Effect of agitation on the interaction of coal and kaolinite in flotation

In this work, the interaction behavior and underlying mechanism of coal and kaolinite particles in the presence of agitation was investigated by flotation tests, homo and hetero settling tests, turbidity meter, zeta potential distribution, focused beam reflectance measurement (FBRM) and scanning electron microscope (SEM). The results show that, in the presence of kaolinite, the flotation combustible matter recovery of coal decreases from 0 rpm to 1200 rpm and then increases from 1200 rpm to 2000 rpm, indicating that the mild agitation enhances kaolinite-coating and the high intensity agitation mitigates the kaolinite-coating, which is demonstrated by the zeta potential distribution and turbidity measurements. However, the degree of the heterocoagulation between coal and kaolinite is not serious. It is found that the kaolinite particles partially cover on the coal surface by two morphologies includes individuals and aggregates through the size-based scanning electron microscope analysis. In addition, the affinity between fine kaolinite and fine coal particles is more pronounced. The kaolinite-coating enhancement caused by the mild agitation is explained by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. (C) 2017 Elsevier B.V. All rights reserved.