Insights into the synergistic adsorption mechanism of mixed SDS/DDA collectors on biotite using quartz crystal microbalance with dissipation

•The flotation performance of biotite using the mixed anionic/cationic collectors has been studied.•Adsorption behavior of SDS, DDA and their mixtures onto biotite is investigated using QCM-D.•A rigid and compact multilayer is formed on biotite surface after treated with the SDS/DDA collectors.•Mixed SDS/DDA collectors are co-absorbed on the biotite surface.