Electric Arc Furnace

I. INTRODUCTION Stainless steels may be defined as alloy steels containing at least 12% chromium with or without other elements. It has been customary to include with those stainless steel alloys that contain as little as 4 % chromium. Together, these steels form a family known as stainless and heat resisting steels. Few of these contain more than 30% chromium.1The corrosion resistance and ability to remain been attributed to the passive film formed on the surface. Passivity is due to the formation of a thin tenacious protective oxide layer on the surface of the metal. The serious mode of attack on stainless steel concerned with breakdown of the passivity, resulting in the localized attack such as pitting, crevice, inter granular corrosion

In the 60s the increased demand for such qualities led to the development of ultra high power EAF (UHP-EAF) introducing foamy slag and long arc practice, water cooler wall panels and roof burners as well as slag-free tapping. Increasing the productivity, resulted in reduced tap-to-tap time as well as reduced energy consumption. The rapid growth of EAF steel making processes has created a growing demand for steel scrap, as a result of which the scrap is in short supply throughout the world in general and in particular for India. Also, rising costs unreliable supply of electrical power in India is a matter of great concern to EAF operators. These problems can be overcome by using hot metal from mini blast furnace (MBF) as iron bearing charge materials in EAF. The use hot metal offers the possibility of producing steel at lower costs than in traditional scrap based EAFs.11Use hot metal in EAF steel making has resulted in major cost saving, (including power) increased productivity and independence from steel scrap shortage and its price fluctuations. Recently, Jindal steel and power ltd. Raigarh is installing a BF of 351 m3volume for production of hot metal to be used in EAF for steel making. This furnace is rated to produce 0.238 Mt / year of hot metal / pig iron.

The left vessel is working as a converter and the right one as an electric arc furnace.

The steel making process in the CONARC can be divided in two steps.

1. Converter step: The hot metal poured into the hot heel is decarburized by oxygen blown via top lance.

2. Electric arc furnace step: The cold charged materials (DRIor scrap) are melted and the tapping temperature is adjusted by electric energy.

The CONARC process starts with charging of hot metal into a liquid heel, small part of the previous melt kept in the furnace. As soon as the top-lance is being brought only the position, the oxygen blowing is initiated, during the converter phase; the content of carbon, silicon; manganese and phosphorus in the bath are reduced. The reactions are exothermic, so large amount of heat energies are generated. Then cold charge materials like DRI or scrap is added to the furnace to utilize this enormous heat energy and thus to avoid overheating of the bath. After completion of the decarburization process, the top lance is moved away and the electrodes are brought into operating positions. In the arcing phase, the remaining solid charge material like scrap or DRI is fed into the bath to achieve the tapping weight. The temperature of the bath is adjusted and the heat is tapped into