The principle of operation of electric arc furnaces
Electric arc furnaces operate on three-phase electric current. Metal smelting in an arc furnace occurs by forming an electric arc between the graphitized electrodes and the charge to be melted. Such equipment is called a straight arc furnace. There are also electric arc furnaces of indirect action, in which the arc is at some distance from the heated metal.
The main element of such melting furnaces is a metal casing, the inner walls of which are lined with refractory material. To load the charge into the arc furnace, a removable erection is used, which must be lifted and set aside. The housing also has a drain hole with a gutter through which the molten metal is discharged into the bucket. A special cradle with an electric or hydraulic drive is used to tilt the housing towards the working window or outlet.
Electricity is supplied from transformers to the arc furnace body via copper busbars. Carbon or graphite electrodes are used during operation. The length of the arc in the furnace is adjusted automatically. Spent electrodes are constantly replaced with new ones. The melting process takes place in a limited space, the walls of which are lined. Increasingly common is a three-phase furnace, in which arcs occur between the three electrodes and the metal being processed.
As one of the alternative energy sources for gas melting furnaces, a new type of fuel can be used, which is obtained by underground gasification of coal. The production of this synthesis gas, the content of the combustible fraction in which is more than 90%, occurs by blowing an oxygen mixture into coal deposits that are not subject to development in the usual way.
Metal smelting in an arc furnace
When smelting a metal in electric arc furnaces should take into account both its physical and chemical properties. Each metal has its own transition temperature from solid to liquid, at which the melting process begins directly. In order to accelerate it in electric melting furnaces, different types of oxidants are used.
What is usually the main component of the charge during metal smelting in an arc furnace? The basis of the charge is steel scrap, to which iron ore pellets are added. Recycling of steel in electric arc furnaces requires appropriate material quality. Scrap laid in melting furnaces of this type must meet the following characteristics:
- Have a minimum of impurities of non-ferrous metals;
- Be not very oxidized, without rust;
- Contain no more than 0.05% phosphorus.
- Nowadays, the share of use in electric arc furnaces of such primary products of iron ore processing as sponge iron and metallized pellets is growing.
Electric heating and heating stoves can also be used, which can be used to maintain a comfortable temperature in your own home. Systems that reproduce the appropriate humid atmosphere in the bath or sauna should work both as a stove and air conditioner.
