An Electrochemical Study of Pyrite Oxidation in 0.1 M Sulfuric Acid at High Temperature and High Pressure

摘要

Open circuit potential, potentiodynamic polarization plots and electrochemical impedance spectroscopy for pyrite in 0.1 M sulfuric acid in the temperature range of 200 to 350 °C and pressure range of 25 to 40 MPa were measured, with the aid of a self-designed electrochemical measurement set-up which can operate at high temperature and high pressure. Results show that increased temperatures benefit the oxidation of pyrite: at 40 MPa, when the temperature was rised from 200 to 350 °C, corrosion potential (Ecorr) decreased from -199.83 to -778.78 mV, corrosion current density 2 (icorr) increased from 4.33 to 22.16 mA/cm , polarization resistance (Rp) decreases from 34.11 to 3.85 2 2 Ω·cm , resistance of the passive layer (Rpl) decreased from 42.16 to 2.48 Ω·cm . Effects of pressure were also considered, at 300 °C, when pressure was increased from 25 to 40 MPa, Ecorr decreased from -621.48 to -713.25 mV, however, icorr and Rp rarely changed.