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<p>Fluorine-containing sludge (FCS) generated by the semiconductor and photovoltaic industries is hazardous waste, and its treatment and resource utilization are both urgent and critically important. To address the issues of lengthy process flows and low efficiency in the current resource recovery of CaF<sub>2</sub> in FCS, a novel method for converting CaF<sub>2</sub> through low-temperature calcination using Mg(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O was proposed. The effect of roasting parameters on the conversion efficiency of CaF<sub>2</sub> was explored and optimized, and the reaction kinetics were clarified. Under the optimal conditions, 98.12% of CaF<sub>2</sub> in FCS was converted to MgF<sub>2</sub>. The roasting of CaF<sub>2</sub> follows a chemical diffusion-controlled mechanism with an activation energy of 23.28 kJ/mol. Ultimately, a MgF<sub>2</sub> product with a purity of 98.30% was obtained. Density functional theory calculations showed that Mg(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O remained molten at low temperatures, reducing the chemical energy barrier for breaking the Ca-F bond and promoting the reaction. This method offers a straightforward, quick, and effective way to treat FCS and recover fluorine resources, laying a foundation for producing other fluorides and opening a new path for future FCS treatment strategies.</p>

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Efficient conversion mechanism of calcium fluoride in fluoride-containing sludge by calcination

  • 期刊论文

  • 发表日期：

    2026年1月10日

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  • Hang Zhao,
  • Mengjun Chen,
  • Feihua Yang,
  • Haile Yan,
  • Xiaoguang Zhang,
  • De’an Pan

摘要

Fluorine-containing sludge (FCS) generated by the semiconductor and photovoltaic industries is hazardous waste, and its treatment and resource utilization are both urgent and critically important. To address the issues of lengthy process flows and low efficiency in the current resource recovery of CaF2 in FCS, a novel method for converting CaF2 through low-temperature calcination using Mg(NO3)2·6H2O was proposed. The effect of roasting parameters on the conversion efficiency of CaF2 was explored and optimized, and the reaction kinetics were clarified. Under the optimal conditions, 98.12% of CaF2 in FCS was converted to MgF2. The roasting of CaF2 follows a chemical diffusion-controlled mechanism with an activation energy of 23.28 kJ/mol. Ultimately, a MgF2 product with a purity of 98.30% was obtained. Density functional theory calculations showed that Mg(NO3)2·6H2O remained molten at low temperatures, reducing the chemical energy barrier for breaking the Ca-F bond and promoting the reaction. This method offers a straightforward, quick, and effective way to treat FCS and recover fluorine resources, laying a foundation for producing other fluorides and opening a new path for future FCS treatment strategies.