Recovery of vanadium from high-iron chlorination titanium-white waste acid using D2EHPA/iso-octanol: From laboratory to pilot test

Abstract

The D2EHPA extraction − H2O2 stripping process offers a significant advantage over traditional methods for recovering vanadium (V) by eliminating the generation of ammonia-containing wastewater. However, the main challenge in industrial settings is the rapid decline in stripping efficiency due to the instability of peroxides. For instance, the efficiency can decrease from 80 % to 40 % within 4 min. To address this issue, the iso-octanol was added to the organic phase as a modifier to reduce the coordination ability of P = O in interacting with V, thereby lowering the decomposition rate of VO(O2)2- and lengthening the duration of peak stripping efficiency. A novel method of organic phase pre-oxidation and stepwise addition of H2O2 was introduced to further stabilize the stripping process. In optimal conditions, the V stripping efficiency can reach 98.16 % through a 3-stage counter-current process, while reducing the amount of H2O2 by approximately 50 % compared to a single-time addition. Furthermore, the organic phase was successfully regenerated with 6 mol/L HCl after stripping. The main impurity Fe was removed with an efficiency of 92 %, allowing for the organic phase recycling. The process produced the end-product V2O5 (>99 %) by heating hydrolysis of the stripping liquor and roasting of the hydrolysis precipitate. Overall, this method provides a complete recovery process for V from high-iron chlorination titanium-white waste acid (CTWA), which is characterized by its efficiency, environmental friendliness, and short process. These results could serve as a valuable reference for the industrialization of the H2O2 stripping process.