Micro-nano bubbles properties induced by hydrodynamic cavitation and their influences on fine mineral flotation

By using a homemade micro-nano bubbles generator based on hydrodynamic cavitation principle, the properties of micro-nano bubbles generated and their effects on the flotation behaviors of fine diaspore minerals were studied through laser particle size analyzer, Zetasizer and surface tension meter, etc. The results show that hydrodynamic cavitation pretreatment of sodium oleate solution(NaOl) can produce micro-nano bubbles in the bulk solution. With the increase of NaOl concentration, the pH values of solution and cavitation intensity, the average size distribution of micro-nano bubbles in the solution continuously decreases. When the cavitation time is short, submicron and nanoscale bubbles can be formed in NaOl solution, while as cavitation time raises, the average size distribution of bubbles in the solution system increases. The additional aeration provides a large number of gas nuclei for the cavitation system, which promotes the generation of a large number of micro-nano bubbles in the cavitation process, and the bubble merger results in a significant increase in the size distribution of the micro-nano bubbles. Micro-nano bubbles have good stability, especially submicron and nanoscale bubbles, which can stably exist in the solution system for more than one hour. Lastly, the introduction of micro-nano bubbles in the flotation agent solution before flotation can significantly enhance the fine diaspore flotation, especially at low agent concentration. © 2019, Science Press. All right reserved.