INTERACTION OF COLLECTORS WITH PRE-OXIDISED SULFIDE MINERAL SURFACES; ADSORPTION OF ISO-BUTYL XANTHATE ON GALENA

摘要

To elucidate the effect of pre-oxidation on the interaction of sulfide minerals with thiol collectors, the galena/iso-butyl xanthate system has been investigated by means of X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. The behaviour of pre-oxidised surfaces was compared with that for fresh fracture surfaces at pH 9.2. It was found that most of the oxidation products formed on galena during exposure to air for 2 h could be removed from the surface by immersion for 10 min in the alkaline medium alone. Immersion of both fresh and pre-oxidised surfaces in 10~(-4) mol dm~(-3) collector solution for 10 min resulted in the formation of chemisorbed xanthate. Similar immersion in 10~(-3) mol dm~(-3) solution gave rise to lead hydroxo xanthate in addition to the chemisorbed collector. The formation of lead hydroxo xanthate rather than lead xanthate is consistent with the carbonate-deficient environment of the laboratory system investigated. It is expected that, under flotation conditions, chemisorbed collector will be the hydrophobic species formed at pre-oxidised sulfide mineral surfaces.