Urea granulation process

Claim 1

THE PROCESS OF BUILDING UP SUB-PRODUCT SIZE UREA SEED PARTICLES TO GRANULAR PRODUCT SIZE SO THAT THE PRODUCT GRANULES HAVE LOWER BIURET CONCENTRATION THAN A UREA FEED SOLUTION FROM WHICH SAID SEED PARTICLES ARE DERIVED, THAT INCLUDES PASSING A STREAM OF SAID SEED SIZE PARTICLES THROUGH WETTING AND DRYING ZONES AND THEREIN WETTING THE PARTICLES WITH AN AQUEOUS UREA FEED SOLUTION AND DRYING THE WETTED PARTICLES TO DEPOSIT THIN COATINGS OF UREA THEREON AND AT TEMPERATURES SUFFICIENTLY BELOW UREA MELTING TEMPERATURE THAT SUBSTANTIALLY NO ADDITIONAL BIURET FORMS, AGITATING SAID STREAM IN SAID ZONES TO INHIBIT COATED PARTICLE AGGLOMERATION AND TO FLAKE OFF AS FINES THE OUTERMOST DEPOSITED COATINGS IN WHICH BIURET CONCENTRATES, SEPARATING CONTENTS OF THE RESULTANT STREAM INTO PRODUCT GRANULES, SEED PARTICLES AND FINES SMALLER THAN SAID SEED AND PRODUCT, SAID SEED PARTICLES BEING LARGER THAN 40 MESH TYLER SCALE, RETURNING A SIDE STREAM OF SAID SEPARATED SEED PARTICLES TO SAID WETTING ZONE, SAID STEPS BEING CARRIED OUT SO THAT THE SEED PARTICLES BEING RETURNED TO THE WETTING ZONE REMAIN DISCRETE AND UNMELTED BETWEEN AND DURING SAID RETURN AND PASSAGE THEREOF THROUGH SAID WETTING AND DRYING ZONES, SAID FINES AND SEED PARTICLES SEPARATION BEING SUFFICIENTLY COMPLETE THAT FINES SMALLER THAN 40 MESH TYLER SCALE IN THE SEED PARTICLE STREAM BEING RETURNED TO SAID WETTING ZONE COMPRISE LESS THAN 8% OF THE SIDE STREAM WEIGHT, AND PERMANENTLY REMOVING FROM SAID PROCESS STREAMS THE BULK OF THE SEPARATED FINES WHICH ARE NOT RETURNED TO THE WETTING ZONE IN SAID SEED PARTICLE STREAM.