Consumption and use of graphite electrodes in electric arc furnace smelting (3)
Apr 15, 2022
Factors affecting the consumption of graphite electrodes in smelting
The electric arc furnace smelting in the steelmaking process is divided into roughing and refining, but the graphite electrodes transfer electric energy into the electric furnace and convert it into heat energy to achieve the purpose of heating and melting the solid charge. Rough smelting is an oxidation process for the purpose of melting scrap steel and discharging harmful gases and impurities, while refining is also a reduction process that adjusts steel elements and removes gas and impurities by heating up. It can be seen that the electric arc furnace smelting is to use the graphite electrode to adjust the furnace temperature to realize the redox reaction and meet the requirements of the steelmaking process. The consumption of graphite electrode in smelting can be divided into active consumption, natural consumption or technology consumption. Reactive power consumption is the physical consumption that does not participate in the heating process or does not participate in the heating process completely, and is also non-technical consumption.
The main factors affecting the consumption of graphite electrodes
The consumption of graphite electrodes in electric furnace steelmaking runs through the entire smelting process, and its consumption is affected by many factors. Here, only the operation of the smelting process is analyzed.
(1) Poor scrap quality or improper ratio leads to poor slagging effect and prolonged smelting time; The increase of feeding times and well penetration times increases the damage and fracture probability of electrode bottom. Longer smelting time is the direct factor leading to the increase of power consumption and electrode consumption and loss.
(2) The electric furnace power supply equipment does not match the electrode specifications and varieties
Electric arc furnace power delivery is a high-current, low-voltage operation. If the capacity of the power supply equipment is too large and exceeds the limit load of the electrode, the electrode within 5~10min of the arc will appear red from bottom to top, the boundary line of the connection is very obvious and most of them have broken accidents; the current is too high or the fluctuation is too large, The fracture frequency of the joints at the joints is increased and the bottom consumption is tapered. If the power supply capacity is low, the furnace temperature will not meet the process requirements within the effective medium heat time, and the operation will be delayed. The loss and consumption of the graphite electrode is the largest in overload and overtime operation.
(3) The oxidation period is forced to increase chemical energy and improve smelting strength
In smelting, the amount of oxygen blowing (generally less than 45M3/T) is forcibly increased to achieve rapid melting and increase the furnace temperature, which is easy to make the furnace condition worse and the furnace and the furnace are in a rich state, so that each phase electrode is in a high temperature flame. When the electrodes are in this furnace environment, most of them have serious phenomenon of layering and surface oxidation.
(4) The technicality of the configuration and operation of the electric furnace
There are essential differences between modern eAF and traditional eAF. The emergence of ultra-high power large-scale EAF and hot charging steelmaking process improves smelting intensity and production capacity, and thus puts forward higher technical requirements for the quality of graphite electrode. During the operation, the choice of power transmission curve and gear, the control of arc starting and arc stabilizing voltage and current, the use of long, medium and short arcs, the configuration and application of water cooling system all play a key role in the service life and consumption of electrode.
(5) Quality of graphite electrodes
At present, the smelting and process of electric arc furnace have more and more strong requirements for the anti-oxidation performance and thermal shock resistance of graphite electrodes, and the high consumption caused by quality fluctuation has attracted great attention from direct users. Therefore, the balance and stability of graphite electrode quality are the most important factors in determining consumption.
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