Primary de-oxidation of Basic Oxygen Furnace steel by means of carbon

The aim of this investigation was to reduce the cost of primary steel de-oxidation by substitution of aluminium primary de-oxidation with a practice that uses carbon. The cost of carbon is four times lower than that of aluminium. The application of carbon would directly result in raw material cost savings. Investigations were conducted at Iscor's Newcastle steel plant on various steel grades. Specific production aspects were emphasized to ensure that the cost savings accrued would not create secondary expenses. These production aspects entailed: Yields on de-oxidation elements De-oxidation capabilities Alloying yields (Mn and Si) Carbon-pickup Nitrogen-pickup Temperature loss during tap Steel cleanliness Slag morphology. This project proved that carbon de-oxidation, apart from reducing de-oxidation raw material cost due to cheaper raw materials being used and lower consumption rates, resulted in steel that is cleaner and has lower nitrogen concentrations. Carbon primary de-oxidation has been implemented at Iscor's Newcastle plant on a large range of steel grades, ranging from ultra-high carbon (> 0.60% C) to ultra-low carbon (< 0.03% C) grades. A net saving of between R100.000 and R200 000 per month was achieved.