Multistage desulfurization mechanism to reduce sulfur content of high ferrotitanium prepared using thermite method

Abstract

High ferrotitanium is used as a deoxidizer and alloying agent in steelmaking processes and is mainly produced using high-cost remelting processes. The thermite method is a simple and low-cost method for preparing low ferrotitanium. However, the high levels of S, Al, and O residues in the product severely restrict its applicability in the low-cost preparation of good-quality high ferrotitanium. In this study, a novel multistage deep reduction method for preparing high-quality high ferrotitanium is proposed, and the multistage desulfurization mechanism is systematically investigated. The results indicate that multistage desulfurization is an effective method for reducing the S content of high ferrotitanium prepared via the thermite method. During the strong desulfurization stage, Ti2S reacts with CaO at the slag–metal interface and produces CaS. The S content decreases, while the O content increases, with the increase of CaO in the CaO–Al2O3-based slag. During the deep desulfurization, Ti2S is deeply reduced by the Ca and produces CaS, thus further reducing the S content. The S content decreases with the incremental addition of Ca and can be reduced to 0.035 wt% after multistage desulfurization.