Role of oil droplet size on dynamic pore wetting of active carbon and particle-bubble interaction: New inspiration for enhancing the porous mineral floatability

The dynamic pore wetting plays a vital role in the flotation separation process of porous mineral particles, such as low-rank coal, fly ash and chrysocolla, etc. This paper investigated the dynamic pore wetting behavior of active carbon particles in the water-oil emulsion by 1 H low-field nuclear magnetic resonance ( 1 H LF-NMR). The influence of oil droplet size on pore wetting process was revealed. The change in the surface properties of particles before and after wetting was analyzed by contact angle and FTIR measurements. The particle-bubble attachment process in the emulsion and pure water was compared. The total pore wetting percentage of active carbon had a first-order kinetic relationship with the wetting time. The emulsion was beneficial to decrease the pore wetting percentage of particles compared with water. And the pore wetting percentage decreased with the decrease of oil droplet size in emulsion. The pores were easily filled by the oil droplet with small size and the hydrophobicity of sample surface was improved, which prevented the subsequent pore wetting by water. As a result, the detachment force of particle-bubble was increased with the help of micro-oil droplets. This work attempts to provide a new inspiration for the study of porous mineral flotation.