INTERFACIAL PROPERTIES OF COAL AND THEIR ROLE IN COAL BENEFICIATION (WETTABILITY, FLOTATION)

A better understanding of the interfacial properties of coal and their role in coal flotation is essential for establishing the basic principles of coal flotation and/or coal chemistry in general. Four different rank coals were first characterized by proximate and ultimate analyses in conjunction with density and surface area measurements. Effects of oxidation on surface properties of coal were investigated in terms of oxygen functionality, electrokinetic behavior, salt flotation response and heat of displacement. Coal wettability was assessed by measurements of immersion time and contact angle. Coal flotation tests were carried out with a set of miniature vacuum flotation cell and a modified Hallimond tube. A good correlation of flotation and wetting was found, which indicates that immersion time measurement is a tool in assessing vacuum flotation and that contact angle measurement is valuable for assessment of adsorptive-bubble flotation.