In today’s environment of tightening environmental policies and rising energy prices, one of the most pressing concerns for fertilizer producers is: can granules be produced without drying? The answer is yes—roller extrusion granulation lines offer just such a solution, requiring no heating and forming at room temperature.
Core Principle: Physical Extrusion, Replacing Chemical Bonding
Unlike traditional drum granulation (which requires water, steam, and hot air drying), roller extrusion granulators rely on two counter-rotating rollers to directly press dry powder into flakes or strips, which are then crushed and sieved into uniform granules. The entire process is conducted at room temperature, requiring no drying; energy consumption primarily comes from the hydraulic system and motor.
Key Advantages: Eliminates the need for coal-fired or natural gas boilers, reducing overall energy consumption by approximately 50%. No process wastewater is generated, and there are no exhaust heat emissions. The equipment footprint is reduced by approximately 30% compared to a rotary drum line. Suitable Raw Materials: Both NPK compound fertilizer and organic fertilizer are compatible.
This production line has a wide range of raw material adaptability, mainly including:
Compound fertilizer raw materials: Potassium chloride, potassium sulfate, ammonium sulfate, diammonium phosphate, urea (pay attention to controlling the ratio to avoid sticking to the rollers).
Organic fertilizer raw materials: Pure organic materials that have been fermented and pulverized (such as chicken manure, humic acid), but the moisture content must be ensured to be ≤12%, otherwise it is easy to stick to the rollers.
Organic-inorganic compound fertilizer: The two are mixed in a certain proportion to produce slow-release granules.
Special Note: Roller extrusion has requirements on the particle size of the raw materials—all powders should pass through a 40-mesh sieve and should not contain fibrous impurities (such as straw fragments, feather powder, etc.), otherwise they will get stuck in the roller grooves, causing difficulty in demolding.
Key Equipment Points: Three Core Components of a Double Roller Extrusion Granulator
A complete double roller press granulation line mainly consists of the following equipment:
Forced Feeder:This feeder uses a screw to push material into the wedge-shaped gap between two rollers, ensuring continuous feeding and stable pressure. This step is particularly crucial for materials with poor flowability (such as humic acid powder).
High Wear-Resistant Rollers:These are typically made of 65Mn steel or alloy steel with a wear-resistant overlay. The roller surface can be designed with hemispherical, rod-shaped, or square grooves. When processing urea-based formulations, rollers with chrome plating or ceramic coating should be selected to prevent material adhesion.
Granulation and Screening System:The extruded flakes are broken up by a crusher and then screened through a double-layer drum to separate the finished product (1-4mm), fine powder (returned for regranulation), and coarse material (further crushing). Four Major Advantages: Energy Saving, Uniformity, Flexibility, and Cleanliness
Significant Energy Saving: Producing 1 ton of NPK granules requires approximately 25-35 kWh for a roller line, compared to 50-70 kWh for a drum line (including drying).
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Uniform Granules: Due to the material being forcibly pressed into a precisely designed die, the finished granules achieve a particle size qualification rate of over 90%, with a smooth surface requiring no further polishing.
Quick Changeover: Cleaning the rollers and screens takes only 30 minutes, making it ideal for small-batch, multi-formulation orders.
No Wastewater or Exhaust Gas: Fully compliant with current Class A environmental standards, facilitating smoother environmental impact assessment approvals.
Before introducing this production line, we recommend conducting a roller pressing test with a small amount of raw material: Take 5 kg of dry powder and test it using a small laboratory roller press to observe whether a continuous thin sheet can be formed without sticking to the rollers. If the raw material viscosity is too low, 1%-3% clay or bentonite can be added as a binder. During daily production, regularly check the seals on the roller end faces to prevent fine powder leakage. This solution is particularly suitable for small and medium-sized fertilizer plants with an annual output of 10,000 to 50,000 tons, with an investment payback period of generally 8 to 14 months.
The roller extrusion granulation line is a prime example of a dry granulation process, achieving fertilizer granules compaction through a fertilizer compactor (double roller press). This fertilizer compaction machine is the core of a roller press granulator production line. In the npk fertilizer production process, it offers a distinct alternative to a rotary drum granulator (wet process). Key advantages: eliminates drying, reducing overall energy consumption by ~50% (25-35 kWh/ton for roller vs. 50-70 kWh/ton for drum). No process wastewater, no exhaust heat emissions, and 30% smaller footprint. Suitable for both NPK and organic fertilizers, with moisture ≤12% and particle size through 40-mesh. Avoid fibrous impurities. Key equipment: forced feeder (for poor-flowability materials), high wear-resistant rollers (65Mn or alloy with overlay, hemispherical/rod-shaped grooves; chrome or ceramic coating for urea-based formulations), and granulation/screening system (double-layer drum, 1-4 mm product). Advantages: energy saving, uniform granules (90% qualification rate), quick changeover (30 minutes for cleaning), zero wastewater/exhaust gas (Class A environmental standards). Recommended for small to medium-scale plants (10,000-50,000 t/year), with investment payback of 8-14 months. Pre-test: take 5 kg dry powder for small lab roller press test; if low viscosity, add 1%-3% clay or bentonite as binder. Daily maintenance: regularly check roller end face seals to prevent fine powder leakage. Understanding the trade-offs between a fertilizer compactor and a rotary drum granulator is key to selecting the optimal fertilizer granules compaction technology for your raw materials and production goals.