Combined oxidation and 2-octanol extraction of iron from a synthetic ilmenite hydrochloric acid leachate

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, organic/aqueous (O/A) phase ratio, temperature, and hydrochloric acid concentration were studied. Using pure oxygen as the oxidant and 100% (v/v) 2-octanol as extractant, the oxidation of ferrous iron and subsequent ferric iron extraction reached 99.3% and 86.1%, respectively. In addition, with an O/A ratio of 1:3, a hydrochloric acid concentration of 935 mol/L at 35 degrees C for 30 min, titanium co-extraction was not observed. Over two stages of cross-current operation, the total iron extraction reached 99.6%, again with no titanium co-extraction. Furthermore, 100% iron stripping was obtained through a single contact, using distilled water as the stripping liquor with an O/A ratio of 1:1. Thus, an almost complete separation of iron(II) from titanium(IV) in the simulated leachate was achieved. The composition of the extracted complex was determined to be HFeCl4 center dot 5(2-octanol). The kinetics of both the iron(III) extraction and stripping were rapid, while the iron(II) oxidation was slow despite a new reactor with significantly enhanced gas-liquid contact being employed. Further enhancement of the oxidation through catalysis is expected, and so an improved method of iron(II) extraction from titanium for use in a hydrochloric acid TiO2 pigment production process is proposed. (C) 2015 Elsevier B.V. All rights reserved.