Alumina and ferrosilicon extraction from nepheline syenite by carbothermal reduction; optimization by response surface methodology

The production of alumina from nepheline syenite via lime sintering generates significant waste due to the presence of silica. In this study, a carbothermal reduction process was proposed to simultaneously produce alumina and ferrosilicon, optimizing conditions using response surface methodology and the Box-Behnken design. The maximum conversion of silica to ferrosilicon was achieved at ۱۱۲۵°C with a soaking time of ۱۴.۸۶ minutes, a graphite-to-nepheline syenite mass ratio of ۰.۵۳, and a ferric oxide-to-nepheline syenite mass ratio of ۰.۷۲. The ferrosilicon produced was separated magnetically, leaving alumina, sodium, and potassium in the nonmagnetic fraction with efficiencies of ۹۰.۸۵%, ۹۱.۹۸%, and ۹۲.۰۱%, respectively. Following leaching, the overall extraction efficiencies were ۷۷.۱% for alumina, ۶۸.۴% for sodium, and ۸۲.۶% for potassium. This process provides a cleaner, more efficient alternative to lime sintering by minimizing waste and producing a valuable ferrosilicon by-product for industrial applications.

کلیدواژه ها:

Alumina extraction ، Carbothermal reduction ، Nepheline syenite ، Ferrosilicon