There are some problems and difficulties in the
npk fertilizer production line. When we produce npk fertilizer granules, we should pay attention to the following points, which can help you to make better compound fertilizer particles.
1. Humidity problem: the optimum moisture content of urea system material is about 3%, which is lower than other material, and the qualified rate of granulation is only 30%, and the production capacity is low.
2.Temperature problem: when the temperature of fertilizer granulation is high, the amount of liquid phase of the system will increase, because the inorganic salt will increase with the increase of solubility, the amount of compound salt generated by mutual dissolution and reaction will increase, the degree of uniformity will increase, the amount of external liquid phase should be appropriately reduced, and the wet content of granulation should be adjusted with the change of solubility of raw materials.
3. The problem of material solubility: in the compound fertilizer with high nitrogen ratio, the amount of urea added should be more than 50%, and the solubility is large, so the amount of liquid phase is very high. It can be improved by adding powdered urea at lower operating temperature. However, the operation of urea dissolution and heat absorption reduces granulation temperature of the
rotary drum granulator and increases the operation difficulty. In addition, the mixture with low melting point is more difficult to control granulation.
4. Return material problem: it mainly affects the granulation temperature, humidity, high solubility of materials and the core of granulation. The qualitative temperature, particle size distribution, temperature and humidity of return material are very important for granulation and must be strictly controlled.
5. PH problem of materials: pH is an important index to determine whether the compatibility of materials system is appropriate. In NPK fertilizer production line, it is appropriate to control the pH value of materials between 6.0-6.5. When the material is slightly acidic, the solubility of the material is large, and the reaction is violent, the particles are easy to bond to form a ball, resulting in large particles. If it is slightly alkaline, the ammonia loss will be large, the reactivity of the material will be poor, and the material will not be easily granulated if it is divergent. The pH value can be adjusted by adding ammonium bicarbonate, calcium magnesium phosphate and so on.
