<p>Potassium was extracted from nepheline syenite (NS), primarily an alumino-silicate rock, using eggshell, a bio waste. Nepheline syenite has significant potassium content in the host matrix. Calcite is the main material that makes up eggshells, and it was utilized as a rich supply of calcium. The nepheline syenite was roasted using eggshell powder and sodium chloride. When NaCl and eggshell powder were mixed and roasted, calcium chloride was synthesized, which melted at the roasting temperature. The molten CaCl₂ penetrated the alumino-silicate matrix to replace potassium with calcium. K⁺ ions combined with Cl⁻ ions to form KCl, which dissolved in water when the roasted NS was subjected to lixiviation. The activation energy determined from the Arrhenius plot is approximately 140.4&#xa0;kJ per mole. Diffusion through the product layer is the main factor controlling the process rate, according to the analysis of the shrinking core models and the calculated activation energy for nepheline syenite roasting.</p>