Study on Separation of Fine Particles Using Rising Microbubbles

Abstract

Bubbles with a diameter of 1 to 100 μm are defined as microbubbles (hereinafter, this is called "MB"), and are used for floatation separation because of their adhesion to suspended substances. However, there are few research reports on floatation separation, and standardization for device design has not been performed, so improving the efficiency of floatation separation devices has become an issue. Therefore, in this study, the experiments were carried out to clarify the floatation separation characteristics by microbubbles as a basic research of floatation separation by microbubbles. In the experiment, the soft flour was used as a suspended substance, and as basic characteristics, the state of adhesion with microbubbles, the relationship with bubble diameter, and the rising velocity rate were measured. In addition, as the actual floating separation performance, the concentration time with each initial concentration was investigated. The conclusions are as follows: About 60% of the adhered form of the microbubbles and the soft flour was observed as a form in which a single microbubble adhered to the soft flour. The number of microbubbles with a bubble diameter of 80-90 μm was attached in the case of single microbubble attachment to flour is large. In the floating separation characteristics, floatation the soft flour concentration in the tank decreases sharply at the short time, and then gradually decreases. The higher the initial concentration, the longer the processing time required to reach the target concentration, but the tendency of the concentration decrease was the same. The final concentration remains around 20 ppm in all experimental conditions. These results are important for standardization of floatation separation characteristics in the future.