Chalcopyrite–quartz mineral surfaces: controlled wetting and spreading by xanthate-tallow diamine emulsions

Abstract

This study investigated emulsions formulated with water-soluble xanthates, including potassium amyl xanthate (PAX) and a novel α-tocopherol polyethylene glycol 400 succinate xanthate (TPGS-X), combined with oil-soluble N-hydrogenated tallow-1,3-propylene diamine (tallow diamine). The emulsion droplets were examined for selective attachment and controlled oil spreading onto homogeneous and heterogeneous chalcopyrite–quartz mineral surfaces, with particular focus on targeting chalcopyrite regions over pure quartz surfaces. The stability and characteristics of kerosene-in-water emulsions containing xanthate and tallow diamine were studied across different pH values, examining both mostly protonated and deprotonated states of the tallow diamine. The emulsions became unstable when tallow diamine was mostly protonated due to electrostatic interactions between the cationic tallow diamine and anionic xanthates resulting in near zero zeta potentials. Conversely, the emulsions exhibited relative stability when tallow diamine was mostly deprotonated and the droplets were stabilised by negatively charged xanthates at the interface. Under these stable conditions, TPGS-X demonstrated superior performance compared to PAX, with the higher molecular weight enhancing emulsion stability. Oil contact angle measurements revealed that oil preferentially wetted chalcopyrite over quartz when the oil-soluble emulsifier was mostly deprotonated, but wetted both minerals when tallow diamine was mostly protonated. Similarly, oil droplets selectively wetted chalcopyrite patches via xanthate interactions when tallow diamine was mostly deprotonated, but subsequently spread onto quartz surfaces of heterogeneous minerals when tallow diamine became mostly protonated. These findings demonstrate the potential for applying oil-containing hydrophobicity modifiers to achieve selective oil attachment and controlled spreading onto composite chalcopyrite–quartz minerals. This approach offers promising opportunities for selective recovery of chalcopyrite over coarse quartz mineral particles through pH-controlled emulsion behaviour and targeted surface interactions.