ABSTRACT
An industrial (NH4)2WO4 solution was used to directly prepare ammonium metatungstate solution using bipolar membrane electrodialysis. The effects of current density, initial concentrations of NH4HCO3 and WO3 in feeds, temperature and pH of product solution on the process were investigated. A continuous running test was carried out under the optimum conditions and the results showed that the direct recovery of WO3 reached 99.97% with average current efficiency of 72.5% and power consumption of 0.877 kWh kg−1 WO3 using a feed solution containing 172.3 g L−1 WO3 and a base solution containing 1.5 mol L−1 NH4HCO3 with a current density of 700 A m−2 and a solution pH in salt compartment of 2.8 at 31°C for 600 min, indicating easy and stable operation of the bipolar membrane electrodialysis process.
RÉSUMÉ
On a utilisé une solution industrielle de (NH4)2WO4 pour préparer directement une solution de métatungstate d’ammonium en utilisant l’électrodialyse à membrane bipolaire. On a examiné les effets de la densité de courant, des concentrations initiales de NH4HCO3 et de WO3 dans l’alimentation, de la température et du pH de la solution produite, sur le procédé. On a effectué un essai de fonctionnement continu sous conditions optimales et les résultats ont montré que la récupération directe de WO3 atteignait 99.97% avec un rendement moyen du courant de 72.5% et une consommation d’énergie de 0.877 kWh/kg de WO3. On utilisait une solution d’alimentation contenant 172.3 g/L de WO3 et une solution de base contenant 1.5 mol/L de NH4HCO3 avec une densité de courant de 700 A/m2 et un pH de 2.8 de la solution dans le compartiment salin à 31°C pendant 600 min. Ceci indiquait une opération facile et stable du procédé d’électrodialyse à membrane bipolaire.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes on contributors
Wenjuan Guan is a lecturer at the School of Metallurgy and Environment, Central South University, China. The recovery of tungsten from its mineral ores and secondary resources such as spent catalysts is one of the areas of her research work.
Guiqing Zhang is a professor at the School of Metallurgy and Environment, Central South University, China.The novel process for tungsten hydrometallurgy based on direct solvent extraction in alkaline medium is one of the areas of his reserach work.
Li Zeng is an associate professor at the School of Metallurgy and Environment, Central South University, China. The novel process for nickel hydrometallurgy based on direct solvent extraction in acidic medium is one of the areas of his research work.
Chengwei Zeng completed his master degree studies at the School of Metallurgy and Environment, Central South University, China 2 years ago. He now works as a registered EAI engineer in a domestic company.
Guanghao Shang has recently completed his PhD studies in the BMED process applied to the treatment of waste water containing trace amount of heavy metals at the School of Metallurgy and Environment, Central South University, China.