Abstract:Traditional electrolytic flotation uses iron mesh as electrodes for the flotation of fine-grained minerals. The neglect of bubble property control and the mixing of hydrogen and oxygen have prevented the accurate assessment of the key mechanisms governing the recovery of fine-grained minerals. By separating gases， electrolytically active hydrogen microbubbles can be generated in situ. These bubbles are characterized by a hydrogen atmosphere，high surface activity，and small bubble size. This study investigated the regulatory processes of active hydrogen microbubble gas production and particle size under varying electrolytic process parameters （electrolyte type， concentration，current），electrode material density，and foaming agent （type and addition amount）. The optimal gas production conditions were applied to experimental studies on the flotation of microfine graphite particles using active hydrogen microbubbles. Experimental results indicated that the catalyst prepared using 1 mol/L Na2SO4 and a 90 ppi substrate could achieve optimal gas production and bubble size at a current of 1 A,while -10 μm bubbles account for 36%，and 10-20 μm bubbles account for 58%. The types and concentrations of electrolytes，current intensity， electrode material density，and foaming agents regulated the surface properties of hydrogen microbubbles and their growth and desorption through the ionic environment，electrochemical driving force，microbubble interaction forces， and microbubble surface tension. Compared with traditional electrolytic flotation，active hydrogen microbubbles with smaller particle size and higher surface activity could effectively recover micro graphite particles ranging from 1 to 11 microns in size and significantly improved the recovery rate of micro graphite. The interaction between active hydrogen gas microbubbles，reagents，and graphite was investigated by measuring surface tension，contact angle， Zeta potential，and FT-IR. The results indicated that the essence of electrolytic active hydrogen microbubble- enhanced fine-grained graphite flotation lied in the regulation of the gas-reagent-mineral interface by active hydrogen microbubbles. Electrolytic active hydrogen microbubbles reduced the electrostatic repulsion between graphite particles and enhanced hydrophobicity. The addition of collectors formed a stable hydrophobic coating on the graphite surface， further enhancing the adhesion between active hydrogen microbubbles and graphite. Therefore，the strategy proposed in this study for regulating the gas production rate and bubble size of active hydrogen microbubbles can effectively improve the flotation recovery rate of fine-grained graphite by adjusting the surface activity of active hydrogen microbubbles. It also provides new insights for the electrolytic flotation recovery of fine-grained minerals.