NPK Compound fertilizer coating machine Introduction

Tongli fertilizer rotary coating machine also known as rotary coater is a type of equipment used in the agricultural and fertilizer production plant to apply a protective or functional coating onto granular fertilizers. The main purpose of using a rotary coating machine is to enhance the quality, performance, and effectiveness of fertilizers by adding a layer of specific materials onto the surface of the fertilizer particles. Tongli compound fertilizer coating machine also equipped with automatic pumping coating oil tank and a plc interlock control system that controls the amount of coating agent spray onto the product to improve the quality.

Compound fertilizer coating machine structure

A fertilizer coater, also known as a fertilizer coating machine or equipment, is a device used in the agricultural industry to apply a protective or functional layer to fertilizer granules. The purpose of coating fertilizers is to enhance their performance, improve handling characteristics, and provide controlled release of nutrients to plants over time. The structure of a compound fertilizer coating machine can vary based on the specific design, generally it is composed of the following parts: riding rings, girth gear, supporting device, pinion, hood cover, gear cover, shell, transmission and so on.

Coater Shell: The npk compound fertilizer coater shell is a thick, steel cylindrical structure that provides the necessary strength and rigidity to withstand the load inside the coating machine. The central component of the machine is the rotating drum or pan. This is a cylindrical or conical container where the products to be coated are placed. The drum rotates around its axis to facilitate the coating process. Tongli dryer shell has good sealing performance, the edge of each shell is machined smoothly, enhance the sealing and service life of the rotary drum.

Coater Flights: Compound fertilizer coating machine flights, also known as "flights" or "lifters," are the inclined, curved structures that are attached to the internal shell of a rotarycoater. A rotary coater is a device used to put ptotective coatings on the finished product. It consists of a large cylindrical drum that rotates while the material is fed into one end and is discharged from the other end after being coated.

Riding Rings(Tyre): The Compound fertilizer coater shell is supported on multiple riding rings usually 2~3, which are attached to the shell with point-welded padding on the inside. The Compound fertilizer coater riding rings allow the coater to rotate smoothly on its axis and help distribute the coating machine's weight. The thickness of the plate under the riding ring is increased to facilitate strength of the shell.

Girth Gear: The Compound fertilizer coating machine girth gear is a large gear ring encircling the dryer, usually mounted on the coater shell. It is driven by a pinion gear, and together they form the primary drive unit to rotate the coater.

Supporting Device: Compound fertilizer coater supporting device is composed of the supporting roller and thrust roller, the shaft is a forged object to prolong the service life time of the Compound fertilizer coating machine. One thing features about Tongli Supporting device is all the metal casting are produced by our own, the quality is guaranteed. All the metal casting supporting roller, metal casting thrust roller are machined and heat treated, the performance measure is reliable.

Compound fertilizer coater thrust roller：The thrust roller is a critical part of the Compound fertilizer coater system. It serves the purpose of supporting the coating machine's weight and maintaining its axial position, ensuring that the dryer remains properly aligned along its axis. The thrust roller is typically positioned on the downhill side of the coating machine and is attached to the dryer shell. It consists of a central shaft or journal and a roller assembly.

Rotary coater pinion: The pinion is an essential part of the Compound fertilizer coater's drive system, responsible for transmitting rotational motion and torque from the driving mechanism to the Compound fertilizer coater itself. It consists of a gear wheel with teeth that mesh with the teeth of a larger gear, often referred to as the "girth gear" or "ring gear." The girth gear is attached to the outer shell of the Compound fertilizer coater. When the pinion is rotated by the drive system, it drives the girth gear, causing the Compound fertilizer coating machine to rotate.

Compound fertilizer coater bearing housing: The bearing housing serves as the support structure for the coater's rotating motion and is responsible for holding and guiding the coater's roller shaft. Bearings are large, heavy-duty bearings that support the weight of the coater and allow it to rotate smoothly. These bearings are subject to high loads, extreme temperatures, and potentially harsh environments due to the nature of the processes occurring inside the Compound fertilizer coater. The bearing housing provides a stable mounting point for the trunnion bearings and ensures proper alignment of the coater's rotation. It is typically designed to accommodate the axial and radial forces generated during the rotation of the coating machine.

Hood Cover: The Compound fertilizer coating machine hood is located at the entrance side of the coater and provides sealing to retain heat and gases. The Compound fertilizer coating machine operates under the negative pressure, therefore Tongli implied SS304 lining plate and ceramic felt both in the front and back end to prevent dust leakage.

Compound fertilizer coating machine Transmission device: The transmission device of the Compound fertilizer coater is mainly composed of main transmission, auxiliary transmission, mechanical thrust roller/hydraulic thrust roller, motor, gearbox and other components. The unique design of tongli transmission can greatly improve the service life and safety performance of the equipment.

PLC control system: A PLC is a digital computer-based system that is designed to control various industrial processes automatically. In the context of a Compound fertilizer coater, a PLC is used to monitor and control parameters such as temperature, rotation speed, air flow, fuel flow, and other critical variables that affect the performance of the coater and the quality of the products being processed. Usually, the Compound fertilizer coating machine control system is integrated in the whole factory’s plc system, therefore we will provide the on-site cabin and a signal cable to the central plc.

Design principles of compound fertilizer rotary coater

Uniform Coating Distribution: The primary goal of a rotary coating machine is to achieve uniform coating distribution across the substrate material. This requires careful consideration of factors like drum design, rotation speed, and spraying mechanisms to ensure that the coating material is evenly applied.

Controlled Process Parameters: Designers need to ensure that the machine allows for precise control of process parameters such as temperature, humidity, airflow, and spraying rate. Maintaining consistent conditions throughout the coating process helps achieve uniform coating thickness and quality.

Spraying Mechanism: The design of the spraying mechanism is crucial for achieving uniform coating. The machine can use various methods like atomization, pneumatic nozzles, or electrostatic spraying to break down the coating material into fine droplets and distribute them evenly over the substrate.

Material Handling: The design should facilitate efficient material loading and unloading. This includes considerations for material flow, avoiding cross-contamination between different batches, and minimizing downtime during product changeovers.

Drum Design: The rotating drum within the machine plays a significant role in the coating process. The drum's shape, size, and surface texture can impact the movement and agitation of the coated material. Designers need to ensure that the drum design promotes optimal mixing and tumbling of the substrate to facilitate even coating distribution.

Process Monitoring and Control: Modern rotary coating machines often include advanced automation and control systems. These systems allow operators to monitor and adjust process parameters in real time to maintain consistent coating quality and troubleshoot any issues that may arise during operation.

Cleaning and Maintenance: Designing for easy cleaning and maintenance is essential to prevent product contamination and ensure the longevity of the machine. Accessible components, removable parts, and efficient cleaning mechanisms should be part of the design.

Safety Features: Safety is paramount in any industrial machine design. Rotary coating machines should incorporate safety features like emergency stops, protective covers, interlocks, and proper ventilation to ensure the well-being of operators and compliance with safety regulations.

Energy Efficiency: Designers should aim to create a machine that is energy-efficient by optimizing heating and drying processes, minimizing heat loss, and using efficient motors and components.

Specifications of compound fertilizer coating machine

Note: *The diameter is the inner diameter.

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Zhejiang Tongli Heavy Machinery Manufacturing Co., Ltd (Formerly known as Tongxiang Coal&Mining Machinery Factory) established in year 1958 is a member of the Chinese National Building Material Machinery Association. Tongli is on the vendor list of designated production enterprise of the Ministry of Coal Industry. ISO9001、ISO14001、ISO45001 certified, accredited as High-tech & new technology enterprise of Zhejiang Province. With 65+ years of experience, Tongli has earned first class R&D and manufacturing capabilities, dedicated to provide satisfactory manufacturing equipments for global customers.   

Industry Knowledge extension

What is the cost of setting up a fertilizer plant?

The cost of setting up a NPK compound fertilizer production line is based on different factors. TONGLI defines the cost of building a NPK fertilizer production line into the following categories: civil construction cost, factory complete design cost, equipment procurement cost, installation cost, and labor cost. There might be miscellaneous cost involved as well.  A huge part of the investment for building up a NPK compound fertilizer production plant is on the civil construction, it depends on the scale of the NPK fertilizer production plant, TONGLI’s standard NPK fertilizer production line’s capacity ranges from 50,000 tons per year to 300,000 tons per year, therefore the civil construction cost may vary based on the scale of the NPK fertilizer production plant. The civil construction cost also depends on the location of the NPK fertilizer production line, for example the cost of purchasing a piece of land in downtown Manhattan is more expensive than purchasing a piece of land in suburbs. Therefore, choosing a good location to build the NPK fertilizer production line Is crucial.Another big part of the investment for building up a NPK compound fertilizer production plant is the design cost and the equipment procurement cost. A good fertilizer equipment manufacturer will not only supply the equipment but also design the whole production line for you according to your required process flow and your specific raw material. A professional NPK compound fertilizer manufacturer should be able to give you precise P&ID list and precise equipment specification and layout design. TONGLI is a professional compound fertilizer manufacturer that is able to offer the above service based on its expertise. The cost of procurement of equipment for compound fertilizer production line is around 4.0 million US dollars.The price of the NPK compound fertilizer equipment is determined on different requirements, for example if the equipment is made of mild steel than it is cheaper than that made of S304 stainless steel. The equipment cost of a 150,000 tons per year fertilizer production line is more expensive than that of 50,000 tons per year NPK fertilizer production line. Therefore, the cost of building a NPK compound fertilizer production line may vary according to unique process flow.There are a lot of factors involved in setting up a NPK compound fertilizer production line, the cost can vary significantly depending on various factors such as location, process flow, equipment. Therefore, it is necessary to do a feasibility analysis before you invest in building up a NPK compound fertilizer production line. TOGNLI is glad to offer you proposals if you want to build a NPK compound fertilizer production line.

(Reference: "What is the cost of setting up a fertilizer plant" https://npk-fertilizer.com/news/industry-news-71.html)

How is npk fertilizer manufactured?

NPK fertilizer is produced through fertilizer manufacturing equipment, which requires the use of equipment such as granulators. It involves several steps, including raw material preparation, ingredient mixing, crushing and screening, wet granulation, drying, screening, and packaging. These steps are necessary to produce high-quality products.

Raw material preparation: The manufacturing of NPK fertilizer requires selecting appropriate proportions of nitrogen, phosphorus, and potassium sources. Common nitrogen sources include urea, ammonium salts, and ammonium nitrate; phosphorus sources can be diammonium phosphate, monoammonium phosphate, or ammonium phosphate; potassium sources typically come from potassium chloride, potassium sulfate, or potassium nitrate. The proportions of raw materials can be adjusted based on the requirements of different crops and soils.

Ingredient mixing: Pre-weighed nitrogen, phosphorus, and potassium raw materials are mixed according to specific formulas. Precise control of the proportions of each component is necessary during the mixing process to ensure the final product meets the required standards. Additionally, trace elements and other nutrients may be added to enhance the overall effectiveness of the fertilizer.

Crushing and screening: The mixed raw materials need to undergo crushing and screening to achieve the desired particle size and uniformity. This can be achieved using crushers and screening equipment. The process of crushing and screening helps improve the solubility and absorption rate of the fertilizer.

Wet granulation: After crushing and screening, the raw materials enter the wet granulation process. During this process, the raw materials are mixed and moistened with additives such as binders or coagulants. The moistened materials are then fed into a rotary granulator or extrusion granulator, forming granular materials inside the machine. The added binders or coagulants enhance the stability and crush resistance of the granules.

Drying: The granules produced through wet granulation need to be dried to remove excess moisture. Drying methods such as air drying, airflow drying, or rotary drying are typically employed. The dried granules become hard and resistant to breakage.

Screening and packaging: The dried NPK fertilizer granules undergo screening to remove particles that do not meet the specified standards, ensuring a uniform product. Subsequently, the qualified fertilizer granules are packaged, usually in bags or bulk form.

(Reference: “how is npk fertilizer manufactured” https://npk-fertilizer.com/news/industry-news-201.html)