Study on Dynamic Behavior and Mechanism of Reverse Flotation of Micro-fine Hematite (MFH) Enhanced by Nanobubbles (NBs)

In order to enhance control of hematite reverse flotation systems, we investigated desiliconization mechanism of surface nanobubbles (NBs) in reverse flotation of micro-fine hematite (MFH). The reverse flotation mechanism of NBs enhancing MFH was studied based on flotation dynamics tests, adsorption dynamics, adsorption dynamics calculations, and zeta potential tests. The results showed that the reverse flotation desilication of MFH can be completed 180 s earlier compared to the process without NBs, and that NBs can efficiently recover ultra-fine hematite with a particle size less than 10 mu m, which is about 5% higher than that without NBs. In addition, the presence of NBs improved the adsorption rate and adsorption capacity of the collector on quartz surfaces compared to the absence of NBs; especially; the adsorption rate was significantly higher than the absence of NBs when the adsorption time was less than 1.7 min and the maximum adsorption capacity was higher than the absence of NBs by 0.10 mg/g. The zeta potential test showed that NBs reduce the potential of the quartz surface, mainly because they promote the adsorption of Ca2+ on the quartz surface to provide more active sites for the second adsorption of the collector, thus improving the desilicification rate of reverse flotation for MFH.