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<p>Diamond wire saw Si powder (DWSSP) is a valuable secondary resource rich in Si, but it is also a hazardous air pollutant. CaF<sub>2</sub>–MgO waste slag containing F is produced during the steelmaking process. This study presents a new low–cost method for recovering both DWSSP and CaF<sub>2</sub>–MgO waste slag. The Al reduction smelting process was used to prepare Al–Si–Ca alloy, AlF<sub>3,</sub> and MgF<sub>2</sub> from the CaF<sub>2</sub>–MgO slag and DWSSP, and these fluorides were volatilized under negative pressure (<i>P</i> = 2.46 × 10<sup>4</sup>&#xa0;Pa). Additionally, the study investigated the effects of holding time and CaF<sub>2</sub>–MgO slag compositions on O removal, preparation of Al–Si–Ca alloys. The results demonstrated that upon 120&#xa0;min of smelting using solely CaF<sub>2</sub> slag at 1450℃, the deoxygenation efficiency reached 99.89%, with the O concentration in the alloy being reduced to 170 ppmw. Compared to CaF<sub>2</sub> slag, when CaF<sub>2</sub>–30 wt.% MgO slag was employed, the deoxygenation efficiency was enhanced to 99.98%, resulting in an O concentration of merely 24 ppmw in the alloy. The alloy produced using CaF<sub>2</sub>–12 wt.% MgO slag exhibited the highest Si extraction efficiency from DWSSP, reaching 93.65%. When using CaF<sub>2</sub> slag, the products obtained were Al-Si-Ca alloy and AlF<sub>3</sub>. In contrast, the use of CaF<sub>2</sub>-MgO slag enabled the simultaneous preparation of Al-Si-Ca alloy, AlF<sub>3</sub>, and MgF<sub>2</sub>. Finally, the reaction mechanism of the approach was revealed through thermodynamic analysis.</p>

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A New Method for Producing Al–Si–Ca Alloys, AlF3, and MgF2 Using Diamond Wire Saw Si Powder and CaF2–MgO Waste Slag

  • 期刊论文

  • 发表日期：

    2025年3月22日

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  • Guangxiang Ming,
  • Shijie Li,
  • Yakun Zhang,
  • Yun Lei,
  • Yongsheng Ren,
  • Guoqiang Lv,
  • Kuixian Wei,
  • Wenhui Ma

摘要

Diamond wire saw Si powder (DWSSP) is a valuable secondary resource rich in Si, but it is also a hazardous air pollutant. CaF2–MgO waste slag containing F is produced during the steelmaking process. This study presents a new low–cost method for recovering both DWSSP and CaF2–MgO waste slag. The Al reduction smelting process was used to prepare Al–Si–Ca alloy, AlF3, and MgF2 from the CaF2–MgO slag and DWSSP, and these fluorides were volatilized under negative pressure (P = 2.46 × 104 Pa). Additionally, the study investigated the effects of holding time and CaF2–MgO slag compositions on O removal, preparation of Al–Si–Ca alloys. The results demonstrated that upon 120 min of smelting using solely CaF2 slag at 1450℃, the deoxygenation efficiency reached 99.89%, with the O concentration in the alloy being reduced to 170 ppmw. Compared to CaF2 slag, when CaF2–30 wt.% MgO slag was employed, the deoxygenation efficiency was enhanced to 99.98%, resulting in an O concentration of merely 24 ppmw in the alloy. The alloy produced using CaF2–12 wt.% MgO slag exhibited the highest Si extraction efficiency from DWSSP, reaching 93.65%. When using CaF2 slag, the products obtained were Al-Si-Ca alloy and AlF3. In contrast, the use of CaF2-MgO slag enabled the simultaneous preparation of Al-Si-Ca alloy, AlF3, and MgF2. Finally, the reaction mechanism of the approach was revealed through thermodynamic analysis.