Advantages for steelmaking

The use of EAF allows steel to be made from 100% scrap metal raw material.This significantly reduces the energy required to make steel compared to ore primary steelmaking.Another benefit is flexibility: While blast furnaces cannot drastically change output and can run for years at a time, electric arc furnaces can be started and stopped quickly, allowing steel mills to vary output according to demand.While steelmaking EAFs typically use steel scrap as the primary raw material, blast furnace hot metal or direct reduced iron can also be used as a charge if it is economically viable.Because EAFs require large amounts of electricity,many companies schedule their operations to take advantage of off-peak electricity rates.Typical steelmaking electric arc furnaces are the source of steel for minimills, producing bar or strip products.Minimills can be built relatively close to markets for steel products,so transportation requirements are lower than integrated mills, which are often built near ports for better transportation.EAF steelmaking has low CO2 emissions, producing around 0.6 tons of CO2 per ton of steel, which is significantly lower than conventional production routes via blast furnaces and basic oxygen furnaces.In theory, electric arc furnaces could be powered using only low-carbon energy sources such as wind, solar, hydro and nuclear.This would even further reduce the emissions and embodied energy associated with making steel or any other material that requires a furnace, including glass.This makes EAF an attractive option for green industries.

Issues 

While the modern electric arc furnace is an efficient scrap recycling facility, the operation of an electric arc furnace shop can have a detrimental impact on the environment.Much of the capital cost of new installations will go towards systems designed to reduce these impacts,including:

• Enclosures to reduce high sound levels

• Furnace exhaust gas dust collector

• Slag production

• Cooling water requirements

• Heavy truck traffic for scrap, material handling and product

• Environmental impact of power generation

Due to the very high dynamic quality of EAF loads, power system measures may be required to maintain power quality for other customers; flicker and harmonic distortion are common power system side effects of EAF operation.

Other electric arc furnaces

For steelmaking, a direct current (DC) electric arc furnace is used, with an electrode at the top and current returning through a conductive substrate or pins at the bottom.The advantage of direct current is lower electrode consumption per ton of steel produced, since only one electrode is used, as well as fewer electrical harmonics and other similar problems.The size of a DC arc furnace is limited by the current carrying capacity of the electrodes available and the maximum allowable voltage.The maintenance of the conductive hearth is the bottleneck of the long-term operation of the DC electric arc furnace.In steel mills, ladle furnaces (LF) are used to maintain molten steel temperature or change alloy composition during processing after EAF tapping. One of the first uses of ladles is to use them when there are delays late in the steelmaking process.

The ladle furnace consists of a refractory roof, a heating system and, if necessary, a device for injecting argon into the bottom of the melt for stirring. Unlike scrap melting furnaces, ladle furnaces have no tilting or scrap charging.Electric arc furnaces are also used for the production of calcium carbide, ferroalloys and other non-ferrous alloys, as well as for the production of phosphorus.Furnaces used for these services are physically distinct from steelmaking furnaces and can operate continuously rather than batchwise.Continuous process furnaces can also use pasted Søderberg electrodes to prevent interruptions due to electrode replacement.Such furnaces are called submerged arc furnaces because the electrode tips are buried in the slag/charge and the arc occurs through the slag between the copper matte and the electrodes. In contrast, steelmaking electric arc furnaces conduct electric arcs in the open air.The key is the resistance, which generates the required heat: the resistance in a steelmaking furnace is the atmosphere,while in a submerged arc furnace, the slag (or charge) provides the resistance.The liquid metal that forms in either furnace is too conductive to form an effective heating resistor.Hobbyists build various electric arc furnaces, usually based on silicon blocks or arc welding kits contained in pots.Although humble, these simple furnaces can melt a variety of materials, create calcium carbide..