Coal slime rotary dryer Introduction

Slime dryer also known as coal slime dryer belongs to the drum type or rotary drum dryer equipment, which is a very mature drying equipment produced by the mining equipment manufacturer Tongli. It is suitable for drying coal slime, sludge, metal and non-metallic ore concentrates, and clay in the coal mining, metallurgy, magnetic separation, flotation, and cement industries. It has the characteristics of high productivity and easy operation. The shell is a horizontal rotating cylinder, which is welded with various types of lifting plates with different angles from front to back. According to different user needs, the inside of the coal slime dryer cylinder can be designed and equipped with heat-resistant materials for insulation. At the feeding end, there is a ring and a spiral lifting plate to prevent backflow. It has the advantages of reasonable structure, excellent production, high output, and low energy consumption.

Coal slime rotary dryer structure

Dryer Shell: The rotary dryer shell is the main body of the dryer, where the material is loaded and rotated. It has a cylindrical shape and is equipped with lifting plates or flights to lift and disperse the material. The drum is heated by hot air or gas that flows through it, either in parallel or countercurrent direction. The drum transfers heat to the material and evaporates the moisture.

Dryer Flights: Rotary dryer flights, also known as "flights" or "lifters," are the inclined, curved structures that are attached to the internal shell of a rotary dryer. A rotary dryer is a device used to remove moisture from materials like powders, granules, and bulk solids through the process of drying. 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 dried.

Dryer thrust roller：The thrust roller is a critical part of the rotary dryer system. It serves the purpose of supporting the dryer'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 dryer and is attached to the dryer shell, it consists of a central shaft or journal and a roller assembly.

Dryer pinion: The pinion is an essential part of the rotary dryer drive system, responsible for transmitting rotational motion and torque from the driving mechanism to the rotary dryer 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 rotary dryer. When the pinion is rotated by the drive system, it drives the girth gear, causing the rotary dryer to rotate.

Dryer bearing housing: The bearing housing serves as the support structure for the dryer's rotating motion and is responsible for holding and guiding the dryer's trunnion bearings. Trunnion bearings are large, heavy-duty bearings that support the weight of the dryer 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 rotary dryer. The bearing housing provides a stable mounting point for the trunnion bearings and ensures proper alignment of the dryer's rotation. It is typically designed to accommodate the axial and radial forces generated during the rotation of the dryer.

Dryer Hood Cover: The rotary dryer hood is located at the discharge end of the kiln and provides sealing to retain heat and gases. The rotary dryer operates under the negative pressure, therefore Tongli implied SS304 lining plate and ceramic felt both in the front and back end to prevent heat leakage.

Rotary dryer Transmission device: The transmission device of the rotary dryer 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 rotary dryer, 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 dryer and the quality of the products being processed. Usually, the rotary dryer 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 slime rotary dryer

Slime rotary dryers are designed to efficiently remove moisture from materials that are viscous or have a high moisture content, such as slurry or sludge. The design principles of a slime rotary dryer are based on several key factors that enable effective drying while ensuring energy efficiency and product quality. Here are some of the key design principles:

Rotary Drum Design: The core component of a slime rotary dryer is the rotating drum. The drum's design plays a crucial role in achieving efficient drying. The drum's inclination and rotation speed are important factors that affect the material's movement and exposure to heat. The drum is designed to lift and cascade the material, maximizing its exposure to the drying medium.

Flights and Lifters: Inside the rotary drum, there are often flighted structures or lifters that help lift and distribute the material as the drum rotates. These components promote better heat transfer by exposing different parts of the material to the drying medium, ensuring even drying.

Drying Medium Flow: The flow of the drying medium, usually hot air or gases, is carefully designed to optimize heat transfer. The drying medium should be evenly distributed across the drum's cross-section to ensure consistent drying of the material.

Material Handling and Discharge: The design of the dryer also considers the dried material will be discharged from the system. Efficient material handling mechanisms are crucial to prevent product degradation or re-absorption of moisture.

Energy Efficiency: Tongli Slime rotary dryers are designed with energy efficiency in mind. This involve incorporating insulation to reduce heat loss, optimizing airflow patterns, and using advanced control systems to regulate the drying process based on real-time conditions.

Safety and Environmental Considerations: The design of the dryer consider safety aspects, including the prevention of fires or explosions, and environmental factors, such as minimizing emissions and ensuring proper disposal of any byproducts.

Specifications of slime rotary dryer

Note: *The initial moisture is assumed to be 2~6% and final moisture is 1~4%; Inlet temperature of hot air is 150~250 Celsius and outlet temperature is 70~90 Celsius; Production Capacity will vary according to the composition and moisture of the material.

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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 application of dried coal slime? 

Dried coal slime, also known as coal slurry or coal fines, refers to the fine particles and moisture left over after coal processing and preparation. These particles can be mixed with water to form a slurry that can be transported through pipelines. The application of dried coal slime or coal slurry includes:

Coal Combustion: Dried coal slime can be burned as fuel in power plants or industrial facilities. While it may have a lower energy content compared to regular coal, it can still be used as a supplementary fuel source, helping to reduce waste and increase energy efficiency.

Brick and Tile Production: Coal slime can be used as an additive in the production of bricks and tiles, providing binding properties and contributing to the structural integrity of the final product.

Cement Manufacturing: Similar to its use in brick production, dried coal slime can be used as a supplementary material in cement manufacturing, helping to improve the strength and durability of concrete.

Land Reclamation and Soil Improvement: Coal slime can be mixed with soil to improve its fertility and structure, making it suitable for land reclamation or agricultural purposes.

Coal-to-Liquid Conversion: Coal-to-liquid (CTL) technology involves converting coal into liquid fuels. Coal slime can be processed and used as a feedstock in such conversion processes to produce synthetic fuels like diesel or gasoline.

Building Materials: Coal slime can be used in the production of building materials like lightweight aggregates, which are used in construction to reduce the weight of concrete and improve its insulation properties.

Environmental Applications: Coal slime can be used in environmental remediation efforts, such as capping landfills or covering contaminated sites to prevent the spread of pollutants.

Manufacturing Briquettes: Dried coal slime can be compressed into briquettes, which can then be used as a fuel source for heating, cooking, or industrial processes.

Gasification: Coal slime can be gasified to produce syngas, a mixture of hydrogen and carbon monoxide, which can then be used as a feedstock for producing chemicals, fertilizers, and other products.

What is the difference between rotary dryer and rotary kiln?

Rotary dryer: A rotary dryer is used to remove moisture from materials, such as minerals, ores, chemicals, food products, and biomass. The primary purpose of a rotary dryer is to reduce the moisture content of the material through the application of heat and the movement of the material within the drum. In a rotary dryer, materials are fed into the rotating drum, and hot gases or air are introduced to evaporate the moisture. The material is tumbled and agitated as it moves through the drum, allowing for efficient drying. Rotary dryers operate at elevated temperatures to facilitate drying, the temperatures used are generally lower compared to those in rotary kilns. Rotary dryers are used in industries such as agriculture, mining, chemicals, and food processing to remove moisture from bulk solids, powders, and other materials.

Rotary Kiln: A rotary kiln is designed for high-temperature processes, such as calcination, sintering, pyrolysis, and other thermal treatments. It's used to process raw materials or products at elevated temperatures, often in a controlled atmosphere, to bring about physical or chemical changes in the material. In a rotary kiln, materials are typically fed into one end of the kiln and gradually move towards the other end. The kiln is heated to very high temperatures, and the material undergoes chemical reactions, phase changes, or thermal treatments as it progresses through the kiln. Rotary kilns operate at much higher temperatures, often reaching well over 1000 degrees Celsius (1800 degrees Fahrenheit), depending on the specific process. These high temperatures are necessary to achieve the desired chemical or physical transformations in the material. Rotary kilns are used in industries such as cement production, lime calcination, metallurgy, and waste incineration. They are designed for processes that require high-temperature reactions, phase changes, or material transformation.