THE INTERACTION OF AQUEOUS SILVER SPECIES WITH SULFUR-CONTAINING MINERALS AS STUDIED BY XPS, AES, SEM, AND ELECTROCHEMISTRY

The interaction of aqueous silver ions with pyrite, galena, and sphale rite and of silver chloride complexes with pyrite and galena has been investigated using X-ray photoelectron and Auger electron spectroscopi es, scanning electron microscopy, and open circuit potentials. For the interactions with silver ions, silver sulphide was observed as the fi rst surface product on all mineral surfaces. At longer reaction times, the occurrence of polysulphide species and metallic silver was also o bserved. For interactions of the aqueous silver chloride complexes wit h galena, the same surface products were observed as in the chloride-f ree system, with the amount of total silver present on the surface inc reasing with increasing chloride ion concentration. In the case of pyr ite, the uptake of silver by the mineral decreases at elevated concent rations of chloride which causes a decrease in the concentration of to tal free silver ion in solution. Differences in reactions of the miner als with silver species in solution are attributed to the differences in the change in the oxidation state of sulphur. In galena and sphaler ite, no change in oxidation state of sulphur occurs on dissolution, wh ile S- in pyrite forms S2-.