Magnesium oxide rotary kiln Introduction

Magnesium oxide rotary kiln structure

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

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

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

Kiln Shell: The rotary kiln shell is a thick, steel cylindrical structure that provides the necessary strength and rigidity to withstand the high-temperature environment inside the kiln. It also serves as a containment vessel for the materials and gases during the manufacturing process. Inside the kiln shell is the refractory lining usually refractory bricks or sometimes refractory castable. Tongli kiln shell has good sealing performance, the edge of each shell is machined smoothly, enhance the sealing and service life of the rotary drum.

Kiln Hood Cover: The rotary kiln hood is located at the discharge end of the kiln and provides sealing to retain heat and gases. The rotary kiln 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 Kiln Transmission device: The transmission device of the rotary kiln 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 kiln, 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 kiln and the quality of the products being processed. Usually, the rotary kiln 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 magnesium oxide rotary kiln

Thermal Efficiency: One of the primary goals of the design is to achieve high thermal efficiency. This involves maximizing the transfer of heat from the combustion of fuel to the material being processed. Insulation materials, refractory linings, and kiln shell design are all critical factors that impact thermal efficiency.

Material Flow: The kiln design should facilitate a consistent and controlled flow of material through the kiln. This ensures that the material is exposed to the required temperature and residence time for the desired chemical reactions to occur.

Temperature Control: Precise temperature control is crucial for the production of high-quality magnesium oxide. The kiln design should incorporate mechanisms for monitoring and controlling temperature throughout the kiln's length. This may involve the use of thermocouples, infrared sensors, and automated control systems.

Combustion System: The design of the combustion system is essential for efficient fuel utilization and consistent heat generation. Proper mixing of fuel and air, along with adequate combustion chamber design, can contribute to stable and controlled heat release.

Kiln Rotation and Inclination: The kiln rotates on its longitudinal axis to ensure even exposure of the material to heat. The inclination of the kiln controls the flow of material through the kiln and affects residence time. Both rotation and inclination need to be carefully considered in the design.

Finite element analysis: Finite element analysis is adopted during the design of the magnesium rotary kiln, make sure all the rotary kiln components girth gear, riding ring(tyre), supporting roller, pinion, shell is well suited for its specific job.

Sealing: Both the inlet and the outlet has a hood cover which improves the sealing effect, integrates labyrinth sealing, ceramic felt sealing, double leaf sealing, ss304 fish scale sealing to remain heat escape inside the kiln.

Filler padding: Floating padding are used under the riding ring to strengthen the shell and reduce the heat induction to the riding ring.

Girth gear spring plate: Due to the high temperature of the rotary kiln, Tongli magnesium rotary kiln is equipped with spring plate that is attached in between the girth gear and the shell to ensure smooth rotation and reduce heat transfer.

Girth gear/riding ring: All the metal casting are quality assured, Tongli has its own foundry and from the raw material to the finished product, the quality is reliable.

Quality inspection: Tongli offers magnetic testing and ultrasonic testing, which ensures the quality of all the metal castings and the welding seam.

Specifications of magnesium rotary kiln

Note: *The diameter is the inner diameter, Weight excludes refractory material.

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Industry Knowledge extension

What is the application of calcined bauxite?

Calcined magnesium oxide, also known as calcined magnesia or magnesite, is a versatile material with various applications across different industries due to its unique properties. It is produced by heating natural magnesite ore (magnesium carbonate) at high temperatures to remove carbon dioxide and convert it into magnesium oxide.

Refractory Bricks and Shapes: Calcined magnesium oxide is used to manufacture refractory bricks and shapes for high-temperature applications. It has excellent thermal resistance and stability, making it suitable for lining furnaces, kilns, and other industrial equipment.

Steelmaking: Calcined magnesium oxide is used as a refractory material in steelmaking processes, particularly in basic oxygen furnaces (BOFs) and electric arc furnaces (EAFs). It helps maintain the high temperatures required for steel production.

Ceramic Production: Calcined magnesium oxide is used as a raw material in the production of ceramics, including tiles, sanitaryware, and ceramic insulators.

Soil PH Adjustment: Calcined magnesium oxide is applied to acidic soils to adjust pH levels and improve soil fertility. It provides magnesium, an essential nutrient for plant growth.

Livestock Nutrition: Calcined magnesium oxide is used as a magnesium supplement in animal feed. It helps prevent magnesium deficiency in livestock and poultry, which can lead to health issues.

Construction Chemicals: Calcined magnesium oxide is used in construction chemicals like cement additives and mortars to improve adhesion, workability, and durability.

Wastewater Treatment: Calcined magnesium oxide can be used in wastewater treatment processes for pH adjustment and the removal of heavy metals.

FGD Systems: Calcined magnesium oxide can be used in FGD systems to remove sulfur dioxide (SO2) from flue gases emitted by industrial processes and power plants.

Filler Material: Calcined magnesium oxide can be used as a filler in rubber and plastics to improve strength, stiffness, and other mechanical properties.

Fireproofing Materials: Calcined magnesium oxide is used in fireproofing materials and flame retardants due to its ability to withstand high temperatures and act as a heat insulator.

Pharmaceutical Industry: Calcined magnesium oxide can be used as an excipient in pharmaceutical formulations, serving as a binder, diluent, or disintegrant in tablet and capsule preparations.

Magnesium Fertilizers: Calcined magnesium oxide can be used in the production of magnesium-based fertilizers to provide essential nutrients to plants.

What is the difference between rotary kiln and vertical roller mill?

The rotary kiln and vertical roller mill are both essential pieces of equipment in the cement manufacturing process, but they serve different purposes and are used at different stages of the process.

The rotary kiln is a large cylindrical vessel used for calcining raw materials at high temperatures. It's a core component of the cement manufacturing process and is responsible for transforming raw materials, particularly limestone and clay, into clinker. In the rotary kiln, the raw materials are heated to temperatures exceeding 1400°C (2552°F), where chemical reactions occur that result in the formation of clinker nodules. And they need to be ground into a fine powder to produce cement. This final grinding process is often performed using a vertical roller mill. The clinker is mixed with gypsum and possibly other additives to create the final cement product.

Vertical Roller Mill (VRM): The vertical roller mill is a grinding machine that grinds materials into fine powders, after the raw material is crushed by the crusher, it enters the vertical roller mill. It is typically used for grinding raw materials, clinker, and additives in the cement manufacturing process. The VRM operates by applying hydraulic pressure and vertical force to the grinding rollers, which then grind the materials between the rollers and the grinding table. This grinding process results in a fine powder that is later used as a key ingredient in the production of cement which is important for the subsequent chemical reactions in the rotary kiln.