Cage Crusher

Equipment Introduction

A cage crusher, also known as a cage mill, squirrel cage crusher, or medium-sized horizontal cage bar crusher, is an industrial crushing equipment designed based on the principle of impact crushing. This equipment belongs to the category of mechanical impact crushers. Its core feature is the repeated impact, collision, and shearing of materials by two sets of high-speed, counter-rotating cage rotors, thereby achieving fine crushing of the materials.

Cage crushers are widely used in various industries such as fertilizer, mining, building materials, chemicals, feed, food, pharmaceuticals, and plastics due to their simple and compact structure, high crushing efficiency, stable operation, good sealing performance, and ease of cleaning and maintenance. They are especially considered a powerful tool for crushing compound fertilizers.

Equipment Structure

The cage crusher mainly consists of the following core components:

1. Casing and Base: Typically welded from thickened steel plates, the casing has internal linings to prevent wear. The base supports the entire transmission system.

2. Cage Rotor (Core Component): Composed of an inner and outer cage. The cage is formed by welding high-strength round steel bars (cage ribs) evenly spaced onto a disc. The inner and outer cages are concentrically arranged and nested within each other.

3. Transmission System: Includes two independent motors, pulleys, a drive belt, and bearing housings. The two motors drive the inner and outer cages to rotate at high speed in opposite directions.

4. Feed Hopper and Discharge Port: The feed hopper is located on the side of the machine (usually directly opposite the center of the inner cage), and the discharge port is located at the bottom of the machine.

Working Principle of the Equipment

The cage crusher follows a combined crushing mechanism of impact crushing + shearing grinding + material collision.

1. Two motors start, driving the inner and outer cages to rotate at high speed in opposite directions, creating a speed difference.

2. Material falls into the center of the crushing chamber through the top feed inlet.

3. The material first contacts the high-speed inner cage bars, undergoing initial crushing due to the violent impact.

4. Under centrifugal force, the material diffuses outwards, entering the area where the inner and outer cages intersect.

5. The material continuously encounters impact and shearing from the counter-rotating outer cage bars, while particles collide with each other (material-on-material effect).

6. The material is continuously and repeatedly crushed. Particles meeting the required size pass through the gaps between the cage bars and are discharged from the bottom outlet by gravity. Coarse particles continue to circulate and crush within the crushing chamber.

7. Due to the absence of a screen, high-moisture, easily agglomerated materials are less prone to clogging. The fineness of the finished product is adjusted by the cage bar spacing, rotor speed, and feed rate. Key mechanism differences: Hammer crushers rely on screens to control the output particle size, which makes them prone to screen clogging by wet materials; cage crushers rely on centrifugal force fields for classification, making them the preferred fine crushing equipment for agglomerated fertilizers and fermented organic fertilizers.

Applications of the Equipment:

1. Fertilizer Industry: The primary application area, used for breaking down raw materials for compound fertilizers, pulverizing urea, and re-pulverizing finished fertilizers.

2. Chemical Industry: Crushing clumps of chemical raw materials, pigments, etc.

3. Building Materials Industry: Crushing brittle materials such as gypsum, chalk, and clay lumps.

4. Environmental Protection: Used for breaking down certain brittle components in waste treatment.

Suitable Raw Materials for the Equipment

Cage crushers have certain requirements for raw materials and are mainly suitable for materials with the following characteristics:

Equipment Operation and Maintenance Methods

1. Installation and Debugging

Before use, place the crusher flat in a designated location in the workshop. No special equipment foundation is required; simply connect the power supply.

It can be designed as a mobile unit according to user requirements. Move it to the appropriate location when in use and remove it when not in use.

The entire machine installation requires a secondary grouting foundation. After tightening the anchor bolts, a dynamic balance check must be performed.

After installation, check that all components are secure, and then conduct a no-load test run.

Run the machine under no-load for 8 hours. The temperature of each bearing should rise steadily. At the end of the test run, the temperature of each component should not exceed 50℃.

2. Daily Operation Points

The fineness of the crushing is controlled by the gap between the two rollers. The smaller the gap, the finer the fineness, but the output is relatively reduced. Uniform feeding results in better crushing and a relatively higher output.

Operators must carefully read the product manual, understand the structural principles, and be familiar with the performance and operating procedures. The feed particle size is generally 1/4 to 1/3 of the cage length.

3. Routine Maintenance

(1) The pulverizer motor is sealed with lead before leaving the factory, and the coupling is calibrated; do not loosen it.

(2) Regularly clean iron impurities from the permanent magnet cylinder and the permanent magnet plate of the pulverizer feeder.

(3) Regularly check the fineness of the pulverized product.

(4) Regularly clean or replace the dust collector bag, and regularly check the operation of the solenoid valve.

(5) Regularly check the wear of each vulnerable part.

(6) Pay attention to the vibration of the pulverizer.

(7) Add 80 grams of grease to the main shaft bearing every 40 hours of operation, but only up to 60%. After 1800 hours of operation, remove the bearing housing cover and replace all used grease.

(8) Establish a "three checks daily" system: check cage bar wear, bearing temperature, and feed uniformity.

(9) Perform comprehensive maintenance weekly: clean internal equipment residue, replace grease, and calibrate clearances.

(10) Conduct in-depth overhaul monthly: check rotor balance and screen sealing. 4. Management of Wear Parts The steel bars are the main working parts of the cage crusher and also the most easily worn parts. Steel bars generally have a service life of only 400-800 hours. The diameter of the steel bars is generally around 3cm. When the wear exceeds 3/4, they should be replaced or repaired immediately; otherwise, the cage will lose its balance. The wear surface of the steel bars should face inwards and in the direction of movement, and their cross-section can be designed as an ellipse to accommodate uneven wear.
Common Equipment Problems and Solutions

Equipment Applications in Production Lines

(I) Applications in Compound Fertilizer Production Lines

In the compound fertilizer production process, the cage crusher mainly undertakes the two core processes of raw material crushing and screening/return material crushing. It is a key piece of equipment to ensure granulation quality and stabilize the particle size of the finished product.

Complete Process Flow: Raw Material Batching → Raw Material Mixing → Cage Crushing → Raw Material Granulation → Granule Drying → Granule Cooling → Granule Grading → Finished Product Coating → Finished Product Packaging

Raw Material Crushing Before Batching

Urea, ammonium phosphate, potassium salt, and other easily agglomerated, large-particle fertilizer raw materials are finely crushed to the fineness required for the granulation process, ensuring uniform batching and stable granulation in subsequent batching.

Return Material Crushing After Screening

Oversized and unqualified particles screened out in the granulation grading process are returned to the cage crusher for further crushing. After being refined, they are re-involved in batching and granulation, reducing waste loss and improving the finished product qualification rate.

(II) Application in Organic Fertilizer Production Lines

In the organic fertilizer production process, cage crushers are mainly used for the fine crushing of fermented and decomposed materials. They are suitable for medium- to high-moisture organic materials, are not prone to clogging, and are a core piece of equipment in organic fertilizer pretreatment.

Complete Process Flow: Organic raw material collection → High-temperature fermentation and decomposition → Cage crusher fine crushing → Ingredient mixing → Granulation → Drying and dehydration → Finished product screening → Finished product packaging

The moisture content of the fermented organic materials is generally 30%–35%. After screening and iron removal, they enter the cage crusher for fine crushing. The crushed powder is uniform in particle size, loose, and free of lumps. It can be fully mixed and homogenized with nitrogen, phosphorus, and potassium inorganic raw materials, significantly improving the subsequent granulation rate and particle uniformity, ensuring stable quality of the finished organic fertilizer.

(III) Production Line Equipment Combinations

The cage crusher can be flexibly combined with various fertilizer equipment to form a complete automated production line. The supporting equipment is divided into front-end, back-end, and auxiliary systems:

1. Front-end Supporting Equipment

Belt conveyor, bucket elevator, automatic batching system, screening and impurity removal equipment, iron remover

2. Back-end Supporting Equipment

Twin-shaft mixer, rotary drum granulator, extrusion granulator, drum dryer, cooler, grading and screening machine, automatic packaging machine

3. Auxiliary Supporting Equipment

Cyclone dust collector, induced draft fan, complete electrical control system, safety protection and sealing dust removal device

Key Features of the Equipment:

1. Simultaneous crushing and mixing: Multiple materials can be fed simultaneously, achieving both crushing and mixing.

2. Concentrated and uniform particle size range in the finished product, with minimal over-crushing.

3. Compact structure, small footprint, simple foundation construction, and some models can be made mobile.

4. Sealed casing facilitates the integration with dust collection systems, ensuring controllable dust levels.

5. Wear parts are concentrated in the cage bars, allowing for convenient disassembly and replacement, and intuitive maintenance.

Cage crushers, as a classic impact crushing equipment, occupy an irreplaceable position in industries such as fertilizer, chemical, and building materials due to their advantages of simple structure, high crushing efficiency, and uniform particle size. Although traditional limitations such as rapid steel bar wear and high noise levels exist, the development of technologies such as dust-free operation, intelligent systems, and wear-resistant materials has significantly improved modern cage crushers in terms of environmental friendliness, reliability, and automation. When selecting a model, users should fully consider material characteristics, production capacity requirements, environmental requirements, and maintenance costs to choose the most suitable model for their production scenario. Through standardized operation and scientific maintenance, long-term stable and efficient operation of the equipment can be ensured.

We have been deeply involved in the fertilizer equipment field for many years, and our products cover process design, equipment manufacturing, installation, commissioning, and after-sales maintenance for multiple categories of production lines, including organic fertilizer, compound fertilizer, BB fertilizer (blended fertilizer), and bio-fertilizer, providing you with full-process services.