Pyrolysis Behavior of Pyrite under a CO–H₂ Atmosphere

Abstract

The transformation behavior of pyrite (FeS 2 ) 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 2 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 2 is almost completely reduced to FeS under various CO–H 2 atmospheres. H 2 S and carbonyl sulfide (COS) are the main gaseous sulfides formed through the pyrolysis reactions of FeS 2 under a CO–H 2 atmosphere. A higher H 2 concentration can reduce the pyrolysis reaction temperature of FeS 2 , which is favorable for the conversion of sulfides to H 2 S, while a higher CO concentration promotes the conversion of sulfides to COS. Besides, the pyrolysis products of FeS 2 by order from the former to latter under a strong reductive atmosphere (CO–H 2 ) with increasing temperature are as follows: COS → S → H 2 S → S 2 → CS 2 .

Operando exploration of tribochemical decomposition in synthetic FeS2 thin film and mineral iron pyrite

“…70 The process stops when sulfur concentration in the mineral reaches an equilibrium value depending on the pressure of sulfur gas and temperature. Reduction with hydrogen occurs at around 773 K. As the temperature gradually increased from 673 to 1073 K under H 2 –CO gas mixture 91 the predominant gaseous products shifted on the following order: COS → S → H 2 S → S 2 → CS 2 . Under oxidative environments, pyrite remains stable up to 673 K, 70,83,87 while the emitted gas was usually SO 2 .…”

“…As the temperature gradually increased from 673 to 1073 K under H 2 -CO gas mixture 91 the predominant gaseous products shied on the following order: COS / S / H 2 S / S 2 / CS 2 . Under oxidative environments, pyrite remains stable up to 673 K, 70,83,87 while the emitted gas was usually SO 2 .…”