Comprehensive Utilization of Diamond Wire Saw Silicon Powder Waste and Low-Grade Mn Ore to Prepare a MnSi1.73–1.75-Rich Alloy

The rapidly developing photovoltaic industry is generating an increasing amount of diamond wire saw silicon powder waste (DWSSPW), and the current shortage of high-grade iron ore necessitates the utilization of low-grade Mn ore. The treatment of DWSSPW and low-grade Mn ores is important for the sustainability of Si and Mn resources. In this study, a concept of comprehensive utilization of low-grade Mn ore and DWSSPW is proposed. DWSSPW (90.1 wt % Si) was used as a cheap reductant to extract Mn from low-grade Mn ore (25 wt % MnO) and can be recycled as a raw Si–Mn alloy. The results showed 96.35% of the MnO in the low-grade Mn ore could be extracted by DWSSPW at 1500 °C. The oxide molten slag formed by the low-grade Mn ore eliminates the main impurity, O, from DWSSPW. The results showed 99.3% of the O in DWSSPW could be eliminated. Thereafter, electromagnetic directional solidification was used to separate and purify the raw Si–Mn alloy to prepare a useful MnSi1.73–1.75-rich alloy with a purity of 95.75%, a promising raw material for preparing Si–Mn composite anodes in lithium-ion batteries, thermoelectric materials, and a high-quality deoxidization and alloying agent in steelmaking. Finally, the method proposed in this study is considered green and economical compared to conventional methods.