Rare earth elements (REEs), which are found and produced in only a limited number of countries worldwide, are projected to be insufficient to meet the growing global demand in the near future. This situation has prompted increasing interest in alternative production routes from secondary geological sources with low uranium (U) and thorium (Th) contents. Among these, ionic clays, red mud, fly ash, bauxite, and related ores have emerged as promising potential sources. In particular, bauxite and its associated ores are considered significant secondary geological resources due to their relatively high REE concentrations.

In this study, the recoverability of REEs and aluminum (Al) from high-silica bauxite ore that cannot be processed by the Bayer method was investigated. The Kemiklitepe bauxite ore (Karaman, Türkiye), characterized by its high silica content and appreciable REE concentrations, was evaluated as a potential alternative source of these critical materials. A novel and sustainable process was developed for the simultaneous recovery of Al and REEs through an alkali roasting–acid leaching route. The finely ground ore was alkali-roasted with Na₂CO₃ at 800–1000 °C, followed by a two-step leaching procedure involving water and sulfuric acid (H₂SO₄). Acid leaching achieved a total REE recovery of approximately 87%. Subsequently, the selective extraction of REEs and Al from the pregnant acidic leach solution was investigated using the solvent extraction (SX) method. Key operational parameters including extractant (D2EHPA) concentration, reaction time, pH, and organic-to-aqueous phase ratio were optimized using the Taguchi design method. The results demonstrate that the proposed process enables efficient and environmentally sustainable recovery of both Al and REEs from high-silica bauxite, highlighting its potential for resource diversification and zero-waste processing.