Metal/Slag Separation Behavior of CCA with Various Slag Systems and Effect of Slag Composition on the Content of Sulfur and Phosphorus in Iron Nugget

Abstract

The smelting reduction of high Al2O3 ores with petroleum coke containing various slags was investigated in the temperature range of 1 673 to 1 773 K with a special focus on the effect of slag composition on the desulfurization and dephosphorization of iron nugget. The efficient smelting reduction of the carbon composite agglomerate (CCA) would greatly be affected by the mineralogy of iron ore, coal and additives used in the preparation of CCA although the design of final slag composition is important for the ultimate separation of metal and slag. The separation of metal and slag in the reduction progress was retarded due to the delayed melting of CCA with high basicity slag of low SiO2 content. The content of sulfur in iron nugget decreased to about 0.07 mass% by incorporating high basicity slag to CCA at the temperatures above 1 723 K, which is compatible with the minimum sulfur content in iron of the conventional ITmk3 process (0.05-0.07 mass%). About 80-90% of phosphorus in CCA was eliminated using high basicity slag (CaO-Al2O3) at 1 723 K, which is believed to be much better dephosphorization efficiency compared with the conventional process.