The granulation process in the NPK compound fertilizer production line refers to mixing raw materials such as N (nitrogen), P (phosphorus), K (potassium), and other trace elements, and processing them into granular fertilizers with a certain shape (usually round) through physical or chemical methods. This process not only improves the physical stability of fertilizers, but also facilitates precise application and reduces nutrient loss. The following are the detailed steps and related equipment of the NPK fertilizer production line granulation process:
Overview of granulation process
Raw material pretreatment:
Grinding: Use a fertilizer grinder to grind raw materials (such as urea, diammonium phosphate, potassium chloride, etc.) to the appropriate particle size to ensure uniform mixing.
Mixing: Using a dual axis mixer or a multi screw mixer, accurately mix and thoroughly blend all ingredients according to the formula.
Granulation:
Dry granulation: suitable for certain specific raw material combinations, forming hard particles by high-pressure compression of raw material powder. Commonly used equipment includes roller press granulators and flat mold granulators.
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Wet granulation:
Spray granulation: spray adhesive solution (such as water or dissolved polymer) inside the drum granulator to agglomerate raw powder into particles.
Drum granulation: Raw materials and a small amount of water or adhesive roll in the drum granulator, gradually forming spherical particles through friction and gravity.
dry:
Use a rotary kiln dryer or fluidized bed dryer to heat the granulated fertilizer particles, evaporate the surface and internal moisture to enhance particle strength and stability.
Cooling:
The cooling machine quickly lowers the dried hot particles to near room temperature to prevent clumping and excessive hardening, facilitating subsequent packaging and storage.
Screening and coating:
Screening: Use a vibrating screen to screen out particles that do not meet the size requirements for rework.
Coating: In order to increase the smoothness and moisture resistance of the particles, a fluidized bed coating machine can be used to coat the surface of the particles with a thin layer of wax or resin.
packing:
The automatic quantitative packaging machine weighs and packages qualified fertilizer particles into plastic or woven bags, labels them, and prepares them for shipment.
Introduction to Key Equipment
Granulator: such as drum granulator, extrusion granulator, drum granulator, etc., they achieve particle formation based on different principles. Among them, drum granulator is one of the most commonly used equipment, favored for its ability to produce uniform and sturdy fertilizer particles.
Drying machine and cooling machine: The rotary kiln drying machine and fluidized bed cooling machine are responsible for drying and cooling the particles respectively, ensuring the stability of the physical properties of the particles.
Screening machine and coating machine: vibrating screen is used to screen out unqualified particles, while fluidized bed coating machine is used to coat particles, improving appearance quality and preservation performance.
The granulation process of NPK fertilizer production line involves multiple continuous processing stages, each with dedicated equipment and technical support, working together to complete the entire process from raw materials to finished products. Modern NPK fertilizer factories often adopt integrated control systems to achieve automated production, greatly improving efficiency and accuracy, and reducing errors and costs caused by manual intervention.