The NPK blending production line (also known as the BB fertilizer production line) follows the "granule-to-granule" route. The production of BB fertilizer (blended fertilizer) is essentially a purely physical process—directly blending pre-granulated single-element basic fertilizers such as large-particle urea, monoammonium phosphate, and potassium sulfate according to soil testing and formulation data, without involving any chemical reactions. The entire production line consists of four main modules: a raw material storage and conveying system, a dynamic batching and metering system, an NPK blender, and an automatic packaging system. The batching system is the "brain" of the entire production line. It employs centralized PLC control and utilizes high-precision sensors and intelligent weighing algorithms to minimize errors in the nitrogen, phosphorus, and potassium nutrient ratios. After batching, the materials enter the NPK blender. This equipment uses a twin-shaft paddle or zero-gravity blending structure, achieving rapid and uniform mixing through the stirring of paddles at a specific angle. A batch can typically be blended in 3 to 5 minutes.

Unlike the "granule-to-granule" process of BB fertilizer, the organic fertilizer disc granulator (also known as a bio-organic fertilizer disc granulator) performs the "powder-to-granule" granulation task. The core working component of this equipment is an inclined circular disc, with the inclination angle typically adjustable between 35° and 55°. Powdered material is conveyed by a conveyor belt into the rotating disc. Under the combined action of centrifugal force, friction, and gravity generated by the disc's rotation, the material moves along a parabolic trajectory, adheres to each other, rolls, and grows, gradually forming spherical particles that eventually overflow naturally from the edge of the disc. The disc granulator achieves a granulation rate of over 93%. The granulation disc features an integral arc structure, reinforced at the bottom with multiple radial steel plates, ensuring durability and preventing deformation. The disc is lined with high-strength fiberglass for corrosion and wear resistance.

The double axis mixer plays a crucial connecting role between these two processes. This equipment uses two parallel mixing shafts that rotate synchronously in opposite directions. Under the combined action of the two shafts, the material undergoes multiple processes of shearing, compression, and convection. The twin-shaft mixer achieves a mixing uniformity of over 95%, making it particularly suitable for processing organic materials with high fiber content and high viscosity. In actual production lines, the twin-shaft mixer is typically positioned after the crusher and before the disc granulator—the powdery material is first evenly moistened with atomized water in the twin-shaft mixer to form granules, before being fed into the disc granulator for granulation.

NPK blending production lines are known for their flexible formulations, low investment, and quick returns, making them suitable for precise formulation using finished granules as raw materials. Organic fertilizer disc granulators, with their high granulation rate and ability to protect microbial activity during room-temperature operation, are a classic choice for organic and bio-organic fertilizer production. Organic fertilizer twin-shaft mixers act as a bridge between these two types of equipment, facilitating material homogenization. Each of these three technical routes has its strengths; choosing the one that best suits your needs is more important than blindly pursuing an "all-rounder" solution.