Valorization of Feldspar Processing Tailings by Flotation: Effects of Reagent Scheme, Flotation Cell and Bubble Size

This study investigates the potential for recovering valuable minerals from feldspar tailings generated during industrial processing and commonly discarded as waste, causing both economic losses and environmental concerns. A hydrocyclone overflow sample obtained from a feldspar processing plant in the Muğla region of Türkiye was characterized and evaluated for the production of a marketable feldspar concentrate by flotation. Bulk and selective reverse flotation tests were performed using Denver and TK Lab flotation cells incorporating different impeller–stator configurations to evaluate the combined effects of reagent chemistry, flotation cell hydrodynamics, and bubble characteristics on flotation performance. The Sauter mean bubble diameter (d32) was measured under both two-phase and three-phase conditions to characterize bubble size. Compared with the conventional plant reagent scheme (Derna-7 and Der A4), the sequential flotation scheme employing sulfonate collectors (R801–R825) for Fe–Ti-bearing minerals followed by the amine collector DAHC for mica significantly improved impurity rejection. The highest concentrate quality was achieved in the TK Lab Cell, producing a feldspar concentrate containing as low as 0.49% Fe2O3 while maintaining a total alkali content of 9.57%, satisfying the Fe2O3 requirement for second-grade ceramic applications. Despite producing larger bubbles than the Denver Cell, the TK Lab Cell exhibited superior rejection of Fe–Ti-bearing minerals. The consistently larger bubbles generated by the TK Lab Cell, irrespective of the reagent scheme employed, indicate that the different impeller–stator configurations played a key role in governing bubble generation and gas dispersion, while reagent chemistry primarily modified bubble characteristics within the hydrodynamic environment established by each flotation cell. The results demonstrate that flotation performance is governed by the combined effects of reagent chemistry, flotation cell hydrodynamics, and bubble characteristics, providing new insights into the sustainable valorization of feldspar processing tailings.