Abstract

Differential thermal analysis (DTA), thermogravimetry (TG), and mass spectrometry (MS) were used to study the thermal behavior of the blast furnace (BF) and basic oxygen furnace (BOF) sludges generated from the iron-making industry. The results indicated that under air atmosphere the two types of sludge are different in their thermal behavior. In BF sludge, the exothermic carbon gasification (CO/CO₂) reaction dominated the process, while in BOF sludge, the significant reaction occurred at 755 °C and was associated with a slight mass gain owing to the partial oxidation of Fe₃O₄ to Fe₂O₃. Under inert atmosphere, the thermal behavior of both BF and BOF sludges were dominated by a reduction reaction. In BF sludge, the endothermic reactions ranged from 785 to 1115 °C due to the reduction of iron oxides as follows: Fe₂O₃ → Fe₃O₄ → FeO → Fe. A total mass loss of about 27.78% was observed in the TG curve. While in BOF sludge, the endothermic peaks corresponded to magnetite reduction to iron (Fe). The overall mass loss of the BOF was approximately 16.92%. The mass spectrum of gases evolution for both BF and BOF sludges revealed that CO/CO₂ gases were released from the sludges.