Secondary ion mass spectrometry investigation of the interaction of xanthate with galena

Static SIMS has been used to study the interaction of xanthate with freshly cleaved and oxidised galena surfaces in neutral and alkaline pH conditions . Three xanthate fragments together with O and S negative ion images have b een compared. At low xanthate concentration (10(-5) mol dm(-3)) and high Eh (pH 7.1), freshly cleaved galena surfaces show very low xanthate adsorptio n due to dissolution. At low xanthate concentration and low Eh (pH 8.7), su rface oxidation and dissolution are reduced with an overall higher concentr ation of mono-molecularly adsorbed xanthate. At high xanthate concentration s (10(-2) mol dm-3, pH 8.7-9.9), freshly cleaved galena surfaces adsorb col loidal PbX2 from solution. Oxidised galena surfaces have relatively low con centrations of adsorbed xanthate compared with freshly cleaved galena surfa ces at both low and high xanthate concentrations and at low and high Eh (pH 7.1-9.9). Adsorbed colloidal PbX2 is not found even at high xanthate conce ntrations apparently due in part to surface oxidation products passivating against continuing dissolution. Colloidal lead oxide/hydroxide particles ha ve been imaged after 10(-5) mol dm(-3) lead nitrate addition at pH 7. Follo wing xanthate addition (10(-5) mol dm(-3)) at pH 8.7, large, roughly circul ar regions (25-75 mum) of high xanthate concentration were obtained in init ial images apparently nucleating at lead oxide/hydroxide precipitate sites. The behaviour of this system is consistent with ion exchange between xanth ate and hydroxide followed by oxidation to dixanthogen and diffusion of thi s species across the surface. The precipitated lead oxide/hydroxide may pla y a catalytic role in the formation of the dixanthogen on the galena surfac e. (C) 2001 Elsevier Science B.V. All rights reserved.