Sustainable route for silica preparation from silica fume.

Silica fume (SF) is a major voluminous and bulky by-product of the ferrosilicon industry, and its disposal poses a significant environmental concern. To address this issue, a sustainable approach was employed to transform SF into silica powder using a precipitation method. The process involved calcination, acid precipitation, aging, and drying, utilising industrial by-products such as silica fume and calcium oxide. Various parameters, including hydrochloric acid concentration, water bath temperature, aging pH, aging temperature, and aging time, were systematically investigated to optimise the properties of the resulting silica product. The physical and chemical attributes of the processed silica were thoroughly examined using techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), laser particle size analysis, and dibutyl phthalate (DBP) absorption tests. Under optimal conditions (hydrochloric acid concentration of 20%, water bath temperature of 90℃, aging pH 3-4, aging temperature of 90℃, and aging time of 8 hours), the resulting silica product achieved a purity of 98.5866%, a DBP absorption value of 2.85 mL/g, and a particle size of 6.07 µm, meeting national industry standards. This environmentally benign and cost-efficient synthesis route offers a practical solution for large-scale production.