Powder grinding ball mill

Ball mill, as the key equipment for crushing materials after crushing, plays an important role in industrial production. There are many types of ball mills, including tubular ball mill, rod ball mill, ceramic ball mill, cement ball mill, etc., which are widely used in many industries such as mineral processing, building materials and chemical industry.

According to different discharge methods and cylinder shapes, ball mills can be divided into grid type, overflow type, short cylinder ball mill, long cylinder ball mill and other types. Here I will deeply analyze the “cement ball mill” equipment produced by SMAT. This equipment plays a vital role in cement production, and its performance and efficiency are of great significance to improving the overall production efficiency. In this article, let you know more about cement mill.

What is a cement ball mill?

Cement mill, also known as cement grinding mill, is a key equipment used to grind cement clinker and appropriate amount of gypsum into cement powder. Cement ball mill is a widely used grinding equipment in China.

During the crushing process, cement ball mill can not only reduce the particle size of materials, but also mix two or more materials. It is widely used in metallurgy, chemical industry, power and other industrial and mining enterprises to grind various ores and other grindable materials.

How does cement mill work?

Cement mill is a horizontal cylindrical rotating device with gear transmission on the outside. It is usually a two-bin grid ball mill. The working principle of cement mill has four steps:feeding, coarse grinding, fine grinding, and discharging.

1.Feeding:

The material is fed into the first bin of the mill evenly through the feeding hollow shaft spiral from the feeding device.

2.Coarse grinding:

There is a stepped liner or corrugated liner in the first bin, which contains steel balls of different specifications. The centrifugal force generated by the rotation of the cylinder brings the steel balls to a certain height and then falls, which has a heavy impact and grinding effect on the material.

3.Fine grinding:

After the material reaches coarse grinding in the first bin, it enters the second bin through a single-layer partition board. The second bin is inlaid with a flat liner and steel balls to further grind the material.

4.Discharging:

The powder is discharged through the discharging grate plate to complete the grinding operation

Two types of cement ball mill

1. Ordinary cement ball mill:

.Most of ordinary cement ball mills are used in circle flow grinding system. Its characteristics are high grinding efficiency, large mill output and low power consumption, especially when grinding slag cement. The performance is more prominent.

Generally, the cement mill output can be increased by 15-20%, and the power consumption can be reduced by about 10%. In addition, the finished product temperature can be reduced by 20-40°C, and the product fineness is also easy to adjust.

2. High-fine and high-yield cement ball mill:

High-fine and high-yield cement ball mill is mainly used in open flow grinding system. The characteristics of high-fine and high-yield cement ball mill are simple system equipment and process flow, low investment, and small plant area;

The cement mill structure adopts advanced internal powder selection special compartment device, the fine grinding chamber adds an activation device, and the mill tail has a special discharge grate plate to minimize the size of the grinding medium in the grinding chamber, greatly improve the grinding efficiency, and achieve the purpose of high output and low energy consumption.

Cement grinding mill specification

Structure of cement mill

SMAT cement mill adopts central transmission, with sliding bearings at both ends, and adopts new combined partition plates and discharging grate plates to improve the efficiency of grinding and screening.

Ball mill cement is mainly composed of feeding device, sliding bearing, rotating part, discharging device, sliding bearing lubrication device, transmission device and other parts.

1. Feeding device

The material is fed into the mill through the feeding device, which is composed of a feeding pipe, an air inlet pipe and a bracket. A movable wheel is installed at the bottom of the bracket, and an adjustable valve is provided at the end of the air inlet pipe. An adjusting gasket is inserted between the air inlet pipe and the bracket to adjust the center height of the feeding device when necessary.
The material passes through the hollow shaft, and the main function of the feeding device is to smoothly deliver the material into the mill. There are mainly two types:
• Slide pipe feeding: The material enters the conical sleeve in the hollow shaft neck of the mill through the slide pipe, and then slides into the mill along the inner wall of the rotating sleeve.
• Screw feeding: The material enters the charging pipe from the feed port, and is carried by the partition into the sleeve and pushed into the mill by the spiral blade.

2. Sliding shoe bearing

The mill uses a movable sliding shoe bearing at the feed end. A single-side fixed sliding shoe bearing is used at the discharge end. The sliding shoe bearing is supported by two support shoes at an angle of 30° to the vertical direction. Each support shoe is equipped with a concave and convex ball structure at the bottom.

The convex ball sits in the ball socket of the concave ball. There is spherical contact between the two, so that the mill can automatically adjust its position when it rotates. The entire support shoe is seated on the roller through the ball, so that the support shoe can move axially with the rotating part of the mill when the whole body expands and contracts.

The support shoe on the upper side of the rolling ring in the sliding shoe bearing at the discharge end is seated on a fixed support through the ball. This ensures the fixation of the sliding shoe bearing on the transmission side of the cement mill. This support mechanism ensures good contact between the shoe and the rolling ring.

The support bearing body is a casting, and a bearing alloy lining is laid. The lining should be combined with the bearing body by pouring method, and the specific pressure should not exceed 2200kpa. In order to form an oil wedge, the inner diameter of the sock should be slightly larger than the outer diameter of the rolling ring, and its surface roughness Ra≦0.8um. ​​In principle, the bearing should not be scraped. There is an oil bag on the surface of the support bearing, so that the high-pressure oil can enter between the support bearing and the rolling ring.

The sliding shoe bearing is equipped with a high-pressure starting lubrication device, and each sliding shoe bearing is equipped with a set. The high-pressure lubrication system is used for the start-up, shutdown and turning maintenance of the mill, that is, a layer of oil film is formed between each support bearing and the rolling ring by static pressure.

Low-pressure lubrication is that the circulating oil is sent to the two oil pans of the sliding shoe bearing by a low-pressure pump, one of which is placed under the rolling ring, and the other is placed in front of a support bearing (front and upper in the direction of rotation).

The rolling ring can be immersed in the oil in the oil pan, and after the mill rotates, it is brought between the rolling ring and the support bearing, thereby forming dynamic pressure lubrication. An oil scraper brush is installed on the upper side of both ends of the roller ring to prevent the lubricating oil from flowing out. The oil scraper brush pull rod is tightened with a spring, which can be adjusted during installation so that the oil scraper brush fits well with both sides of the roller ring.

3. Discharging device

The discharging device is a steel plate cover, with an exhaust port on the upper part and a discharging port on the lower part.
After the material is discharged from the discharging grate plate, it is lifted by the blade and sent to the discharging cone sleeve in the hollow shaft along the outer wall of the discharging cone, and then enters the control screen through the elliptical hole. The screened material is discharged from the discharging port at the bottom of the cover. A pipe connected to the dust collection system is installed on the top of the cover.

4. Transmission device

The transmission device includes the main motor, reducer, oil station, coupling, auxiliary transmission, etc. The ball mill has low mill speed and requires a reducer.
• Mill transmission: edge transmission and center transmission.
• Auxiliary transmission device: to meet the mill startup, maintenance and ball addition and pouring operations.
•The transmission device of the mill is usually arranged at the discharge end
•Large-sized steel balls of bulk materials at the feed end can be arranged at the discharge end to avoid impact;
The feed end is a free end for thermal expansion and contraction, and arranging it at the feed end affects the meshing of gears.

5. Main bearing

•It bears the entire mass of the mill body, grinding body and materials, and also bears the impact load caused by the falling of grinding body and materials;
•The feed end has a structure that adapts to the thermal expansion and contraction of the cylinder;
•Lubricating oil and cooling water are required!
•Lubrication is the key to equipment management in cement plants, and it is also easy to ignore. For example, inferior oil is not replaced regularly, and the oil volume, oil pressure and oil temperature should be monitored daily.
•It is divided into sliding bearings and rolling bearings

6. Rotating part

The rotating part consists of a partition plate, a discharge grate plate, a front plate, a full-body lining plate, etc.
The combined partition plate consists of a coarse screen plate, a fine screen plate, a front plate, a support plate, a center grille and a lining plate. The discharge grate plate consists of a grate plate, a support plate, etc. The first bin of the mill uses a stepped lining plate, and the second bin uses a double-step graded lining plate.

7. Combined partition plate

Generally composed of a front grate plate and a rear blind plate, with a lifting device in the middle. The material enters the middle of the two plates through the grate plate, and the lifting device lifts the material to the central cone and enters the next bin. It is a forced discharge with a fast flow rate. It is not affected by the filling rate before and after the partition plate, which is convenient for adjusting the filling rate and ball distribution. It is suitable for one bin, especially closed-circuit mills. However, the ventilation resistance is large and the volume of the mill is large.

• Grate holes in the partition plate
The grate holes of the partition plate allow the material to pass through, but the grinding body is not allowed to run into the bin. There are certain requirements for the shape and arrangement of the grate holes.

a. Grate hole arrangement The arrangement of grate holes can be mainly divided into concentric circles and radial shapes. The concentric circle
arranged grate holes are parallel to the movement path of the grinding body material. The material is easy to pass through, but it is also easy to return and not easy to block; the radial shape is the opposite. The radial grate plate has a greater lifting effect on the grinding medium near the grate plate, and is not suitable for the discharge end.

b. Grate hole shape
The percentage of the total area of ​​all grate holes on the partition plate (referring to the area of ​​small holes) to the total area of ​​the partition plate is called the through-hole rate, which is generally 3-15%, and the through-hole rate of the dry mill is not less than 7%-9%. If you want to adjust the through-hole rate of small holes, you can first block the outer ring of grate holes.
The partition plate is generally installed with a double-layer partition plate between the first and second bins. When installing the grate plate, the small end faces the feed end, and the large end of the grate hole should face the discharge end. It cannot be installed reversely.

what doae cement mill used for?

Cement mills are widely used in the following fields

Cement production: used to grind cement clinker into fine powder, which is the core equipment in the cement production line. Silicate products: grinding silicate materials. Refractory materials: grinding refractory materials. Fertilizers: used in the grinding process in fertilizer production. Ferrous and non-ferrous metal beneficiation: grinding ore in the beneficiation process. Glass ceramics: grinding glass ceramic raw materials

Two types of grinding in cement grinding mill

The so-called cement grinding production process is the general term for the cement grinding production process. The ultimate goal of the production process is to achieve the best production efficiency and the lowest energy consumption through the optimization combination of cement grinding production equipment and raw materials.

Cement mill near me for sale

SMAT Machinery is located in Zhengzhou, Henan Province. SMAT has 37 years of export experience. The company specializes in the production of various ball mills and crushers, including fly ash ball mills, wood ball mills, etc. It is China’s top cement ball mill manufacturer, widely used in cement, chemical, metallurgy, mining, thermal power generation and other industries.