Single Axis Urea Crusher

Single Axis Urea Crusher

The single axis urea crusher is a specialized piece of equipment designed for the pretreatment of fertilizer raw materials—specifically those prone to deliquescence and caking—within production lines for compound fertilizers, organic-inorganic compound fertilizers, and water-soluble fertilizers. Its primary function is the shearing, fine crushing, and breaking up of granular urea that has caked due to moisture or hardened at ambient temperatures (it is also suitable for processing other low-to-medium hardness fertilizer lumps, such as ammonium nitrate, ammonium sulfate, and potassium chloride).
Urea is a widely used straight nitrogen fertilizer in agriculture, yet it is highly susceptible to caking under moisture and pressure during storage. Large urea lumps cannot be directly utilized for blending, water-soluble application, or mechanical spreading. Traditional methods—such as manual breaking or the use of standard crushing equipment—often result in uneven crushing, excessive fines (powdering), material spatter and waste, and machine jams, making it difficult to meet the standardized material requirements for compound and water-soluble fertilizer production. The single axis urea crusher was specifically developed to address these unique physical characteristics of urea.
The equipment operates on the principle of grinding and shearing within the gap between a high-speed rotating drum and a concave plate; the size of this gap determines the degree of material pulverization. Compared to dual axis or multi axis crushers, the single axis urea crusher features a compact structure, a small footprint, and low energy consumption. It also incorporates an air-cooling system designed for heat-sensitive materials like urea, effectively controlling temperature rise during the crushing process (typically keeping it ≤40°C) to prevent melting, re-caking, or nitrogen loss caused by frictional heat. The unit is compact and easy to operate; it requires no complex foundation installation and is ready for use once connected to a power source.

Structural composition of the equipment

The single axis urea crusher features a scientifically sound and rational overall structure, comprising the following core components:
(I) Feeding Device: Includes a feed hopper and a toothed lump-breaking roller located at the inlet. The toothed roller performs preliminary crushing on urea lumps to prevent clogging and ensure continuous operation, while also guaranteeing uniform and controlled material feeding into the crushing chamber.
(II) Single Axis Crushing Chamber: The core working section of the equipment, consisting of upper and lower casings, crushing plates, and curved impact plates. The chamber features a fully sealed design to prevent dust leakage. Its inner walls are lined with anti-stick high-molecular-weight polyethylene (UHMW-PE) panels to prevent urea from adhering due to moisture absorption. Parts in contact with the material are primarily made of 304 stainless steel or carbon steel treated with special anti-rust coatings.
(III) Single Axis Rotor Assembly: Composed of a main shaft, end discs, and wear-resistant cutter heads (or hammers). High-strength alloy hammers—arranged radially and evenly—are secured to the rotor via keyed connections. The blades/hammers are typically made of 65Mn spring steel or Cr12MoV alloy tool steel, heat-treated to enhance wear and impact resistance.
(IV) Concave Plate and Adjustment Mechanism: The gap between the rotor and the concave plate can be flexibly adjusted within a range of 3–12 mm via the adjustment mechanism; this gap size directly determines the degree of material pulverization. Screen plate apertures can be easily changed to meet specific finished-product granularity requirements (commonly φ1.0–3.0 mm).
(V) Transmission and Drive System: Includes the electric motor and V-belts. The motor drives the rotor to rotate at high speeds via V-belts, with main shaft speeds reaching 1,440–2,900 rpm. It utilizes a national-standard pure copper motor with a power range of 5.5–30 kW.

The working principle of the equipment

The working principle of the single axis urea crusher relies on the synergistic effect of “grinding/shearing” and “impact crushing.”
Feeding and Primary Crushing Stage: Urea granules or lumps are introduced through the feed inlet, where a toothed crushing roller performs preliminary breaking on large lumps to prevent clogging and ensure continuous operation.
High-Speed ​​Impact Stage: Upon entering the fully sealed crushing chamber, the material is immediately subjected to violent impact from a high-speed rotating drum (speeds up to 1440 rpm). Granules shatter upon striking the chamber walls and baffles, and are instantly pulverized by the forceful blows of the hammers and intense friction against the toothed plates.
Grinding and Shearing Stage: The pre-crushed material undergoes repeated grinding and shearing between the drum and the toothed concave plate; the size of the gap determines the degree of pulverization. Once the material reaches the desired particle size, it passes through the screen plate; particles that do not meet the requirement remain in the chamber for repeated impact until they pass through.
Air Cooling: To address the heat-sensitive nature of urea, the equipment features an air-cooling system that effectively controls temperature rise during the crushing process (typically ≤40°C), preventing melting or agglomeration caused by frictional heat.
Discharge Stage: The pulverized material is discharged directly; the machine features a fully sealed design to prevent dust leakage.

Types of suitable raw materials

The single axis urea crusher is designed to process specific types of raw materials:
Primary materials: Granular urea, moisture-caked urea, and hardened urea lumps (individual lump size typically ≤150 mm).
Secondary materials: Ammonium chloride, ammonium sulfate, ammonium nitrate, compound fertilizers, potassium chloride, potassium magnesium sulfate, calcium ammonium nitrate, and other fertilizers of low-to-medium hardness that are prone to caking.
Other applicable materials: Brittle materials such as coal, furnace slag, shale, and loose limestone. The compressive strength of the material to be crushed should not exceed 12 MPa, and surface moisture content should be below 13%.
Inapplicable materials: Not suitable for crushing extremely hard materials, materials in a liquid/slurry state, or materials containing significant amounts of undissolved mud or impurities.

Equipment Operation and Maintenance Procedures

Operational Highlights: The equipment is simple and convenient to operate, featuring a variable-frequency speed control system that allows operators to flexibly adjust rotation speed and crushing force based on material agglomeration levels and desired output particle size. To use, simply place the unit on a level surface in the workshop and connect the power supply. Uniform feeding yields superior crushing results and relatively higher output.
Routine Maintenance: Thoroughly clear any accumulated material from the crushing chamber after each shift. Pay close attention to hammer wear; replace the entire set if wear reaches one-third of the original thickness. Inspect the screen plate for damage or clogging. Periodically apply lithium-based grease and check the motor belt tension. The equipment features a rational structural design free of complex “dead zones” where material might accumulate, making routine disassembly, cleaning, and maintenance highly convenient.
Long-term Shutdown: When the equipment is taken out of service, thoroughly clean the crushing chamber, apply anti-rust measures, and ensure the motor terminals are protected against water and dust.