Sodium Benzoate and Urea as Promoters in Sillimanite Flotation

Abstract

Sillimanite is an alumino-silicate mineral with the chemical formula Al2SiO5. Sillimanite in general is concentrated by gravity separation methods followed by froth flotation. Hydrophobicity is induced to sillimanite surface by adsorbing surfactant (oleic acid/oleate) molecules selectively and the mineral is collected into froth as concentrate. Other reagents used are; sodium silicate to depress garnet and silica and sodium hydroxide to adjust the pulp pH. In the present study, hydrotropes (sodium benzoate and urea) were introduced to improve the solubility of oleic acid in aqueous phase that is flotation pulp. It is noted that hydrotropes improve the recovery of sillimanite with marketable grades of concentrate.