A simple successive calcination-H₂C₂O₄ leaching method was employed to recycle the W in spent V₂O₅-WO₃/TiO₂ catalyst with high efficiency. The results showed that W partially reacts with calcium and form CaWO₄ after the first calcination. The CaWO₄ was leached by diluted H₂C₂O₄, during which the W was converted into the soluble chelate compound (H₂[WO₃(C₂O₄)H₂O]), while the calcium remained in the solid in form of CaC₂O₄. After filtration, the chelate compound in the filtrate could be precipitated by adding HCl to obtain H₂WO₄, while the filter residues were roasted for the second time to increase the recycling ratio of W. During the second calcination, the CaC₂O₄ was decomposed into CaO and reacted with the residue W to form CaWO₄, which can be further leached by H₂C₂O₄ and recycled as H₂WO₄. Finally, the H₂WO₄ can be roasted at 773 K for 1 h to obtain the WO₃. As a result, the leaching efficiency of W could reach 87%, while the purity of the final WO₃ was as high as 91%.

采用简单的连续煅烧-H ₂ C ₂ O ₄浸出法高效回收了废V ₂ O ₅ -WO ₃ / TiO ₂催化剂中的W。结果显示，第一次煅烧后，W与钙发生部分反应并形成CaWO ₄。通过稀释的H ₂ C ₂ O ₄浸提CaWO ₄，其间W转化为可溶性螯合物（H ₂ [WO ₃（C ₂ O ₄）H ₂O]），而钙以CaC ₂ O _4的形式保留在固体中。过滤后，可以通过加入HCl沉淀出滤液中的螯合物，得到H ₂ WO ₄，同时对滤渣进行第二次焙烧，以提高W的循环利用率。在第二次煅烧中，CaC ₂ O ₄分解成CaO并与残留物W反应形成CaWO ₄，可以用H ₂ C ₂ O ₄进一步浸出并作为H ₂ WO ₄再循环。最后，H ₂ WO ₄可将其在773K下焙烧1小时以获得WO ₃。结果，W的浸出效率可以达到87％，而最终的WO ₃的纯度高达91％。