SURFACE-CHEMISTRY OF CARBONACEOUS GOLD ORES .2. EFFECTS OF ORGANIC ADDITIVES ON GOLD ADSORPTION FROM CYANIDE SOLUTION

The effects of model surface active organic compounds (dodecylamine (DDA), tricaprylylmethylammonium chloride (Aliquat 336), sodium dodecylsulfate (SDS) and dinonylnaphthalene-sulfonic acid (HDNNS)) on gold adsorption by Prestea (Ghana) carbonaceous gold ore were investigated with the aid of adsorption and electrophoretic mobility experiments. The influence of SDS on the uptake of gold by the carbon extract obtained was also studied. The results indicate that gold uptake in aqueous cyanide solution is enhanced by Aliquat 336 and slightly by DDA or SDS, while HDNNS has a strong opposite effect. Gold loading was also reduced by 37% when pretreatment with hexane was used. The influence of the additives is interpreted in terms of coulombic and hydrophobic interactions between the surfactants and the solid surface, competition between the organic reagents and the aurocycanide complex for interfacial sites, and electrostatic and chemical interactions.