Replacement of fluorspar in the desulfurization of hot metal

Arthur Silva Bahiense Moreira,Itavahn Alves Silva,Carlos Antônio Silva

doi:10.1590/0370-44672017710039

Arthur Silva Bahiense Moreira, Itavahn Alves Silva + Show 1 more

Open Access

https://doi.org/10.1590/0370-44672017710039

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Abstract

Abstract In the steel industry, lime is used as a desulfurizing agent and fluorspar as flux in the hot metal desulfurization process. However there are environmental concerns regarding the use of fluorspar, even when its harmful effects are not fully known. In order to reduce such risks and also to anticipate possible future restrictions, which could undermine the sustainability of steel production, it is proposed to replace the fluorspar for alternative materials in the composition of the desulfurizing lime based mixture. For this purpose new mixtures using aluminum dross, ilmenite, sodalite and ulexite were tested, comparing them with a reference mixture containing fluorspar. The impact of these mixtures on the refractories commonly used in hot metal pretreatment was also checked, since this is an important cost parameter for the steel industries. The laboratory tests showed ulexite as a feasible substitute since the lime (84.03%) - ulexite (10.97%) - graphite (5%) mixture presented the highest desulfurization ratio and low refractory wear (less than the standard fluorspar mixture). The sodalite mixture was the worst by comparison. The ilmenite and aluminum dross mixtures showed similar behavior when compared to the fluorspar mixture.

Highlights

Fluorspar is a common raw material used at ironmaking and steelmaking facilities
According to VOLKMANN (2002), sodalite nepheline has been evaluated for fluorspar substitution in BOF operations
Using a 1:1 replacement, a ratio of 88.8% de-P was achieved for fluorspar and 88.1% for sodalite nepheline

Summary

Introduction

Fluorspar is a common raw material used at ironmaking and steelmaking facilities. It is a powerful fluxing agent, its benefits are to be weighed against health and environmental concerns. Depending on temperature and slag composition compound such as NaF(g), KF(g) and (SiF4), AlF3, CaF2, BF3 can be emitted, Figure 1. Other reasons for fluorspar substitution is refractory wear and availability (it is becoming scarce). According to VOLKMANN (2002), sodalite nepheline has been evaluated for fluorspar substitution in BOF operations. Using a 1:1 replacement, a ratio of 88.8% de-P was achieved for fluorspar and 88.1% for sodalite nepheline. Refractory wear due to sodalite was evaluated under laboratory conditions and deemed to be smaller than that of fluorspar.

Results

Materials and methodology

Results and discussion

Conclusions