Disc Granulator

What Is a Disc Granulator?

A disc granulator, also known as a rotary disc pelletizer or pan pelletizer, is a machine used to form granules/pellets from powders or semi-wet materials by rolling and agglomeration on a sloped rotating disc. Commonly used in fertilizers, feed, and chemical industries, this equipment enables continuous production of uniform granules with controlled size, density, and moisture content.

How Does a Disc Granulator Work?

1. Material Feeding
   Powdered raw material—either dry or wetted with binder or water—is introduced onto the tilted rotating disc.
2. Rolling & Agglomeration
   As the disc rotates (typically at 8–25 rpm depending on size), the material moves up the slope, rolling and agglomerating into granules due to cohesive forces, friction and the disc’s motion.
3. Growth & Discharge
   Granules grow to target diameter (commonly 3–8 mm or higher) on the disc surface and are discharged over the rim into a granule classifier, dryer or packaging line.
4. Recirculation
   Oversize or coolant material may be returned to the disc or crushed for recycling, maintaining size uniformity and material yield.

Typical Technical Specifications (Reference Ranges)

These are typical operating data in the fertilizer/industrial granulation sector. Final values depend on material properties, binder, moisture, and desired granule size.

• Disc Diameter: 1.2 m, 1.8 m, 2.2 m common for medium-scale.
• Disc Tilt Angle: 30°–45°.
• Rotation Speed: 8–20 rpm (smaller disc can run higher speed ~20–25 rpm).
• Capacity: ~5–60 t/h (medium-size disc granulator in fertilizer lines).
• Motor Power: ~15 kW – 55 kW typical for 1.8 m to 2.2 m diameter machines.
• Disc Thickness / Material: ≥12 mm thick carbon steel or stainless steel for corrosive materials; liner inside with wear-resistant plate.
• Granule Size Range: 3–8 mm diameter typical; adjustable by speed, binder/feed ratio and disc tilt.
• Binder Addition: ~3%–10% by weight (material dependent) when wet granulation is used.

Advantages & Benefits

• High Production Efficiency – Continuous production enables high throughput lines with stable granulation quality.
• Granule Uniformity – Disc motion and controlled feed/binder ratio give excellent size distribution and density.
• Simple Structure & Easy Maintenance – Fewer parts compared to drum granulators; easy access for cleaning and inspection.
• Versatile Material Compatibility – Handles dry-wet granular systems, chemicals, fertilizers, feed, and even certain mineral materials.
• Energy Efficiency – Rolling-granulation method is generally less energy-intensive than high-pressure extrusion pelletizers.

Common Applications

• Compound Fertiliser Manufacturing – For urea, ammonium phosphate, potassium sulphate, mixed salt systems.
• Feed & Animal Nutrition – For pelleting soybean meal, corn gluten, mineral blends with controlled sizes for animal feed.
• Chemical Granulation – For pigments, catalysts, chemical salts, agrochemical formulations needing granulated form.

Selection & Design Guide

1. Material Properties

• Moisture content: Typically 10–30% when wet binder granulation; dry granulation for lower moisture.
• Powder particle size: Finer powders require higher binder or slower disc speed.
• Corrosive/abrasive nature: Choose stainless steel or wear-resistant liners if necessary.

2. Capacity & Granule Size

• Throughput required: Match disc diameter and speed to target tonne/hour.
• Target granule diameter: Smaller granules use higher disc speed or higher binder ratio.

3. Disc & Drive Specification

• Disc diameter & tilt: Larger diameter yields higher capacity at same rpm; tilt influences rolling path and growth time.
• Motor & gear drive: Select motor power with margin (20%+ above calculated load). Ensure gear reducer quality.

4. Supplemental Equipment

• Classifier / Screen: To separate off-size granules for recirculation.
• Dryer / Cooler: Especially if granules have elevated moisture post-rolling.
• Dust/Exhaust system: Especially for fine powders or chemical granulation to meet environmental regulations.

Troubleshooting — Typical Issues & Solutions

Summary

The disc granulator offers a highly efficient, continuous method for producing uniform granules across fertilizers, feeds and chemicals industries. Key to successful operation is balancing disc speed, binder/feed ratio, tilt angle and moisture. Proper selection and optimization lead to stable production, excellent granule quality and lower maintenance overhead.

Note: The values shown are for guidance only — always refer to manufacturer’s datasheet and perform process trials when integrating into production lines.