Rotary Drum Granulator

Rotary drum granulator
A rotary drum granulator, also known as a rotary granulator or cylindrical granulator, is a molding machine that uses the rotation of a cylinder to form spherical granules from powdery or slurry materials. This equipment is a key molding device in the compound fertilizer industry and a core piece of equipment for the granulation of powdered materials in organic fertilizer, chemical, metallurgical, and building materials fields. The rotary drum granulator employs a wet granulation process, where the base fertilizer is moistened by water or steam within the drum, allowing for a thorough physicochemical reaction. Under liquid phase conditions, the rotation of the drum causes the material particles to agglomerate into granules due to the compressive force. The equipment features high granulation strength, good appearance quality, corrosion resistance, wear resistance, low energy consumption, long service life, and convenient operation and maintenance. This equipment is suitable for cold and hot granulation and large-scale production of high, medium, and low concentration compound fertilizers, and is also widely used in the organic fertilizer production field.

Overall structure and functional modules

The rotary drum granulator boasts a scientifically designed structure, comprising five main functional modules:

(I) Drum Body: This is the core working component, welded from high-quality medium carbon steel plates and lined with special rubber or acid-resistant stainless steel. The drum interior features lifting plates and guide plates to enhance material mixing and lifting. Drum dimensions typically range from Φ1×6m to Φ2.0×20m, and the drum is installed at a certain inclination angle (generally 3°-6°).

(II) Support Frame and Support Device: This includes rollers, roller shafts, and bearing seats. All rotating parts of the machine are supported by the support frame, resulting in significant stress. Therefore, the roller frame is constructed from medium carbon steel plates and channel steel, undergoing strict quality control and specific process requirements. The roller device supports the drum, ensuring stable operation.

(III) Transmission Device: This consists of a main motor, reducer, pulleys, split gears, and a large gear ring. The main motor drives the belt and pulley, which transmits power to the drive shaft via a reducer. A split gear mounted on the drive shaft meshes with a large gear ring fixed to the machine body, driving the cylinder to rotate. The motor power range is generally 5.5-75kW.

(IV) Spraying and Water Distribution System: This includes a water distributor, nozzles, etc., used to evenly spray water, steam, or binder into the cylinder, providing the necessary liquid phase conditions for material agglomeration and granulation.

(V) Auxiliary Devices: These include an adjustable-angle frame device, a guide wheel device, a spiral material distribution device, a scraper device, a rake device, etc. The cylinder is equipped with a large gear, a front belt, and a rear belt, which are supported by the front and rear support roller devices.

Applicable fields and industry coverage
Rotary drum granulators have a wide range of applications. In the fertilizer industry, they are the core granulation equipment for the production of compound fertilizers, organic fertilizers, blended fertilizers, and bio-organic fertilizers. In the chemical industry, they can be used for granulating powdered chemical raw materials such as laundry detergent and catalysts. In the metallurgical industry, they can be used for pelletizing mineral powders. In the building materials industry, they can be used for granulating building material raw materials such as cement. In addition, they are widely used in mining, ceramics, pharmaceuticals, food, and other industries.

Types of available raw materials
Rotary drum granulators can process a wide variety of raw materials. In compound fertilizer production, raw materials include nitrogen sources such as urea, ammonium chloride, ammonium sulfate, and ammonium bicarbonate; phosphorus sources such as superphosphate, superphosphate, monoammonium phosphate, diammonium phosphate, and calcium magnesium phosphate; and potassium sources such as potassium chloride. In organic fertilizer production, raw materials include fermented and decomposed livestock and poultry manure such as chicken, pig, and cow manure, as well as organic materials such as straw powder, edible mushroom residue, distiller's grains, medicinal residue, humic acid, and municipal sludge. In the chemical and metallurgical fields, they can also process various industrial raw materials such as slag, coal powder, and iron concentrate.

Operating principle and granulation mechanism
The working principle of a rotary drum granulator is based on the combined motion of materials within a rotating drum. During operation, a geared motor drives a sprocket to rotate a support roller. Under the influence of friction, the support roller causes the drum, which is at a certain angle, to rotate at a low speed. After the material is fed into the drum from the inlet, it rises to a certain height along the drum wall under the influence of friction and centrifugal force, and then rolls down under gravity. The descending material and the rising material generate relative motion, rolling into spheres. These spheres tumble circumferentially while moving along the drum axis from the high end to the low end, eventually being discharged from the low end. During this process, a spraying device evenly sprays water, steam, or a binder onto the material, allowing it to better agglomerate into spheres while moistened. For compound fertilizer production, steam, gaseous ammonia, or phosphoric acid or nitrogen solutions can also be introduced to complete the chemical reaction and heating granulation process within the drum. Due to the continuous input of material and the continuous rotation of the granulator, large-scale continuous production can be achieved.

Production range and suitable scale
Rotary drum granulators offer a wide range of production capacities, from small to extra-large models. Small models have a capacity of 5-10 tons per hour, suitable for small organic fertilizer plants and cooperatives; medium-sized models have a capacity of 10-30 tons per hour, suitable for small and medium-sized compound fertilizer plants and chemical enterprises; large models have a capacity of 30-50 tons per hour, suitable for large-scale production bases and solid waste treatment centers. A single unit can have a daily capacity of over 200 tons, easily supporting the production pace of large-scale compound fertilizer production lines.
Target customer group
The main customer groups for rotary drum granulators include: equipment procurement and production management personnel of compound fertilizer and blended fertilizer production enterprises; technical heads and production managers of organic fertilizer production enterprises; investors in large-scale livestock farm manure resource utilization projects; operators of urban sludge and kitchen waste treatment projects; powder processing demanders in industries such as chemical, metallurgy, and building materials; and large-scale production units such as agricultural cooperatives and solid waste treatment centers.