Production of low sulphur spheroidal graphite pig iron in mini blast furnace by optimising slag

Abstract

Blast furnace slag has very significant effect on its physicochemical characteristics which affects the smoothness of operation, degree of desulphurization, coke consumption, hot metal productivity and its quality etc. The slag properties basicity which affects most are viscosity, sulphide capacity, alkali capacity and liquidus temperature. These properties have great influence on the overall blast furnace process. Variation of these slag characteristics with composition and temperature has, therefore, been a field of active research. Mini Blast Furnace has now been used frequently used for production of Basic Grade Merchant Grade , Foundry Grade as well as Steel Grade Pig Iron . This technology can easily be combined with EAF / IF /EOF /LD to produce quality grade Iron & Steel . But today it has become an essential process route for hot metal production economically and to meet the gap between demand & supply of Iron & Steel. The quality of SG Grade pig iron is very crucial particularly with respect to sulphur, silicon and phosphorous content of pig iron. Generally, SG iron is produced in Electric Arc Furnace and Induction Furnace utilizing steel scrap, SG Scrap and Cast iron scrap of low sulphur, low phosphorous and low silicon. But the availability of good quality steel scrap and SG scrap are in scarce as well as expensive. The cost of electrical energy is also very high in India; therefore, there is a win-win situation considering the above mentioned constrained, the combination of Mini Blast Furnace and Electric Arc Furnace are becoming essential process route for the production of SG Grade pig iron.