The anodic surface oxidation of natural pyrrhotite in 0.3mol/L KCl and HCl solution （pH 4.0） and0.1mol/L Na2B4O7 solution （pH 9.18） respectively was investigated by using cyclic voltammetry, Tafel plot, and chronoamperometry. In 0.3mol/L KCl and HCl solution （pH 4.0）, at potential less than 0.5V（vs SHE）, the production of anodic oxidation on pyrrhotite surface can not maintain a stable phase to form a passive film. In 0.1mol/L Na2B4O7 solution （pH 9.18）, when the electrode potential increases to more than 0.5V （vs SHE）, part of S is oxidized to sulfate, making the passive film somewhat porous, but elemental S and metal oxidates Fe（OH）3 still remain on the electrode surface, and the passive film can not be broken down totally. According to PARCalc Tafel analysis, the corresponding corrosion current density （J0） is 5.34μA/cm2, which is also the exchange current density of the oxidation reaction on pyrrhotite electrode surface in 0.1mol/L Na2B4O7 solution （pH 9.18）. The electrochemical dynamics equation of the oxidation was determined.
The electrochemical reaction of xanthate on the surface of pyrite was studied using cyclic voltammogrametry, chronopotentiometry and rotating-disc electrode measurements.Experimental results demonstrate that the first step in the reaction is electrochemical adsorption of xanthate ion,and then the adsorbed ion associates with a xanthate ion from the solution and forms a dixanthogen on the pyrite electrode surface.The diffusion coefficient of butyl xanthate on pyrite electrode surface can be determined to be about 1.09×10- 6cm2/s.Using the galvanostatic technique,the kinetic parameters of oxidation of the butyl xanthate ion on the pyrite surface are calculated as Ja=200μA/cm2 ,β=0.203 and J0=27.1μA/cm2.
