Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 15 No. 4 August 2005|
（School of Resources Processing and Bioengineering, Central South University, Changsha 410083, China）
Abstract: The anodic surface oxidation of natural pyrrhotite in 0.3mol/L KCl and HCl solution (pH 4.0) and 0.1mol/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.
Key words: pyrrhotite; electrochemical oxidation; aqueous solution; electrochemistry