Compound fertilizers, with their comprehensive nutrients and stable efficacy, are the main fertilizers used in modern agriculture. The production process directly determines the quality of fertilizer granules, their efficacy characteristics, and their applicability. Currently, disc granulation, drum granulation, and extrusion granulation are the three most widely used and practical core processes in compound fertilizer production. These three processes rely on different forming principles to adapt to different production scales and fertilizer types, supporting the large-scale and refined production of compound fertilizers.

Disc granulation is a classic wet agglomeration granulation process. The equipment has a simple structure and is easy to debug, making it the mainstream process for small and medium-sized compound fertilizer production lines. Its working principle involves feeding the pre-mixed nitrogen, phosphorus, and potassium powder raw materials into an inclined rotating granulation disc. Through continuous spraying of water, steam, or a special binder, the powder materials adhere to each other under the rolling and centrifugal action of the disc, gradually agglomerating to form spherical granules. This process is flexible in operation, has low production costs, and produces round granules with moderate looseness and good water solubility, making it suitable for the production of various general-purpose compound fertilizers. However, its disadvantages include limited automation, difficulty in controlling particle uniformity, and relatively weak stability during mass production.
Rotary drum granulation is a large-scale wet granulation process specifically designed for large-scale compound fertilizer production lines, offering significant advantages in mass production. The core equipment is a horizontal rotary drum. After the raw material powder and binder are fed into the drum, the material continuously tumbles, rubs, and agglomerates as the drum rotates at a uniform speed, gradually forming regular granules. Combined with subsequent drying and screening processes, continuous production line production can be achieved. Compared to disc granulation, drum granulation has higher production efficiency, larger capacity, more stable operation, and extremely strong raw material adaptability, suitable for processing various compound fertilizer formulations. Its disadvantages include a large footprint, the need for comprehensive drying and dust removal equipment, and relatively high overall energy consumption.
Extrusion granulation is an energy-saving and environmentally friendly physical dry granulation process that requires no water, heating, or binders. This process relies on high-pressure extrusion equipment to forcibly compact and press the powder raw material into strips, followed by crushing and screening to obtain regular solid granules. Its greatest advantage lies in its simple process flow, extremely low energy consumption, and zero emissions of wastewater, exhaust gas, or other pollutants, making it environmentally friendly. Furthermore, it achieves precise fertilizer nutrient ratios with minimal production losses. The finished granules are compact, hard, and resistant to caking, with a slow and sustained release of fertilizer effects, making it suitable for producing long-acting, slow-release compound fertilizers. The disadvantage is that the granules have relatively low water solubility, making them unsuitable for rapid-acting fertilization applications.
In summary, disc, rotary drum, and extrusion granulation processes each have their own advantages and disadvantages, respectively suited for flexible small-batch production, large-scale mass production, and the production of green, long-acting fertilizers. These three processes complement each other, forming the core technological system for compound fertilizer production and continuously contributing to the efficient and green development of modern agriculture.