Production line roles and processes

Rotary drum granulators play a crucial role in the granulation process of organic and compound fertilizer production lines. A complete rotary drum granulation production line process is as follows: raw material pretreatment (fermentation/crushing) → batching and mixing → rotary drum granulation → drying → cooling → screening → coating → packaging.

In compound fertilizer production, rotary drum granulators can achieve both cold and hot granulation processes. Cold granulation mainly involves adding water to agglomerate the material into granules; hot granulation uses steam or chemical reactions to promote material formation. In organic fertilizer production, fermented and decomposed livestock manure, straw, and other raw materials are crushed, batched, and then fed into a rotary drum granulator for granulation. The granulated material has a high moisture content and needs to be dried and dehydrated in a rotary drum dryer, then cooled in a rotary drum cooler, and subsequently graded and screened in a rotary drum screener. Qualified granules proceed to the packaging process, while unqualified powder and broken granules can be recycled for re-granulation.

Granulation process and stages

The granulation process of a rotary drum granulator is a typical wet granulation process. The entire process is divided into the following stages:

Raw Material Preparation Stage: Various raw materials are crushed and mixed according to the formula. For compound fertilizer production, nitrogen, phosphorus, and potassium base fertilizers need to be mixed in proportion; for organic fertilizer production, fermented and decomposed organic materials need to be crushed.

Moisture Conditioning and Agglomeration Stage: The uniformly mixed raw materials are fed into the inclined rotating drum from the feed end. During the drum's rotation, a spray system evenly sprays water, steam, or a binder onto the material. The material undergoes a "lifting-scattering-tumbling" cyclical motion within the drum, agglomerating into spheres under liquid phase conditions through interparticle compression.

Forming and Discharge Stage: As the drum continues to rotate, the material particles grow larger and move along the drum axis from the high end to the low end, finally being discharged from the discharge end. The granulation rate can reach over 85%, and the particle size can be adjusted within the range of 2-8 mm. Screening and reflux stage: The discharged particles are classified by a screening machine. Qualified products enter the next process, while unqualified fine powder is returned to the granulator to participate in granulation again.

Pre-fermentation and material preparation
While the rotary drum granulator itself does not directly participate in the fermentation process, it is a crucial link in the post-fermentation material processing chain. In organic fertilizer production, the fermentation process is typically completed before granulation: organic raw materials such as livestock and poultry manure first enter the fermentation zone, undergoing aerobic fermentation and secondary aging and stacking. During this process, fermentation bacteria are added to decompose coarse fibers, and the fermentation temperature is generally controlled within a suitable range. After fermentation and maturation, the material is dried, crushed, and mixed before entering the rotary drum granulator for granulation. The rotary drum granulator is adaptable to various organic and inorganic raw materials; fermented and maturated livestock and poultry manure, straw, etc., can be directly granulated, realizing the resource utilization of livestock waste.
Operating procedures and key control points
Proper operation of the rotary drum granulator is crucial for ensuring granulation quality and extending equipment lifespan. Pre-start preparation: Check that all bolts are tight and that sufficient lubrication points are filled with lubricating oil; inspect the wear of the drum liner and lifting plates; confirm that the spray system is unobstructed. No-load test run: Start the motor and observe whether the drum rotation direction is correct and whether there is any abnormal vibration or noise. Load adjustment: Feed material slowly and gradually adjust the drum speed and tilt angle according to the material characteristics. Precisely control the amount of water or steam added through the spray system. Operation monitoring: Closely observe the granulation process and equipment operating status during operation.

Application effectiveness and industrial contribution
Rotary drum granulators have demonstrated outstanding performance in large-scale production. In compound fertilizer production, the equipment can process 50-500 tons per day, meeting the demands of large-scale production. In organic fertilizer production, the low-temperature granulation process effectively preserves nutrient activity. The equipment operates stably, has low maintenance costs, and its energy consumption per unit product is 10%-15% lower than that of traditional granulators. Overall, with its high efficiency, stability, and wide adaptability, the rotary drum granulator has become one of the most cost-effective core equipment in the fertilizer production field.