Flotation separation of diaspore and kaolinite by using dodecanamide and cetyltrimethylammonium bromide as an effective mixed collector

•DDAA and CTAB as a mixed collector presented an excellent flotation performance.•The difference value of the CTAB adsorption amounts was enlarged.•Dodecanamide played an auxiliary role in the flotation process.•The adsorption mechanism of mixed collector was investigated. The performance of dodecanamide (DDAA) and cetyltrimethylammonium bromide (CTAB) used as the mixed collector on flotation separation of diaspore and kaolinite was investigated in this paper. The results of flotation experiments for single minerals showed that the kaolinite presented a good flotability but diaspore presented a poor flotability by using the mixed reagents of DDAA and CTAB as a collector around pH 5. The results of artificial mixed minerals showed that not only the mass ratio of Al2O3 to SiO2 (A/S) was remarkably increased but also the effective flotation separation of diaspore and kaolinite was carried out by using DDAA and CTAB as a collector. FTIR spectra indicated that DDAA and CTAB were adsorbed on the minerals surface. Zeta potentials analysis, adsorption amounts and XPS analysis illustrated that the difference value of the adsorption amounts of CTAB between diaspore and kaolinite was enlarged due to the addition of DDAA. Moreover, the adsorption mechanism of DDAA and CTAB on the minerals surface by molecular dynamics simulation indicated that DDAA with diaspore exhibited more negative interaction energy while CTAB with kaolinite exhibited more negative interaction energy. The interaction energy difference resulted in the varied relative concentrations of the reagent molecules on the minerals surface. The theoretical calculations supported the experimental results. The enlarged difference was favorable to the increase of the flotation separation performance of minerals.