Estudio de la remoción de tensoactivos colectores en efluentes de flotación de minerales sulfurados con carbón activado.

Abstract

The removal of collecting surfactants (potassium amyl xanthate and sodium diethyl dithiophosphate) reagents used in the flotation process of sulfide minerals, through their adsorption on activated carbon, is studied. These collectors reduce the surface tension of the water, causing serious damage to aquatic ecosystems. In Ecuador, more than 40 000 m3.day-1 of flotation effluents with high concentrations of surfactants are discarded into water bodies. For the collector removal tests, microporous activated carbon was used with 1 200 m2.g-1 with synthetic solutions and aqueous effluents from the laboratory flotation process of a polysulfurized mineral (0.5% Cu, chalcopyrite, pyrite, chlorite). We worked with a dosage of 0,25; 0,5; 0,75 and 1 g for both activated carbon and activated carbon modified by surface oxidation with HNO3, in a stirred bed for 24 hours with pH values of 3, 7 and 10 and in a packed column filter. An analysis methodology was developed for collectors in aqueous solution using UV-visible spectrophotometry. The recovery values of potassium amyl xanthate and sodium diethyl dithiophosphate at pH values 3, 7 and 10 in an aqueous effluent were 66, 40, 100% and 55, 99 and 76% respectively. Column filtration achieved removals of 97 and 56% with filtration kinetic constants of 1221,4 day-1 and 323 day-1. The modified carbon in the aqueous effluent achieved removals of 100 and 76% for potassium amyl xanthate and sodium diethyl dithiophosphate with initial concentrations of 20 and 60 mg.L-1 respectively.