Process for preparing potassium carbonate

摘要

The invention relates to a process for preparing potassium carbonate 1.5-hydrate (sesquihydrate) by crystallisation from a solution and separating the crystallisate off from the mother liquor, with a substream of the mother liquor being taken out of the process to avoid supersaturation of sodium carbonate and the remaining stream of the mother liquor being recirculated to the potassium carbonate crystallisation step. To improve a process of the generic type in such a way that these disadvantages described do not occur and to obtain an as pure as possible, i.e. sodium-free, potassium carbonate, with the yield being as high as possible, it is proposed that the substream of the mother liquor taken out of the process be subjected to evaporation at a temperature significantly higher than that of the potassium carbonate crystallisation step and that, after separating off the double salt potassium sodium carbonate which crystallises out, the remaining mother liquor be likewise recirculated to the calcium carbonate crystallisation step.