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Matters needing attention during granulation of NPK compound fertilizer
2020-08-26
NPK compound fertilizer in the process of granulation is a little difficult, about the fertilizer production line granulation problem, we summarized the following points, can help fertilizer plant to make better compound fertilizer particles.
1. Humidity
The optimum moisture content of urea ammonium phosphate series materials is about 3%, which is lower than other systems. The qualified rate of granulation is only 30%, and the production capacity is low.
2. Temperature
When the granulation temperature is high, the liquid phase quantity of the system will increase, because the inorganic salt increases with the increase of solubility, the amount of compound salt generated by mutual dissolution and reaction increases, and the uniformity degree is improved. The amount of added liquid phase should be appropriately reduced, and the content of granulation should be adjusted according to the solubility of raw materials. For example, when the granulation temperature of urea ammonium phosphate system is changed from 60 ℃ to 90 ℃, the material moisture content should be reduced from 3.2% to 1.2%. In addition, the viscosity and surface tension of the liquid phase decrease, so that the particles with higher strength can be obtained under the external force of the rotary drum granulator.
3. Material return
The results show that the temperature, humidity, solubility and core of granulation are affected by the returned materials. During the processing of fertilizer granulator, the temperature and humidity of the returned material are very important to granulation and must be strictly controlled.
4. Melting point and viscosity of materials
The melting point of the mixture is generally lower than the lowest melting point of each component. The co melting point of urea, potassium chloride and monoammonium phosphate system is about 115 degrees, which is the viscosity temperature. The temperature in the vicinity of the granulator should be operated. The viscosity temperature of urea based compound fertilizer decreases with the increase of water content. Therefore, the granulation conditions of high temperature and low water content can not only improve the granulation condition, but also benefit the subsequent drying and screening operation.