Dry material mixing and granulation: In the early process of mixing solid powder materials to make powdered fertilizers, the process steps of granulation, drying, coarse-grain crushing and fine-grain return to continue granulation are added, and finally dry granules are obtained. Finished product. Urea-general calcium-potassium chloride aggregate type compound fertilizer belongs to this category.
Adding part of the dry powder of liquid raw materials for mixing and granulation: When mixing solid powder materials for granulation, the drum granulator
introduces sulfuric acid, phosphoric acid or nitric acid, and supplements a certain amount of water vapor, and blows in gas ammonia to neutralize the added acid or neutralization. And acidic components in solid materials. Relying on the enthalpy brought in by the neutralization reaction heat, saturation and steam, the liquid phase (including the salt solution and water generated by the reaction) is introduced to promote agglomeration and granulation. The granulation of urea-ammonium phosphate-potassium chloride series and ammonium chloride-ammonium phosphate-potassium chloride series materials belongs to this category.
Slurry granulation process: The slurry produced by the reaction material is coated on the surface of the returned particles, and the particles are enlarged through continuous slurry coating, and then the particles are dried and evaporated to remove water, thereby obtaining a hard and Granular product with good fluidity. Due to the wide range of particle size distribution of the returned material, the coating and bonding effects always occur at the same time. For certain materials and npk fertilizer granulator
models, a kind of granulation is always the dominant. The granulation of ammonium phosphate fertilizer belongs to this category.
Melt granulation process: the molten slurry (melt with very low moisture content) is cooled or condensed to make it into granules. Ammonium nitrate melt granulation belongs to this category.