Figure 4.

Flow sheet of zinc oxalate process as developed by Fischer et al. In the bottom left in the first cycle, CO₂ is converted to zinc oxalate and removed by filtration. The oxalate is dissolved in sulfuric acid in the second cycle, and oxalic acid is extracted from the zinc sulfate solution, which is recycled to sulfuric acid and zinc in the zinc electrolysis cell shown at the top. Pure oxalic acid is obtained by evaporation of the extractant in the last step in the bottom right. Reproduced with permission from Ref. [147]. Copyright 1981, Springer.