Arc melting furnace principle and Arc melting furnace price
By:Win Nov 12, 2020
Arc melting furnace means is a furnace that heats charged material by means of an electric arc. A device for melting metal, such as scrap steel, by electric arc without changing the chemical properties of the metal.
Arc melting furnace
Arc melting furnace is a type of metallurgical furnace which makes use of an electrical arc to heat the material, mostly metal ore or scrap metal in the production of steel.
There are mainly two types of electric furnaces. They are alternating current (AC) and direct current (DC) operated electric furnaces.
AC Electric Arc Furnace
The main parts of electric furnace are the roof, hearth (lower part of a furnace, from where molten metal is collected), electrodes, and side walls.
The roof consists of three holes through which the electrodes are inserted. The roof is made up of alumina and magnesite-chromite bricks. The hearth includes metal and slag. The tilting mechanism is used to pour the metal that is molten to the cradle by shifting the furnace. For the electrode removal and furnace charging (topping up scrap metals), roof retraction mechanism is incorporated. The provision for fume extraction is also given around the furnace considering the health of operators. In AC electric furnace, electrodes are three in number. These are round in section. Graphite is used as electrodes because of high electric conductivity. Carbon electrodes are also used. The electrodes positioning system helps to raise and lower the electrodes automatically. The electrodes get highly oxidized when the current density is high.
DC Electric Arc Furnace
DC Arc Furnace is recent and advanced furnace compared to AC Arc Furnace. In DC Arc Furnace, current flows from cathode to anode. This furnace has only a single graphite electrode and the other electrode is embedded at the bottom of the furnace. There are different methods for fixing anode at the bottom of the DC furnace.
The first arrangement consists of a single metal anode placed at the bottom. It is water cooled because it gets heated up fast. In the next one, the anode be the conducting hearth by C-MgO lining. The current is given to the Cu plate positioned at the bottom portion. Here, the cooling of anode is by the air. In the third arrangement, the metal rods act as anode. It is entrenched in MgO mass. In the fourth arrangement, the anode is the thin sheets. The sheets are entrenched in MgO mass.
In AC electric furnace, current flows between the electrodes through the charges in metal. In this furnace three graphite electrodes are used as cathode. The scrap itself acts as an anode. When compared to DC arc furnace, this is cost effective. This furnace is most commonly used in small furnaces.
Arc melting furnace principle
The working of electric furnace includes charging the electrode, meltdown period (melting the metal) and refining. The heavy and light scrap in the large basket is preheated with the help of exhaust gas. For speeding up the slag formation, burnt lime and spar are added to it. The charging of furnace takes place by swinging the roof of the furnace. As per requirement, the hot metal charging also takes place. The electrodes are moved down onto the scrap in this period. Then the arc is produced between the electrode and metal.
After the arc is shielded by electrodes, the voltage is increased for speeding up the melting process. In this process, carbon, silicon, and manganese get oxidized. The lower current is required for large arc production. The heat loss is also less in this. Melting down process can be fastening by deep bathing of electrodes.
Arc melting furnace price
The electrodes used in Arc melting furnace are of three types namely carbon electrodes, graphite electrodes and self-baking electrodes. Material of the electrodes namely carbon and graphite has been selected on account of their electrical conductivity, insolubility, infusibility, chemical inertness, mechanical strength and resistance to thermal shock. The size of these electrodes may be 18 cm to 27 cm in diameter. With graphite or carbon electrode, the temperature obtainable from the arc is between 3,000 °C and 3,500 °C.