Cage Crusher

The cage crusher serves as a core piece of pulverizing equipment in organic and compound fertilizer production lines, acting as a crucial link between raw material pre-treatment and the subsequent stages of batching and granulation. Thanks to its high-efficiency impact pulverization capabilities and broad material adaptability, it plays an indispensable role in the fertilizer manufacturing sector.

In organic fertilizer production lines, the cage crusher efficiently pulverizes materials such as large, hardened clumps resulting from fermentation, agglomerated livestock and poultry manure, and straw additives. It eliminates the need for intensive material drying; standard semi-wet fermented materials can be fed directly into the machine without prior screening or impurity removal. Its high tolerance for varying moisture content effectively simplifies the pre-treatment process and reduces costs associated with drying and air-curing. In compound fertilizer production lines, the cage crusher reduces caked raw materials—such as urea, ammonium phosphate, and potash—to the optimal particle size, thereby ensuring the accuracy of the batching process.

Component Composition and Functional Zoning

From a process perspective, the cage mill comprises the following functional units:

(I) Feeding unit: Includes the feed hopper and feed inlet. Material enters the crushing chamber uniformly through this unit; the inlet is designed to ensure smooth material flow.

(II) Dual-cage impact crushing unit: The core component of the equipment, consisting of a large cage assembly (outer cage) and a small cage assembly (inner cage). The two cages rotate at high speeds in opposite directions, subjecting the material to multi-stage impact crushing.

(III) Discharge unit: Includes the discharge outlet and discharge channel. Crushed material is discharged from the lower section of the machine housing.

(IV) Drive unit: Includes two electric motors, pulleys, and V-belts. This unit provides the power for the counter-rotating dual-cage rotors.

(V) Dust removal and sealing unit: Includes a fully enclosed machine housing and an optional cyclone dust collection system.

Production Line Roles and Process Flow

The cage crusher serves as a core component in the crushing stage of organic and compound fertilizer production lines. The complete organic fertilizer production process involves: raw material pre-treatment → aerobic fermentation → cage crushing → batching and mixing → granulation → drying → cooling → screening → packaging.

During the post-fermentation processing stage, the cage crusher performs critical tasks: efficiently pulverizing large, compacted clumps of fermented material; controlling the particle size of the crushed material within an optimal range (with over 80% of particles smaller than 0.5 mm); and providing suitable raw materials to ensure uniform batching and high-quality granulation. In compound fertilizer production, the cage crusher effectively reduces raw materials—such as urea, ammonium phosphate, and potash—that have formed clumps into the appropriate particle size.

The equipment integrates seamlessly with upstream and downstream machinery, such as other crushers, batching systems, granulators, and dryers. It features a high level of automation and is easy to operate; equipped with a variable-frequency drive (VFD) system, it allows for flexible adjustment of operating parameters based on factors such as material moisture content, fiber content, and required fineness.

Description of the Crushing Process and Stages

The pulverization process of the cage mill can be divided into the following stages:

Feed distribution stage: Material enters the central area of ​​two counter-rotating cages from the feed inlet. Feeding must be uniform and continuous; consistent feeding yields better pulverization results and relatively higher output.

Coarse crushing stage: Material undergoes coarse crushing while being axially advanced through the gap between the spiral feed sleeve and the machine housing.

Multi-stage impact fine crushing stage: Coarsely crushed material enters the fine crushing zone. Material fragments pass sequentially through the innermost ring of steel rods, the next inner ring, and so on, until they have traversed all the rings. With each ring passed, the material undergoes impact pulverization, with the direction of impact alternating. Inside the cage mill, the material is subjected to three simultaneous crushing actions: impact by the steel rods, collisions between material particles, and impact against the inner wall of the housing.

Discharge stage: The pulverized material falls to the lower part of the housing and is discharged through the outlet.

Preparation and Requirements for Pre-production Materials

The cage crusher has specific process requirements for feed materials. Moisture content: The feed moisture content must be ≤40%; standard semi-wet fermented materials can be fed directly into the machine for crushing. Feed particle size: The average feed particle size should be less than 150–200 mm. Impurity removal: Iron impurities on the permanent magnet drum and the feeder's permanent magnet plate must be cleared regularly. Feed uniformity: Uniform feeding yields better crushing results and relatively higher output.

Operational Guidelines and Key Control Points

Proper operation of the cage mill is crucial for ensuring grinding quality and equipment longevity:

Installation and Pre-start Preparation: Place the mill on a level surface in the workshop; no special foundation is required, and it is ready for use once connected to the power supply. Check all bolts to ensure they are secure. The motor is factory-sealed and the coupling is pre-aligned; do not loosen these components.

Operational Control: Grinding fineness is controlled by the gap between the double rollers; a smaller gap yields finer particles but results in relatively lower output. Operating parameters can be flexibly adjusted based on material moisture content and fiber levels. A variable frequency drive (VFD) system is used to precisely control the output particle size.

Shutdown and Cleaning: Periodically check the fineness of the ground product. Shut down the machine immediately for inspection if abnormalities such as excessive vibration or noise occur. Regularly clean or replace the dust collector filter bags.