Comprehensive Utilization of Diamond Wire Saw Silicon Powder Waste and Low-Grade Mn Ore to Prepare a MnSi_1.73–1.75-Rich Alloy

Abstract

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.

Achieving Rapid Synthesis of High-Purity SiC at 1923 K via a Liquid-State Reaction

“…The residual Si–La–C solution remained on top of the agglomerated SiC crystals (Figure a,c), indicating that it could be recycled or reused. Separation of the SiC crystals from the Si–La–C solution was similar to our previous studies, in which Si crystals were separated from Si–Al solutions, TiSi 2 crystals were separated from Si–Ti solutions, and CrSi 2 was separated from Si–Cr solutions …”

“…Separation of the SiC crystals from the Si−La−C solution was similar to our previous studies, in which Si crystals were separated from Si−Al solutions, 30 TiSi 2 crystals were separated from Si−Ti solutions, 31 and CrSi 2 was separated from Si−Cr solutions. 32 Small amounts of solidified Si−La−C solutions were entrapped among the SiC crystals as solvent inclusions (Figure 7a), indicating that these solvent inclusions had to be eliminated before the purity of the obtained SiC crystals was determined with GD-MS. Acid leaching was used to eliminate these solvent inclusions after grinding the agglomerated SiC crystals into powders (Figure 8a).…”