Industry Info

Effect of raw material selection and matching on compound fertilizer agglomeration

 With the development of compound fertilizer, more and more formulations have emerged. More and more nutrient-rich, water-soluble raw materials are used in the NPK fertilizer production. Based on years of industry experience, our company has found that the combination of different raw materials has a great influence on the anti-caking of compound fertilizer.

Commonly used raw materials for compound fertilizer are mainly urea, ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium hydrogencarbonate, monoammonium phosphate, diammonium phosphate, superphosphate, potassium chloride, potassium sulfate, etc. These raw materials have different degrees of hygroscopicity, and the critical moisture absorption point after mixing different raw materials will be significantly lower than that of the single object. When the air humidity is high or the chemical reaction between the different components of the compound fertilizer in fertilizer manufacturing process has not yet been completed, a double salt and a solid solution are formed during the storage process. These reactions occur between the surface components of the particles, and where the particles of different components come into contact with each other with the release of heat and moisture, which may cause recrystallization between the surfaces of the particles, forming a crystal bridge and causing agglomeration. Because low and medium concentration compound fertilizers are mixed with inert materials (fillers), such as silica, calcium sulfate, calcium carbonate and the like. The high-concentration compound fertilizer is less soluble in water than the inert material, and the binding bond between the water and the water-binding bond is relatively large, so the lower-concentration compound fertilizer is more likely to agglomerate. The following is an analysis of the influence of raw material selection on agglomeration. N fertilizer: urea, ammonium chloride, ammonium sulfate, ammonium nitrate.

In the nitrogen and phosphorus binary fertilizer, adding a small amount of urea, it is easy to cause fertilizer compaction. For example, adding 30kg of urea in the 20-20-0 formula, the product agglomeration is difficult to suppress by the anti-caking agent.

In the urea (or in the urine), gypsum powder gypsum (CaSO4•2H2O) is added to react with urea to form a stable double salt CaSO4•4CO(NH2), thereby slowing down the formation of double salts between urea and other substances.

Adding more than 10% ammonium sulfate to the high tower nitrate-based formula tends to result in reduced strength and chalking of the fertilizer. Because ammonium nitrate and ammonium sulfate are mixed to form 2NH4NO, (NH4): double salt of SO4, the material is thermally decomposed during drying to decompose into its own components, and is reduced to double salt upon cooling, which easily causes powdering and agglomeration of granular fertilizer..