Self‐induced floatability of sulphide minerals: Examination of recent evidence for elemental sulphur as the hydrophobic entity

Abstract

Recent evidence, based on spectrophotometric analysis of ethanol extracts, for elemental sulphur being present at the surface of sdphide minerals dry-ground in air has been reexamined. Analysis of ethanol and cyclohexane extracts of ground galena, and electron spectra of abraded galena surfaces, have revealed that while ethanol does extract or leach a sulphur species from galena, sulphur is not present in elemental form on a freshly ground mineral surface.cyclohexane

Oxygen and sulfur isotope systematics of sulfate produced by bacterial and abiotic oxidation of pyrite

“…Abiotic oxidation of pyrite by Fe(III) aq can result in intermediate sulfur species between pyritic sulfur and sulfate (Goldhaber, 1983;Moses et al, 1987;Schippers et al, 1996;Schippers and Sand, 1999;Borda et al, 2003;Druschel et al, 2003). Elemental sulfur and polysulfides have been suggested as intermediates of pyrite oxidation (Buckley and Riley, 1991;Sasaki et al, 1995;Kamei and Ohmoto, 1999). The incomplete oxidation of these intermediates to sulfate at low pH in the presence of excess Fe(III) aq has been reported elsewhere (Schippers and Sand, 1999;McGuirre et al, 2001;Druschel et al, 2003;Descostes et al, 2004) and this may have caused the sulfur isotope fractionation observed in the pyrite oxidation experiments with Fe(III) aq .…”

An improved pyrite pretreatment protocol for kinetic and isotopic studies

“…[30] (Method 1).While existing pyrite pretreatment methods putatively remove various soluble intermediate sulfur oxidation products by rinsing with water, as well as water-insoluble oxidation products (iron oxides and sulfates) by rinsing in HCl, the elimination of S 0 , reported to compose a relatively large portion of pyrite grain impurities [34][35][36], has not been addressed. Our data demonstrate the presence of large fractions of S 0 on untreated pyrite particle surfaces, suggesting that S 0 removal is a necessary step when investigating reactions involving pyrite.…”

“…Longer exposure to moist air typically results in the wetting of the pyrite surface by formation of Fe-H 2 SO 4 solutions, and ultimately the precipitation of Fe 3+ or mixed-valence Fe 3+ /Fe 2+ sulfates [15,33]. Adhered patches of elemental sulfur (S 0 ), present as a cyclic octaatomic solid (S 8 ), are a common product of incomplete pyrite oxidation [34][35][36], and aqueous S 0 is a known product of pyrite oxidation under acidic aqueous conditions [16]. Both iron sulfates and S 8 may decrease the reactive surface area of pyrite and bias reaction rates downwards.…”

The adverse effect of disrupted water-borne bacteria cells on flotation

“…The galvanic reaction between chalcopyrite and pyrite leads to a decrease in chalcopyrite surface negative charges and an increase in the surface hydrophobicity (Buckley and Riley, 1991;Fairthorne et al, 1997;Zachwieja et al, 1989). This causes the electrostatic repulsion between the negatively charged lysed cells and chalcopyrite to reduce and therefore the attachment of the lysed cells to chalcopyrite surfaces to increase (Han and Lee, 2006), leading to an intensification of the depression effect on the simulated ore.…”