MOLECULAR DESIGN OF FLOTATION COLLECTORS: A RECENT PROGRESS Guangyi Liu, Xianglin Yang, Hong Zhong College of Chemistry and Chemical engineering, Central South University, Changsha, 410083, China ABSTRACT The selective adsorption of a flotation collector to a targeted mineral plays a key role in enhancing the hydrophobicity of mineral particles for attaching air bubbles. The development of special flotation collectors for recovery of valuable minerals from the refractory complex ores has been an urgent demand in recent years. The molecular design offers an indispensable approach to research and develop novel flotation collectors which contains head group and tail chain in their molecular structure. The conditional stability constant, molecular mechanics and dynamics, quantitative structure-activity relationship (QSAR), and first-principle theory, especially, density functional theory (DFT) have been adopted to build the criteria for designing head group. Acyl thioureas and thionocarbamates, guanidines, aromatic and heterocyclic thiones, double head group collectors such as Gemini, diamines, dithiourea, dithionocarbamate, sulfydryl-oximido surfactants have recently been developed. In evaluation of tail chain, hydrophilic-hydrophobic balance parameters such as CMC (critical micelle concentration), HLB (hydrophile-lipophile balance number) and LogP (oil - water partition coefficient) have been extensively adopted. Replacement of aryl tail with aliphatic tail, introduction of oxygen into the alkyl tail and addition of trisiloxane to the tail terminal have been found to be effective approaches for adjusting hydrophilic-hydrophobic balance of collectors. Furthermore, amide groups grafted to tail chain of a collector have been proved to improve the hydrophobicity of mineral particles adsorbed the collector by aligning neighboring collector species closer through intermolecular hydrogen bonds and weakening the effect of water molecules on the interfacial tension of mineral particles. Based on the crucial review, some comments and prospects for further investigation on molecular design of flotation collectors were also presented in this paper. KEYWORDS Flotation collector, Molecular design, Head group, Tail chain, Criteria, Hydrophobicity Corresponding author. Tel.: +86 731 88830654, fax: +86 731 88879616; E-mail addresses: [email protected] (Guangyi Liu).