Close-circiut cement grinding plant Introduction

A closed-circuit cement grinding plant is a set of equipment used to grind and mix raw materials (such as limestone, clay, shale, sand, and iron ore) into a fine powder. This set of equipment is called "closed-circuit" because it operates in a closed-loop system where the ground material is continuously circulated and refined using powder separater until it meets the desired quality and fineness requirements. The closed-circuit cement grinding plant is a part of the cement production line which generally includes the following parts: raw material storage, grinding and milling, material handling, final product storage, dust collecting, etc. The cement clinker produced by the rotary kiln in the cement production plant is coarse-grained and cannot be used directly. It needs to be ground by the vertical roller mill or ball mill in order to be processed to be the final product. The grinding process enhances the reactivity of the clinker and allows it to achieve the desired properties of cement, such as setting and hardening.

Close-circuit cement grinding plant equipment 

There are various equipment involved in the close-circuit cement grinding plant, some of them are as follows: vertical roller mill, cement ball mill, cement roller press(HPGR high pressure grinding roller), cement separator, cement dust collector, cement belt conveyor, cement automatic packing machine, cement bucket elevator etc. Tongli offers customized design for your specific need to ensure the smooth operation of the plant.

Closed-circuit ball mill: A closed-circuit ball mill is a type of ball mill that operates in a closed-loop configuration. In this milling process, the ground material is not discharged from the mill but is instead returned to the mill for further grinding. This is achieved by using a classifier to separate the fine particles from the coarse ones and then recirculating the fine material back into the mill.

Ball mill coupling: The coupling in a central drive ball mill serves as a connection between the motor and the gearbox or pinion gear. It allows the rotational power generated by the motor to be transmitted to the gearbox, which, in turn, drives the mill's rotation. The coupling is an important component because it ensures the efficient transfer of power while accommodating any misalignments or variations in torque. There are different types of couplings used in central drive ball mills, including gear couplings, flexible couplings, and other.

Ball mill transmission: The transmission system of a ball mill typically consists of a motor, a gearbox, and the mill itself. The motor, often an electric motor, provides the power to rotate the mill's cylindrical shell, which contains grinding media (such as steel balls) that pulverize the material inside the mill. The gearbox is used to control and adjust the speed and torque of the mill's rotation, allowing for precise grinding operations and optimization of the grinding process. Different configurations of transmission systems can be employed, including direct drives or indirect drives with pinion and gear arrangements, depending on the size and requirements of the ball mill, enabling efficient energy transfer and reliable operation in various industrial applications.

Vertical roller mill: The cement vertical roller mill has become a popular choice for grinding raw materials in the cement industry due to its significant advantages over traditional ball mill systems, compare to the traditional cement ball mill, it is more energy-efficient and can be exposed outside. The main components of the cement vertical roller mill include the grinding table, grinding rollers, rocker arms, separator, transmission system, base frame.

Closed-circuit HPGR: A close-circuit high-pressure grinding roller (HPGR) is a specialized grinding technology used in the cement industry to reduce the energy consumption and improve the efficiency of cement clinker grinding. It operates in a closed-loop system, which means that the material being processed is subjected to multiple grinding stages within the same circuit, in Tongli closed circuit grinding system, the high pressure grinding roller is connected to the static powder separator and then the dynamic powder separator to enhance the grinding efficiency.

Closed-circuit HPGR drive:A High-Pressure Grinding Roller (HPGR) drive system is a crucial component of HPGR, it provides the necessary power and control to operate the rolls efficiently and effectively. It is composed of a powerful electric motor responsible for providing the rotational power to the HPGR rolls. A gearbox, which is responsible for transmitting the power from the motor to the rolls. A Universal joint couplings which is to accommodate the space between the two rolls.

V-type static powder separator: A V-type powder separator, also known as a V-separator or V-classifier, is a type of equipment used in various industrial processes, especially in cement manufacturing and similar industries. Its primary function is to separate and classify fine particles from a mixture of materials based on their size and density. It is usually connected to the dynamic powder separator, inside of the static powder separator there are baffle plates that are arranged in different angles to classify the coarse particles from the stream.

Dynamic powder separator: A dynamic powder separator, also known as a dynamic air classifier or dynamic classifier, is a device used in various industrial processes to separate fine particles from a stream of air or gas based on their size, shape, density, or other properties. This separation process is commonly used in industries such as mineral processing, cement manufacturing, chemical processing, and pharmaceuticals, among others.

Cement dedusting bag filter: A cement bag filter, also known as a cement baghouse, is a piece of equipment used in the cement manufacturing process to control air pollution and capture particulate matter (dust) that is generated during various stages of cement production. It is an essential component of the environmental control systems in cement plants to ensure compliance with environmental regulations and maintain air quality standards. Also in a cement grinding plant, the bag filter also used as the equipment to collect the finished product after the air stream is classified by the separator.

Cement silo dedusting bag filter: A cement silo bag filter, also known as a baghouse filter, is a piece of equipment used in the cement industry to control air pollution and capture particulate matter that is generated during the process of storing and handling cement or other bulk materials. It is an important component of environmental protection and safety measures in cement manufacturing plants.

Cement low voltage power distribution system: A cement plant low voltage powder distribution system refers to the electrical distribution system used in a cement manufacturing facility to supply power to various equipment and processes involved in the production of cement. This system typically operates at low voltages, which are typically defined as voltages up to 1,000 volts in industrial settings.

PLC close-circuit cement grinding system: A Programmable Logic Controller (PLC) system in a cement plant is an industrial control system used to automate various processes and functions within the plant's operations. PLCs are computer-based devices that are widely used in manufacturing and industrial settings to control and monitor machinery and equipment.

Process flow of close-circuit cement grinding plant

Clinker Storage: Clinker is the primary raw material used to produce cement, and it is typically stored in silos or other storage facilities before it is fed into the grinding mill.

Grinding Mill: The heart of the cement grinding plant is the grinding mill, which can be a ball mill, vertical roller mill (VRM), or other types of mills. The clinker, along with various additives such as gypsum, slag, or fly ash, is ground to a fine powder in the mill. The grinding process reduces the clinker particles to the desired fineness, which is essential for cement properties.

Classifier: In a closed circuit system, a classifier is used to separate the finer particles (product) from the coarser particles (return material). The classifier ensures that the desired product fineness is achieved, and it directs the coarse material back to the grinding mill for further grinding.

Separator: Some closed circuit systems also incorporate a separator, which further refines the separation of product and return material. Separators can be integrated within the mill or be external units.

Recirculation of Return Material: The coarse material separated by the classifier or separator is typically recirculated back into the grinding mill. This process continues until the desired product fineness is achieved.

Product Storage: Once the desired product fineness is reached, the finished cement product is transported to storage silos for further distribution or packaging.

Control System: A closed circuit cement grinding plant is equipped with a control system that monitors and adjusts various parameters such as mill speed, feed rate, and separator efficiency to maintain product quality and optimize energy consumption.

Design Principles of closed-circuit cement grining plant

The closed-circuit process flow is relatively complicated, involving a lot of equipment, covering a large area, requiring high technical requirements for operation, maintenance, and management, and requiring a large investment. It is necessary to add a powder separator on the basis of the open-circuit process ball mill to screen out the qualified finished products and send them to the next process, and return the unqualified coarse powder to the ball mill for re-grinding to eliminate the phenomenon of "over-grinding". It is beneficial to increase the output of the ball mill and reduce power consumption. Typical closed-circuit process equipment also includes vertical roller mill, which has a powder separator that can control the fineness of the finished product, and the finished product is excellent in terms of fineness and particle shape.

Tongli cement grinding plant innovation:

The design principles of Tongli closed circuit cement grinding plant are focused on optimizing the overall efficiency and performance of the grinding process while ensuring product quality and minimizing energy consumption.

Control System: Tongli cement grinding plant Implementing a sophisticated control system is essential for closed circuit grinding plants. This system monitor and adjust various parameters, such as mill speed, separator settings, and feed rates, to optimize the grinding process and maintain product quality, gas analyzer is also implemented to ensure the safe production.

Closed Circuit Operation: Tongli closed circuit grinding system, the mill and the separator are connected in a loop, the fine powder will proceed to the next procedure and the coarse powder is recirculated for further grinding. This design principle helps achieve a more efficient and controlled grinding process.

Separator Selection: High efficiency powder Separator is crucial to ensure proper particle size distribution and product quality. The separator separates the finer particles from the coarser ones, allowing the fine material to be sent back to the mill for further grinding, all the impellers has pass through the balance test in our factory and are surface welded to enhence the wear-resistance.

Efficient Grinding Mill: Grinding mill is essential part of the grinding system, the vertical roller mill or ball mill is capable of handling the required production capacity and have efficient grinding mechanisms to reduce energy consumption,  the quality is time proven and the reputation is well-recognized by global customers.

Proper Sizing: Proper model sizing of the equipment (mill, separator, and other components) match the production requirements of the plant to prevent oversized or undersized equipment which can lead to inefficiencies and increased energy consumption.

Circulating Load Management: Managing the circulating load (the amount of material returned to the mill for re-grinding) is critical. Balancing the circulating load to maintain a stable grinding process and prevents overgrinding.

Product Quality Control: Continuous monitoring of product quality through particle size analysis and other quality parameters. The closed circuit design ensures that the final product meets the required specifications.

Energy Efficiency: Energy consumption is a significant concern in cement grinding. Our design is Implementing energy-efficient equipment, optimizing process parameters, and using alternative fuels or grinding aids can help reduce energy consumption.

Dust and Environmental Control: Adequate dust collection systems and environmental controls should be in place to minimize emissions and maintain a clean working environment.

Specifications of close circuit cement grinding plant vertical roller mill

Note: *The diameter is middle diameter of the grinding table

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Industry Knowledge extension

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

Both coal ball mills and coal vertical roller mills plays a vital role in the coal pulverizing plant. Coal ball mills are versatile and cost-effective, suitable for various materials and simple to maintain. In the coal powder pulverizing industry, the vertical mill is more widely used, because the vertical roller mill occupies a small area and has a drying function. Generally, the raw coal needs to be sprayed with water to prevent spontaneous combustion during transportation, so the moisture content is very large, so the drying function is particularly important. Another reason is that vertical mills have a high safety factor and are equipped with nitrogen explosion-proof systems and gas detection, so vertical mills are more widely used than ball mills in the coal powder preparation industry. The choice between the two depends on specific requirements, budget constraints, and technical expertise.

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

The rotary kiln is usually used as an intermediate process. The large raw materials are crushed by the crusher and then enter the grinding equipment for grinding. After being mixed with other raw materials, they are added to the rotary kiln for redox reactions. The calcined finished products need to enter the vertical roller mill or ball milling for secondary grinding to get the finished product. In the cement production line, it is usually equipped with a coal powder vertical roller mill. After the raw coal is ground by the vertical roller mill, it is evenly sent to the burner of the rotary kiln through the rotor scale for combustion, and then the tail gas generated by the rotary kiln enters the vertical roller mill to dry the raw coal, thereby achieving a cycle which saves energy while improving resource utilization.

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.