What are the commonly used granulators in fertilizer production?

Granulation is a core process in fertilizer production, turning powdered raw materials into uniform granules, improving fertilizer utilization, facilitating storage, and enabling mechanized fertilization. Based on production processes, raw material characteristics, and production capacity requirements, commonly used granulators in the fertilizer industry are mainly divided into four categories: disc granulators, rotary drum granulators, double roller press granulators, and flat die pellet machines. They are widely used in the production of various fertilizers such as organic fertilizers, compound fertilizers, and slow-release fertilizers.

Disc granulators are the mainstream equipment in small and medium-sized fertilizer production lines, with extremely high applicability. They rely on the centrifugal force generated by the rotation of an inclined disc to continuously roll and bind the powder into balls, achieving a granulation rate of over 90%. This equipment has a simple structure, is easy to operate, and has low maintenance costs. It is suitable for various organic raw materials such as livestock manure, straw, and humic acid, and can also be used in the production of ordinary compound fertilizers. The disadvantage is that the uniformity of the granules is easily affected by the moisture content of the raw materials and the rotation speed, making it more suitable for small- to medium-scale routine production.

Rotary drum granulators are mostly used in large-scale compound fertilizer production lines and belong to the wet granulation equipment category. The first type of equipment uses continuously rotating drums, combined with sprayed steam or binders, to cause materials to roll and agglomerate within the drum, forming the granules. It boasts high capacity and continuous operation, producing round, plump, and uniform granules with excellent appearance. However, it requires a large footprint, has strict requirements for raw material ratios and humidity, necessitates supporting drying equipment, and has relatively high overall production costs, making it suitable for large-scale industrial production.

The second type of equipment, the double-roller press granulator, is a dry granulation device that requires no added water or binders. It relies on high-pressure extrusion by two rollers to compress powdered raw materials into granules, which are then crushed and shaped to obtain pellets. It has low energy consumption, requires no drying, and produces no waste. The pellets have high hardness and are not prone to caking, making it suitable for the production of high-concentration compound fertilizers, inorganic fertilizers, and slow-release fertilizers. Its disadvantage is that the pellets are mostly oblate, resulting in a less desirable appearance.

The third type of equipment, the flat die pellet machine, is primarily designed for the production of organic fertilizers and is suitable for organic materials with high humidity and high fiber content. The equipment uses pressure rollers to extrude materials through die holes, resulting in compact and stable granules. This maximizes the retention of nutrients in the raw materials and effectively solves the problems of difficult and loose granulation of organic materials. It is one of the core pieces of equipment in organic fertilizer processing.

In summary, each type of granulator has its advantages. During production, it is necessary to select the appropriate model based on the type of fertilizer, production scale, and cost requirements to ensure both the quality of the finished fertilizer and production efficiency.