Separation of ferrous iron from titanium (IV) in a simulated ilmenite hydrochloric acid leachate by simultaneous oxidation and 2-Octanol extraction was investigated. The effects of extraction time, 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) 2-Octanol as extractant, the oxidation of ferrous and extraction of iron were up to 99% and 86%, respectively 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 ºC and reaction time 30 min. With two stages of cross-current operation, the total iron extraction amounted over 99.5% and still no titanium was co-extracted. The composition of extraction complex was HFeCl4·5(2-Octonol). 100% of iron stripping was obtained using distilled water as a stripping liquor at an O/A ratio of 1:1 through a single contact. Thus, an almost complete separation of iron (II) and titanium (IV) from the simulated leachate by simultaneous oxidation and 2-Octanol 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.
Keywords: solvent extraction; iron; 2-Octanol; oxidation; hydrochloric acid process
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