مشخصات پژوهش

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 1125 °C with a soaking time of 14.86 minutes, a graphite-to-nepheline syenite mass ratio of 0.53, and a ferric oxide-to-nepheline syenite mass ratio of 0.72. The ferrosilicon produced was separated magnetically, leaving alumina, sodium, and potassium in the nonmagnetic fraction with efficiencies of 90.85%, 91.98%, and 92.01%, respectively. Following leaching, the overall extraction efficiencies were 77.1% for alumina, 68.4% for sodium, and 82.6% 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.