Critical fall height for particle capture in film flotation: Importance of three phase contact line velocity and dynamic contact angle

The capture of a falling particle at a horizontal gas-liquid interface (film flotation) is determined by the particle impact velocity and the subsequent motion of the three phase contact line (TPCL) as the particle penetrates into the liquid. In this study, the three phase contact lines were observed experimentally using high speed video camera for a number of different particle liquid systems. The particles comprised hydrophilic glass bead particles with and without surface hydrophobicity treatment. The liquid comprised water, and NaCl, sucrose and hexadecyltrimethylammonium bromide (CTAB) aqueous solutions with different concentrations. Previous modelling of Liu et al. (2010a) was extended to include the advancing velocity of TPCL on dynamic contact angle. The critical fall height predictions by the modified model compared favourably with experimental measurements.