Effects of slurry density and viscosity on gas dispersion in a gas-inducing stirred tank for mineral flotation

Gas-inducing stirred tanks (GISTs) are widely applied in mineral flotation, where the elevated density and viscosity of mineral slurries strongly influence gas induction and gas–liquid dispersion. However, the effects of slurry physical properties on gas-inducing performance have not been systematically quantified. In this study, computational fluid dynamics (CFD) simulations combined with experimental validation were conducted to investigate the effects of agitation speed, slurry density, viscosity, and surface tension on the gas dispersion characteristics of an inner draft-tube GIST. A gas flux predictive model was subsequently established based on the simulation results. Agitation speed was identified as the dominant operating parameter, while slurry density exhibited a non-monotonic influence on gas dispersion, with a pronounced minimum near 1000 kg/m 3 followed by recovery at higher densities. Increasing viscosity markedly suppressed gas induction, and the gas-inducing capability deteriorated rapidly when the viscosity approached 0.1–0.2 Pa·s, indicating a practical operating limit for high-viscosity slurry systems. In contrast, surface tension showed only a minor influence on macroscopic gas-inducing performance under the investigated conditions. The proposed predictive model showed satisfactory agreement with the CFD data, with R 2 ≥ 0.868 and MAPE ≤ 9.1%. These findings provide new insights into gas dispersion in high-density mineral slurries and offer a practical tool for the design, optimization, and scale-up of gas-inducing stirred tanks for mineral flotation. The proposed model is applicable to the investigated inner draft-tube GIST within the studied ranges of operating conditions and slurry properties.