I. Wear mechanism of medium speed coal mill
Medium speed coal mill is suitable for grinding bituminous coal, lean coal and other medium hardness material powder grinding operation. It can be widely used in the pulverization system of power, metallurgy, cement, building materials, chemical and other industries, especially in the blast furnace coal injection pulverizing system which needs to use a lot of bituminous coal.
As an important pulverized coal preparation equipment, medium speed mill has been facing the test of wear since its birth. According to statistics, about 80% of the parts that fail in medium speed grinding belong to the direct or indirect consequences caused by metal wear. Metal wear will reduce the operating efficiency of equipment, lead to frequent workpiece replacement and maintenance, and increase energy consumption. Therefore, how to choose the appropriate wear resistant materials and wear resistant way has become a common concern of many equipment and manufacturers. The effective improvement of wear resistance of medium speed grinding can thus improve the service life and reliability of equipment.
The materials processed by the medium speed grinding cylinder are particles of various sizes and hardness. These materials move inside the medium speed grinding cylinder and constantly cause friction, erosion and impact on it so the wear is inevitable. The causes of wear of medium-speed grinding cylinder are complex, which include abrasive wear caused by coarse particle material sliding, wind erosion wear caused by high-speed scour of high-concentration dusty gas, and impact wear caused by high-speed impact of coarse particle material or even grinding body broken by the mill.
Wear-resistant ceramic liner for medium speed coal mill
Ⅱ. The role of vertical coal mill wear liner
Vertical mill lining plate is used to protect the coal mill barrel and shell from direct impact and friction. At the same time, different forms of lining plate can be used to adjust the motion state of the abrasive body to enhance the grinding effect of the abrasive body on the material. This helps to improve the grinding efficiency of vertical mill, increase production and reduce metal consumption. Conventional vertical wear - resistant lining plate type has corrugated, trapezoidal, T - type, etc.
Especially in the mill barrel area 2 meters above the mill disc, not only serious erosion will occur, but also large particle material impact. If the traditional anti-wear treatment is used, good results can not be achieved.
Therefore, we suggest that the adhesive wear-resistant ceramic lining plate can be used in the area of 2 meters above the millstone. This plate is made of unique technology with high hardness and toughness. At the same time, the traditional paste installation method has changed into adhesive and screw double fixation, which is especially suitable for the parts with certain impact and temperature.
Wear-resistant ceramic liner installed in the vertical grinding cylinder
Ⅲ. What are the types of mill liner? How to choose?
1. Alloy material
After the alloy liner is quenched, the comprehensive performance has both hardness and toughness. The hardness can reach above HRA65, and the impact toughness can reach 10J/cm2 (U-notch value). The characteristics are acceptable price, stable performance, easy installation and usage, cut and welded ability; the main disadvantage is that the wear resistance is average, and if the hardness need to be improved, the price will rise sharply.
2. Medium chrome steel material
Due to the high chromium content of medium chromium steel and the addition of molybdenum, nickel and other elements, the wear resistance is higher than that of low alloy materials, and the service life is longer; the disadvantage is that the weldability is poor, the welding difficulty is high, and it is not easy to install .
3. High chromium cast iron series
The high-chromium liner material has high wear resistance, but the cost is also high, the weldability and cutability are poor, the brittleness is high, and the processing is very difficult. Therefore, it is not recommended to be used as a coal mill liner.
4. High manganese steel
High manganese steel has impact hardening properties and is generally used in high impact conditions. In the case of large impact force, the wear resistance is excellent, but in the case of small impact force such as coal mills, most manufacturers have already eliminated them.
5. Wear-resistant ceramics
As a coal mill lining material that has risen in recent years, wear-resistant ceramics have been quickly recognized by many manufacturers after appearing in the market. Its hardness can reach HRA90, and its wear resistance far exceeds that of metal. Although the impact resistance of wear-resistant ceramics is not as good as that of metals, the impact resistance can also be greatly improved after adding special materials such as zirconia. Moreover, although the coal mill has impact wear, the impact force is not large, and the use of thicker wear-resistant ceramics is enough to deal with it. The most important thing is that the price of the wear-resistant ceramic lining plate is moderate, but the service life is more than 10 times that of the metal lining plate. It is an economical choice after comprehensive consideration.
Ⅳ. KINGCERA’s special ceramic coal mill wear-resistant ceramic lining
The wear-resistant ceramics produced by KINGCERA are made of imported high-purity alumina powder. The dense α-alumina is calcined at a high temperature of 1700 ℃ with a rare element formula. The product has the characteristics of high hardness, high wear resistance, corrosion resistance and high temperature resistance.
Due to the impact of the coarse-grained materials squeezed by the grinding rollers and the high-temperature and high-concentration powder closest to the static ring, the scouring of the bottom of the barrel of the medium-speed coal mill is very serious.
After years of experience summarizing, KINGCERA has designed different anti-wear solutions for the coal mill barrel and coal mill casing according to the operating characteristics of the coal mill, which completely solves the wear problem of medium-speed grinding.
1.Ceramic liner for coal mill barrel
The wear-resistant ceramic liner with dovetail slot is adopted for the running conditions of large material particles, high temperature, fast wind speed, large wear and large impact in the height area within 500mm-1500mm at the bottom of the grinding barrel.
The lining plate is a two-in-one ceramic lining plate, which is fixed to the arc steel plate by dovetail clamping technology and welding. Its ceramic spacing is zero, with smooth surface. The backing plate is equipped with countersunk head bolts, which can be fixed to the wall of medium speed grinding cylinder by bolts or welding, forming a strong protective layer of wear resistance, high temperature resistance and impact resistance.
2. Ceramic liner for coal mill housing
For the shell area where the grinding barrel is more heavily worn, the straight adhesive ceramic liner with lower cost and easier installation is adopted, because of the low impact force and low temperature. The thickness of the tiles is 5mm-7mm. The ceramic is fixed by the combination of high-temperature resistant inorganic adhesive and 360° dislocation bonding. The cracks are staggered to ensure the inner wall is smooth.
3, the advantages of KINGCERA’s wear liner
(1) Wear resistance: alumina corundum ceramic hardness of HRA85 or more, super wear resistance;
(2) Impact resistance: toughened ceramic formula to ensure that the ceramic is not easy to break and can resist the impact of coal mill materials;
(3) High temperature resistance: it can run stably under high temperature condition of coal mill for a long time;
(4) anti-falling off: according to different working conditions to choose different installation methods, fixed firmly does not fall off;
(5) Long service life: the equipment life can reach more than 5 years.
Ⅴ. How to install, repair and replace?
The wear-resistant ceramic liner of coal mill can be installed in two ways: one is the construction on site, which requires the cylinder to be smooth and uneven; Another way is to install the ceramics on curved steel plates in the factory and weld them to the cylinder walls.
The service life of wear-resistant ceramic liner of coal mill barrel is more than 5 years, and the replacement times are very few. Because of the modular design, production and installation of the composite liner, it is also easy to replace all the lining boards. It is only necessary to remove the worn and damaged lining board, and then reinstall it by double-end bolts or welding.
Installation and Replacement of Wear-Resistant Ceramic Composite Liner for Coal Mill
Ⅵ. About Us
KINGCERA was founded in 1993. As a professional manufacturer of wear-resistant ceramics, KINGCERA has focused on the development and application of anti-wear technology for industrial equipment for nearly 30 years. With high-quality innovative products, reasonable prices, perfect after-sales service and good reputation, we have won the recognition and praise of tens of thousands of customers around the world.
Relying on strong technical strength and years of accumulated practical experience, KINGCERA can not only produce a series of high-performance alumina or zirconia wear-resistant ceramic materials such as K92, K95, K99, ZTA, ARZ, but also design and customize personalized and systematic comprehensive anti-wear solutions for industrial heavy wear equipment. We specialize in solving the problem of equipment wear under various complex working conditions.
Let's take vertical mill system as an example, in addition to vertical mill cylinder body and chassis, such as Protective sleeve of vertical mill roller shaft, Air guide ring, concentrator (inverted) cone, support rod, concentrator housing, concentrator fixed guide vane, grinding chute, tubing protective sleeve, vertical grinding to cyclone pipe, cyclone drum, vertical grinding roller seal ring etc, we have a large number of mature and reliable anti-wear solutions, and successfully applied in cement, thermal power, steel, smelting and other industries. This helps customers reduce the frequency of equipment maintenance, prolong the service life of equipment, and improve enterprise productivity.