Coal ball mill Introduction

Coal ball mill structure

The pulverized coal ball mill, It is composed of the mill shell, trunnion, slide shoe bearing, liners, diaphragm, grinding media, transmission device and so on. Depends on the transmission method, if the coal ball mill is edge drive, then it will have girth gear and pinion.

Mill Shell: The foundation of the coal ball mill, the mill shell, is a sturdy cylindrical structure crafted from premium-grade steel. This robust shell encases the grinding process, confining it within a controlled environment. Tongli heavy machinery is equipped with a large annealing furnace of 6.5x6.5x20m and a 6.5x6.5x20m large sandblasting room, which can conduct overall heat treatment and sandblasting on the ball mill to ensure the service life and appearance of the ball mill.

Bearing Bush: Coal ball mill bearing bush ensures the smooth rotation of the ball mill and empowers the ball mill to maintain optimal grinding conditions. It is equipped with a forced lubrication system and also cooling system.

Transmission connection: Tongli’s coal ball mill is equipped with a transmission connection, which is welded on the cylinder and machined together with the ball mill shell to avoid assembly errors and ensure the concentricity of the ball mill.

Hood Cover: The discharge hood of the coal ball mill is installed at the discharge end of the ball mill, and there is a screen inside. After grinding, the material with a qualified size will enter the discharge hood through the screen and enter the next process. There is a vent on the upper part of the discharge hood, and a discharge funnel on the lower part.

Diaphragm: The ball mill Diaphragm (compartment plate) is fan-shaped plate or bow-shaped grate plate fixed in the ball mill with bolts. Its function is to divide the ball mill into two or more chambers, the material moves to the next compartment through the holes on the grate plate. The function of the compartment plate is to prevent the grinding media running from one compartment to another compartment, so that the materials can be reasonably finely ground.

Liner: The function of the liner is to protect the shell of the ball mill and the trunnion, some special-shaped liners can also design to lift the grinding media to a certain position. According to the shape of the liner, it can be divided into flat liner, beaded liner, corrugated liner, ribbed liner, stepped liner, etc.

Cement ball mill transmission: Central drive ball mill refers to the arrangement of the driving mechanism for the mill. In a central drive configuration, the motor and gearbox are positioned at the center of the mill, usually between the grinding chamber and the mill shell. This design is in contrast to an edge or end drive configuration where the motor and gearbox are situated at one of the ends of the mill. Central drive transmission systems typically involve a motor that powers a gearbox, which then transfers the rotational energy to the mill's main shaft. The central drive design can provide advantages in terms of power distribution and efficiency compared to other drive arrangements. It can also offer better control over the mill's operation.

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 ball mill, 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 ball mill and the quality of the products being processed. 

Design principles of coal ball mill

Explosion-proof design: Because pulverized coal ball mills are different from ordinary ball mills, pulverized coal is flammable and explosive. When the concentration exceeds a certain range or the temperature exceeds a certain range during the grinding process, it may cause an explosion. Therefore, Tongli’s pulverized coal ball mill, the safety factor is fully considered in the design.

Explosion-proof door: During the operation of the coal ball mill, if the inlet and outlet of the coal ball mill are blocked, it will cause the accumulation of high-temperature and high-pressure gas inside the equipment, increasing the risk of combustion. In order to avoid this situation, the coal ball mill is equipped with an explosion-proof door, release the pressure in time to ensure timely removal of internal gas accumulation, protect the equipment and production safety. 

Real-time gas monitoring: Tongli's pulverized coal ball mill is equipped with CO and O2 gas analyzers at multiple points for real-time monitoring of the internal conditions of the ball mill. Tongli's pulverized coal ball mill is also equipped with a temperature monitoring system to prevent the risk of explosion due to excessive temperature.

Flexible Operation: coal ball mill can handle a wide range of coal types and moisture levels, making them versatile for different coal specifications.

Efficient Grinding: The coal ball mill provides efficient grinding of coal, resulting in a fine powder suitable for efficient combustion in industrial furnaces and power plants.

Energy Efficient: Use of the exhaust gas from the kiln, at the bottom of the mill, there are air inlets that allow the primary air to enter. The primary air, which is preheated in the rotary kiln, is responsible for carrying the pulverized coal particles upward to the classifier.

Lubrication system: Tongli coal ball mill is equipped with force lubrication system, there is an oil station equipped for the transmission part, another oil station for the gearbox to ensure smooth operation and prolong service life of the ball mill.

Cooling system: The main bearing bush of coal ball mill is equipped with a water-cooling system at the bearing bush, and a cooler is also installed in the lubrication system to forcibly cool the lubricating oil.

Cutting-edge design: As one of the professional ball mill manufacturers, Tongli coal ball mills are advanced in design, integrating the cutting-edge technology, adapt to different product qualities.

Transmission connection: Tongli’s ball mill is equipped with a transmission connection, which is welded on the cylinder and machined together with the ball mill shell to avoid assembly errors and ensure the concentricity of the ball mill.

Heat treatment: Tongli Heavy Machinery is equipped with a large annealing furnace of 6.5x6.5x20m and a large sandblasting room, which can conduct overall heat treatment and sandblasting on the ball mill to ensure the service life and appearance of the ball mill.

Specifications of coal ball mill

Note: * Mill diameter refers to the inner diameter, while the mill length refers to the effective grinding length.

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Industry Knowledge extension

Why coal grinding ball mill system is different with other grinding system?

Because the sparks generated by the pulverized coal system ball mill may cause an explosion. The pulverized coal system ball mill is a kind of equipment used to grind coal powder into fine powder, which includes a coal mill and a pulverized coal separator. In the process of coal grinding, due to the friction and collision of coal powder, a certain amount of heat and sparks will be generated. If these sparks are mixed with coal powder in the air, a flammable mixture may be formed. If it encounters an ignition source, it will ignite explode. In order to prevent this from happening, Tongli has taken the following measures, installing explosion-proof equipment, such as explosion-proof doors, explosion isolators, etc., installing temperature detectors and spark detectors at the outlets of coal mills and pulverized coal separators, and timely spot sparks and high temperature conditions. Control the temperature and humidity of pulverized coal to reduce the generation of sparks. In summary, the spark of the pulverized coal system ball mill may cause an explosion, and a series of measures need to be taken to ensure the safety of the production process.

What are the types of ball mill?

Tongli ball mill has following categories: according to the product material can be divided into cement ball mill, mineral ball mill, limestone ball mill, gypsum ball mill, slag ball mill, ore ball mill, raw material ball mill, coal mill, etc; according to the size of the crushed material can be divided into: coarse ball mill, high-fine powder ball mill, ultra-fine powder ball mill; according to the transmission mode, it can be divided into edge transmission ball mill and center transmission ball mill(Gear-less Motor Drive); according to the transmission method, it can be divided into sliding shoe ball mill, bearing bush ball mill and bearing ball mill;

What is the difference between central drive ball mill and edge drive ball mill?

Central Drive Ball Mill and Edge Drive Ball Mill are two common types of grinding mills used in various industrial applications. 

Central Drive Ball Mill: In this configuration, the motor is positioned in the center of the mill, and the shaft is driven directly through the central axis. The motor's power is transmitted to the mill via a gear unit, resulting in a balanced and efficient power distribution.

Edge Drive Ball Mill: In contrast, the edge drive mill utilizes a gearbox located on the periphery of the mill. The motor's power is transmitted to the mill through the gears, which are positioned around the shell. This design offers certain advantages in terms of installation and maintenance.

What is the difference between ball mill and vertical roller mill?

Both ball mills and vertical roller mills plays a vital role in the coal grinding plant. Ball mills are versatile and cost-effective, suitable for various materials and simple to maintain. On the other hand, vertical roller mills offer superior energy efficiency and particle size control, making them ideal for coal and raw material grinding applications. The choice between the two depends on specific requirements, budget constraints, and technical expertise.