Kinetics of bubble-particle attachment and detachment at a single-bubble scale

Abstract

Bubble-particle attachment and detachment are fundamental subprocesses of flotation, a deep understanding of which is essential for predicting flotation kinetics. This paper focuses on the kinetics of bubble-particle attachment and detachment at a single-bubble scale. Kinetics experiments of attachment, detachment, and flotation using coal samples with low-density fraction (LDF), middle-density fraction (MDF), and high-density fraction (HDF) were conducted. Models of bubble-particle attachment and detachment kinetics were proposed by an analogy with flotation kinetics equations. With an increase in coal density, the attachment rate constant decreased, while the detachment rate constant increased, which was consistent with the decrease in floatability of coal. In addition, the experimental data of the attachment and detachment kinetics was compared with flotation kinetics (multi-bubble scale). The optimal fitted models for LDF and MDF were the classical first-order models of attachment/detachment/flotation kinetics. These consistencies indicated the floatability of coal could be characterized by the attachment and detachment kinetics at a single-bubble scale. This was not the case for HDF (gangue minerals in essence), since its optimal models of the attachment/detachment kinetics were the third-order models, while for flotation kinetics was the first-order model with rectangular distribution. This contradiction indicated the flotation of the high-density particles might be significantly affected by the bubble concentration.