High Temperature Corrosion of Titanium Under Conditions Relevant to Pressure Leaching: Mass Loss and Electrochemistry

The corrosion behavior of titanium was studied using mass loss and electrochemical measurements in sulfuric acid with Cl-, Cu2+, and Fe3+ additions up to 175 degrees C. The corrosion rate of titanium in 30 g L-1 H2SO4 + 12 g L-1 Cl-solution at 150 degrees C measured by mass loss was higher than 62 mm y(-1). The corrosion rates of titanium under simulated pressure-leaching conditions determined by both mass loss and polarization resistance measurements were consistent, and also suggest that Cu2+ and Fe3+ ions are excellent corrosion inhibitors for titanium. Results from mass loss and electrochemical measurements all confirmed that the corrosion rate of titanium decreased remarkably with the addition of 1 g L-1 Fe3+ to the leaching solution at 150 degrees C, and that the presence of Fe3+ is the most important factor for the growth of titanium oxide films under pressure-leaching conditions. In addition, iso-corrosion diagrams, with 0.1, 0.5, and 1 mm y(-1) lines for titanium in H2SO4 solutions from room temperature to 175 degrees C, were constructed from mass loss data.