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The influence of box structure on the quality of tube mill

Date:2019-06-28 17:21     writer:cement editor     Views:

How to achieve high yield, high quality and low consumption of ball mill? The internal structure of the mill is the main factor. The reasonable division of the length of each silo, the form of the lining, the over-feeding capacity of the silo, and the discharge capacity of the discharge raft are essential. The internal structure of the mill must be adapted to the requirements of the process. Most manufacturers use the ball mill, the lack of design of the internal structure of the mill, usually directly using the uniform configuration of the mill manufacturers, without the combination of their own process characteristics to do targeted design, the results naturally can not get good results. I have been engaged in the commissioning and production of grinding machines for many years. I am deeply impressed by the internal structure of the mill, especially the influence of the partition board and the discharge board on the quality of the production. The following is only a brief view of the individual.

1. The role and process requirements of the compartment board.

(1) The primary task of the compartment is to meet the requirements of the warehouse. Separate the steel balls of different diameters in the grinding to suit the reasonable principle of using large balls and fine balls for coarse-grained grades in the grinding process of materials. At the same time, the coarse particles are stuck to prevent it from going backwards to the warehouse. Once the coarse particles run to the back warehouse, there is no big ball in the back warehouse, it can't be crushed and will run rough, which affects production and quality.

(2) Control the material flow rate. The material levels of each bin are adapted to each other, and the ball to material ratio is appropriate to meet the changes of different grinding processes and operating systems.

The proper discharge structure of the compartment plate and the combination of the pupil width and the shape of the pupil ensure a non-blocking and reasonable flow rate, so that the material has a suitable residence time in the mill.

(3) Convenient internal ventilation. For cement mills, ventilation is required to dissipate heat to cool the cement, and at the same time, the finely ground powder can be removed in a timely manner to reduce over-grinding. The compartment device must eliminate the influence of uneven ventilation, have sufficient ventilation and over-feeding area, and have less pressure loss.

2. Common drawbacks of improper compartment boards.

(1) Single-layer compartment board. The single compartment is basically overflow discharge. When the fine material below the surface layer passes, the resistance is large, the flow rate is slow, and the filling rate of the front warehouse is higher than that of the rear warehouse. This structure is not conducive to the adjustment of the balance of the grinding capacity of each warehouse, and is now basically not used.

(2) Double-layer compartment board without screening. Such compartment boards are usually composed of a seesaw and a blind plate with a lifting device in the middle. It is forced to discharge, the flow rate is fast, and it is not affected by the filling rate before and after the compartment. Even if the material level in the front bin is low, it can be smoothly discharged. One of the drawbacks is that due to the limitation of the casting process of the slab, the quilting width is usually only 6mm, and the less than 5mm of the material at the partition plate is easy to pass through the quilting into the next bin. The rear bin is usually a small-sized ball forging, which cannot crush the pellets and will run rough. Second, because the back layer is a blind plate structure, it is not conducive to uniform ventilation inside the mill. This structure is ventilated almost entirely from the center at a distance from the front and rear of the partition plate. The wind speed at the center is too fast and the ventilation resistance is large. Since the wind passes through the center, there is almost no wind at the quilting, and the negative pressure is also small. If the material has a slightly larger moisture or a small quilting, the quilting is easy to be blocked, and the material passing capacity will not meet the process requirements. Thereby affecting the production and quality of the mill.

(3) The rear road is a double-layer partition board for the blind board. This kind of compartment board, after the rafter, has a layer of thin steel plate stamped and formed façade sieve plate, which can control the large granules to enter the next bin. However, since the rear channel is a blind plate structure, like the above-mentioned type of partition plate, the wind speed at the center is large, the negative pressure at the sieve plate is small, the screening ability is poor, the fine powder material is easy to be blocked at the sieve joint, and the material passing capacity is poor. The material is usually discharged from the center circle into the next position by the high-speed wind at the center, and the screening effect is lost. Due to poor material throughput, it is not particularly suitable for use in closed circuit mills. When the material passing capacity is poor, it will cause the front warehouse to be fully ground, and the consequences of the empty warehouse after the warehouse will seriously affect the production and quality of the mill.

(4) Double-layer compartment board with curved sieve plate. The compartment board is provided with a curved plate type curved screen in the radial direction. When the material enters the curved screen surface, the material is mainly sieved by gravity during the operation of the mill, and the fine material enters the next warehouse, and the coarse material enters the next warehouse. Return to material. This kind of structure has higher screening efficiency, but because the width of the curved screen is only more than 100 mm, the length is only equivalent to the radius of the mill, and the number is only 8 to 10, and the total screening area is small. Small, can not be used for closed circuit grinding.

3. The ideal compartment structure.

In view of the structural defects of the above-mentioned compartment board, we designed a uniform wind that does not block the compartment board. The main features are as follows. (1) Both sides of the compartment board are boring plates with boring holes. The quilting of the slabs of the warehouse is self-cleaning. The quilting is not easy to block, ensuring the requirements of ventilation and overfeeding. The ventilation resistance is small and there is no center. Wind tunnel effect. (2) Using the sloping screen, the high-quality board is used, the sieve hole distribution is reasonable, the screening area is large, and the material passing capacity is strong. (3) Adding a coarse material lifting plate between the raft and the sieve plate is beneficial to the timely return of the coarse granules. (4) The flow is adjustable. The material is transferred from the discharge hole to the next chamber through the lifting of the fine powder lifting plate, and the outlet area of ​​the holes is easily adjusted by the operation slide. According to the situation of the rear ball and ball ratio, the outlet area is adjusted by adjusting the fixing screw on the sliding plate to ensure the proper ball-to-batch ratio of each bin, and the balance of the grinding capacity of each bin is achieved. When producing different kinds of products, the export area can also be adjusted according to its characteristics to meet the requirements of different material passing capacity. (5) The second warehouse face slab adopts a new type of anti-blocking composite raft, and its structure adopts a hollow slab frame and a sieve joint to form a 4-6mm sieve plate to form an anti-blocking raft. Since the sieve plate is relatively thin, the thickness is only 6~10mm, and the small abrasive body enters less part, and it is easy to return under the push of other grinding bodies. Even a small grinding body of about 6mm is not easy to be blocked in the sieve joint. Since the hollow space is relatively small, the movement of the grinding body therein is not large, and the wear on the sieve plate is also small. At the same time, since the sieve plate is thin, its elasticity is large, and even during the operation, even if the water is large, a small amount of material is easily sticky, and it is easily ejected. Therefore, it is not easy to be clogged during operation, and is not easy to stick, so that the material passing ability is strong and the ventilation resistance is small. In the actual use, the seesaw can completely solve the shortcomings of the small grinding body being easy to block and stick to the paste. Since the jaws are not blocked, most of the material and wind are ensured to pass through the jaws. The wind speed in the mill is uniform and small, and there is no local wind speed too fast. The ratio of the ball in the mill is suitable, thereby improving the grinding efficiency and improving the mill. Yield.

Anti-blocking raft structure is shown below

Anti-blocking slab sieve plate thickness 8~12mm, mesh hole 4~6mm, milling and processing, high strength, long life, the structure is shown below.

At the same time, we design a reasonable through-hole rate according to the specific production process. According to the design output, the through-hole ratio of the fascia is designed specifically. For example, the open slag grinding through hole rate is 3 to 4%, and the closed circuit grinding requires 4 to 6%. For cement grinding without pre-grinding, the open-hole ratio is 5 to 6%, the closed circuit is 8 to 10%, and the through-hole ratio of pre-grinding needs to be increased by 40 to 60%.

4, the application of the wind does not block the compartment board.

The cement grinding system of Jiangsu lvssn is a combined grinding open system consisting of φ1800X1200 roller press + V4000 + VSR4000 dynamic classifier and φ4.2X13m ball mill.The compartment board is a double-layer sieve partition board. The second warehouse surface of the compartment is a blind board, the screening board is easy to paste, and the compartment board has poor material throughput. The discharge plate design has low through-hole ratio and is easy to block. When producing P.O42.5 cement, the production capacity is 180~190t/h, the specific surface area is 320~420, the fluctuation is large, the cement demand is high, and the production is easy. mill. During the transformation, the double compartment compartments are all changed to the uniform wind without blocking the raft, the sieve sifter is enlarged, the discharge raft is changed to not block the raft, and the designed through hole ratio is designed. After the transformation, the partition board and the discharge board have the appropriate material passing capacity. The grinding ball is suitable, the grinding efficiency is improved, the grinding aid is stopped, the table rises to 220~230t/h, and the specific surface area is stable at 320~350m2. /kg, the energy saving effect is very significant.

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