Enhanced Recovery by Hydrotropes in Oxidized Coal Flotation

Abstract

Abstract

So far flotation proved its best in improving the concentration of low grade fines by recovering the maximum with the use of advanced flotation reagents. In this context we propose the process optimization with the use of hydrotropes as activators in the coal flotation process. It is observed that sodium benzoate a known hydrotrope helped in increasing the recovery of the concentrate percent from 12.8% at plant condition to 31% when sodium benzoate is used as hydrotrope in coal flotation as well as it reduced the ash percent of concentrate from 22.21% at plant condition to 18.60% with hydrotrope. Hydrotropes are a class of amphiphilic molecules that cannot form well organized structures, such as micelles, in water but do increase the aqueous solubility of organic molecules. Hydrotropes are usually anionic compounds and are composed of an aromatic ring substituted by a sulfate, sulfonate, or carboxylate group, typical examples of hydrotropes being sodium xylene sulfonate (SXS) or sodium benzoate. Hydrotropes contain both hydrophobic and hydrophillic fractions in them. In comparison to surfactant, they contain very small hydrophobic fraction. The efficiency of hydrotrope solubility depends on the balance between hydrophobic and hydrophillic part of hydrotrope. The larger is the hydrophobic part of an additive the least is the hydrophobic efficiency, the presence of the charge on the hydrophillic part is less significant.