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Key points of formula design for extrusion granulation of NPK fertilizer production line

2021/04/23

From a technical point of view, the important influencing factor in the formulation design of the extrusion granulation product of the NPK fertilizer production line is the characteristics of the material. Next, we will discuss another aspect of the influencing factor, that is, the influence of the type of raw material on the formulation.

1. Material compatibility

Theoretically speaking, basic fertilizers containing N, P or K can be formulated in any proportion, and trace elements and even pesticides and other pesticides should be added when necessary. However, the materials must be restricted by compatibility. The materials in the formula cannot undergo chemical reactions during the NPK fertilizer production process, nor are they allowed to react occasionally.

2. The influence of urea on the formula

The International Fertilizer Center has conducted a large number of experiments on the effect of urea on the performance of compound fertilizers. Although the report has not mentioned an example that is exactly the same as our investigation of the product formula, and most of the experiments are not made for the extrusion granulation method. Yes, but its conclusions are still useful for us.

Because urea is easy to absorb moisture, it obviously reduces the critical relative humidity of NPK compound fertilizer. At the same time, the International Fertilizer Center also found that when potassium chloride is used as the potassium source of compound fertilizers, the impact is more serious.


Due to the low critical relative humidity, compound fertilizers based on urea are easy to absorb moisture and block screens, pipes, chutes, etc.


When the temperature raises, the critical relative humidity of the urea-based compound fertilizer drops quickly.


The production capacity of the dryer is determined by many factors. Some urea-based NPK fertilizers begin to soften at 70°C. If the outlet temperature of the dryer is higher than this temperature, the fertilizer particles will be too soft and the NPK fertilizer manufacturing process will be out of control. (The particles are too large), the inside of the dryer is scarred, and it causes difficulties in screening and conveying.