Extraction equilibria and kinetics of Ti(IV) from leached chloride liquors of ilmenite

Extraction of titanium (IV) from real chloride leach liquor of ilmenite was carried out with 0.1 mol·L⁻¹ di-(2-ethylhexyl) phosphoric acid (HDEHP) in kerosene. Equilibrium and kinetics studies for Ti(IV) were carried out in the presence of impurities that were leached with Ti(IV). Parameters affecting extraction rate of Ti(IV) from chloride media in the presence of Fe(III), Mg(II), and Al(III) were studied to evaluate the stoichiometry of extracted Ti(IV) species. It is found that the extraction rate of Ti(IV) is dependent on the extractant concentration and pH of solution. Under the optimum conditions, more than 95 % Ti(IV) can be extracted. On the basis of slope analysis method, the extracted species of Ti(IV) appears to be [TiO(H₂A₂)₂]_org, where H₂A₂ refers to HDEHP. Further, the kinetic studies of the extraction process of Ti(IV) and other metal ion impurities were carried out by a Lewis cell with a constant interfacial area of 16.7 cm². Analysis of the experimental results suggests that TiO²⁺ extraction rate by HDEHP is the first with respect to hydrogen ion concentration and HDEHP concentration. The results are interpreted by a reaction mechanism where the extraction process is controlled by a diffusion process at the interface rather than in the bulk phase.