ARTÍCULO
Dextrin as a regulator for the selective flotation of chalcopyrite, galena and pyrite.
LOPEZ VALDIVIESO A., SÁNCHEZ LÓPEZ A.A., SONG S.,
GARCÍA MARTÍNEZ H.A. and LICÓN ALMADA S.
Canadian Metallurgical Quarterly, Vol 46, No 3 pp 301-310, 2007, 2007.
ABSTRACT:
The adsorption of both dextrin and xanthate ions at the pyrite/aqueous solution and the galena/aqueous solution interfaces have been studied through batch adsorption tests. Batch flotation tests were also carried out on a chalcopyrite ore and a chalcopyrite-galena scavenger concentrate using dextrin. Dextrin adsorption isotherms on two types of surfaces of pyrite show that the greater the initial surface density of iron hydroxides, the higher the adsorption of dextrin is. These adsorption isotherms exhibit two plateaus suggesting that dextrin adsorbs on pyrite not only on ferric hydroxide sites, but also on ferrous hydroxide sites. Adsorption of xanthate ions gives rise to a partial desorption of dextrin lowering the surface hydrophilicity of pyrite. This desorption of dextrin is proposed to occur due to the dissolution of ferric hydroxide which is associated with the oxidation of xanthate ions to dixanthogen. It is shown that dextrin is an effective depressant for pyrite in flotation of copper in the chalcopyrite ore at pH 8, but the pulp needs to be aereated in order to promote the surface oxidation of pyrite and enhance the adsorption of dextrin. On galena, adsorption of xanthate ions also leads to the desorption of dextrin, but, dextrin can be an effective depressant only if the surface of galena is sufficiently oxidized to have dextrin left on the surface after xanthate adsorption. This surface oxidation of galena is more effective with pyrite than using air. Results are presented on the flotation of chalcopyrite from a chalcopyrite-galena bulk concentrate high in pyrite using dextrin as a depressant for galena and pyrite at pH 8.