Title: Study on the technology of reducing the consumption of graphite electrode
Keywords: graphite electrode consumption
According to the consumption mechanism of graphite electrode in eaf steelmaking, the experiment shows that the side oxidation of electrode is mainly related to the oxidation atmosphere and smelting time in the furnace, and the consumption of electrode at the extreme is mainly related to the working current and carbon distribution system. To the existing power supply, negative pressure, carbon distribution and sampling technology system into the optimization into a single furnace refining time shortened by 13%, tons of slag stone ink electrode consumption down by 20%, the results are significant.
The importance of reducing graphite electrode consumption in reducing titanium slag smelting
The production cost of titanium slag smelting in electric furnace mainly includes raw material consumption, graphite electrode consumption, electricity consumption, equipment depreciation, etc., among which the consumption of stone and ink electrode and electricity consumption are variable costs, and the cost of graphite electrode accounts for about 20% of the variable costs. Therefore, it is important to reduce the electrode consumption to reduce the cost of titanium slag smelting
- Cause analysis of graphite electrode consumption
- Lateral oxidation:
Electrode side oxidation is caused by the interaction of oxygen in the furnace atmosphere with graphite to form CO or CO. The oxidation consumption of electrode side is mainly determined by the parameters of electrode surface area, smelting time, slag yield and oxidation rate. When the electrode used is fixed, that is, the electrode surface area remains unchanged, the longer the smelting time, the less slag produced, the faster the oxidation consumption rate, and the larger the electrode consumption.
Effect of oxidation rate on side oxidation of electrode:
When the amount of slag produced per unit hour is fixed, the consumption of electrode oxygenation depends on the oxidation rate, which is closely related to the gas atmosphere in the furnace. The titanium slag smelting in preparation for half closed electric furnace, and the type of continuous charging, the whole smelting process for negative pressure operation, particularly in the furnace and when feeding time clearance for the warranty card electric security operations, with a big negative pressure control, pressure operations in a given negative pressure value by the wind machine frequency rate after automatic tuning section, and often hold as member connected in material section, the fan when you pick up the sample frequency rate to the highest value (50 hz). The fan frequency is positively proportional to the negative pressure. The larger the fan frequency is, the greater the negative pressure is and the more gas enters the furnace. The titanium slag electric furnace is a semi-closed electric furnace, the door opening and the cover of the furnace cannot be effectively closed, when feeding, the use of a large negative pressure, the amount of air into the furnace increased, this is the main reason for the oxidation of the electrode side
The influence on the oxidation of electrode side during smelting:
When the oxygenation rate is fixed, the oxidation on the electrode side is mainly determined by the smelting time and the amount of slag, while the amount of slag is mainly determined by the amount of feed. In normal production process, the error difference control of single furnace feeding amount is ±5t, which can be considered as a certain amount of slag from single furnace. Therefore, the oxygenation of the electrode side is very large and depends on the smelting time. The shorter the smelting time, the smaller the electrode consumption. In general, the oxidation on the electrode side is mainly related to the oxidizing atmosphere in the furnace and the smelting time.
- End consumption:
The consumption at the electrode end includes the rising of the arc due to the high temperature of the arc (also known as arc light consumption or evaporation consumption) and the loss of the electrode end due to the reaction of molten slag (also known as chemical consumption). Arc light dissipation is due to the production of high temperature electric arc (3000℃) between the electrode and the material, leading to the end of the electrode continued stone ink consumption. The high temperature rise and consumption at the electrode end is mainly related to the evaporation rate at the electrode end, while the evaporation rate of the electrode mainly depends on the current density passing through the electrode, and is also related to the diameter of the electrode end after oxygenation (shaped cone body).
The higher the arc current, the greater the consumption at the electrode end. Therefore, the selection of reasonable working current is an effective method to reduce the consumption at the electrode end. In addition to the consumption of stone and ink, there is also a part of the electrode tip is the erosion consumption of the molten pool to the electrode. When the electrode is in contact with the molten pool, the electrode will react with the gold smelting in the furnace, and the consumption of the electrode is mainly determined by the amount of carbon in the smelting. In a word, the main consumption of electrode end of titanium slag electric furnace is related to smelting current and carbon.
- Measures to reduce graphite electrode consumption:
- Improvement of power supply system
The consumption on the side of the stone-ink electrode is related to the smelting time, while the consumption on the tip of the electrode is related to the working current. The purpose of shortening the smelting time can be achieved by increasing the power of the electric furnace, and the increase of the power transfer rate is mainly realized by raising the voltage. Since the current level has an influence on the consumption of the electrode, it is one of the effective ways to shorten the smelting time by raising the voltage and lowering the operating current.
- Improvement of negative pressure operation
Titanium slag smelting for the negative pressure operation, in order to prevent the dust from the plug caused by the explosion in the furnace, each time to add materials to take a large negative pressure of 80 ~ 6OPa control system. In addition, in order to improve the safety operation, a large negative pressure of 20 ~ 15Pa was taken during the normal smelting process, and the single furnace feeding batch was 4 ~ 5 times. This kind of negative pressure control system led to extremely severe electrode oxygenation. Therefore, a reasonable negative pressure operation system is very important for reducing electrode consumption. By reducing the negative pressure in the furnace, the thermal efficiency of the electric furnace can be increased, the loss can be reduced, and the consumption of electrode can be decreased.
- Improvement of carbon distribution system
The influence of chemical measurement of carbon in furnace material on the consumption of electric electrode is very great. When the charge carbon is not sufficient, the electrode carbon will participate in the metallurgical reaction, and with the increase of the furnace carbon deficit, the amount of electrode carbon and metallurgical reaction increases, that is, the electrode consumption increases. Therefore, it is very important to optimize the carbon distribution system and reduce the electrode reduction consumption at high temperature.
- Improvement of sampling system
Titanium slag smelting is carried out under the atmosphere of reversibility and the electrode consumption in the reversibility process is relatively small. The original number of sampling in a single furnace is 2-3 times, and each sampling can only be completed by opening the furnace door. During the sampling process, the air from the outside enters the furnace, which not only destroys the original atmosphere and reduces the temperature of the molten pool, but also has a certain effect on the electrode oxidation. Therefore, the number of sampling times in a single furnace was adjusted from 2 ~ 3 times to 1 time in a single furnace, which effectively shortened the smelting time and reduced the consumption of electrode. After the process was improved, the oxygenation atmosphere in the furnace was well controlled, and the original environment in the furnace was improved effectively. During the smelting in a single furnace, the shrinkage was 13%. The single consumption of the graphite electrode for tons of slag was reduced from 19.5kg to 15.6kg, with a reduction of 20%.
- Conclusion the consumption of graphite electrode was reduced
- The actual consumption of titanium slag electrocalcinite ink electrode was analyzed. The main consumption of electrode was oxygenation on the side of electrode and consumption on the end of electrode.
- According to the mechanism of consumption of steel stone ink electrode in electric arc furnace and the analysis of junction test, it can be known that the oxygenation of the electrode side is mainly related to the oxidizing atmosphere in the furnace and the smelting time, and the consumption of electrode end is mainly related to the working current and carbon distribution system.
- After changing into the technical system, the smelting time of the single furnace shortened by 13%, and the single consumption of the graphite electrode of tons of slag decreased by 20%.