Abstract: Improved, simple, energy-efficient, and easy-to-operate process for producing granular diammonium phosphate (DAP) fertilizers from anhydrous ammonia, phosphoric acid, sulfuric acid, and water utilizing a rotating drum granulator and a pipe reactor in combination with a specially designed slurry distributor. The pipe reactor operates at pressures of more than 80 pounds per square inch gage and utilizes a special low-impact distributor to uniformly distribute a wide-angle spray of slurry onto the bed of recycled solids in the drum granulator and to provide for a minimum of bed disruption and deformation. This energy-efficient process produces dry, free-flowing granular DAP with little or no fossil-fuel heating requirements for drying and with low recycle ratios which allow for high production rates or increases in production rates when the process is retrofitted into existing plants.