Effect of ultrafine kaolinite particles on the flotation behavior of coking coal

Abstract

Abstract Kaolinite, as a mineral in fine coal, has an important influence on the flotation of coal particles. In this study, the effects of ultrafine kaolinite particles on the flotation recovery of coal particles were investigated. Flotation tests were carried out using a mixture of coal particles and different amounts of ultrafine kaolinite particles. Combined with the Stefan–Reynold theory, the effect of liquid film drainage rate between coal bubbles in a kaolinite suspension was calculated. The yield of flotation clean coal increases quickly with the increasing content of ultrafine kaolinite particles. The ultrafine kaolinite particles can reduce the surface tension of the suspension, weaken the bubble coalescence, and stabilize the structure of the froth layer. In addition, the ultrafine kaolinite particles increase the apparent viscosity of the flotation pulp slightly. It is concluded that the role of ultrafine kaolinite particles on the positive effect of froth properties conceals the negative effect on the liquid film drainage rate between coal particles and bubbles caused by the kaolinite particles, which ultimately leads to an increasing yield of clean coal with an increasing content of kaolinite particles. This study is important for understanding the influence of ultrafine kaolinite on coal particle flotation.

Keywords

• Coal flotation
• Surface tension
• Apparent viscosity
• Liquid film drainage