Mechanism of sulfide ore flotation activation by precipitated lead xanthates

The authors justify feasibility of sphalerite flotation activation by physisorbed products of interaction of heavy metals and ion xanthates as a case-study of activation with lead ethyl xanthate. It is shown that the collecting agent derivatives can remove the kinetic constraint of the particle-bubble attachment, i.e. they remove water from the interlayer between a mineral particle and a gas bubble. The spreading rate of the collector derivatives governs the rate of the interlayer removal, the induction time and the collectability of this type of adsorption. The tests reveal that the increase in pH from 7 to 10 accelerates spreading of ethyl precipitates of lead xanthate over water surface from 8.5 to 15 cm/s, which correlates with the flotation performance. Based on the mechanism of physisorption, the suppression of sphalerite flotation at higher concentrations of salts of heavy metals is explained.