Determining the Dispersion Characteristics of a modified Venturi Using CFD and Validating them in a Flotation Column within a Water-Air-Mineral system

Abstract

The design, evaluation, and metallurgical validation of a modified Venturi-type gas disperser for controlling the dispersion characteristics (bubble diameter, retained gas volume, and bubble surface area) in a laboratory flotation column are presented. The design was carried out using CFD simulations in a transient regime, evaluating different geometric and air-supply configurations. The optimal configuration corresponds to a 3:1 diameter ratio and four air inlets at 45°, which generated stable pressure drops and homogeneous dispersion.The simulated disperser was fabricated from polyamide and experimentally characterized in a water-air system under 35 operating conditions. Bubble diameters (Db) ranged from 0.63 to 2.31 mm, with retained gas fractions (εg) from 13 to 19% and bubble surface area flux (Sb) between 65 and 81 s⁻¹; these ranges are within the values typically recommended to improve particle capture and transport in column flotation.The characteristics of the simulated and experimental dispersions show similarities with differences of less than 20%.Subsequently, the disperser was evaluated in a three-phase system (water-air-mineral) for the concentration of a mineral containing 54 ppm of gold by reverse column flotation. The appropriate operating variables were established: superficial liquid velocity (Jl) of 0.0127 m/s, and superficial gas velocity (Jg) of 0.0085 m/s, achieving concentrations of up to 76 ppm Au in the tailings stream. Experimental results demonstrate that controlling Db, εg, and Sb through CFD design and experimental validation directly affects the metallurgical performance of the process, establishing a comprehensive methodology for designing dispersers for mineral applications.