Apparatus for production of phosphoric acid

Claim 1

IN AN APPARATUS FOR THE PRODUCTION OF PHOSPHORIC ACID COMPRISING A SERIES OF COMMUNICATING COMPARTMENTS TO HOLD POOLS OF A CONTINUOUSLY FLOWING BODY OF A REACTION SLURRY FORMED OF AQUEOUS SULFURIC ACID AND GROUND PHOSPHATE ROCK, AN EVAPORATION CHAMBER AT A LEVEL ABOVE SAID COMPARTMENTS A SLURRY FEED PIPE EXTENDING UPWARDLY INTO SAID CHAMBER FROM BELOW THE SLURRY LEVEL OF ONE OF SAID COMPARTMENTS, AN OPEN TOP DECANTING VESSEL AT THE UPPER END OF SAID PIPE WITHIN SAID CHAMBER FOR SPREADING OUT AND DECANTING SLURRY LIFTED THROUGH SAID FEED PIPE, SAID VESSEL HAVING A HORIZONTAL OVERFLOW RIM SPACED ABOVE THE BOTTOM OF SAID CHAMBER FOR DECANTING SUCH SLURRY TO SAID BOTTOM IN A SHEET-LIKE FREE LIQUID DOWNFALL, MEANS FOR MAINTAINING A PREDETERMINED VACUUM IN SAID CHAMBER SUFFICIENT TO COOL, CONCENTRATE AND CRYSTALLIZE GYPSUM IN THE SLURRY DECANTED THEREIN, SAID BOTTOM BEING SLOPED DOWNWARD TO DRAIN THE DECANTED SLURRY FREELY THEREFROM AND ANOTHER PIPE EXTENDING FROM ONE OF SAID COMPARTMENTS TO A LOWER PART OF SAID CHAMBER BOTTOM FOR RECEIVING THE DRAINED SLURRY AND RETURNING IT INTO SAID BODY.