EXPANDED WINDOWS FOR TITANIUM USE IN THE PULP PAPER PEROXIDE BLEACH PLANT/

A corrosion database for Grade 2 titanium derived from laboratory weig ht-loss testing has been developed in uninhibited and inhibited alkali ne 0.2-0.3 wt% H2O2 solutions at 65 degrees to 85 degrees C. Although titanium resistance to uninhibited hot alkaline peroxide solutions is very limited, useful resistance dramatically expands in solutions cont aining inhibitive species commonly existing in bleach plant processes. Effective inhibitors in descending order include Ca+2 ions, silicates , and Mg+2 salts. Addition of EDTA and DTPA chelants has no detrimenta l effect on Ca+2 ion inhibition unless chelant is added to excess. Bas ed on this corrosion database, expanded application guidelines for acc eptable use of Grade 2 titanium in solutions containing a maximum of 0 .3 wt% H2O2 are derived at 65, 70, 80, and 85 degrees C as a function of Ca+2 ion concentrations.