Simultaneous oxidation and extraction of iron from simulated ilmenite hydrochloric acid leachate

Separation of ferrous iron from titanium (IV) in a simulated ilmenite hydrochloric acid leachate by simultaneous oxidation and MIBK extraction was investigated. The effects of oxygen flow rate, O/A phase ratio, temperature, and hydrochloric acid concentration were studied. The results showed that with pure oxygen as oxidant and 100% (v/v) MIBK as extractant, the extraction of iron was over 97% while no titanium was co-extracted under O/A 1:3, hydrochloric acid concentration 9.35 mol/L, oxygen flow rate 1000 mL/min, reaction temperature 35 °C and reaction time 30 min. With two stages of cross-current operation, the total iron extraction amounted up to 99.5% and still no titanium was co-extracted. 85% of iron stripping was obtained using distilled water as the stripping liquor at an O/A ratio of 1:1 through a single contact. McCabe–Thiele plot analysis predicts that a 98% of iron stripping can be obtained with two stages of counter-current operation at O/A ratio of 1:1. Thus, an almost complete separation of iron (II) and titanium (IV) from the simulated leachate by simultaneous oxidation and MIBK extraction was feasible. The process could by-produce Fe2O3 with high purity. The kinetics of both the extraction and stripping of iron (III) were very fast while the oxidation of iron (II) was comparatively slow. The oxidation could be accelerated significantly by increasing hydrochloric acid concentration and reaction temperature. Enhancement of the oxidation through improving the structure of gas–liquid–liquid multiphase reactor was also expected. An improved hydrochloric acid process for pigment production was proposed.