A clean ammonia-free vanadium recovery process for titanium-white waste using D2EHPA extraction, hydrogen peroxide stripping, precipitation and calcination to produce V2O5
Traditional vanadium extraction process, which involves H 2 SO 4 stripping after solvent extraction followed by ammonium vanadate precipitation, faced the issues of large amount of reagent consumption and discharge of ammonia contaminated wastewater. Hydrogen peroxide stripping and precipitation of vanadium products by heating process was considered as a novel alternative for H 2 SO 4 stripping - ammonium vanadate precipitation route due to the ammonia-free wastewater and high efficiency. However, it was found that the V stripping efficiency was in the range of 54.9% ∼ 97.7% during the pilot test of 3-stage counter-current stripping, which was extremely unstable, as the high stripping efficiency (>95%) could only be achieved in a very short operation time (within 30 s). To solve these issues, the ion species transformation and the stripping mechanism of V with H 2 O 2 were systematically investigated. In this study, experimental results demonstrated that re-extraction led to a decrease of stripping efficiency. The use of D2EHPA alone without TBP as a modifier had a clear effect on prolonging the duration of maximum stripping efficiency at the optimal conditions so that the continuous operation of the pilot test was possible. The optimal stripping conditions were a molar ratio of H 2 O 2 :V of 4:1, phase ratio (O/A) of 3:1, temperature of 20 °C，stripping time of 8 min and the operation time of 3 min which resulted a ∼ 98% V stripping efficiency. In addition, the precipitation of vanadium products by heating, proposed in this work was a cleaner and more efficient V precipitation procedure that didn't require any reagents and produced no wastewater. Eventually, heating the strip liquor at 100 °C for 1 h resulted a precipitation efficiency of 96% V. The intermediate precipitated products (V 5 O 12 ∙6H 2 O and V 10 O 24 ∙12H 2 O) were roasted to obtain V 2 O 5 with a purity of >99%. Finally, the new process saves 885.2 $/t V 2 O 5 compared with the traditional process according to the cost analysis. The research results provide an efficient, clean and economical process for recovering V 2 O 5 from titanium-white waste.
危险品化学品经营许可证（带存储）