Steel Manufacturing

18 Pages 4444 Words

l injection of oxygen or some other fuel-gas mixture can accelerate the melting phase. The maximum transferable electric power and the heat stability of the refractory lining determine the time needed for melting. The most up-to-date furnaces with a hi specific apparent power (UHP furnaces) achieve melting periods of about 40 to 60 minutes and tap-to-tap times of about 1.5 hours.

During the refining stage, iron oxides included in the slag react with the carbon of the bath. This gives rise to the gaseous carbon monoxide, which causes the heat to boil, and rinses impurities such as phosphorus, hydrogen, nitrogen and non-metallic compounds from the heat. These impurities escape as gases or are included in the slag. Sulphur cannot be completely eliminated.

The advantages of steelmaking in the electric arc furnace are :
· All possible grades of steel can be melted · Low capital outlay · The melting process can be programmed and automated · Good efficiency
But it has some shortcomings as well. Because it uses scrap , the EAF route can only be used to produce steel grades with low purity requirements. Major new developments in steel making have taken place in EAF based steel making. Innovations such as DC arc technology, scrap preheating, post combustion, oxygen and carbon injection etc have led to a tremendous increase in productivity and a decrease in electric consumption









COKE OVENS-SINTER-BF-BOF ROUTE
The most common steel making technology is the Bf-Bof Route. Coke is used in Blast Furnace (BF) both as a reductant and as a source of thermal energy. It involves reduction of ore to liquid metal in the blast furnace and and refining in convertor to form steel. The various stages of the steel plant is described below.
COKE MAKING - COAL CARBONISATION Coking coals are the coals which when heated in the absence of air, first melt, go in the plastic state, swell and resolidify to produce a solid cohere...