Process for production of ammonium phosphate fertilizers

Claim 1

A ONE-STEP CONTINUOUS PROCESS FOR THE PRODUCTION OF GRANULAR FERTILIZER OF ABOUT 15-50-0 GRADE WHICH COMPRISES CONTINUOUSLY INTRODUCING FINES OF LESS THAN ABOUT 12-MESH SIZE RECYCLED FROM A LATER MENTIONED SIZING STEP INTO THE UPPER END OF A HORIZONTALLY INCLINED ROTATING DRUM, CONTINUOUSLY INTRODUCING IMPURE PHOSPHORIC ACID INTO THE UPPER END OF SAID ROTATING DRUM AT A CONTROLLED RATE, CONTINUOUSLY INTRODUCING AMMONIATING FLUID INTO THE UPPER END OF SAID DRUM AT A RATE TO NEUTRALIZE THE PHOSPHORIC ACID TO A DEGREE SUCH THAT APPROXIMATELY EQUAL PROPORTIONS OF MONOAMMONIUM PHOSPHATE AND DIAMMONIUM PHOSPHATE ARE FORMED, MAINTAINING A BED OF ROLLING DISCRETE PARTICLES IN THE DRUM, CONTINUOUSLY WITHDRAWING GRANULATED MATERIAL FROM THE LOWER END OF THE DRUM AT A TEMPERATURE IN THE RANGE FROM ABOUT 150*F. TO 210* F., SUPPLYING SUBSTANTIALLY ALL OF THE HEAT FOR MAINTAINING SAID TEMPERATURE RANGE FROM THE HEAT OF REACTION OF THE REACTANTS, MAINTAINING THE MOISTURE CONTENT OF GRANULATED MATERIAL LEAVING THE DRUM IN THE RANGE FROM ABOUT 1.5 PERCENT TO 7.0 PERCENT, SIZING THE WITHDRAWN GRANULAR MATERIAL, SEPARATING THE FINE PORTION THEREOF, SEPARATING A PORTION OF PRODUCT-SIZE MATERIAL, CRUSHING THE REMAINING PORTION OF PRODUCT-SIZE MATERIAL AND ALL THE OVER-SIZE MATERIAL AND RECYCLING SAID CRUSHED MATERIAL TOGETHER WITH SAID FINE PORTION AS FINES TO THE ROTATING DRUM.