DETERMINATION OF FLOTATION KINETICS OF COAL GRAIN TYPES IN A PILOT SCALE JAMESON CELL USING COAL GRAIN ANALYSIS METHOD

摘要

Coal’s ability to be recovered by the froth flotation process is due to its hydrophobic nature.Hydrophobicity is influenced by intrinsic properties such as the coal rank, particle size andcomposition, and degree of oxidation. In coal flotation particles of different components of the coal,such as maceral groups and mineral matter and their associations, have different hydrophobicitiesand therefore different flotation responses.The semi-automated optical imaging system, Coal Grain Analysis (CGA) can be used to assessflotation performance of individual grain types present in coal samples. The technique involves theuse of optical microscopic imaging techniques to provide a reflectance fingerprint of the sample andhence an industry standard measure of coal rank as well as size, composition, density and ash valueinformation on individual grains of fine coal. With this method microlithotype nomenclature wasused for the single component grains, with grains comprised of >95 per cent vitrinite, inertiniteand minerals classified respectively as vitrite, inertite and minerite. The composite grains weresubdivided based on their maceral/mineral associations as being vitrinite-rich composites (VitRich),inertinite-rich composites (InertRich) or mineral-rich composites (MinRich).This technique was used to analyse laboratory flotation feed samples of coal from the MoranbahNorth Coal Mine in Central Queensland. A matched set of five concentrate samples (sampled atdifferent time intervals) and a tail sample were obtained from laboratory flotation kinetic testconducted using a laboratory scale Jameson Cell were analysed by the CGA method. This informationenabled the kinetics of flotation of the coal and for the individual grain types to be determined.The flotation rate constants for all the grain types determined show vitrite has the highest flotationrate constant following the other grain types vitrinite rich, inertinite rich, inertite, mineral rich andminerals in order.