Authors
Zanhong Chen, Yinliang Liu, Yong Liang, Ting Pu, Wei Lai
Published in
BMC chemistry. Volume 19. Issue 1. Pages 149. May 29, 2025. Epub May 29, 2025.
Abstract
The traditional alkali autoclaving tungsten smelting process has several disadvantages, such as high production costs, high water consumption and prominent "three wastes" problem, all of which seriously hinder the sustainable development of the tungsten smelting industry. We found that tungstic acid (H2WO4) can be dissolved in oxalic acid and that H2WO4 can be easily precipitated from a solution at relatively high temperatures. Thus, traditional ammonium para-tungstate (APT) can potentially be replaced by H2WO4 as the smelting intermediate, which is expected to overcome the problems associated with the alkali autoclaving process, and solve the problem of ammonia/ammonium pollution at the source. To provide theoretical guidance for the development of novel tungsten smelting processes, the law and mechanism of H2WO4 dissolution in oxalic acid are urgently needed. These results indicate that when H2WO4 is dissolved in an oxalic acid solution, H2C2O4 and H2WO4 can ionize C2O2-4 and WO2-4, respectively. Then, some of the oxygen atoms bonded with W in WO2-4 are replaced by free C2O2-4 to form [WO3(C2O4)·H2O]2-. H2[WO3(C2O4)·H2O] is subsequently formed by combining [WO3(C2O4)·H2O]2- with H+ in solution. Under the conditions of an oxalic acid concentration of 0.05-0.4 mol/L, a reaction temperature of 25-65 ℃ and a liquid-solid ratio of 2:1-10:1 mL/g, the dissolution efficiency of H2WO4 in oxalic acid increases with increasing oxalic acid concentration or liquid-solid ratio; a low temperature (25 ℃-35 ℃) is more conducive to the dissolution of H2WO4 than a high temperature (45 ℃-65 ℃).
PMID:
40442769
Bibliographic data and abstract were imported from PubMed on 30 May 2025.
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