Functions of Mg and Mg-CaO mixtures in hot metal desulfurization

David Lindström (1) , Patrice Nortier (2, 3, 4) , Du Sichen (1)

1 MSE - Department of Materials Science and Engineering [Stockholm]
2 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
3 PROPICE-ENSMSE - Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements
4 LGF-ENSMSE - Laboratoire Georges Friedel

The mechanisms of hot metal desulfurization using Mg and Mg-CaO mixtures were studied in a newly designed set-up. It was found that most of the added Mg quickly escaped in 2 s. MgS was not formed by homogeneous nucleation but by its formation on the MgO particles originated from oxide shell of the Mg particles. When tiny CaO particles were added together with Mg, the particles efficiently transformed to CaS. It was found that Mg-gas helped the distribution of the CaO particles in the hot metal and improved the kinetic condition. Most of the CaO particles smaller than 10 µm were completely transformed to CaS whereas CaO particles >10 µm still had CaO in the center after 20 s. The CaO particles as nuclei were also found to help Mg gas in forming MgS. The ratio of CaO and Mg added was found to have strong impact on the kinetic conditions of desulfurization. This ratio would need further study in any reactor of interest, as the kinetic conditions would differ considerably. The optimized ratio is expected to be a function of the size and geometry of the reactor, the position and the depth of the addition, the manner of addition and more.

Mots clés: hot metal desulfurization; Mg; CaO; reaction mechanisms

Domaines: Génie des procédés

David Lindström, Patrice Nortier, Du Sichen. Functions of Mg and Mg-CaO mixtures in hot metal desulfurization. Steel Research International, 2013, 85 (1), pp.76-88. ⟨10.1002/srin.201300071⟩. ⟨hal-00870339⟩