Decomposition of xanthate collectors with ozone in alkaline solutions

In a previous paper, ozone was shown to remove residual xanthates in flotation pulp solutions as well as to destroy the xanthate coating on bulk copper-nickel sulfide concentrates before differential flotation (Iwasaki and Malicsi, 1985). The oxidation and decom- position mechanisms of xanthate solutions in the presence of commonly used oxidants such as oxygen, chlorine, hypochlorite, bromine, iodine, and hydrogen peroxide at different pH levels have been reported in the past (Rao, 1971). Most of these studies have been restricted to xanthate solutions of pH less than 10. Very few references are available on xanthate decomposition in highly alkaline (pH > 12) solutions (Jones and Woodcock, 1983; Philipp and Fichte, 1960; Tipman and Leja, 1975). No systematic study of xanthate oxidation by ozone has been reported, although its use in flotation has been recognized of late (Allegrini et al., IWO; Ishii et al., 1970; Matsubara et al., 1978). To improve the efficiency of ozone use in flotation, it is essential to understand the mechanisms involved in the decomposition of xanthates with ozone, more specifically, to establish the stoichiometry and decomposition rate. In the present work, a preliminary attempt was made to investigate the effect of pH on xanthate decomposition, and probable mechanisms of xanthate oxidation with ozone.