Quantitative Aspects of the Role of Oxygen in the Interaction between Xanthate and Galena

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Abstract
The reaction between potassium ethyl xanthate, oxygen, and galena over periods of 20 to 30 hr has been studied. Quantitative results are presented for the reaction at pH 10, but it is shown that the general features of the behavior are the same within the range pH 8 to 11. Two types of reaction are observed. The first involves adsorption of the xanthate and takes place at a rate, dq/dt, that decreases exponentially with the quantity of reagent adsorbed. The second is thought to involve reaction between the xanthate and the oxygen catalyzed by the surface. Its rate increases with time until it reaches a constant value, Rf. A product of reaction may be ethyl monothiocarbonate. The parameters of the adsorption rate equation, and, therefore, the rate and extent of adsorption at any time, vary directly with the square root of partial pressure of oxygen (p) for p  131 torr. Rf varies with p 1/2 for values of p up to the maximum used (313 torr). Possible mechanisms of reaction are discussed in the light of these findings.