Preparation of high-purity TiSi2 and eutectic Si–Ti alloy by separation of Si–Ti alloy for clean utilization of Ti-bearing blast furnace slag

Abstract

Titanium-bearing (Ti-bearing) blast furnace slag is not only industrial waste but also an important Ti resource. However, the cleaning of Ti-bearing blast furnace slag for utilization is a difficult problem. In this study, a new process is proposed to prepare Titanium disilicide (TiSi2) and eutectic Si–Ti alloy (Si/TiSi2), using Ti-bearing blast furnace slag and low-purity Si as raw materials. Firstly, Titanium oxide (TiO2) in the Ti-bearing blast furnace slag was reduced by Si and an Si–Ti alloy was obtained. The obtained Si–Ti alloy was then separated into TiSi2 and eutectic Si–Ti alloy by directional crystallization. In addition, MgO, Al2O3 and graphite crucibles were used and their influences on the results were investigated to obtain the optimal reaction container to prepare high-purity TiSi2 and eutectic Si–Ti alloy. The results show that the separation of Si–Ti alloy using an MgO crucible as a reaction container has little influence on the purity of the TiSi2 (>98%) and eutectic Si–Ti alloy (>97%) and that most of the impurities could be eliminated from the bulk TiSi2 crystal and eutectic Si–Ti alloy. The results of this study provide a theoretical and experimental basis for the simultaneous preparation of TiSi2 and eutectic Si–Ti alloy materials and proposes a new approach for the comprehensive utilization of Ti-bearing blast furnace slag.