Adsorption of xanthate and starch on synthetic graphite

In the processing of sulphide ores containing graphite, starch is occasionally employed for depressing graphite while xanthate is used as a sulphide collector. In such a system the adsorption of starch by graphite is also influenced by xanthate. In the present investigation the adsorption of xanthate and starch at various values of pH and adsorbate concentrations have been carried out. The results show that xanthate is hardly adsorbed in the xanthate-N₂ system, but in the presence of oxygen it is catalytically oxidised to dixanthogen which adsorbs on graphite. Xanthate and starch are partly adsorbed at the same or adjoining sites of graphite with starch being adsorbed faster than xanthate. The ability of starch to depress graphite is reduced in the xanthate-starch system.