Study on the preparation and formation factors of frother emulsion

The conventional method of dropwise adding frothers causes waste of reagents and fluctuations in the flotation performance. An improved method was proposed to break the frother into tiny droplets to prepare emulsions. This work focused on the formation factors and mechanisms in preparing qualified frother emulsions for industrial applications. Selected emulsification objects, isopentanol, methyl isobutyl carbinol, and 2-octanol, were compounded with Span80 and Tween20 under different HLB. The best HLB of the three emulsions were 13, 15, and 13, respectively. The control variable method was adopted to prepare the emulsions with single-factor variables, including shear time, shear rate, emulsifier dosage, and frother content. The optimized experimental conditions to prepare frother emulsion were a shear time of 8 min, the shear rate of (4000 ± 1000) r/min, emulsifier dosage of (3.5 ± 1) %, and frother content of (30 ± 5) %. The response surface optimization experiment was carried out with Design Expert 8.0. Optimized conditions to prepare isopentanol emulsion, methyl isobutyl carbinol emulsion, and 2-octanol emulsion include shear rate of 3910, 4082, 4156 r/min, emulsifier dosage of 4.04, 3.28, 3.72%, frother content of 26.51, 30.07, 27.49%, and predicted particle sizes of 247, 202, 196 nm, respectively. The formation mechanism of frother emulsion prepared by the shearing method was analyzed based on the analysis of formation factors. Under shearing action, the frother was broken into small oil droplets and well dispersed in the oil-water system. The emulsifier formed an interface film on the frother droplets surface to prevent the droplets from coalescing, enhancing emulsion stability. In addition, the ionic emulsifier could also form an electric double layer, which further prevented the coalescence through electrostatic repulsion and boosted the emulsion stability. The flotation experiment results showed that emulsified 2-octanol produced a higher concentrate yield than 2-octanol, confirming the emulsification's promotion effect.