Experimental study on the preconditioning of fine coal particles surface modification using a new type flow mixer

Abstract

The preconditioning process prior to flotation separation has crucial effects that increase the hydrophobicity difference between coal and minerals. In this study, a new type of flow mixer without an agitator was designed to conduct preconditioning experiments of fine coal particles with different conditioning times. The hydrophobicity enhancement of the conditioned coal was quantitatively characterized by the contact angle and induction time analyses with appropriate conditioning time. The Fourier transform infrared and X-ray photoelectron spectroscopy measurement results indicated that the fluid intensification for coal surface modification principally appeared as surface cleaning and interaction improvement between the collector and coal particles. The flotation performance of a seven-minute conditioning, such as the flotation recovery and rate, was comprehensively better than that of other conditions, and the flotation process was more reasonable to be described using the matrix first-order model. The particle size distributions in the flotation products experienced three main changing stages of the fine-intermediate-coarse size fractions. The scanning electron microscopy–energy dispersive spectroscopy results further demonstrated the positive effects of fluid intensification on the surface microcosmic characteristics by the seven-minute conditioning.