Chalcocite-Oxygen-Xanthate System

The electrochemical reaction of formation of cuprous xanthate is defined by the following equation 

The decomposition of cuprous xanthate by oxidation is defined by the following reactions  

The stability of cuprous xanthate in high pH media is determined by the reaction of the type  

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Abstract In the beginning, the mixed potential model, which is generally used to explain the adsorption of collectors on the sulphide minerals, is illustrated. And the collector flotation of several kinds of minerals such as copper sulphide minerals, lead sulphide minerals, zinc sulphide minerals and iron sulphide minerals is discussed in the aspect of pulp potential and the nature of hydrophobic entity is concluded from the dependence of flotation on pulp potential. In the following section, the electrochemical phase diagrams for butyl xanthate/water system and chalcocite/oxygen/xanthate system are all demonstrated from which some useful information about the hydrophobic species are obtained. And some instrumental methods including UV analysis, FTIR analysis and XPS analysis can also be used to investigated sulphide mineral-thio-collector sytem. And some examples about that are listed in the last part of this chapter. 

Figure 4.32 Electrochemical phase diagram for the chalcocite/ethyl xanthate/oxygen system and the observed lower ( ) and upper ( ) limiting flotation potential at which flotation recovery is greater than 50%, dashed line is the formation of dixanthogen...

Figure 29. Eh-pH diagrams for the chalcocite/water/ethyl xanthate system for an initial xanthate concentration of 10 mol dm (A) and 10 mol dm (B). Sulfur-oxygen anions are not considered. Species designated Cu2.j(S cover the same range of stoichiometries...

It was considered that hydrogen peroxide is formed at silver and chalcocite surfaces when oxygen is present as this compound is an intermediate in the cathodic reduction of oxygen. Clearly, then, there is interaction between the two reactions that make up the mixed potential system, namely, xanthate oxidation and oxygen reduction. Thus, care must be taken in considering the individual processes in isolation. 

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