Electrochemical investigation of contact angle and of flotation in the presence of alkylxanthates. I. Platinum and gold surfaces

Abstract

The contact angle between a nitrogen bubble and platinum or gold electrode surfaces immersed in xanthate solutions has been determined as a function of the quantity of dixanthogen on the metal surface for the methyl, ethyl and butyl compounds. Significant angles result from fractional coverages, but multilayers are required before the maximum angle, characteristic of the particular alkyldixanthogen, is reached.The quantity of dixanthogen required to float a particulate bed electrode of gold spheres was determined for a number of alkylxanthates. The required quantity varied from multilayers for methyl to low fractional coverages for the longer chain compounds. Nevertheless the static contact angle corresponding to these coverages was in each case found to be close to 55' for the three alkyldixanthogens studied.When butyl-or pentyl-xanthates were used at typical concentration levels applicable to practical situations (10 p.p.m.), flotation was inhibited when the quantity of dixanthogen formed was more than two to four times greater than the minimum amount necessary for flotation to occur. This inhibition arose from flocculation of the gold particles.

AFM force measurements between gold and silver surfaces treated in ethyl xanthate solutions: Effect of applied potentials

“…On the cathodic scan, three reduction peaks are shown, indicating more than one type of oxides were formed during the anodic scan. The contact angle measured after repeated potential sweeps (Fischer et al, 2009) and cathodic polarization was 15°, which was close to the value reported ($10°) (Gardner and Woods, 1974).…”

Electrochemical interactions of industrially important platinum-containing minerals

“…2. Pt-Te 2 shows a strong anodic behaviour at potentials >120 mV in the presence of xanthate; this potential corresponds well with the reversible potential for the xanthate-dixanthogen couple (Gardner and Woods, 1974). A strong cathodic peak appears on the reverse scan.…”

Flotation of Gold and Gold-Bearing Ores

“…These adsorb onto mineral surfaces, rendering the mineral hydrophobic. This is a neutral oil that will adsorb onto the surface of any naturally hydrophobic solid, rendering it floatable (Gardner and Woods, 1974). This is a neutral oil that will adsorb onto the surface of any naturally hydrophobic solid, rendering it floatable (Gardner and Woods, 1974).…”

“…This is a neutral oil that will adsorb onto the surface of any naturally hydrophobic solid, rendering it floatable (Gardner and Woods, 1974). The longer-chain xanthates are more readily oxidized, generating dixanthogen at lower potentials (Gardner and Woods, 1974). Studies have shown that the development of a finite contact angle and the onset of flotation of gold particles occur at a potential close to that of dixanthogen formation (Woods et al, 1994).…”

“…The presence of oxygen is a prerequisite for the flotation of sulfide minerals with thiol collectors (Gardner and Woods, 1974). Electrochemical investigations have shown that the role of oxygen is to provide a cathodic reduction process that allows anodic oxidation processes, involving the flotation collector, to occur on the mineral surface.…”