THE ADSORPTION BEHAVIOR OF NONIONIC REAGENTS ON 2 LOW-RANK BRITISH COALS

Reagent usage and particle size are important factors in the beneficiation of coal by froth flotation. For ultrafine particles, the recovery and purity of the final product obtained depend on the froth structure, which is affected by reagent adsorption on the solids and the nature of solids. In this study, the -5 mum size fractions of two low rank British coals, taken from Bickershaw and Rawdon collieries, were used in reagent adsorption measurements. The adsorption studies were carried out using two different non-ionic reagents; diacetone alcohol and 2-ethyl hexanol. The fine coal fractions were chosen to reflect the degree of fine grinding required to liberate the mineral particles from the coal. Measurements of the internal pore distributions showed marked differences between Rawdon and Bickershaw coals. Molecular modelling of the surfactants was performed and it was found that both diacetone alcohol and 2-ethyl hexanol were small enough to penetrate the interior pores, in a randomly oriented fashion. The adsorption of the reagents strongly depends on the chemical nature of the reagents and the coal surface. Molecular orientation of the reagent molecules to the coal surface also plays an important role on the adsorption process.