ABSTRACT
The use of inorganic salts in coal flotation, named “salt flotation” dates some decades ago. Along the time, many studies have tried to explain the inorganic salt influence that often is a positive one on the flotation process results. The resulted ions in electrolyte dissociation can be adsorbed on the coal surface and they become the potential determining ions. The adsorption capacity of these ions depends on the coals surface character – on the metamorphism degree, its petrography composition and oxidation degree. The flotation of the fine coals with less floatability than those with high contents in very fine fractions, ash and oxidized surfaces can be favourably influenced by the presence of an electrolyte. The aim of this research is to establish the effect of natrium sulphide, as modifying reagent, on two fine coal samples of bituminous and subbituminous type.
