Selective flotation of lepidolite from albite and quartz using a Hyperbranched surfactant THQ-8: Insights through foam property and adsorption behavior

THQ-8 has selectivity for lepidolite over albite and quartz under near-neutral conditions; • THQ-8 addresses key limitations of conventional cationic collectors by excellent foam properties; • THQ-8 achieves coordination adsorption between its conjugated structure and Al-F sites; • THQ-8 represents a molecular design strategy for environmental lithium resource recovery. The efficient flotation separation of lepidolite from quartz and albite remains challenging in conventional cationic systems, primarily due to poor selectivity and excessive foam stability. To address these issues, a novel oligomeric surfactant, THQ-8, was synthesized and investigated as a potential collector for lepidolite flotation. Micro-flotation results confirmed the superior selectivity of THQ-8, with recoveries of 95.94% for lepidolite versus only 6.32% for albite and 9.57% for quartz, enabling efficient separation. This performance surpassed that of the traditional collector dodecylamine (DDA), which required a highly acidic pulp (pH 2.0), and the Gemini collector PDDA, which lacked selectivity. Complementing this selectivity, also produced foam with markedly lower stability and height than both counterparts, indicating favorable froth properties for mineral processing. A multi-faceted adsorption mechanism study, incorporating contact angle measurements, FTIR, XPS, and AFM, confirmed that THQ-8 selectively chemisorbs onto the lepidolite surface. The primary mechanism involves coordination between the electron-donating nitrogen atoms in its large conjugated structure and the aluminum sites in the natural Al-F and AlF 3 /AlF x layers of lepidolite. In contrast, only weak physisorption or hydrogen bonding occurred on albite, and virtually no adsorption was detected on quartz. This work establishes THQ-8 as a highly effective and selective collector for lepidolite, operating under milder process conditions and overcoming the key limitations of foam stability and corrosion associated with conventional reagents. Download: Download high-res image (212KB) Download: Download full-size image