This paper aims to understand the fundamental interaction mechanism between molybdenite and kaolinite in gypsum solution using kerosene as collector. Micro-flotation tests were conducted to study the effect of gypsum solution on the flotation performance of mixed −74 μm molybdenite and −10 μm kaolinite mineral. The results showed that the recovery of molybdenite decreased from 86% to 74% while the gypsum solution concentration increased from 0 to 800 mg/L, indicating the detrimental effect of

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... olinite on molybdenite flotation could be enhanced by gypsum solution. This is mainly caused by the slime coating of kaolinite on molybdenite through dissolved calcium ion of gypsum solution. In order to confirm the slime coating phenomenon, zeta potential distribution, scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements were used to investigate interaction characteristics and mechanisms. The zeta potential distribution results revealed that mixed samples had the value between signal molybdenite and kaolinite samples in gypsum solution, which proved the coating phenomenon of kaolinite on molybdenite. Moreover, the coating phenomenon was becoming more and more obvious with the gypsum solution concentration. The coating phenomenon of kaolinite on molybdenite surface was also directly observed from SEM results. The AFM results provided further evidence for the possibility of slime coating, as the adhesion force increased with the gypsum solution concentration, which means the aggregates of molybdenite and kaolinite were becoming more stable.