This is to introduce a process for making diammonium phosphate fertilizer of 18-46 in which the raw materials used are dilute wet-process phosphoric acid and ammonia. The authors have studied the degree of neutralization of phosphoric acid with ammonia in relation to the ratio between N and P2O5 in product

the ratio between the liquid and solid phases in paste

the amount of water and ammonia evaporated from paste

etc.. At the same time

the authors have also studied the pelletizing and drying of the product

the recovery of dust from the tail gas

as well as the construction of various equipments. From their studies

they have found the following results. I. The optimum conditions for making diammonium phosphate fertilizer of 18-46 grade are as follows. a. The optimum concentration of phosphoric acid is 32% P2O5

b. the proper degree of neutralization of phosphoric acid with ammonia is at 1.78

and c. in pelletization

the recycling material which is 40% -6 to +12 mesh

60% -12 mesh

and the quantity ratio is about 11 times of the product. II. They have also determined the construction and the materials for making the reactor

the pelletizer of horizontal type with double axis

the rotary dryer

and the scrubber of impingement type

etc..