When choosing the granulation method for organic fertilizer production line, the purpose of granulation and the problems to be solved should be clarified first, and then compared with the following factors, the inappropriate method should be eliminated and a suitable and simple method should be determined.
(1) Material characteristics. It should be considered whether the material is powder or molten liquid, whether the slurry and sound paste materials can be pumped and atomized, whether the materials have heat sensitivity, etc.
(2) Requirements for production capacity. If the production capacity of fertilizer production line is large, there are many methods that can not be applied.
(3) The requirements of particle size and particle size distribution. Some methods, such as spray drying granulation, can only get very fine particles. The granulation method of powder can only get smaller particles, while other methods such as pressing can get large lumps. (4) The shape of the granulas. The spherical particles can be obtained by drum granulation, stirring granulation and spraying granulation; spherical particles can be obtained by shot peening cooling solidification granulation; and columnar particles can be produced by extrusion granulation. The possible influence of particles of different shapes on the follow-up work should be estimated.
(5) The strength of the granulas. The mechanical strength of the particles obtained by powder agglomeration and shot peening is weak. If high strength particles are needed, they need to be strengthened by pressing or sintering or roasting, and high strength binders should be selected for extrusion molding.
(6) The void ratio and density void of the granulas. The porosity and density are closely related to the strength. Some extrusion granulation organic fertilizer production processes can better control the porosity and density to meet the needs of some applications.
(7) Wet and dry methods. Wet granulation needs expensive solvent, and drying after granulation may cause solvent loss. Some materials may be sensitive to solvent and not suitable for wet granulation. Some materials may recrystallize into different shapes during drying, and wet granulation is not suitable for processing toxic chemicals and other hazardous materials.