Types of organic fertilizer materials and processing characteristics suitable for rotary drum granulators

The rotary drum granulator, with its strong adaptability to various materials and high granulation rate, has become a core piece of equipment in organic fertilizer production lines. It can process organic materials from multiple sources, covering various fields such as livestock farming, agriculture, and industrial processing.

Livestock and poultry manure is the most common suitable material, including chicken manure, pig manure, cow manure, and sheep manure. These materials are rich in basic nutrients such as nitrogen, phosphorus, and potassium. After fermentation and composting, they have a loose texture and a certain viscosity, which meets the granulation requirements of the rotary drum granulator. The rotating agitation of the drum allows the manure material to be fully mixed with auxiliary materials, resulting in granules with moderate strength, effectively solving the problems of seedling burning and environmental pollution caused by the direct application of livestock and poultry manure.

Agricultural straw materials can also be processed by the rotary drum granulator, such as corn stalks, wheat stalks, and rice stalks. Straw is rich in cellulose and organic matter. After crushing and fermentation, it needs to be used in combination with viscous materials such as livestock and poultry manure. The rolling granulation of the drum allows the straw powder to be evenly coated and formed, which not only increases the organic matter content of the organic fertilizer but also realizes the resource utilization of agricultural waste.

In addition, the rotary drum granulator can also process industrial organic waste materials, such as distiller’s grains, vinegar residue, furfural residue, and pharmaceutical waste. These materials are rich in nutrients, but their composition is complex and their moisture content fluctuates greatly. The rotary drum granulator can adapt to the characteristics of different wastes by adjusting the rotation speed and material ratio, converting them into qualified organic fertilizer granules. At the same time, urban and rural organic waste such as kitchen waste and garden fallen leaves, after sorting and fermentation, can also be granulated and recycled through the rotary drum granulator.

From raw materials to granules: The journey to the birth of modern NPK fertilizer

NPK compound fertilizers, widely used in modern agricultural production, undergo a precise and systematic industrial processing procedure. From basic chemical raw materials to uniformly shaped granules, this NPK fertilizer production line integrates chemical synthesis and physical processing technologies, forming a standardized manufacturing system.

Production begins with the precise measurement and synthesis reaction of raw materials. Different proportions of nitrogen, phosphorus, and potassium base materials undergo chemical reactions under controlled conditions to generate a complex containing the target nutrients. This chemical stage establishes the core nutrient content and ratio of the product.

The synthesized slurry then enters the crucial physical molding stage. The rotary drum granulator plays a vital role in this process. By precisely controlling temperature and humidity, these granules achieve a stable physical morphology, preparing them for subsequent processing.

The newly generated granules require complete post-processing. After drying and cooling, the sieving process grades the granules according to their specifications. At this point, lumps with excessively large particle sizes are returned to the previous process, re-crushed in a fertilizer crusher, and then re-granulated. This cycle ensures high raw material utilization and uniform product particle size.

It is worth mentioning that some of the large-particle base fertilizers obtained after drying and screening can be used as raw materials to directly enter another flexible production path—through bulk blending fertilizer machines, they can be quickly and physically mixed with other single-element fertilizers or micronutrients according to actual field needs to produce customized blended fertilizers.

NPK compound fertilizer additives: The key to quality improvement in the production process

In NPK compound fertilizer production, although additives account for a small proportion of the total volume, they directly affect product quality, storage stability, and application effectiveness. Different types of additives need to be precisely matched to each stage of the NPK fertilizer production line. Scientific application can effectively solve problems such as caking, loose granules, and nutrient loss, thereby enhancing product competitiveness.

Anti-caking agents are a core category, mostly added during the raw material mixing stage in the fertilizer mixer machine or after granulation in the granulator. Common types include hydrophobic (mineral oil, silicones) and adsorbent (zeolite powder, diatomaceous earth). The former forms a protective film on the surface of the granules to isolate water and oxygen, while the latter adsorbs free moisture. Both can reduce the risk of caking, especially suitable for NPK fertilizers with high nitrogen and high humidity formulations.

Binding and conditioning agents are suitable for the granulation stage, ensuring molding quality. Binders (starch, lignin sulfonate) increase material viscosity, improving the molding rate of NPK fertilizer granulators and reducing powdering; conditioning agents optimize granule strength and smoothness, adapting to different granulation processes such as rotary drum granulator. The amount of additive needs to be adjusted according to the characteristics of the raw materials to avoid excessively hard granules or slow dissolution.

Nutrient efficiency enhancers need to be added during the mixing stage in the fertilizer mixer machine to improve fertilizer utilization. For example, urease inhibitors delay nitrogen volatilization, phosphorus activators reduce phosphorus fixation, and trace element chelating agents improve nutrient stability. Strict adherence to the formula ratio is necessary to ensure synergy with the main nutrients and avoid affecting fertilizer efficiency.

In summary, the core of additive application is “functional matching to the process stage and precise dosage.” Scientific selection based on raw materials and product requirements is essential to maximize their value and consistently produce high-quality NPK compound fertilizers.

How to build a rotary drum granulation production line for fertilizer production?

Rotary drum granulation production lines are widely used in organic and compound fertilizer production due to their wide adaptability and excellent molding effect. Their construction requires following a scientific process, considering both production capacity requirements and environmental standards.

Preliminary Planning: First, clarify the production raw materials (such as organic fertilizer fermentation materials, NPK compound fertilizer raw materials) and production capacity targets.  Determine the process route based on local environmental policies, such as whether drying and dust removal equipment are needed. Simultaneously, conduct a cost assessment, covering core expenses such as equipment procurement, site construction, and energy consumption.

Equipment Selection and Matching: The core equipment, the rotary drum granulator, needs to be selected according to the characteristics of the raw materials, ensuring that parameters such as rotation speed and inclination angle meet the granulation requirements; supporting equipment needs to be precisely matched. The pre-treatment stage should include fertilizer crushers and screening machines to ensure the particle size of the raw materials. After granulation, dryers and coolers should be connected to optimize particle quality, and dust collection devices should be installed.

Site Layout and Installation: The site needs to accommodate sufficient spacing and operating space for the equipment. The ground should be treated with anti-slip and anti-corrosion coatings, and areas for raw material and finished product storage should be reserved; during installation, ensure the equipment’s levelness and sealing, especially the transmission system of the rotary drum granulator, to avoid vibration or leakage problems during operation. Also, rationally plan the pipeline layout to improve production efficiency.

Commissioning and Operation: First, conduct a no-load test run to check the stability of the equipment; then conduct a load test, optimizing the granulation effect by adjusting parameters such as raw material moisture and drum rotation speed. During the test run, record key data to establish a standardized production process and ensure stable mass production.

How to process DAP/MAP compound fertilizers using an NPK fertilizer production line?

DAP (diammonium phosphate) and MAP (monoammonium phosphate) compound fertilizers, due to their high phosphorus content, have stringent granulation requirements. Using an NPK fertilizer production line for granulation requires careful adaptation and control throughout the entire process, focusing on raw material characteristics while balancing granule quality and equipment wear to achieve stable production.

Pre-treatment before granulation is fundamental. DAP/MAP raw materials must be crushed to 80-100 mesh, with moisture content controlled at 8%-12%; nitrogen, potassium, and other auxiliary materials are precisely measured according to the formula and fed into the fertilizer mixer machine of the NPK production line along with the DAP/MAP raw materials for thorough mixing. The mixing speed must be strictly controlled to prevent frictional heat from causing nutrient decomposition, laying the foundation for a uniform material.

Equipment adaptation and parameter adjustment during granulation are crucial. The rotary drum granulator or flat die pelleting machine of the NPK production line should be prioritized: for rotary drum granulation, adjust the inclination angle to 3°-5°and the rotation speed to 20-30 r/min, and precisely control the moisture content to 15%-18% through spraying; for flat die granulation, adjust the die hole diameter and roller pressure to match the raw material viscosity. Additionally, DAP requires a slight increase in ammoniation to maintain strength, while MAP requires strict control of the conditioning liquid to prevent moisture absorption.

Post-granulation quality verification is essential. The granules must be dried promptly (temperature 80-100℃) and screened to ensure the finished product has a moisture content of ≤2% and a particle size of 2-4.75mm; unqualified granules are returned to the fertilizer mixer machine for reprocessing. Granule strength and nutrient uniformity are monitored throughout the process, and equipment parameters are fine-tuned to ensure consistent quality.

High-efficiency granulation in large-scale rotary drum granulation production lines

In large-scale organic fertilizer production, rotary drum granulators, as the core type of organic fertilizer granulator, have become the “central equipment” of rotary drum granulation production lines due to their excellent adaptability and production capacity advantages.

The core advantages of rotary drum granulators are “wide adaptability and high production capacity.” Compared with other organic fertilizer granulators, they have a higher tolerance for raw material moisture and viscosity, and can process diverse materials such as composted livestock and poultry manure and straw fermentation materials with a moisture content of 20%-30%, without the need for excessive fine pre-treatment. The equipment’s molding rate is stably above 90%, and the hourly production capacity of a single unit can reach several tons to tens of tons, perfectly meeting the needs of large-scale production.

The efficient operation of the rotary drum granulation production line relies on the precise coordination of the rotary drum granulator with other equipment. The pre-treated raw materials are uniformly mixed by the batching and mixing system and then directly fed into the rotary drum granulator, while water or binders are precisely added through a spraying device; after granulation, the granular materials directly enter subsequent equipment such as dryers, coolers, and screening machines, forming a complete closed-loop process of “batching – granulation – post-processing.”

Whether producing pure organic fertilizer or organic-inorganic compound fertilizer, the rotary drum granulation production line can achieve diversified output with the flexible adaptability of the rotary drum granulator. It not only lowers the operational threshold for large-scale organic fertilizer production but also ensures the stability of finished product quality.

Why does wet granulation dominate the production of high-quality organic fertilizers?

In the field of high-quality organic fertilizer production, wet granulation has become the dominant choice due to its precise adaptation to raw material characteristics and stable assurance of finished product quality. Compared to dry granulation, it effectively addresses the core needs of organic fertilizer raw materials, which are complex and require a balance between nutrient retention and molding effect. This is the key to its dominant position.

Organic fertilizer raw materials are mostly animal manure and fermented crop residues, with significant fluctuations in moisture content and composition. In organic fertilizer production lines, wet granulation can precisely control moisture to create suitable viscosity in the raw materials, allowing for efficient molding without excessive binders. Both rotary drum granulators and disc granulators operate based on this principle. This reduces costs and avoids the impact of external additives on the purity of organic fertilizers, ensuring the natural safety of the product.

High-quality organic fertilizers require uniform particle size, moderate strength, and good water solubility. Wet granulation, through a continuous process of mixing, crushing, and granulation, ensures thorough mixing of raw materials and even distribution of nutrients; the formed granules have a dense structure, making them easy to store and transport without breaking; and the appropriate moisture content also improves the water solubility of the granules, accelerating nutrient release and better meeting the absorption needs of crops.

From a production feasibility perspective, wet granulation technology is mature and suitable for large-scale organic fertilizer production lines. Wet granulation lines composed of rotary drum granulators and disc granulators can adapt to different raw materials by adjusting moisture and rotation speed, offering strong flexibility; and the granulation process produces less dust, and when combined with subsequent drying and screening steps, it can achieve clean production, meeting environmental protection requirements.

Comparison of flat die, double roller press, and rotary drum granulators: Choosing the Right equipment

Flat die pelleting machines, double roller press granulators, and rotary drum granulators are the mainstream granulation equipment in fertilizer production. These three types differ significantly in core dimensions such as molding principle, raw material suitability, and production capacity and quality. Choosing the right equipment requires considering production scale, raw material characteristics, and product requirements.

Molding Principle and Raw Material Suitability: Flat die pelleting machines form granules through mold extrusion, suitable for both wet and dry raw materials, especially suitable for organic fertilizers and NPK compound fertilizers with moderate viscosity, and have low requirements for raw material particle size; double roller press granulators use double rollers to extrude dry materials for granulation, requiring no water addition, suitable for low-viscosity dry powder raw materials, and can save the drying process; rotary drum granulators form granules through drum rolling and spraying conditioning, more suitable for high-humidity, easily agglomerating fermented organic fertilizer raw materials.

In terms of production capacity and quality, flat die pelleting machines have medium production capacity, suitable for small and medium-scale production, producing granules with high strength and uniform particle size, but the molds are easily damaged; double roller press granulators have adjustable production capacity, suitable for small and medium-scale production, producing granules with high strength and high molding rate, but the shape is less regular; rotary drum granulators have large production capacity, suitable for large-scale continuous production, producing granules with good roundness and excellent appearance, but the strength is low and prone to pulverization.

Selection Suggestions: For small and medium-scale production, prioritizing granule strength and adaptability to multiple raw materials, choose a flat die pelleting machine; for dry material granulation, needing to save on drying costs, and prioritizing hardness, a double roller press granulator is preferred; for large-scale continuous production, focusing on granule appearance, a rotary drum granulator is more suitable.

Organic fertilizer granulators: Diverse technological approaches enhance fertilizer value

In the organic fertilizer production sector, the diversified development of granulation technology offers a wealth of choices for enterprises of different sizes. From classic rotary drum granulators to innovative new type two in one organic fertilizer granulators, each type of equipment achieves the transformation of powdered raw materials into marketable granules in a unique way.

Rotary drum granulators hold an important position in the industry due to their gentle granulation method. This granulation method is particularly suitable for production scenarios requiring high granule roundness and is easy to integrate with other processes for continuous production. Ring die pelleting machines demonstrate strong forming capabilities. This equipment has wide adaptability to raw materials and can still ensure granule forming quality and output efficiency even when processing organic materials with high fiber content. Flat die pelleting machines are favored by small and medium-sized enterprises for their simple structure and convenient operation. This design effectively controls equipment investment costs while ensuring granulation quality.

In recent years, the emergence of new type two in one organic fertilizer granulators has brought a brand-new solution to the industry. These devices integrate mixing and granulation functions, simplifying the process flow and making them particularly suitable for production sites with limited space.

Different types of granulation equipment have their own characteristics, and companies need to comprehensively consider factors such as raw material characteristics, product positioning, and production scale when making a selection. With the continuous upgrading of the organic fertilizer industry, granulation technology is also constantly improving.

Key equipment for large-scale production of bio-organic fertilizers

Scaling up is a core trend in bio-organic fertilizer production, and efficiency and stability directly determine the competitiveness of the production line. The rotary drum granulator and crawler-type compost turner, as key bio-organic fertilizer equipment, respectively address the efficiency bottlenecks in the fermentation and granulation stages, jointly promoting the efficient and continuous operation of the bio-organic fertilizer production line.

The crawler-type compost turner is the core support for large-scale fermentation. Designed for the large material volume and wide pile area characteristic of large-scale production lines, this bio-organic fertilizer equipment, with its crawler-type walking structure, can flexibly adapt to uneven fermentation sites, achieving deep and wide-ranging turning and mixing. It effectively breaks up material compaction, ensuring ventilation and uniform temperature in the compost pile, enhancing microbial activity, accelerating raw material decomposition, and providing high-quality raw materials for subsequent granulation.

The rotary drum granulator receives the fermented raw materials and is adapted to the needs of large-scale continuous granulation. It boasts advantages such as high processing capacity and strong continuous operation capabilities. In the bio-organic fertilizer production line, the raw materials fermented by the crawler-type compost turner are transported here for uninterrupted granulation, significantly increasing overall production capacity while ensuring stable product quality.

These two pieces of equipment are precisely integrated and work collaboratively, fully leveraging the advantages of large-scale adaptation of bio-organic fertilizer equipment, ensuring efficiency and stability throughout the entire process from raw material fermentation to granule formation.