Method of recovering fluorine from vapor of crude phosphoric acid solution

摘要

To remove fluorides from a vapor generated by evaporation under reduced pressure of an aqueous solution of crude phosphoric acid containing fluorides, the vapor is at first brought into direct contact with cooling water to accomplish a partial condensation of the vapor and transfer the fluorides almost entirely to the condensate, and the noncondensed portion of the vapor is brought into direct contact with a separate cooling water. The mixture of the condensate and cooling water resulting from the partial condensation step is cooled by indirect heat exchange with a cooling fluid and partly recycled as cooling water to the partial condensation step.