Utilization of Fluoride from Treated Spent Pot Lining as a Flux of Mold Powder

This study introduces an innovative method for the treatment of spent pot lining (SPL) that is both environmentally sustainable and resource‐efficient, leveraging mold powder manufacturing and the low caustic leaching & liming process. The proposed approach involves recovering fluorine‐containing wastewater and incorporating it into mold powder as a flux and solvent. The results demonstrated that the temperature significantly affected the leaching concentration of Na + and F − . Upon sintering at 800 °C, the primary crystalline phases identified are cuspidine (Ca 4 Si 2 O 7 F 2 ) and wollastonite (CaSiO 3 ). The concentration of F − ions in the mixture exceeded that found in mold powder slurry, revealing that both SPL‐containing and SPL‐free mold powders undergo a solid‐phase reaction with CaSiO 3 to produce Ca 4 Si 2 O 7 F 2 after heating. Analysis of the crystal spot diffraction patterns of the slurry revealed that the crystals belong to the monoclinic crystal system, confirming that the NaF in the slurry has been successfully transformed into Ca 4 Si 2 O 7 F 2 , thereby achieving fluorine fixation. This also suggested that no amorphization occurred during the preparation of the NaF‐containing slurry.