Pyrolysis Behavior of Pyrite under a CO-H Atmosphere.

The transformation behavior of pyrite (FeS) in the blast furnace process is critical to control the formation and emission of gaseous sulfides in the top gas of ironmaking but has seldom been explored. In present work, the pyrolysis of pyrite from 200 to 900 °C under a CO-H atmosphere was investigated by thermal-gravimetric and mass spectrometry. The thermodynamic theoretical calculations were carried out to further understand the transformation process. The results show that FeS is almost completely reduced to FeS under various CO-H atmospheres. HS and carbonyl sulfide (COS) are the main gaseous sulfides formed through the pyrolysis reactions of FeS under a CO-H atmosphere. A higher H concentration can reduce the pyrolysis reaction temperature of FeS, which is favorable for the conversion of sulfides to HS, while a higher CO concentration promotes the conversion of sulfides to COS. Besides, the pyrolysis products of FeS by order from the former to latter under a strong reductive atmosphere (CO-H) with increasing temperature are as follows: COS → S → HS → S → CS.