Recent Advances in Selective Flotation Separation of Quartz and Feldspar: Separation Processes and Collectors

Quartz and feldspar are used in a range of industrial applications owing to their distinct physicochemical properties. However, their selective separation remains challenging because of the similar bulk and surface physicochemical properties. Froth flotation has become the principal approach for quartz–feldspar separation, whereas conventional hydrofluoric acid-based processes are increasingly restricted by their toxicity, corrosivity, and environmental impacts. This review critically summarized the development of quartz–feldspar flotation from traditional HF systems to fluoride-free acidic processes and emerging fluoride- and acid-free technologies. Particular attention was given to the flotation behavior and adsorption mechanisms of cationic, anionic, and mixed cationic/anionic collectors under different pH conditions. The roles of surface charge, active sites, electrostatic interactions, hydrogen bonding, chemisorption, and synergistic adsorption in governing flotation selectivity were systematically discussed. Recent advances emphasized reduced reliance on HF and molecular-level regulation of mineral interfaces. However, laboratory selectivity does not by itself establish industrial applicability. This review also evaluated constraints imposed by fine particles, slimes, impurities, dissolved ions, recycled process water, and incomplete liberation, and identifies priorities for pilot- and plant-scale validation of promising fluoride-free and acid-free systems.