Structure optimization of pneumatic micro-bubble flotation machine based on numerical simulation

Pneumatic micro-bubble flotation machines have emerged as useful flotation devices in recent years, offering advantages such as high processing capacity, simple structure, and energy and reagent savings. Their pneumatic particle-bubble collision performance and internal flow field characteristics need much development to support current inferior ores. Additionally, systematic theoretical guidance for structural optimization and scaling-up endeavors is necessary. In this study, Computational Fluid Dynamics (CFD) numerical simulation techniques were used to simulate the flow field characteristics within the flotation cell of a pneumatic micro-bubble flotation machine. Theoretical analysis of its particle-bubble collision and separation principles was also conducted. Through the aforementioned investigations, it was observed that the internal flow field of the pneumatic micro-bubble flotation machine exhibited excessively rapid gas–liquid phase ascent, inadequate flow field stability and dispersion, and instances of direct discharge of some pulp and bubbles from the tailings pipe. To address these issues, structural optimization of the pneumatic micro-bubble flotation machine was performed by altering the arrangement of the micro-bubble generator within the flotation cell and adjusting the structure of the micro-bubble generator outlet. Following these adjustments, the ascent velocity of pulp and bubbles within the flotation machine decreased, dispersion within the flotation cell enhanced, air fraction near the flotation cell’s wall decreased, and interference of the flotation cell’s wall with the gas phase weakened, while the phenomenon of gas–liquid phase overflow from the tailings pipe was mitigated.