such as CaO, SiO2 and other neutral compounds. The melting point of the slag is reduced to 1450-1550°C to facilitate slag discharge. Click to review and then expand the crucible. Furnace condition improved.
If there is too much slag in the furnace because the ash content in the coke is too high or there is too much soil on the silica surface, then add lime and react with calcium oxide and aluminum oxide to form calcium aluminate such as 3CaO·Al2O3 and other compounds, which will cause The melting point of the slag is lowered, making it easier to remove the slag.
According to practical experience, lime is often added during smelting, which will have the following adverse effects:
1. Lime is often added to increase the fluidity of the slag, causing the furnace temperature to be higher and seriously eroding and eroding the taphole and the molten iron saturated ingot mold. Burnout and leakage accidents of the tap hole may even occur.
2. Lime is often added to form low melting point slag in the furnace, which washes away the electrodes and speeds up the consumption of the electrodes, causing the consumption of the electrodes to be faster than the sintering speed of the electrodes. Once the working end of the electrode is short, the electrode cannot be lowered on time, affecting normal operation.
3. Lime is often added. After the electrode is inserted deeply and the furnace temperature rises, more of the calcium oxide in the charge is reduced. The generated calcium enters the ferrosilicon and affects the quality of the ferrosilicon. The specific gravity of calcium is 1.5, which is smaller than the specific gravity of silicon. When the calcium content in ferrosilicon is too high, the image uses the specific gravity method to analyze the accuracy of the silicon content.
4. Frequent addition of lime will inevitably consume more heat, and increasing the amount of slag will affect the output of ferrosilicon and the unit power consumption index.
5. When the temperature of molten iron is high, adding limestone is a means to deal with the furnace condition, but it cannot be used as a fundamental measure to achieve high output and reduce power consumption.
