Perxanthates — A new factor in the theory and practice of flotation

Abstract

A compound with a UV absorption maximum at 348 nm was observed in Mount Isa copper flotation plant solution. This spectrum was similar to that of the product of reaction of xanthate and peroxide in dilute, alkaline aqueous solution. The compound was termed perxanthate (more correctly “O”-alkyl dithiomonoperoxycarbonate). A new compound, ammonium sec-butyl perxanthate (C 4H 9 OCSSO·NH 4), was prepared by reacting potassium sec-butyl xanthate and hydrogen peroxide in dilute alkaline solution, acidifying, extracting into iso-octane, and precipitating with anhydrous ammonia. Solutions of this compound were compared with solutions containing the Mount Isa compound. Each compound was found to have the same UV absorption spectrum in a given solvent (alkaline aqueous, acid aqueous, chloroform, iso-octane, iso-amyl alcohol, and n-butyl acetate), but the spectra were different in different solvents (especially in alkaline and acid aqueous solutions). Both compounds could be extracted from acid, but not alkaline, aqueous solutions by organic solvents, and both had similar IR and mass spectra. It was concluded that the perxanthate in plant solution resulted from reaction of xanthate with peroxide derived from reduction of oxygen during flotation. This lends credence to the electrochemical theory of flotation and has some important theoretical and practical implications.