Interaction mechanism of interfacial nano-micro bubbles with collectors and its effects on the fine apatite flotation

[Display omitted] •Instantaneous reduction in ambient pressure generates interfacial nano-micro bubbles (INMBs).•The INMBs show promotional and depression effects in the NaOl and DDA systems, respectively.•INMBs “clean” the adsorbed reagents on the apatite surface.•Single INMBs cannot stabilize the apatite particles into flocs.•INMBs enhance the apatite aggregation in NaOl rather than DDA. This study focuses on the −38 μm apatite as the research subject and investigates the role of interfacial nano-micro bubbles (INMBs) generated by decompression techniques in the collector system of sodium oleate (NaOl) and dodecylamine (DDA). The results reveal that INMBs enhanced the flotation recovery of apatite using the collector NaOl while it had a slight inhibitory effect on apatite flotation with the collector DDA. The impact of INMBs on the apatite flotation was notable in pH 8–9, which could be attributed to the negative surface charge of INMBs. XPS analysis indicates that INMBs did not alter the collector adsorption by which the reagent molecules bonded with the apatite surface. AFM imaging and adsorption capacity experiments further reveal that the INMBs resulted in an adsorption density reduction of the reagent. This drop could be attributed to the nucleation and growth of INMBs, which effectively cleaned the collector molecules from the mineral surface. The transmittance test findings show that INMBs could significantly promote apatite aggregation in the collector system of NaOl rather than DDA. Overall, the difference in the roles of INMBs on apatite flotation using different collectors is considered as the combined influences of negative “surface reagent cleaning” and positive “fine particle aggregation”.