1. Control the three stages of electrode baking
The three stages of electrode baking determine the final quality of the electrode. The first stage is the melting stage from room temperature to 200°C; the second stage is the volatilization stage from 200-600°C; and the third stage is the curing stage at 600-800°C. In order to well control the firing speed of the three stages, especially the temperatures of the two volatilization points of 500°C and 700°C, the secondary current can be intuitively controlled to ensure the normal and effective firing of the electrode.
2. Preparation of the electrode working end before opening the furnace
Treat the contact surface between the end of the electrode and the coke layer at the bottom of the furnace. If it is a new electrode, the steel plate at the bottom of the head should be thicker. If it is the hard tip of the electrode that was shut down the previous time, the bottom of the electrode must be treated relatively flat, so that the bottom of the electrode depends on the weight of the electrode itself and the coke layer at the bottom of the furnace is evenly and steadily contacted, so as to minimize the electrode’s hands during the baking process. Inhomogeneity and the uneven firing speed of the same electrode in the electrode firing process, so as to avoid that almost all the current flows through when the side that first contacts the furnace bottom and begins to sinter, forming a firing area of the electrode as the main electrode, causing internal generation of the electrode Stress, causing electrode accidents.
3. Clean up the thinned area
Under normal production conditions, the crucible in the normal area is relatively large due to emergency power cuts. However, when the furnace is shut down under the power limit, because the electric furnace does not have enough power to maintain the normal crucible area, in this case, when the furnace is shut down to clean the material and start the furnace, the area in the molten pool must be cleaned up. The purpose is to not be subjected to external force from around the crucible during the firing process of the electrode, otherwise, once the electrode is subjected to external force from the crucible during the firing process, the load of the electric furnace will rise to between 16-17MW, and the hard disconnection of the electrode will not be possible. avoid.
4. Electric furnace load control
After fully confirming that the electrode is burned, start to turn the transformer from the star connection to the corner connection, raise the electrode, and send electricity to the electric furnace for feeding. Seal the fire as much as possible after feeding to prevent burning out the electrode shell. The electrode current is controlled at about 40KA. At this time, the tap changer of the transformer is one stage, the voltage is 90.3V, and the electric furnace power is 6-7MW.
According to the sintering condition of the electrode, it takes 30 hours to slowly increase the power of the electric furnace to 17-18MW and the electrode current to 70-75KA. At this time, when the total power consumption reaches about 300,000 KWH from the charging, the first furnace of iron will be produced (if it is a brand-new electric furnace, the power consumption must reach 400,000 KWH). From feeding to the first iron tapping, it is the stage where the electrode develops from low temperature to high temperature. At this time, the electrode is relatively fragile under normal conditions. If the load of the electric furnace rises too fast, it will cause the internal stress inside the electric furnace to change sharply, causing the electrode to hardly break. It is worth noting that the key stage is when the load of the electric furnace is 10-15MW, the voltage is 15-17, and the voltage is 165-175v. At this time, the electrode current must be kept below 65KVA for 3-4 hours to relieve the concentrated stress of the electrode, and then slowly rise to the first Cast iron in one furnace.