Generation of Reactive Oily Bubbles by Microfluidics and Their Applications

Abstract

In this study, we present a new application of droplet microfluidics in the field of mineral flotation with reactive oily microbubbles (Gas-in-Oil-in-Water Emulsion). Different designs of devices were studied. Different flow regimes were found at different flowrate ratios. We found the condition to generate the oily bubbles with the least amount of oil usage and strong robustness against the fluctuation of flowrates. Under this condition, a relation is found between the size of the bubbles and the flowrate ratios. Reactive oily bubbles with collectors in oil phase were prepared using glass microfluidic devices. Thousands of oily bubbles of around 200 μm were collected per minute and used for mineral flotation. With microflotation test, oily bubbles were seen with particles attached. With in-device mixing, more particles attached onto one oily bubble. This technique would improve the collection efficiency of the fine mineral particles by stronger attractions and higher collision efficiency.