Recycling Fluoride from Spent Pot Lining (Spl) as a Flux for Production of Continuous Casting Mold Powder

Abstract

In this study, based on the production process of mold powder and water washing process of SPL, a new method for SPL treatment with harmless and resourceful was proposed, which was to recover the fluorine in SPL and add it as a flux to the mold powder for the fluorine fixation. The results indicated that the temperature significantly affected the leaching concentration of Na+ and F-; when the mold powder was sintered to 800 °C, the main crystalline phase of the sample consisted of gunite (Ca4Si2O7F2), and wollastonite (CaSiO3); the F- concentration was higher than that in the slurry, further revealing that the NaF in the mold powder not caused environmental pollution due to volatilization during spray drying; by analysing the crystal spot diffraction images of the slurry, the crystals are monoclinic crystal system, which further confirmed that the NaF in the slurry to have been converted into Ca4Si2O7F2 to achieve fluorine fixation, and indicated that there is no amortisation in the preparation of NaF-containing mold powder slurry. The granule size range of mold powder containing SPL was calculated by numerical simulation to be 0.18-0.62 mm, which was closer to the ideal granule range (0.2-0.6 mm), and the results of the industrial test were consistent with the above numerical simulation results.

Keywords: Resource recovery, Mold powder, Spent pot lining, Fluorine fixation, Numerical simulation