Melting:

The melting period is the heart of EAF operations. Melting is completed by supplying energy to the furnace interior. This energy might be electrical or chemical. Electrical energy is supplied by the graphite electrodes and usually is the largest contributor in melting operations. At first, an intermediate voltage tap is choosing until the electrodes bore into the scrap. Light scrap is placed usually on top of the charge to accelerate bore-in. About 15 % of the scrap is melted throughout the initial bore-in period. After a few minutes, the electrodes shall have penetrated the scrap adequately so that a long arc (high voltage) tap might be utilized without fear of radiation damage to the roof. The long arc increased the transfer of power to the scrap and a liquid pool of metal shall form in the furnace hearth. At the beginning of melting the arc is unstable and erratic. In current wide swings are observed accompanied by quick movement of the electrodes. Since the furnace atmosphere warm up the arc stabilizes and once the molten pool is created, the arc becomes quite stable and the average power input enhance.

Chemical energy is supplied via various sources including oxygen lances and oxy-fuel burners. Oxy-fuel burners burn natural gas utilizing oxygen or a blend of air and oxygen. Heat is transferred to the scrap through flame radiation and convection by the warm products of combustion. Heat is transferred in the scrap by conduction. Big pieces of scrap take longer to melt into the bath than smaller one. In some of operations, oxygen is injected by a consumable pipe lance to "cut" the scrap. The oxygen reacts with the warm scrap and burns iron to generated intense heat for cutting the scrap. Once a molten pool of steel is produced in the furnace, oxygen might be lanced into the bath directly. This oxygen shall react with various components in the bath as, aluminum, manganese, silicon, carbon, phosphorus and iron. All of these reactions are exothermic (that means they generate heat) and supply extra energy to aid in the melting of the scrap. The metallic oxides that are produced will end up in the slag. The reaction of oxygen along carbon in the bath generated carbon monoxide that either burns in the furnace if there is adequate oxygen, and/or is exhausted by the direct evacuation system where this is burned and conveyed to the pollution control system.