According to the needs, several kinds of fertilizer raw materials dry powder are selected for metering and mixing, and the binder is used as the binder to form granules in the fertilizer granulator machine
. The granulation of dry powder mixture needs heating, adding water or steam to increase the amount of liquid phase, and then agglomerate into compound fertilizer particles in the drum granulator under rolling condition.
At present, acid and ammonia are usually added to increase the liquid volume in the NPK manufacturing process
, and the heat is provided by the chemical reaction. The ammonium phosphate produced by the reaction of phosphoric acid and ammonia becomes the component of compound fertilizer. Better temperature (50-80 ℃) and better moisture content (2.5% - 7.5%) should be controlled for the materials in the drum granulator to achieve the appropriate granulation conditions.
The working principle of the rotary drum fertilizer granulator machine: the material enters the front end of the rotating cylinder through the feeding pipe (the slope of the feeding pipe is greater than the natural inclination of the material), and the steam inlet pipe at the front end of the cylinder sprays a certain pressure of steam. Because the nozzle of the steam inlet pipe is located at the bottom of the material. And the steam has a certain pressure. Therefore, the material obtains some moisture more evenly and forms smaller particles. Because the cylinder has a certain slope. Under the action of gravity and the frictional force of the lining plate, these small particles continuously move in the direction of the circumference and axis of the cylinder. During the movement, the smaller particles gradually form particles of a certain specification.