Cement vertical roller mill Introduction

Cement vertical roller mill also known as vertical grinding mill is an equipment widely used in the cement production plant and cement grinding station, it is also suitable for grinding a wide range of other materials. The cement vertical roller mill has become a popular choice for grinding clinker 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. With more than 65+ years of experience in technical innovation of the cement vertical roller mill, Tongli integrated our technological development strength, core manufacturing expertise, precise quality control into our ZJTL series cement vertical roller mill.

Cement vertical roller mill structure

The main components of the cement vertical roller mill include the grinding table, grinding rollers, grinding roller shaft, grinding roller wheel hub, grinding roller tyre, rocker arms, separator, transmission system, middle shell, base frame. 

Grinding Table: The grinding table is a rotating part of the cement vertical roller mill responsible for grinding materials. It is mounted on a gearbox-driven spindle and can be tilted to control the product fineness and optimize the grinding process. The detailed structure of the grinding table includes guide ring, air ring, retaining ring, liner, disc body, scraper.

Grinding Rollers: Grinding roller is the main part for crushing and grinding materials. The grinding roller is composed of cast steel roller sleeve, forging shaft and wear-resistant surfacing bushing. The grinding roller is installed on the rocker arm of the cement vertical roller mill, under the action of external force, it is pressed tightly on the material of the grinding table, as the grinding table rotates the material is crushed. The grinding roller is equipped with a limit device to ensure that it does not directly contact the grinding table during operation

Grinding Rollers shaft: A forged shaft could refer to various components such as the main shaft that supports the grinding rollers or other critical shafts within the mill's structure. These components need to withstand significant mechanical loads and stresses, and using forged shafts can ensure the necessary strength and durability. The term "forged shaft" refers to a shaft that has been manufactured using a forging process, this process enhances the mechanical properties of the metal, such as strength, durability, and resistance to impact and fatigue.

Grinding Rollers wheel hub: The grinding roller wheel hub is a metal casting part that is mounted on the outside of the grinding roller shaft. The wheel hub refers to the central part of the grinding roller that connects it to the driving mechanism of the mill. The wheel hub is designed to transmit the rotational motion and force from the mill's drive system to the grinding roller, allowing it to rotate and exert pressure on the material.

Grinding roller tyre: The grinding roller tire of a vertical roller mill is a crucial component that directly contacts the material being ground during the milling process. It's also commonly referred to as the grinding roller or roller shell. This component is made up of a cylindrical shell or tire-like structure that rotates around a central shaft. The grinding roller tire is typically equipped with segments or studs that aid in grinding and pulverizing the material as the mill's table or bowl rotates.

Rocker Arms: The function of the rocker arm device of the cement vertical roller mill is to transmit the pressure provided by the hydraulic cylinder to the grinding roller, so that it can be transformed into the grinding force act on the material bed. The rocker arm device is mainly composed of upper rocker arm, lower rocker arm, rocker arm shaft, bearing and bearing housing and other components. The upper rocker arm is used to install the grinding roller, the lower rocker arm is connected to the hydraulic system, and the two rocker arms are connected as a whole through shafts, taper sleeves and taper pins.

Classifier: Powder classifier (also known as coarse powder separator) of the cement vertical roller mill plays a vital role in the selection of powder during grinding. The ground material is carried by the high-speed rotating airflow in the mill and enters the powder classifier through the stationary blades. The material is screened under the high-speed rotation of the cage rotor, and the screened fine particle material is taken out by the exhaust gas and enters the cyclone. The coarse particle material falls into the grinding disc through the lower cone tube for re-grinding.

Middle shell: The middle casing of the cement vertical roller mill is a welded structural part, which supports the weight of the entire separator. There are 4 inspection doors on the middle casing for roll overhaul. The door is designed with a sealing sheath that is in close contact with the grinding roller to Prevent air leakage. The inner wall of the middle shell is laid with a wear-resistant lining to protect the inner shell.

Base Frame: The support base of the vertical mill is generally four peripheral support pedestal and a central support base, and the support base and the installation foundation are connected and fixed by anchor bolts. All the cement vertical roller mills of Tongli will be pre-assembled and leveling calibrated before leaving the factory to ensure that the equipment can be installed smoothly on site.

Transmission device: The transmission device of the cement vertical roller mill is composed of a planetary gear reducer, a motor and a coupling in the middle of 4 supporting beams. The planetary gear reducer is a reduction device with a vertical output shaft, and the output end is connected to the grinding table with a flange. The vertical downward force is supported by the hydraulic thrust bearing on the top of the reducer during 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 vertical roller 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 kiln and the quality of the products being processed. Tongli vertical roller mill is controlled with PLC control system which is capavle of monitoring temperature, vibration, filling rate, output rate. Tongli vertical roller mill also equipped with CO, O2 real-time gas analyzer to ensure save production.

Design principles of cement vertical roller mill

Advanced design: As one of the leading vertical roller mill manufacturers, Tongli cement vertical roller mills are advanced in design, integrating the functions of crushing, drying, grinding, classifying, conveying. Adapt to fluctuating raw material qualities, adapt to different product qualities.

High grinding efficiency: The stand-alone production capacity of the vertical roller mill is large, low energy consumption compared with ball mills, the energy consumption is usually 40%-50% lower than the ball mill;

Dust-free operation: The vertical roller mill system adopts a fully enclosed system, and the whole system operates under negative pressure without dust spillage, which can meet the requirements of clean production

Use of kiln exhaust gas: Use of the rotary kiln exhaust gas as the heat source for dry grinding to save energy, if not hot air furnace can be applied.

Compact layout: The occupation area is only 50% of that of a ball mill and It can be arranged outside, no workshop needed. Due to this reason, it can effectively reduce construction costs and helping enterprises reduce initial investment costs.

Gas sealing system: Tongli cement vertical roller mill is equipped with a high-speed centrifugal blower to send high-speed air into the seal of the roller bearing to form a gas seal to prevent dust from entering the roller bearing. By doing this we can greatly improve the bearing service life.

Water spray system: The vertical roller mill of Tongli is equipped with a water spray system, one is to reduce the outlet temperature of the mill, and the other is to speed up the accumulation of the material layer on the grinding table.

Lubrication system: Tongli vertical roller mill is equipped with a forced lubrication device to ensure the service life of bearings and key components during operation.

PLC control system: Real-time monitoring of the vertical roller mill with operating parameters. Highly automatic, features remote control and touch screen control, Siemens control system.

Specifications of cement 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 ball mills and vertical roller mills plays a vital role in the cement 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 cement and ore grinding applications. The choice between the two depends on specific requirements, budget constraints, and technical expertise.

What is the process of making cement clinker?

The first step of making cement is the raw material crushing, conveying and storage. The limestone raw material from the mine needs to be crushed, ground and mixed, and the crushing process is carried out by cement crusher. When the maximum size of the input ore is ≤1600mm and the output particle size is ≤80mm, the limestone discharged from the crusher is then sent to the Φ80m circular pre-homogenization yard by the belt conveyor for pre-homogenization and storage. After the raw materials are being crushed, the homogenized raw materials enter the cement rotary kiln and heated to a very high temperature around 1500°C, this process creates small marble-sized product called "clinker."