Interaction of finely ground galena and potassium amylxanthate in relation to flotation, 3. Influence of acid and neutral grinding

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Hallimond tube flotation and microelectrophoresis have been utilized to investigate the reactions in the adsorption-abstraction of K-amylxanthate on finely ground galena. The mineral was ground in a laboratory stainless steel rod mill under controlled conditions (pH 4.0 and 7.0) using HCl as a pH regulator. X-ray photoelectron spectroscopic (XPS) studies have been carried out in order to characterize the surface oxidation products after grinding (weak amounts of S_n and PbS₂O₃). The two-stage adsorption process discovered in previous studies was confirmed. For low concentrations or submonolayer capacity, the layer is formed with 1:1 monocoordinated lead xanthate and dixanthogen. For higher values of surface coverage, it is composed of lead xanthate (stoichiometric at pH 7 and non-stoichiometric at pH 4), amyldixanthogen and amylcarbonate disulphide. In the second stage mainly dixanthogen is formed. This stage corresponds to complete flotation and to a sharp decrease in zeta potentials.