Decomposition of flotation reagents in solutions containing metal ions. Part II: Interactions between xanthate and metal ions in solutions

An earlier study (Part I) indicated that Cu2+ ion suppresses while Fe3+ ion promotes xanthate decomposition into CS2. The main factor responsible for the disparate effects was proposed to be the differences in interactions between xanthate and metal ions in solution. UV-vis and FTIR spectrometers were used to examine the products of such interactions in the liquid and precipitate phases, respectively. For both metal ions, it was found that metal xanthate (i.e. cupric xanthate Cu2X2 and ferric xanthate FeX3) and dixanthogen (X-2) are formed. Although for different metal ions metal xanthate and dixanthogen are formed by different mechanisms, generation of CS2 in the gas phase can be correlated to the formation and decomposition of the metal xanthate and dixanthogen. It was found that metal xanthate and dixanthogen both are responsible for the effects of metal ions on SIBX decomposition: with the increase of Cu/SIBX ratio, decrease of CS2 is accompanied by the decrease of Cu2X2 and X-2; with the increase of Fe/SIBX ratio, increases of CS2 are accompanied by the increase of FeX3 and X-2. Which compound, metal xanthate or dixanthogen, play a more important role in affecting the decomposition could not be determined yet. Further studies is also required to elucidate the mechanisms how Cu2X2, FeX3 and X-2 are quantitatively determining the overall decomposition kinetics.