2024 - Sustainable Industrial Processing Summit
SIPS 2024 Volume 2. Anastassakis Intl. Symp / Mineral Processing
| Editors: | F. Kongoli, L. Andric, K. Aravossis, V. Chanturiya, I. Chatjigeorgiou, D. Fuerstenau, C. Kavalopoulos, C. O'Connor, V. Panayotov, J. Rubinstein |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2024 |
| Pages: | 384 pages |
| ISBN: | 978-1-998384-06-8 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
CD shopping page
REDUCTION PRETREATMENT TO PREVENT Fe3+ PRECIPITATION BLOCKAGE IN THE RECOVERY OF SULFURIC ACID FROM VANADIUM ACID LEACHING SOLUTION BY ELECTRODIALYSIS
Yuting Wang1; Yimin Zhang1; Qiushi Zheng1; Nannan Xue1;1WUHAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, Wuhan, China;
Type of Paper: Regular
Id Paper: 90
Topic: 5
Abstract:
Vanadium shale is an important vanadium-bearing resource in China, with total vanadium reserves in vanadium shale accounting for more than 87 percent of domestic vanadium reserves.[1] Numerous studies have shown that the vanadium content of vanadium shale is low and that most of the vanadium is encapsulated in the crystal structure of the mica, which is difficult to destroy.[2] Therefore, excess sulfuric acid is usually used in the leaching process to increase the vanadium leaching rate.[3] Due to the complexity and variety of minerals in vanadium shale, often accompanied by pyrite, hematite and other iron-containing minerals, the vanadium leach solution obtained by acid leaching has a low pH and contains a large number of impurity iron ions.To meet the requirements for vanadium extraction by subsequent extraction methods, the pH of the vanadium-containing acid leach solution needs to be adjusted to above 1.8. Electrodialysis(ED) is considered to be an alternative to alkali neutralisation, which has the advantages of no vanadium loss, recoverable sulfuric acid, low waste residue and environmental friendliness.[4]
Current studies have shown that Fe3+ in vanadium acid leach solution can form precipitate before the pH reaches 1.8, which adversely affects the ion exchange membrane.[5] However, the precipitation pH of Fe2+ is much higher, exceeding 1.8 or more. Therefore, before the recovery of sulfuric acid using ED, the Fe3+ in the vanadium-containing acid leach solution needs to be reduced to Fe2+ to ensure that the ED process is carried out smoothly.
The effects of sodium sulfite, reduced iron powder and sodium hypophosphite on the reduction of Fe3+ and on the ED process were investigated in the present work. XRD, SEM-EDS and the pH tests were used to analyse the changes in the precipitates. UV spectrophotometry and the pH tests were used to analyse the changes in Fe2+ before and after reduction and during the ED process.Titration and ICP results were used to illustrate the migration of vanadium and impurity ions during the ED process.
The results demonstrated that the acid leach solution with sodium hypophosphite as the reducing agent did not produce precipitation during the adjustment of pH to 1.8 by ED. Excess sodium hypophosphite could completely reduce Fe3+ to Fe2+ and prevent Fe2+ from being oxidised to Fe3+ by oxygen during ED. By monitoring the pH of the solution, precipitation formation and vanadium concentration in the acid leaching solution, it is shown that the acid recovery rate by electrodialysis can reach more than 80% and vanadium retention rate can reach more than 95%.